What is science for? What does it do? One answer to this question is that science describes reality: Its foremost job is to provide an account of the world we see around us, and it accomplishes this task via theories that provide a coherent and objective story about the world.  

But what, exactly, is that story? The orthodox view is science provides a narrative of the Universe without us. It’s a story of what I often call the “God’s eye view,” or, as the philosopher Thomas Nagel calls it, “The View from Nowhere.” According to this account, science gives us the story of an external, independent, and objective reality (an EIOR). It’s a beautiful and enticing idea. Unfortunately, there’s a big problem with this story about science that lies in science’s own most powerful tool: quantum mechanics. 

Quantum mechanics is what we physicists use to describe the microworld of molecules, atoms, and their constituents. Besides its century of spectacular success, what really makes quantum mechanics remarkable is that no one knows what it means. The story it tells about reality is so strange that it requires an interpretation to connect its mathematical formalism to the everyday world we experience. There is, however, a long list of these interpretations to choose from: “many-worlds” interpretations, “objective collapse” theories, “pilot-wave” theories, etc.  

QBism

For me, however, there is only one well-developed interpretative framework that has really listened to what quantum physics has been trying to tell us for the last century. It’s called “QBism.” The name is a shorthand for “quantum Bayesianism” (which itself comes from the Bayesian interpretation of probabilities). Over the past few months, I’ve been writing a series of posts introducing and unpacking QBism’s interpretation of quantum theory. Today I want to dive back into it by addressing its view on the question we began with: What is science for? Or to put it another way, what is science about?

Up until the birth of quantum physics in the early 20th century, the dominant philosophy associated with science was that it was all about that world without us. The principal players in this story (now called classical physics) were objects like particles and the laws that governed them (i.e. Newton’s laws of motion). The laws themselves held a special kind of position and were seen as timeless, eternal expressions of an underlying fabric of reality (again, a world without us). The laws were objective structures where “objective” means existing independently of anything associated with human beings and their messy subjective experiences. There were, of course, “observers” in the theory who took data by making measurements. But the presence or the actions of those observers never played any fundamental role in physics.  

Quantum mechanics killed that story forever by forcing measurements into the narrative in a way that classical physics never required. My friend and 13.8 co-conspirator Marcelo Gleiser has written a wonderful history of quantum physics where you can see how measurement appeared in quantum formalism. The single point we want to focus on here is how QBism understands the role of measurement.

While other interpretations of quantum mechanics work very hard to find a way to recover the easy dismissal of the observer enjoyed by classical physics, they must always pay a price. Sometimes that price is allowing for an infinity of unobserved parallel universes (as in the many-worlds interpretation). Other times, the price is different but equally strange. QBism, however, looks the problem straight in the eye and admits that quantum mechanics puts measurement front and center because it’s not a theory about some imagined objective world without us. Instead, QBism says that quantum theory is a potent description of agents taking actions on the world, which then responds.  

Agents and actions

QBism wants us to see that from the very beginning, quantum mechanics was a science that relied on machines to carry out measurements in a world we did not directly experience. In this way, the machines (our instruments) acted as extensions of our experience. Quantum physics acknowledges that an action must be taken — i.e. a measurement — to set its mechanics in motion. But in reality, that action is always taken by somebody (i.e. an agent). You can tell stories about electrons making measurements by hitting a proton but that’s not actually what happens in quantum measurements. It’s always some agent setting up an apparatus and using quantum mechanics to predict what that apparatus will record.  

It’s in this way that measurement’s explicit appearance in quantum mechanics implies that it’s always been a theory about those who make the measurements (i.e. us). We are the agents who use quantum mechanics to learn about the world. From QBism’s perspective, quantum theory is like a rulebook. It’s something we are given by the world (in our investigations of that world) that tells us how to make the best bets about the outcome of our actions. The idea of a “rulebook for betting” appears a lot in the QBist literature because QBism places such a strong emphasis on the fundamental role of probabilities in quantum formalism.

There is no doubt that this emphasis on agents and their actions is a radical idea. As I have written before, every quantum interpretation comes with a price. Gone is that comforting view of the world without us — of science providing a quasi-platonic view into the eternal order of mathematical perfection. What we get instead with QBism is an emphasis on agents and their actions. This new emphasis is, however, not some wooly-headed muddle. Instead, QBism offers a precise account, grounded in the tools of quantum information science, of the world and us together rather than just the one-sided world without us. Given that the price of such world-without-us views is hypotheses about infinite and unobservable parallel universes, QBism’s change in emphasis is not such a loss in my opinion. It responds honestly to quantum mechanics’ emphasis on measurement rather than trying to imagine it away. Just as important, switching to a story of the world and us opens up entirely new vistas for thinking about our place in the Universe.  

Peering into those new horizons is what we will take up in the next installment of our tour of QBism.

This article What reality does quantum theory describe? QBism has a radical answer is featured on Big Think.

Sometimes we must go back to go forward. Old ideas seem to keep resurfacing, even if in different guises. Similar concepts and intuitions emerge in different cultures, as people try to understand what they see in the world. The vocabulary and the cultural context changes, the fundamental concepts, methodology, and even the goals of the explanations are different, but the core ideas are essentially the same. Amazingly, this is the case with how matter arranges itself into the structures that we see — from atoms to galaxies. 

Around 600 BCE in Ancient Greece, Anaximander of Miletus, one of the first Western philosophers, had a powerful vision of the cosmos. He believed that everything was made from a primordial substance and that everything that we see in the world and the skies — from frogs to trees to people to stars — were temporary structures that “in the assessment of Time” revert to this primordial goo. Anaximander called this stuff the “Apeiron,” which translates loosely to the “Boundless.” Whatever the Boundless was, it was part of everything that existed. 

He envisioned a perpetual flow of matter, a constant becoming of things, all connected by their material essence. This being Ancient Greece, there were no details of how this happened or the composition of this stuff. But a couple of centuries after Anaximander, the Greek Atomists proposed that everything was made of indivisible bits of stuff, which they called “atoms.” For the Atomists, the emergence and dissolution of the stuff that we see was due to atoms coming together or breaking apart. The pervasive notion here is the flowing of matter into different structures: a recycling of matter that never stops.

Nature is the ultimate recycler

Some five centuries later in Rome, the wise emperor Marcus Aurelius goes back to some of these ideas, writing in his Meditations:

“Constantly think of the universe as a single living being, comprised of a single substance and a single soul; and how all things issue into the single perception of this being, and how it accomplishes all things through a single impulse; and how all things work together to cause all that comes to be, and how intricate and densely woven is the fabric formed by their interweaving.”

Setting aside how Aurelius describes the cosmos as an organism with a soul, which was a metaphorical way of attributing to the Universe properties that related to those of people, we see the same idea of matter coming into being as part of a universal ebb and flow, an interweaving of all that exists.

Before we look to modern physics, let’s stop at Buddhism, where the notion of the interrelatedness of all things is essential. As Vietnamese monk Thich Nhat Hanh beautifully expressed:

“If you are a poet, you will see clearly that there is a cloud floating in this sheet of paper. Without a cloud there can be no rain, the trees cannot grow; and without trees we cannot make paper…so we can say that the cloud and the paper inter-are…Everything—time, space, the earth, rain, the minerals in the soil, the sunshine, the cloud, the river, the heat, and even consciousness—is in that sheet of paper. Everything coexists with it. To be is to inter-be…as thin as this sheet of paper is, it contains everything in the universe.”

Nowadays, we describe matter as made of atoms, and atoms as made of quarks and electrons. We have a modern cosmological narrative that describes how matter emerged shortly after the Big Bang as its most basic components: the modern version of an atom. It proceeded to interact with itself to create structures of growing complexity: quarks into protons and neutrons, protons and neutrons into atomic nuclei, atomic nuclei grabbing electrons to make atoms (initially especially hydrogen), clouds of hydrogen coalescing into stars that shine by fusing hydrogen into helium, and then, as the stars approach the end of their existence, into heavier chemical elements. 

So, according to our modern cosmic story, matter coalesces into stars that create more matter in the form of atoms, which then disperse through the interstellar medium to help create new stars that create more atoms that disperse again….you get the picture. It’s a story of the constant ebbing and flowing of matter to form new stars that then dissolve into more complex atoms that form planets, moons, water, and, at least here, trees and clouds, and people who invented paper to write articles about the Universe and poems about the interconnectivity of it all. What Anaximander and Marcus Aurelius imagined — and what Buddhist philosophy preaches — are intuitive expressions of the intricate connections and interactions between the material forms we see in the cosmos, the living and the nonliving, all derived, we now know from modern science, from the ebbing and flowing of atoms. Nature is the ultimate recycler.

This article Ancient philosophers understood a key truth of modern cosmology is featured on Big Think.

When people try to define life, they tend to focus on things like reproduction or metabolism. It’s true that moving matter and energy around to simply stay alive or produce offspring is a fundamental characteristic of living systems. But there’s another and perhaps more all-encompassing way of understanding life that puts information front and center. In this view, what makes life special — what makes it different from all the other physical systems — is its ability to use information. Stars, for example, can be described in terms of information but it doesn’t make much sense to think of them as using that information. By “use,” I mean deliberately storing, copying, transferring, and processing information toward some end.  

But what if we want to look at life as a planetary-scale process? The idea of the biosphere — the sum total of Earth’s life — goes back more than a century. The Russian biogeochemist Vladimir Vernadsky coined the term biosphere when he recognized that life was not a passive rider on Earth’s geophysical evolution. Instead, Vernadsky saw that life as the biosphere was an equal player in setting the planet’s trajectory along with the other “geospheres”: atmosphere (air), hydrosphere (water), cryosphere (ice), and lithosphere (land). Since then, the concept of the biosphere has become foundational to fields ranging from climate science to astrobiology.

If we recognize information as an essential component of life and also see life as a planetary-scale process, a question arises: How can we combine those two perspectives to understand information on planetary scales? Given the complexity of information’s involvement with the entire biosphere, that question can seem daunting. But recently, Manasvi Lingam, Amedeo Balbi, and I published a paper taking on the problem — and the results were pretty fascinating.

Manasvi, an astrophysicist at the Florida Institute of Technology, led the study. A prolific theorist with an extraordinary command of topics as disparate as cellular signaling and stellar evolution, I always really enjoy working with him. One of the most important skills a talented scientist must possess is the ability to pick the right problem: Of all the questions you could ask about a certain topic, which ones can you actually answer? In thinking about information and the biosphere, Manasvi saw a way to nail down one particular aspect of the problem: transmission. What, he asked, is the sum total of information that is moved from one place to the other by life on Earth? Getting such a number seems like a pretty tall order. So how did he do it? The answer was to focus on cells.

Measuring the flow of information

To make his estimate, Manasvi first calculated the total number of prokaryotic cells in the biosphere. Numbers like these are actually not that hard to come by since the mass of living matter on Earth in all its different forms (including microbes) has been determined in many different ways. It then becomes a matter of dividing that mass into cells, giving a total number of prokaryotic cells as about 10²⁹ or 100,000 trillion trillion (yikes!). 

Since cells communicate by emitting chemicals, the next step was to estimate how many partners a given cell can communicate with. Manasvi estimated this as six by thinking in terms of nearest neighbors. Finally, based on experiments, it appears that the information transfer rate between cells is 10^-4 bits per second. Putting it all together, including how often a given cell chooses to send a signal, Manasvi found a global information transmission rate of 10²⁴ bits/s for the modern biosphere.  

That’s a wonderful number to know by itself because it shows there is a spectacular amount of information being passed around in the biosphere. But to make sense of it, we need something to compare it with. That’s where things got interesting. 

The technosphere

Manasvi carried out similar estimates for the global information transfer rate for the whole technosphere. The technosphere is the machine equivalent of the biosphere: the sum total of technology that humans have deployed around the globe. Given that we live in the digital age, it’s also possible to calculate how much information the technosphere moves around per second. Estimating that number via internet traffic yields a global transmission rate of 10¹⁴ bits per second. This is more than a billion times less information per second than the biosphere. So, for now, the biosphere is moving much more information than human technology.

For now is the key term here. It turns out that the rapid expansion of digital technology puts us on a path where the technosphere will outpace the biosphere in terms of information transfer by the beginning of the 22^nd century (the exact date Manasvi found was 2113).

So, by 2113 the human-built technosphere will move more bits than the biosphere (from which humans emerged). What will that mean? What will crossing that threshold signal for the evolution of our species and the evolution of the planet? That is a great question which I don’t have an answer for yet. But, just as important, we could not even formulate that question if we hadn’t taken this global view of information and life. That’s the power of a new perspective.

This article Biology or technology: Which moves more information per second? is featured on Big Think.

What are the planetary prerequisites for the evolution of an intelligent, technological species? If humanity is going to search the galaxy for exoplanets with signatures of technological intelligence — and we’re starting to do just that — what kinds of planets should we focus on: Planets with a mix of oceans and land? With plate tectonics? Magnetic fields? In other words, what kinds of planets are conducive to the development of a world-spanning technological civilization?  

This was exactly the kind of question Italian astrobiologist Amedeo Balbi and I asked ourselves about a year ago. The research paper that resulted was recently published in Nature Astronomy, and today I want to unpack it a bit. If we are right, there could be some pretty big implications for where and when intelligent life in the Universe could form.

The “oxygen bottleneck”

The paper was called “The Oxygen Bottleneck for Technospheres” and its idea was simple: To make advanced technology, you need to be able to raise the temperature of the stuff you use to make that technology. Think about metallurgy. If you want to build something like a radio telescope, you’ll need to extract a bunch of iron, nickel, copper, and other raw materials from the ground and then you’ll need to heat them. The heat is required so that the metals melt and can be mixed to make alloys or be fashioned into the shapes you need (like struts or wires). Getting high temperatures may also be important for other things beyond metallurgy, as even the ability to cook food has been implicated in the development of human intelligence (nutrients are more available in cooked food).  

So, what does it take for a young intelligent species to get ready access to high temperatures? One answer from human history is burning stuff (i.e. combustion). If smart creatures who are starting to use tools have easy access to combustion, they can more easily climb the ladder of technological sophistication. 

But what, then, is combustion? This sounds like a simple question, but it took me and my relative ignorance of chemistry some effort to truly understand. Combustion is basically an exothermic chemical reaction that requires a fuel and an oxidizer. The “exo” here means that once a spark is applied, combustion reactions begin giving off heat. The reactions continue until either the fuel or the oxidizer are exhausted. A while back I wrote an entire post on my joy at discovering the details of combustion, so I won’t go through all that again. The main point of it all was that oxygen turns out to be the best all-around oxidizer. (Other elements like fluorine actually give off more energy in combustion, but they tend to be so reactive that they corrode everything they touch.)

It was this simple fact, drawn from the famous periodic table you slept through in high school, that led us to conclude that only planets with oxygen in their atmosphere could host technological civilizations. The next question is how much oxygen an atmosphere needs. Drawing on experiments carried out across disciplines as varied as combustion engineering to biogeochemistry, we found that an atmosphere with anything less than 18% oxygen would not allow open-air combustion. Remarkably, for most of our planet’s 4.5-billion-year history, Earth’s oxygen levels have been way, way below 18%. In fact, only over the past 500 million years or so has the atmosphere held enough oxygen for anything to freely burn in the open air.

Why does any of this matter? Imagine a young and intelligent species on an alien world with an atmosphere that’s just 1% oxygen. Those clever tool-using creatures would never get the chance to watch a tree burn after being hit by lightning and get the idea of using fire for their own purposes. They would never have the chance to learn how fire could be used to cook food, clear land, or, most importantly, melt metals. The poverty of oxygen in their air would likely box these creatures in forever, limiting their development. This is what Prof. Balbi and I meant by the “oxygen bottleneck.” Widespread technological development requires simple and easy access to high temperatures and open-air combustion is the simplest and easiest way for that to happen (would volcanic vents, for example, be so prevalent to allow industries to evolve?). That’s why oxygen-rich atmospheres matter. Planets with them may be the only ones that host intelligence and civilizations. 

But how many of these sorts of high-oxygen planets does the galaxy hold? If the numbers are really small, then we might end up being oxygen-rich but companion-poor.

This article The “oxygen bottleneck” may leave aliens stuck with primitive technology is featured on Big Think.

To celebrate (with a sigh perhaps?) the end of this turbulent year, there’s nothing better than diving into some of the biggest open questions in science — those that have long kept scientists up at night. Though confounding, these questions point to an essential fact in science: the more we know, the more there is to know. There is no end to knowledge as long as we keep asking questions (and receive funding to try to answer them). Even more interestingly, some of these questions simply can’t be answered, at least not through the usual scientific methodology that combines objectivity and reductionism: the notions, respectively, that we can separate ourselves from the objects we are studying, and that it is possible to break complex systems into smaller ones to study their behavior and then infer the behavior of the whole from the behavior of the parts.

Every list of “most important” questions has a dose of arbitrariness, given the author’s subjectivity. However, I would venture to say that these rank among the toughest open questions — and for sure among the more mysterious and attention-grabbing. So, here it goes, in no particular order:

1. What is the Universe made of? We know only 5% of the composition of the Universe. This 5% is made of the familiar atoms of the periodic table, their molecular aggregates, or the components of the atoms: protons, electrons, and neutrons. There are also neutrinos — the elusive particles that can traverse matter as if nothing was there, including the whole of Earth. The mystery is the other 95%, composed of dark matter (roughly 27%) and dark energy (roughly 68%). Dark matter doesn’t shine and is found around galaxies and clusters of galaxies, like an invisible cloak. We know it’s there because it has mass and hence gravity: It pulls on the familiar 5% we can see, and we can measure this effect. Dark energy is much more mysterious, an ether-like medium filling up space with the bizarre property of pushing it apart, making galaxies accelerate away from one another. We don’t know what dark matter or dark energy are, and there are hypothetical explanations that try to modify Einstein’s theory of gravity to accommodate the observations and do away with the darkness. But after decades of searching, we remain quite ignorant.

2. How did life come about? Life appeared on Earth some 3.5 billion years ago, perhaps earlier. The mystery here is how aggregates of nonliving atoms gathered into progressively more complex molecules that eventually became the first living entity, a chemical machine capable of metabolism and reproduction. The fact that living matter is matter with intentionality remains a profound mystery.

3. Are we alone in the Universe? This question is really two questions, given that we want to know not only whether any extraterrestrial life exists but also whether it is intelligent. Ultimately, we would like to know how common life is. We also need to know why, if intelligent life is not so rare, we haven’t yet heard from “them”? On the question of aliens, I recommend the recent book by Big Think columnist Adam Frank, The Little Book of Aliens, for an up-to-date synopsis of the search for life in the cosmos. As I pointed out in my recent book, this question has a direct impact on how we relate to our own future and the planet we call home.

4. What makes us human? We have three times more neurons than a gorilla, but our DNAs are almost identical. Many animals have a rudimentary language, can use tools, and recognize themselves in mirrors. So, what exactly differentiates us from them? The thicker frontal cortex? The opposing thumb? The discovery of fire and the ability to cook? Our culture? When did language and tool-making appear? An excellent intro to this is Jeremy DeSilva’s book, First Steps.

5. What is consciousness? We’ve confronted this question before in these pages, wondering about the nature of consciousness, and even its possible connection with quantum physics, a trendy topic in some circles. How is it that the brain generates the self of self, the unique experience that we have of being unique? Can the brain be reversed-engineered to be modeled by machines or is this a losing proposition? And why is there a consciousness at all? What is its evolutionary purpose, if any?

6. Why do we dream? Even though we spend about a third of our lives sleeping, we still don’t know why we dream. Do dreams have an essential function, physiological and/or psychological? Or are they simply random images of a brain in partial rest? Was Freud right about his theory that dreams are some sort of expression of repressed desires? Or is that all bogus?

7. Why does matter exist? According to the laws of physics, matter shouldn’t exist on its own; each particle of matter — each electron, proton, neutron — should have a companion of antimatter, like twins. So, there should be positrons, antiprotons, and antineutrons in abundance. But there aren’t. The problem is that when matter and antimatter meet, they disintegrate in a puff of high-energy radiation. If you shook hands with your antimatter other, a good chunk of the U.S. would blow up in smoke. So, the mystery is what happened to this antimatter. Clearly, if the Universe had equal amounts of both earlier on, something happened to favor matter over antimatter. What? Was the Universe “born” this way, with a huge asymmetry between matter and antimatter? Maybe some primordial asymmetry evolved to do the job, selecting matter? If so, when did it act in cosmic history, and what would this asymmetry be? We’ve been trying to figure this one out for decades with no great success.

8. Are there other universes? Or is our Universe the only one? Believe it or not, modern theories of cosmology and particle physics predict the existence of other universes, potentially with different properties to our own. Are they there? How would we know, if we could? If we can’t confirm this hypothesis, is it still part of science? I have argued here before that the multiverse hypothesis is profoundly problematic and not particularly useful, even if fun to think about.

9. Where will we put all the carbon? With the global vamping up of industrialization, we are putting more and more carbon (and methane) up in the atmosphere, accelerating global warming. What can be done to change our impact on the environment? And what happens if we don’t? Models of global warming offer a range of predictions, from somewhat mild to dire. But clearly, time is running out to ponder about the issue and do nothing. It’s time to take this seriously at a global scale, for the benefit of the next generation and even just the next decade or so. Politicians are moving too slowly. We need to take this one into our own hands and act individually as well.

10. How can we get more energy from the Sun? We have based our explosive growth mainly on fossil fuels. Nevertheless, we have a remarkable energy source up in the sky, waiting to be explored more efficiently. Also, can we reproduce the solar engine here on Earth, fusing hydrogen into helium in a controllable and viable way to solve the energy problem for the foreseeable future? Progress is coming, but slower than we’d like. Or need.

This article 10 of the most mystifying open questions in science is featured on Big Think.

What would you do if you were in charge of an immensely powerful technological civilization? This might sound like a dorm-room, too-many-beers kind of question, but it lies at the heart of the search for intelligent life in the Universe.  After all, if you are looking for alien technological civilizations, it would help to know what you might be looking for.

In the early 1960s, when people were first starting to think seriously about the possibilities for advanced civilizations in the galaxy, physicist Freeman Dyson asked exactly this kind of question. How, he inquired, would a truly technologically advanced civilization harvest energy? It was the right focus for questions about other civilizations because, while we can’t say much about alien culture or politics, any technologically advanced species would require energy — and likely a lot of it. In this way, Dyson recognized that every civilization that’s climbing up the ladder of technological capacity will easily recognize the big, honking energy source sitting right there at the center of their solar systems: stars. 

A typical star produces about 100 million billion billion watts of power. That’s a million times more power produced every second than all the power plants on Earth produce in one year. Dyson imagined that it would be natural for a truly advanced civilization to harvest all this power from their star. This was the birth of the “Dyson sphere,” one of the most enduring ideas in the Search for Extraterrestrial Intelligence (I’ll note that some people still use the term SETI, but as I explain in my new book, these days the field is also known as technosignatures, which refers to any measurable evidence of technology use).

What is a Dyson sphere?

Think of a vast shell, like a hollow golf ball, that’s the size of Earth’s orbit, surrounding and entirely enclosing a star. Covering the inside of the sphere would be some form of light-collecting technology. In this way, it’s theoretically possible that all of the star’s light could be harvested for energy. Besides energy harvesting, a Dyson sphere could serve other purposes, too. With a surface area of more than a billion Earths, a civilization might use a fraction of their Dyson sphere for living space, too. There’s a lot of real estate in there, after all.  

Is it physically possible to build a Dyson sphere? Despite being such an audacious idea, Dyson worked out the basic requirements for building such a vast machine. Over the years, other researchers have also dedicated time to working out the details associated with building and operating this archetype of an alien megastructure. They found that for a shell one mile thick with a radius the size of Earth’s orbit, you would need to grind up all the mass held in all the Solar System’s planets. All that mass would have to be processed and used for fabricating the Dyson sphere’s components. So, a typical solar system has the material needed to get the job done even if it would require technology that seems god-like to us.

Dyson swarms

One important point that even Dyson recognized, but which has been subsequently emphasized by astrophysicists like Jason Wright, is that Dyson spheres would not be spheres. An actual rigid sphere would be unstable in many ways, being prone to crash against the Sun or warp and bend itself apart. A better bet is a “Dyson swarm” of vast and freely orbiting machines, each of which collects a subset of the star’s power. With enough swarm members, you’d be able to capture a significant fraction of the stellar energy.

The last and maybe most important point about Dyson spheres and swarms is that they should be observable! The second law of thermodynamics tells us you can’t harvest energy and put it to use without generating “waste” heat. This means Dyson spheres would glow in the infrared, making them an excellent target for technosignature searches. In my recent and very fun conversation with Sean Carrol about the frontiers of astrobiology and technosignature science, he raised the interesting point that maybe an advanced civilization just nests a series of Dyson spheres around a star to capture the radiation emitted from the heat all the way down to the cosmic microwave. It’s a cool idea, though it appears that the return on investment after the first sphere drops so quickly that it’d probably not be worth it.

So, if you oversaw an immensely powerful technological civilization, would you build a Dyson sphere? If your answer is yes, then you are in good company: Dyson spheres (or swarms) have been a staple of SETI for more than 60 years for good reason. They seem likely, and maybe even universal. But is that true? There’s no way to know except to go looking for them.

This article Dyson spheres and the quest to detect alien technosignatures is featured on Big Think.

We are now well into a new era of astronomy, where distant planets (called exoplanets) are being detected at a fast clip. At last count, there have been 5,557 confirmed discoveries of exoplanets and another 10,000 candidates awaiting confirmation. These discoveries have given rise to “comparative planetology,” a new area of astronomy dedicated to investigating the properties of different worlds, classifying them according to size, mass, (approximate) atmospheric composition, distance from their parent star, and whether they are rocky, gaseous, or some combination of the two.

The main goal is to compare them to Earth and other planets in our Solar System. For example, when astronomers talk about a “super-Earth,” they mean a rocky planet with a radius somewhat larger than Earth’s, while a “sub-Neptune” is a gaseous planet with a radius somewhat smaller than Neptune’s. These definitions are operational and the boundaries between planetary classes are not very rigid, but they offer a quick way of classifying what we see.

Comparative planetology

Exoplanets are planets that orbit other stars in our galaxy (and stars in other galaxies, too, but those are too distant to be detected). An M-type dwarf star (or red dwarf star) is the smallest and coolest star, the most common in the Milky Way. Around three-quarters of the stars in our galaxy are M-type dwarf stars. In comparison, our Sun is a yellow dwarf star, about five times more massive than a red dwarf. Only about 3% of stars are yellow dwarfs like our Sun.

The diversity of planetary systems is absolutely staggering. There is no obvious or common type of planetary system: Some have huge Jupiter-like planets orbiting very near their host stars, while others have planets distributed more evenly, with some resembling our Earth. These seem to be quite rare.

If you’re not amazed by what astronomers have discovered about planetary systems, consider the sheer difficulty of discovering distant planets. Finding a planet orbiting another star is much harder than finding a flea in front of a floodlight. To detect them, astronomers capture the ever-so-slight dimming of starlight as a planet passes in front of a star. This is called planetary transit. Imagine measuring the dimming of a floodlight as a flea hops over it. Now, move the floodlight incredibly far away — so far as to look like a point source. With this image, you begin to get an idea of how delicate and spectacular the discovery of exoplanets is.

The main motivation, of course, is to figure out how rare or common our planet is. If there are lots of Earth-like planets — not just with similar size and composition, but also located at the so-called “habitable zone” of the star where water, if present on the planet’s surface, would be liquid — then the odds become higher that such worlds could harbor some kind of life. As my Dartmouth colleague Elisabeth Newton reported a few years back while reflecting on her discovery of a young exoplanet orbiting a relatively young star, “One of the overall goals of astronomy is understanding the big picture of how we got here, how solar systems and galaxies take shape and why. By finding solar systems that are different from our own – especially young ones – we can hope to learn why Earth and our own Solar System evolved in the ways that they did.”

So, it all boils down to one of the most exciting questions we can ask in science — the one kids from ages five to 90 ask across all cultures on our planet: Are we alone in the Universe? Studying other worlds — their history, location, and properties — allows us to figure out our own history, and how exceptional (or not) it is. We live in this very special time when we can actually begin to answer this question. And it all points to our planet being a rare gem in a Universe that is very hostile to life.

We are still far from knowing whether other worlds harbor life of any kind. Clearly, given that there are so many worlds out there (trillions in our galaxy alone), and that the laws of physics and chemistry are the same across the Universe (this we do know with confidence), the expectation from a large fraction of scientists is: Yes, there should be other worlds with life. Otherwise, as Jodie Foster’s character in the movie Contact (based on Carl Sagan’s homonymous novel) said, “[It] seems like an awful waste of space.”

But life is not so simple as large numbers. There is a disconnect between the way physical scientists and biologists think about this question. (Of course, there are exceptions in both groups.) Biologists tend to be more careful with such extrapolations, knowing only too well that life is enormously complex. There are many truly mind-boggling steps to go from non-life to the first living creatures, and then on to complex unicellular life and multicellular creatures. What’s more, life doesn’t have a plan to get more complex over time; life cares about reproducing efficiently. If species are well-adapted, mutations won’t do much. Ultimately, the question of how life did emerge on Earth remains very much open.

The “survival equation”

What we do know now, and this is extremely important, is that the life history of a planet — the details of how it evolved, from its atmosphere to cosmic impacts and seismic activity — is imprinted on its creatures. And vice versa: Life changes its host planet in dramatic ways. There is a two-way relationship between a planet’s history and the kind of life it supports. The planet provides the basic support for life to be possible and life acts back on the planet and changes it. Earth now is a different planet from three billion years ago, when it only had single-celled organisms. Their action changed the planet by dramatically increasing the oxygen levels in the atmosphere. Without that, we wouldn’t be here. We can also see this with our own destructive activities, and how they are imprinted on Earth. Human presence has permanently scarred Earth.

Dominant species can change their world, either knowingly or unknowingly. We are living the reality of this fact. Yet, most of us are choosing not to pay attention or change our ways. Alienated from nature, we seem to have forgotten how much our survival depends on it. Bad water + bad air = sick life. That’s the equation everyone should know — call it the “survival equation.” Maybe what we are learning about our planet and its distant cousins will inspire us to rethink how we relate to our world and the creatures we share it with.

This article Exoplanet discoveries reveal Earth’s profound rarity in the cosmos is featured on Big Think.

You hear a lot about people believing that the Earth is flat these days. It’s hard to imagine anyone seriously considering that the world is not a sphere. Still, in researching a new project about life and geological history, I found an entirely new meaning for “flat Earth,” or at least a “flatter Earth,” that has the possibility of actually being true. To understand what I’m talking about, we need to go back to a staple of geology: plate tectonics.

Plate tectonics

The lithosphere is the scientific name for the outer skin of the planet. It extends down a few hundred kilometers and includes both the crust and the upper mantle. The important thing about the lithosphere is that it’s rigid, unlike the deeper mantle, which, over long enough timescales, flows like taffy (or, as one geologist told me, like asphalt on a hot day). The deeper mantle’s motion comprises big circulating swirls called convection. On Earth, as opposed to other rocky planets like Venus or Mars, the lithosphere is broken up into a bunch of plates. These plates sort of float on the convecting mantle below, getting carried along with the mantle motion. Sometimes these motions lead to the plates sliding past each other. But in other places, the plates collide, with one plate diving down into the deeper mantle (a process called subduction) and the other plate being pushed upward. As the plates move, so do the continents, which are made of granite (as opposed to the seafloor material made of basalt).

All of this sliding, subducting, and collision is why the map of the Earth has been continually redrawn over hundreds of millions of years. Supercontinents like Gondwana and Panagia have assembled and broken apart, closing up whole oceans and opening up new ones. All of these continental comings and goings had a pretty profound effect on life. Species that were once living together found themselves isolated a few million years later as rifts opened up and split the land.

Just as important, the collisions between tectonic plates are what has driven Earth’s great mountain ranges like the current Himalayas. Mountain ranges affect life and its evolution in many ways. Most obviously, they can serve as natural barriers to the movement of unadapted species. Less obviously, but perhaps more importantly, these high mountains are prone to serious weathering, getting slowly ground down by wind and rain. All those minerals from eroding mountains eventually find their way into the ocean where they can serve nutrients life uses for its various molecular assembly needs.

This mountain-weathering input to the biosphere is something I was interested in for an astrobiology project I’m working on. It was in the process of analyzing that research that I came across a stunning fact: The Earth did not always have plate tectonics, especially the vigorous kind it has today.

As I wrote above, the other terrestrial planets don’t have plate tectonics at all. Instead, their lithospheres comprise a “single lid.” On Mars, for example, there are no plates and there is no movement of plates. Early on, about 4 billion years ago, the Earth may also have had such a single lid that only broke up slowly. Just as important: Even though separate plates existed a couple of billion years ago, they still were not moving around the way they do today. In particular, the whole subduction and collision thing may have been much more muted. According to the research papers I’ve been reading, the kind of vigorous plate tectonics we see on modern Earth may be a relatively recent phenomenon — dating back only a billion years or less. (Yeah, I know, it’s weird to think of a billion years as being “recent,” but this is geology, after all).

A flatter Earth

So why does that matter? Mountains…big mountains. Without the modern version of plate tectonics, there would be no big mountain ranges like the Himalayas. While there may have been folds and hills, smaller ranges — the kind of long and super-high ranges that we think of as Earth’s most exotic and stunning locales — would not have been possible.

It’s a stunning realization that Earth, for the first three or so billion years, was not at all flat — but it was at least a lot flatter.

This article Flatter Earth: Without plate tectonics, our planet once looked much different is featured on Big Think.

“How did you get interested in astronomy and life in the Universe?” I have been asked this question a lot as I have been doing interviews about The Little Book of Aliens, my new book unpacking the science of astrobiology. Since the book also covers a scientist’s perspective on UFOs/UAPs, when people ask about the overlap of my biography and my scientific inclinations, they are also asking about the origins of my skepticism. That answer, for me, is really simple: “I grew up in New Jersey in the 1970s and that experience gave me everything I needed to become a skeptic and a scientist.”

Belleville, NJ, where I was raised, was mostly an Italian and Irish community. But being right next to Newark, and only about 10 miles from New York City, it was a mix of all kinds of people, and most of them worked hard at blue-collar jobs. I grew up with a lot of truly wonderful people whose families were just one or two generations post-immigration to the U.S. It was a rich and varied world.

But it was also a pretty tough place. I was the only Jewish kid in school (though my family were formally atheists), and my step-father was a civil rights leader in Newark and the only African American in the state legislature. This being the 1970s, anti-Semitism and racism were not hard to find, and when it did show up it was blatant. 

I got into a lot fights.

Luckily, I got into space, astronomy, and aliens early, and that helped me deal with it all. I caught the bug from my dad. While my parents got divorced when I was just 3, my dad lived across the river in Manhattan, and he loved science. His science fiction books, and his guided tours of the Hayden Planetarium, lit the astronomy/life-in-the-Universe fire in my little kid heart. That pre-existing interest in aliens is what eventually led me to Erich von Däniken’s famous book Chariots of the Gods — and that is how New Jersey and all it taught me comes into my story of skepticism.

Ancient aliens

Chariots of the Gods was the book that started the whole “Ancient Aliens” thing. It was a big hit back in the 1970s, laying out the case that Earth had been visited many times by alien astronauts. According to von Däniken, these visitors from other worlds were the real source of Bible stories about angels, and they also taught Egyptians how to build pyramids.

I was particularly struck by von Däniken’s story of Easter Island. A thousand miles from anywhere in the Pacific Ocean, the island hosts an army of giant, enigmatic stone heads that watch over a landscape devoid of trees. How, von Däniken asked, had the islanders moved the multi-ton statues around an island with no trees to roll them on? He concluded there must have been aliens there to help. It all sounded pretty convincing to my 11-year-old self.

Then, a few years later, I was watching TV when a NOVA documentary came on called “The Case of the Ancient Astronauts.” Over the next hour, the show took me on a tour of von Däniken’s ideas, but now through the lens of archaeologists and anthropologists. These are folks who spent their lives actually studying ancient cultures. In every case, these scholars offered pretty simple explanations — grounded in actual data — for von Däniken’s alien visitations. By the time the credits rolled on the documentary, I had been transformed from an excited, alien-obsessed kid into a very pissed off, alien-obsessed kid. 

The Jersey in me

I’d been lied to. I’d been hoodwinked. I’d bought a line of nonsense, and it is here that growing up in the industrial wastelands of northern New Jersey comes in. In this part of the world — and as a teenager, I was old enough to understand it — everybody has a hustle. From the guy selling high end stereo speakers from out of his car that, you know, “fell off the truck” to the other guy who wants you to work for him hawking cooking sets door to door (“Kid, you’ll be flush!”), everybody has an angle. Everybody has a story to get ahead, and they are going to do it through you. Unless you’re skeptical, unless you are expecting the con, you are going to get taken. You are going to be a mark.

That is exactly what happened to me with von Däniken and his ancient aliens. His book was the scientific equivalent of a scam, and I had fallen for it. I vowed never to let it happen again.

In science, we learn that brutal requirements are needed for linking a piece of evidence to a claim about that evidence (like a blurry picture of a flying saucer being proof that aliens are visiting Earth). But I didn’t need physics graduate school to teach me that. I had already got my lessons in the necessity for hard-nosed, keen-eyed skepticism from the Garden State, and it served me well as a scientist for 30 years.

This article The most important lesson about being a scientist I learned in New Jersey is featured on Big Think.

“Time doesn’t stop.” We all say (and feel) this and yet we hardly ever stop to think about the meaning of time and its passage. Time is one of those deeply stirring topics, the kind we tend to push aside and prefer to forget. After all, to think about time and how fast it passes leads quickly to thoughts about death. This is the essence of the human predicament, to have awareness of the passage of time, to know that our days on this planet and in this life are finite.

Past, present, future

Still, some of us do think about the nature of time, and physicists, far from being morbid folks, do that a lot. We tend to split time into three segments, past, present, and future. As everyone knows, past is what comes before the present, what “was,” while the future is what comes next, what “will be.” Even if this split seems obvious, it isn’t. It’s more of an operational definition, which, under further analysis, becomes quite nebulous. We need the present to define the past and the future. But what, exactly, is the present?

Whatever is defined in time needs to have duration. We can look back at our lives and call that expanse of time the past. We can look forward and call what’s to come the future. But what is the in-between demarcation point? The present is as thin as it can be. In fact, mathematically, we define the now as a single point in time. This point is an abstraction and, being a point, it has no duration. Ergo, mathematically, the present is a point in time with no duration: The present doesn’t exist, or at least it doesn’t have duration in the mathematical definition of time!

On the other hand, we do have a sense of the present. Our minds create the feeling of duration so that we can attribute reality to what we call the “now.” (Here’s a TEDx talk addressing how this works cognitively.)

Time is, essentially, a measure of change. When all remains the same, time is unnecessary. That’s why there is no time in Paradise: no change, no time. But if we need to describe the motion of a car, or of the Moon around the Earth, or of a chemical reaction, or of a baby growing into a toddler, we need time.

Einstein’s view of time

Near the end of the 17th century, Isaac Newton defined what we call absolute time, a time that just flows steadily like a stern river and is the same for all observers — that is, people or instruments making measurements of things moving about. Early in the 20th century, Albert Einstein argued that this notion of time is a crude approximation to what really goes on. Time and duration, he said, depend on the relative motion between observers.

A famous example is the definition of simultaneity, when two or more events are said to happen at the very same time. Einstein explained that two events that happen simultaneously for an observer A happen at different times for an observer B in motion with respect to A.

Inspired by the train station in front of his home in Bern, Einstein used trains to illustrate his revolutionary idea. Imagine A is standing by the station as a train goes by. When the train is exactly halfway through, two lightning strikes hit its front and back. Observer A measures the time it takes for light from both strikes to get to her and concludes they arrived at the same time: They were simultaneous.

Observer B, however, was inside the moving train. To him, the lightning strike that hit the front of the train arrived to him before the one hitting the back. The reason is simple, Einstein suggested: Since light travels at the same speed no matter what (and this was his revolutionary assumption), and the train is moving forward, the lighting hitting the front would have a shorter distance to travel and, hence, arrived at observer B before the lightning that hit the back, which had to catch up with the moving train.

Now, for normal train speeds, the difference is ridiculously small. That is why we do not notice such things in ordinary life. And that is why Newton’s approximation of absolute time, irrespective of the observer’s motion, works for everyday stuff. But as speeds increase and approach the speed of light, the differences become noticeable. This effect has been measured countless times in the laboratory and in other experiments, confirming Einstein’s special theory of relativity. Time, and its perception, is indeed quite subtle.

Einstein didn’t stop there. Ten years later, in 1915, he published his general theory of relativity, showing that once we include accelerated motions, we must rethink gravity and the nature of space and time altogether. In a spectacular display of intuition, Einstein realized that gravity mimics acceleration (like when you go up or down in a fast elevator and feel your “weight” change). He realized that to understand accelerated motion with a constant speed of light was equivalent to describing gravity as the bending of space and time. (“Bent” time means that gravity affects the passage of time.)

Very roughly, whenever there is a gravitational pull, it gets harder to move away from it. Even light is affected, not in its speed but in its wave properties, becoming stretched out as it tries to move away from a region with strong gravity, like near a star and, more dramatically, near a black hole. If you think of a light wave as a kind of clock (you can count how many wave crests pass by you per second, for example), you see that gravity decreases the number of crests going by. The stronger gravity is, the fewer crests you will count. This kind of reasoning applies to any sort of clock, and it translates into saying that gravity slows time down. (For more, you can check this link.)

The significance of the passage of time

So, both in what we can call cognitive time (the subjective feeling we have of time passing) and in the time of the physicists, there are many subtleties. A famous debate took place in 1922 between the philosopher Henri Bergson and Einstein to discuss these two apparently conflicting notions of time. If anything, the discussion caused the gulf between the sciences and the humanities to grow even more. Perhaps a useful compromise is not to box time into a single definition but to think of it contextually, as it serves different purposes.

Things get even more nebulous when we think about the origin of the Universe. The word “origin” already says it: It is the moment in time when the Universe as we know it came to be; essentially, when time began to tick. How that happened remains a mystery, one that brings forth a whole slew of conceptual difficulties.

There is, then, yet another kind of clock, a universal, or cosmic clock that started to tick at the Big Bang some 13.8 billion years ago, and, if what we know now of the Universe and its material contents is any indication, seems poised to keep on going for as long as we can imagine. However, and to make things more interesting, given that what we can say about the distant future depends on what we know of the properties of the Universe in the distant future, we can say very little with certainty. Existence, from cosmic to human, is bracketed at both ends by mystery.

This article The physical and philosophical problem of time is featured on Big Think.

If you follow the writings and ideas of many theoretical physicists and scientific magazines and publications, you surely have come across a statement that goes somewhat like this: “The Universe is fine-tuned for life. If you look at the constants of nature, like the mass of the electron and the quarks, the strength of the gravitational or strong nuclear force, and many other constants that physicists use to describe natural phenomena, you realize that their values are such that, if tweaked by even a tiny bit, life in the Universe wouldn’t be possible. So, the universe, or the constants of nature, must be fine-tuned for life to be here.”

It is common to hear that we live in a “Goldilocks Universe,” perfectly tuned for life to exist. Once you frame the story this way, there are three possibilities: (1) It’s just an accident — that is, the Universe is what it is, and we are the ones who tell the story by measuring the constants of nature; (2) there is a “fine-tuner,” and what you call this “fine-tuner” is up to you, be it God or panpsychism (see my conversation last week with philosopher Philip Goff), and the Universe’s purpose is to have intelligent life; or (3) we live in a multiverse, and our Universe just happens to be the one where things work out for life to exist. In other words, if you don’t want God, you had better embrace the multiverse.

Let’s take a closer look at each of these three possibilities, starting with the last two. Consider the second choice, that there is a fine-tuner. The problem with positing some kind of fine-tuner, be it supernatural or panpsychic, is that we cannot prove it. So, we must take this as an article of faith. That is a personal choice, but it is not very useful scientifically even if it is soothing psychologically.

A multiverse of problems

That is why so many scientists embrace the third choice, the multiverse. If you reduce the issue of the values of the fundamental constants to a cosmic lottery, then essentially you are pushing the problem to probabilities. There is a multitude of possible universes out there, each with different values of the constants of nature, and ours happens to be the one where things work out for stars and planets to exist, and for biochemistry to have emerged on at least this planet of ours, possibly many more. The multiverse implicitly assumes that there is some kind of metric to determine the different probabilities for universes to exist with different values for the fundamental constants, even though we have no clue how to establish this comparison.

Also, the multiverse is based on very speculative physics, either string theory or inflationary cosmology, or a combination of the two. In its simplest form, the multiverse comes from a field called the inflaton, which is presumed to have triggered an exponentially fast and very short-lived period of cosmic expansion in the early Universe. Inflationary expansion does solve some of the conundrums of cosmology (and in principle doesn’t need the more exotic physics of string theory), but it does so at the price of calling for a physics we aren’t sure exists (namely, the multiverse).

Even if inflation is the right model for the early Universe, and it could be, the problem is that we cannot ever know if the multiverse exists or not, given that other universes are outside the bubble of information we call the cosmic horizon. So, in practice, the multiverse amounts to a solution of the fine-tuning problem that is not that much different than the supernatural or panpsychic proposals of the second possibility — something that possibly exists but cannot be verified to exist. The multiverse is an article of faith. The hardest challenge in speculative theoretical physics is to discern between the allure of a beautiful idea and what it takes to have it be part of the real world.

There is no fine-tuning problem

This leaves us with the first choice for the fine-tuning problem, which simply states that there is no fine-tuning problem. If we take a historical approach to how our current physical picture of the Universe was built, we realize that the constants of nature are measured parameters we use to create models that describe what we see. We measure the mass and charge of the electron, or the strength of the strong nuclear force, or the masses of the quarks, and then use these values in models that describe how particles and objects interact with each other. It is obvious — and rather unsurprising — that the only reason we can measure these values is because we are here.

This project has been incredibly successful in providing us with a grand picture of the physical Universe. But nowhere in the conceptual framework of physics has it been suggested that we need to explain the values of the constants of nature with some kind of predictive model. In fact, if we think about it a bit, we realize that such a task is fundamentally impossible. Any model of the physical Universe needs to start with some value of a parameter that establishes the energy scale at which this model operates.

For example, in string theory, which many believe to be the closest we can have to such a model, the free parameter is the so-called string tension, essentially telling us the energy per unit length of the fundamental string (which is huge, by the way). One can then ask: But why this value and not another? And the answer usually goes like, “Because this is the Planck energy per Planck length, and nothing else could fit here.” But this is not really an answer. It is an assumption that this is where physics as we know it stops. It is not, and it cannot be, a fundamental “first principles” prediction because every model is built upon a conceptual framework that must assume a starting point.

Astrotheology

So, is the Universe fine-tuned or not for life? Given that we have no evidence of life elsewhere, and that it is conceptually impossible in physics to calculate the constants of nature from “first principles” without other in-built assumptions, it seems that answers to the fine-tuning problem that call either for a fine-tuner or the multiverse are trying to add a dimension to physics that doesn’t belong there. Maybe we could call it astrotheology — which would be fine with me, but it’s not really physics as we know it.

This article Is the Universe fine-tuned for life? Here are 3 answers is featured on Big Think.

The most interesting parts of the Universe are under pressure — a lot of pressure. Deep within planets, especially exoplanets like massive super-Earths, gravity crushes matter into exotic forms not found on planetary surfaces. At the center of stars, the pressures are so high that hydrogen atoms are squeezed tightly until they fuse into helium, releasing energy in a process called fusion that keeps the Sun shining.

The key role that ultra-high pressures play in shaping nature’s most important processes requires scientists to push continually at the frontiers of technology. It is, therefore, ironic that these days my colleagues and I study the Universe’s high pressures not by squeezing matter with steel plates or diamond anvils, but with that most incorporeal of substances: light. 

A light squeeze

It might seem strange that light can be used to crush samples of matter to densities found at the center of a giant exoplanet or star. After all, no one has ever been pushed down the street by a sunbeam. So how do scientists convert light to pressure? The answer is that they don’t use just any old kind of light. They use lasers — very big lasers.

About a mile or so from my office at the University of Rochester’s Physics and Astronomy Department, there is a huge building housing the Laboratory for Laser Energetics (LLE). There, you will find the 60-beam Omega laser system that is a beautiful example of Big Science. Firing once an hour, Omega can deliver up to 60 terrawatts of power to targets placed at the center of an immense soccer ball-shaped chamber studded with instruments. The LLE is also home base for the Center for Matter at Atomic Pressures, a National Science Foundation program that I am a part of that uses the LLE’s lasers to, among other things, push the frontiers of exoplanet interior science.

What happens inside that target chamber that allows Omega to explore high densities? Laser light is coherent, which means it is made up of electromagnetic waves of a single wavelength. This is different from what comes out of, say, a light bulb, which emits light of many wavelengths (i.e., “white” light). The coherence of laser light means a focused beam can deliver extremely high energies to a small target in very short periods of time. It’s the delivery of so much power (energy per time, such as Joules per second) that gives Omega and laser systems like it the punch they need to drive matter to high pressures.

From laser to pressure

But the link between the intense lasers and high pressure is not direct. Instead, it requires a critical intermediate step.

When the lasers hit their target, they couple to the matter by dumping energy into the random motions of the matter’s constituent particles (like electrons). These random motions are, essentially, heat. The lasers rapidly superheat the outer layers of the target, which respond by blowing material outward as in an explosion. Just like a rocket, however, these explosions can be tapped to drive directed motion. In this case, a strong shock wave can be driven in the opposite direction of the explosion — that is, into the target. As the shock wave, traveling at tens of miles per second, rips through the target, it squeezes matter to densities that could not be achieved any other way. Even though it may take only nanoseconds for the shock to traverse the target, that’s long enough for all those sensors and diagnostics arrayed around the target chamber to capture details about the material in these exotic high-pressure states.

The use of this kind of “rocket effect” is also the basis of how scientists achieved their first ever break-even fusion experiments at the National Ignition Facility laser system at Lawrence Livermore National Lab (NIF is LLE’s big brother). For the fusion studies, lasers are fired at a tiny spherical capsule (the size of a BB) containing a hydrogen isotope. The capsule’s outer layers then “ablate,” meaning heat generated by the lasers blows off the outer shell. The ablation acts as a kind of spherical rocket motor pushing the capsule into collapse — an implosion — and squeezing it until the hydrogen fuses into helium. 

So, light can be turned into heat, which can then be turned into motion, and the effect of that motion can be turned into a big squeeze. It is an elegant method requiring big machines that can focus on very small targets, giving scientists deep views into the pressures that shape the Universe.

This article From fusion to exoplanets: How to squeeze matter with light is featured on Big Think.

Today, I am hosting the British philosopher Philip Goff, a professor at Durham University in England. He is a strong proponent of panpsychism, which the New Oxford American Dictionary defines as, “The doctrine or belief that everything material, however small, has an element of individual consciousness.”

Goff just published a new book this week, Why? The Purpose of the Universe, where he masterfully presents his defense of this worldview, connecting it with a much needed way of addressing not only the challenging nature of consciousness but also our search for meaning beyond a strictly material reality. It’s a fascinating conversation that invites many more questions. The following is a Q&A.

I’d like to start with a biographical question to situate the readers. Can you tell us how you got involved with philosophy and, in particular, the kinds of questions you work on?

I’ve been obsessed with philosophy for as long as I can remember. My parents tell me that when I was four, I asked, “Why are we here?” We had recently moved house, so I might have just been confused about the location.

I’ve always been interested in how the different stories we tell about reality fit together. How does free will fit together with near deterministic physics? How do “right” and “wrong” fit together with the value-less facts of natural science? How do feelings and experience fit together with the electrochemical signaling of the brain?

Can you define “panpsychism” to the readers? Are there different schools?

Panpsychism is the theory that consciousness goes down to the fundamental building of matter. Fundamental particles or fields have incredibly rudimentary forms of consciousness, and the complex consciousness of the human and animal brain is somehow built up from these more basic forms of consciousness.

Panpsychism has a long history, with both Western and Eastern philosophers. Leading thinkers of the Enlightenment, such as Gottfried Wilhelm Leibniz and Baruch Spinoza, were panpsychists, and it had something of a heyday in the 19th century. It was not popular in the latter half of the 20th century, but in the last 10 or 15 years, there has been a new wave of interest in panpsychism in academic philosophy, and even to some extent in neuroscience. For its proponents, it offers an attractive middle way between the extravagant belief in the soul on the one hand, and the reductionist “there’s only brain chemistry” view, which I think ultimately denies the reality of consciousness itself.

At some point in the book, you address the issue of fine-tuning, that the constants that determine the strength of the fundamental forces of nature and other physical properties of matter appear to be selected to ultimately allow for life to emerge in the Universe. Tweak the strong force coupling constants and you won’t have stars. Without stars there is no life — no us, no purpose. Physicists try to get around this by assuming the existence of unified theories that preselect those values, for example, the multiverse in string theory. (In fact, one colleague even claimed that if you don’t want God, you had better have the multiverse!) How do you respond to this? Another possibility is that the whole fine-tuning debate is a straw man argument. Who says physics should be able to derive the values of the fundamental constants of nature? (See my book A Tear at the Edge of Creation for an expanded critique of unification and fine-tuning.) It may very well be that these values are simply part of the alphabet of physics, measured quantities we use to build our descriptions of natural phenomena. In other words, maybe we are asking physics to do something it’s not cut out to do. And when we do that, we end up needing to add purpose to physics, which is not a necessary part of it.

This isn’t controversial physics. But I think as a society, we are in denial about its evidential implications, because it doesn’t fit with the picture of the Universe we have gotten used to. It’s a bit like in the 16th century when we started to get evidence that we weren’t in the center of the universe, and people struggled with it because it didn’t fit with the picture of reality they had gotten used to.

Ultimately, we face a choice. Either it’s just an incredible fluke that the numbers in our physics are right for life — an option too improbable to take seriously — or the relevant numbers in our physics are as they are because they are the right numbers for life; in other words, that there is some kind of directedness toward life at the fundamental level. That’s weird, and not how we expected science to turn out. But we should follow the evidence where it leads, without being influenced by our cultural prejudices.

For many, there is a third option: the multiverse. And for a long time, I thought the multiverse was the best explanation of fine-tuning. But over a long period of time, I was persuaded by philosophers of probability that the inference from fine-tuning to a multiverse commits the inverse gambler’s fallacy.

Imagine we walk into a casino and in the first small room we see someone having an incredible run of luck. I turn to you and say, “Wow, there must be lots of people playing in the casino tonight.” You’re baffled, so I explain, “Well, if there are thousands of people in the casino tonight, it’s not so surprising that someone will have an incredible run of luck, and that’s just what we’ve observed.” Everyone agrees that’s a fallacy — the inverse gambler’s fallacy — as our observational evidence concerns the good fortune of a particular individual, and the number of people elsewhere in the casino has no bearing on how likely it is that this particular person will play well.

This flawed reasoning is indiscernible from that of the multiverse theorist. Our observational evidence is that this universe is fine-tuned, and the number of other universes that are out there has no bearing on how likely it is that this universe is fine-tuned. Of course, there’s a lot more to say about the anthropic selection effect, and the alleged scientific case for the multiverse, and I go into all this in the book.

The emergence of life is, next to consciousness and the origin of the universe, one of the ultimate three mysteries. We don’t know how to begin to think about purposeless matter suddenly self-organizing to become purposeful, what I once called “matter with intentionality.” Is this where you situate the need for panpsychism? As an explanation for these three mysteries? If so, is purpose something existing before the Big Bang? What would that mean if this is the case? Are we back to the First Cause problem?

(Editor’s Note: Due to time limitations, Dr. Goff didn’t answer this question. But we are leaving it here for everyone to ponder!)

Can you explain what you mean by pan-agentialism, an idea that reaches, it appears, beyond panpsychism? Some of this conversation brings to mind the philosophical novel Star Maker, by Olaf Stapledon, where the Universe is a large experiment on purpose as life takes different expressions across a multitude of worlds.

Pan-agentialism is the view that not only consciousness but also rational agency goes right down to the fundamental building blocks of reality. Obviously, particles can’t deliberate or do probabilistic reasoning, but I think we can make sense of the idea that they are responding rationally to incredibly basic desires.

I propose this as a solution to the deep and under-explored challenge of accounting for the evolution of consciousness. Rapid progress in AI and robotics has made it clear that you could have incredibly complex behavior without any kind of inner experience. So why didn’t natural selection make survival mechanisms — that is, extremely complicated biological robots which track features of their environment and respond with behavior conducive to survival without being conscious? I believe we need something like pan-agentialism to address this challenge.

Finally, I wanted to talk about teleological cosmopsychism, which you propose to be the one explanation for cosmic purpose with an edge over others. If the Universe has as its purpose the goal of having self-aware life as the ultimate expression of its own consciousness, why did it take so long (at least 10 billion years, if Earth is the main example) for it to do so? Is cosmic purpose self-contingent on the dictates of the laws of physics? Why? Also, how would you consider the existence of other intelligences in the Universe?

The Universe being conscious is not as extravagant a hypothesis as you might think. Physics is just mathematical structure, and there must be something that underlies that structure, something that “breathes fire into the equations,” as Stephen Hawking put it. I argue that the hypothesis that it’s a conscious mind that “breathes fire into the equations” is as parsimonious as any other proposal, and it has the advantage of explaining fine-tuning. As for why it took so long, this isn’t an omnipotent God but rather an entity that pursues certain goals under significant limitations — those recorded by the laws of physics.

We need a hypothesis that accounts for both the goal-directedness evidenced in the fine-tuning of physics for life, but also the arbitrariness and gratuitous suffering we find in the world. Cosmopsychism sounds weird, but it accounts for the data.

This article Is the Universe conscious? A panpsychism Q&A with philosopher Philip Goff is featured on Big Think.

When I was a wee graduate student back in the late 1980s, we didn’t know if there were any planets orbiting other stars (i.e., “exoplanets”). Now, just three decades later, we know that there are planets orbiting pretty much every star in the galaxy. This abundance of worlds was one reason I wrote my new book, The Little Book of Aliens. I wanted people to know all the crazy kinds of planets there are out there (ocean worlds, snowball worlds, magma worlds), as well as all the possibilities that exist for life. 

Now that the book has come out, people have asked me: What’s my favorite alien planet? My answer comes quickly, but it’s not a single planet. Instead, it’s a planetary system. Also, it’s not just my favorite. The TRAPPIST-1 planetary system is the darling of many astronomers, planetary scientists, and astrobiologists, and today I want to tell you why. There is going to be a lot of work on TRAPPIST-1 coming from the James Webb Space Telescope (JWST).

TRAPPIST-1

The star TRAPPIST-1 hosts seven worlds labeled Trappist-1 b through h. All the planets have sizes and masses comparable to the terrestrial planets in our own Solar System (that is, Mercury, Venus, Earth, and Mars). The densities of the TRAPPIST-1 planets tell us that they are rocky worlds. That is good news because the consensus among astrobiologists is that life will need a planet with a surface to get going (as opposed to a gas giant like Jupiter).

Even better than finding rocky planets is finding rocky planets in the habitable zone of a star. The habitable or “Goldilocks” zone is the band of orbits where planetary surface temperatures lie between the boiling temperature of water (inner orbit) and the freezing temperature of water (outer orbit). Since we believe that liquid water may be essential for life (as water is such an amazing solvent), the habitable zone is a key idea in the search for life. The really good news is that planets e, f, and g in the TRAPPIST-1 system all lie in that star’s habitable zone.

This wealth of worlds along with a trio of planets in the star’s habitable zone are why TRAPPIST-1 is the go-to exoplanet system for astronomers. The JWST already has a robust program of observations set up to study each of the worlds. 

The bad news

Now, here comes what may be the bad news. The star TRAPPIST-1 is nothing like the Sun. With a mass and radius of just one-tenth that of the Sun as well as a temperature that is less than half, TRAPPIST-1 is an ultra-cool dwarf, a small version of a red dwarf star (a class of stars that are small, cool, and dim).

Given its pitiful light output (less than one-tenth of 1% of the Sun’s luminosity), the habitable zone of TRAPPIST-1 is snuggled so close to the star that even planet g has a “year” that lasts just 12 Earth days. And given how close all the planets are to their star, they are all likely to be “tidally locked,” which means they always keep one side facing the star and one side facing out into space as they orbit. The Moon is tidally locked to Earth, which is why we never get to see its “far side.” Tidal locking for planets means one side lives under perpetual heating, while the other side always faces into the cold of space.

How does this affect the possibility of life? No one knows. Simulations of climates on tidally locked planets indicate that circulation from the day to the night side may even out temperatures somewhat, so that’s hopeful. There is also the possibility that life might get a hold in the temperate, permanent “terminator” that separates the two hemispheres.

Our favorite exoplanetary system

The TRAPPIST-1 system is a treasure trove of possibilities and questions. Observations by JWST already indicate that the inner-most planet (planet b) has no significant atmosphere and is probably dark in color. JWST observations of planet c ruled out a thick carbon dioxide atmosphere but not a thinner one or one composed of other species (like oxygen). These are, however, just the beginning. Many more observations are coming, and all eyes are going to be on this system over the next few years as we go about exploring our newfound, favorite alien planetary system.

This article Why TRAPPIST-1 is our favorite alien planetary system is featured on Big Think.

This week, I am excited to share this space with my 13.8 partner and research collaborator Adam Frank. Adam has just published a wonderful new book, The Little Book of Aliens, which basically includes all we know and don’t know about alien life. It is a no-nonsense approach to this fascinating topic, and readers will find answers to all of their questions. As I said in my promotional blurb, Adam’s book is not little at all. The following is a Q&A.

I want to start with a biographical question. What attracted you to astrophysics and made you wonder about life on other worlds?

I was five years old when I stumbled upon my dad’s library. He was a writer who loved books by Ernest Hemingway, William Faulkner, and Norman Mailer. But he also had a big interest in science fiction. There were a couple of shelves in his office that were lined with 1950s and 1960s pulp science fiction magazines. Every one of them had covers illustrated with rocket ships blasting through space, astronauts bouncing around on alien planets, or bug-eyed monsters and other aliens. I just fell in love with it all. I thought space and all its possibilities were as exciting as it could get. Eventually he started giving me science fiction books and then taking me to the Hayden Planetarium in New York City. That’s where it all began.

Then, as a I got older and started getting a taste of how math was a language you could use to describe the world, it was kind of like a drug. It felt like you could see through all the garbage of the social world and its contrivances to look directly into something hidden but eternal and absolute.

When we talk about extraterrestrial life, how important is it to differentiate between simple unicellular life and intelligent life?

I don’t think we should, and this is a big theme in the book. Finding either kind of life would constitute the most fundamental discovery in the history of human society. People often think we have to find alien civilizations — that is, extraterrestrial intelligence — for the discovery to matter.  But finding even one world that only had a biosphere (with “dumb” life) would still rework our understanding of the cosmos and ourselves. That’s because life is unlike any other physical system. Rocks, mountains, stars, comets — they are amazing, but they will never surprise you the way life can. Life creates. It innovates beyond itself.

How do you position yourself with respect to UFOs and their many “sightings”? To what do you attribute this urge to see the “other”?

I would never tell someone they did not see something they claim to see. I wasn’t there, so what can I say? But the point is science cannot do anything with personal narratives. If the goal is to establish “public knowledge” about alien life, then we need something else. If we want knowledge that we can all agree on and then use it to expand further to get more knowledge, we must turn to the methods of science. 

We see the beginnings of that happening now from the NASA UAP panel to the Galileo Project, and I think that’s good because people are so interested in the topic. I am skeptical that UAPs have anything to do with life beyond Earth (as Sagan said, “Extraordinary claims require extraordinary evidence”). But in the book, I lay out what a true agnostic scientific study of UAPs would look like.

Do you think interstellar travel is possible?

If you’re going slower than the speed of light, then absolutely! If you want to break the laws of nature as we understand them and go faster than the speed of light or somehow work with Einstein’s general theory of relativity to warp space or use wormholes, then you have to start extrapolating big time. I have a whole chapter in the book where I explore the possibilities for interstellar travel ranging from how we might be able to do that in a century to using known laws of physics as the basis for wild speculation. It was a lot of fun.

Assuming intelligent aliens exist, what is the best way to discover them?

That’s really what the book is about. We have had these amazing revolutions in astrobiology over the last 20 to 30 years. We now know that every star in the sky hosts a family of worlds. We know that billions of these worlds are potentially habitable. Most importantly, we have developed new telescopes that can see into the atmospheres of these alien worlds and sniff out their chemical compositions. That is one way we may find life — by finding the chemical signatures of alien life in light that has passed through their atmospheres. There are many other ideas too. The main point is these techniques can be used right now or will become available over the next few decades as telescopes get better.

The existence of intelligent extraterrestrial life is one of those questions in which either answer is profoundly important: Yes, they exist — or no, they don’t. But there is a problem. We cannot ever be certain that they aren’t there, since science is not good at ruling out what doesn’t exist. Is this what gives believers hope, given the lack of evidence so far? How do you feel about this? Do you “want to believe”?

Well, we can put limits on the prevalence of life based on our observations. Science does this all the time. We have been looking for dark matter particles for quite a while. We haven’t found anything, but the search is setting some firm boundaries on what dark matter might be. If we really look for alien life on lots of alien planets for 50 years and find nothing, that will also establish limits about the probability of its existence.

What do you think would happen if intelligent alien life is discovered? How would that impact society and the meaning of being human?

The last part of the book unpacks this question quite a bit. I think it would be the most important discovery in human history. Right now, it is possible that life on Earth is a complete one-off, an accident that has never been repeated anywhere. But if we find just one other example of biology out there, then life is not an accident. That’s when the Universe gets really interesting, because life is not like any other physical system in the cosmos. Its power of invention and creativity fundamentally changes the options for what can happen in the Universe.

We are making spectacular advances in the search for biosignatures with the JWST. Do you think we are close to detecting some positive results?

I think we will have data relevant to the question in the lifetime of many folks alive today — maybe even old guys like you and me! I can’t say what the data will tell us, but it will be actual hard data. That’s a lot better than the last 2,500 years where people have just been yelling their opinions at each other.

Can you explain what technosignatures are and how we could detect them?

Technosignatures are the imprints, in light, of technological activity on distant worlds (or in the space around them). We will find technosignatures the same way we find biosignatures, by looking at the light from exoplanets (really from reflected or absorbed starlight). There will be patterns in that light that can reveal the presence of technologies, like artificial illumination (city lights) or “industrial” chemicals or the use of solar collectors or lots of other possibilities. This is a big topic in the book.

I know this is not a scientific question, but how would you bet on the existence of intelligent aliens in our galaxy?

As a bet, I am willing to put my money down on alien civilizations existing out there at some point. The big question is how long they last. If every civilization flares out after a short period (like we are threatening to do), then there may have been many civilizations — but they’re all dead now. That means we would be living in a currently sterile galaxy.

This article Aliens, fact vs. fiction: Q&A with astrophysicist Adam Frank is featured on Big Think.

Everybody loves aliens. I know this because everybody tells me they love aliens. Life in the Universe is the first thing people ask me about when they hear I’m an astrophysicist. “Do aliens exist?” is one of those special questions, kind of like “What happens after you die?” Lots of opinions, no real answers, and, most important, actually knowing the answer would change the world. 

The thing is: I love aliens too. In fact, I have been obsessed with them since I was a kid. I first got hooked when I found my dad’s pulp science-fiction magazines as a five-year-old. On the cover of every issue were images of spaceships, barren moons, and bug-eyed alien monsters. From that moment on, I was on a mission to learn everything I could about the stars and alien life. This obsession made me a pretty annoying kid (apparently, I liked to quote the speed of light to four decimal places), but it also drove me to watch all the documentaries, bad sci-fi movies, and Star Trek reruns in existence. Any depiction of an alien was good enough for me as I dreamed of possibilities out there waiting to be discovered. 

Back in the 1970s, at the height of my childhood obsession, the scientific search for life in the cosmos had barely begun. There were only a few very brave and determined pioneers carrying out the search for extraterrestrial intelligence (SETI), and most of them faced the scorn of their colleagues. SETI was considered a little “out there,” marginal at best in the scientific community. A big part of that dismissal was just bias. There just weren’t many astronomers who thought about the problem of life in its cosmic context back then. And it’s true, we really didn’t have much to go on in those days in terms of setting up a true scientific search for life among the stars, smart or otherwise.

Most of all, we didn’t know if there were any planets in the galaxy other than the eight that orbited our Sun. This was a killer point, since scientists expect planets to be necessary to get even simple life started. So not having a single example of an extrasolar planet (an exoplanet) meant we literally didn’t know where to look. We also didn’t know much about how planets and life evolve together in ways that might keep a world habitable for billions of years, long enough for “higher” animals and even technological civilizations to appear. In short, when it came to searching for alien life in the Universe, we were pretty much in the dark. 

Not anymore. 

As you read these words, the human species is poised at the edge of its greatest and most important journey. Over the past three decades, the scientific search for life in the Universe — a field called astrobiology — has exploded. We’ve discovered planets everywhere in the galaxy, and we’ve figured out how and where to look for signs of alien life in the atmospheres of these new worlds. 

We’ve also looked deep into Earth’s almost four-billion-year history as an inhabited world. From this view, we’ve gained new and powerful insights into how planets and life evolve together. Seeing the way life hijacked Earth’s evolution over the eons gives us clues about what to look for on distant planets (like oxygen, which generally can exist in an atmosphere only if life puts it there). 

We’ve also sent robot emissaries to every planet in our Solar System. With their wheels or landing pads on the ground, we’ve begun searching these neighbor worlds for evidence of life existing now or perhaps deep in their past. Most important, we have launched and are building insanely powerful, next-generation telescopes. With these tools, we’ll finally go beyond just yelling our opinions about life in the Universe at each other. Instead, we will get what matters most — a true scientific view of if, where, and when extraterrestrial life exists. 

All these new discoveries, from exoplanets to Earth’s deep history, are transforming what we think of as SETI. A new research field is rising that scientists are calling technosignatures, which embraces the “classic” efforts of SETI while taking the search for intelligent life into new forms and directions. Knowing that the galaxy is awash in planets means we now know exactly where and how to look for alien civilizations. Rather than hoping for someone to set a beacon announcing their presence (one premise of the first generation of SETI), we can now look directly at the planets where those civilizations might be just going about their “civilization-ing.” By searching for signatures of an alien society’s day-to-day activities (a technosignature), we’re building entirely new toolkits to find intelligent, civilization-building life. These toolkits will also allow us to find the kind of life that doesn’t build civilizations. Using our telescopes to find a signature of a planet covered in alien microbes or alien forests (a biosignature) would also be a game changer in terms of how humanity sees its place in the cosmos. 

So now, finally, we are on the road to finding those aliens I was so obsessed with as a kid. Or we’re on the road to finding out we really are alone in the cosmos. Either answer would be stunning. It’s a pretty damn exciting moment.

This article The golden age of astrobiology will change everything is featured on Big Think.

Aliens. Everyone wants to know about alien life. Does it exist? If it does, what is it like? Answering these questions is the focus of my new book, The Little Book of Aliens. But while I was writing that work, I was also involved in new research that asked an equally important question that speaks directly to the question of life anywhere in the Universe: What is it that makes life different from non-life? A key piece of our research was published just this week and that’s what I want to introduce to you today.

Semantic information

Life is weird. It is completely unlike any other physical system in the Universe. One of the key aspects of living systems is their use of information. Sure, a black hole can be described in terms of the information encoded in matter that falls into it. But the black hole doesn’t use that information. Living systems, however, store, copy, and (most importantly) process information. They use it to accomplish their most important task: simply staying alive. All the molecular shenanigans occurring inside every cell evolved to make sure that the cell can sense its environment and respond in complex ways that keep the shenanigans ongoing.

The importance of information and life has been recognized by many researchers, such as Sara Walker and Paul Davies. They have pointed out how the key to understanding life as a physical system lies in understanding how this information-processing capacity arises and functions. In our research, we’ve been trying to understand what kind of information matters and how it matters. To do that, we’ve been focusing on the idea of semantic information. Semantics is another word for “meaning,” and what we’re trying to do in our work is parse out which information carries meaning for a living system and which is irrelevant. To that end, we’ve taken a pretty simple definition of meaning: the information that helps you stay alive. That’s the information that is meaningful.

Our new paper on the question of semantic information and life, called “Semantic Information in a Model of Resource Gathering Agents,” was published this week in PRX Life. It’s a journal in the prestigious Physics Review X series and very, very selective about the papers they accept. We had a great back-and-forth with the referees about the importance of our work (and that’s one of the reasons why the scientific referee process is so important; it makes the papers better). The lead author was our post-doc Damian Sowinski, who developed a simple model of a forager moving through an environment hunting for resources to keep it alive. While the basic model was simplified, the insights Damian pulled out of it were profound (to me at least).

By drawing from a theory by Artemy Kolchinsky and David Wolpert (Kolchinsky is one of our team members), we could show exactly which bits of information about the environment the forager used to maintain itself, and which bits simply didn’t matter. This was exciting by itself, but we could see hints of something else — something bigger that may hold clues as to how life works anywhere, even on alien planets.

The semantic threshold

For a system to be alive, it must forge connections, also called correlations, with its environment. It must sense and store where resources exist, and it also has to sense its own internal state. Is it satiated and does not need food right now or is it dangerously low on energy, needing the first piece of food it can grab? Knowing both its own state and the state of the world around it will determine its foraging choices.

By seeing how this process works from an informational perspective we also gained some insight into what was needed for that whole process to get established. A rock with a single sensor glued to it is not alive. A cell with its vast array of information-gathering machines is. Our results showed us how a sharp threshold seems to exist in the usefulness of bits as more and more of the semantic kind of information was added. We’re hopeful and excited that the threshold we found — the semantic threshold — might eventually lead to a deeper understanding of how life emerges from a soup of chemical reactions and physical processes. 

So how does this relate to alien life? In our search for and (potential future study of) life that forms elsewhere in the Universe, we want to be agnostic about its underlying structure. That means we don’t want to assume it is carbon-based, needs water, or requires DNA. Taking an informational perspective is one way to achieve that agnosticism. We don’t need to think about what life is made of but rather what it does. One thing that seems like a good bet to be universal is that life processes information. That’s why our new results on semantic information and its thresholds may be a step in the right direction toward understanding life as a universal phenomenon.

This article Reimagining alien life: A new model focuses on function over form is featured on Big Think.

There is something quite fascinating about not knowing what’s going on. This is where the boundaries of the known and the unknown meet, and where imagination takes over. We use what we know to guess our best path into what we don’t know. The “guess” here is, of course, educated. Experience and methodology lead the way, and we plow ahead trying to figure out what lies out there in the uncharted territories of reality. This is why, in a very concrete sense, science is a flirt with the unknown.

The history of science is full of mysterious and invisible substances, materials that were proposed into existence as experiments and observations led scientists astray. Even before science as we know it came to be, philosophers in Ancient Greece populated the cosmos with all sorts of substances that would perform whatever function necessary for their worldview to make sense. Around the 6th century BCE, the philosopher Anaximander proposed that the Universe is filled with the apeiron — the “boundless” source that gives rise to all that exists. Worlds emerge from the apeiron and, when the time is ripe, revert to it in an eternal dance of creation and destruction. About 300 years later, Aristotle proposed that there was no empty space and that everything was filled with an element the Greeks called ether (or “aether”). All planets and stars were also thought to be made of ether, being eternal and unchangeable. This was all ancient philosophical speculation that preceded scientific experimentation. Still, the habit of imagining strange substances did not stop with the advent of modern science.

The mysteries of heat

Take the nature of heat. No one could figure out how substances got hot when heated up, or why a piece of wood, when rubbed against another, also got hot, even to the point of catching fire. The first guess was that heat was some kind of substance that would flow from one body to another. The German chemist George Ernst Stahl (1660-1734) postulated that burning resulted from the release of a hypothetical substance called phlogiston. Every combustible substance was made of a combination of phlogiston and the residue left over after the burning. In a sense, phlogiston was the ignitable essence of fire itself. However, the great French chemist Antoine Lavoisier showed that the process of combustion involves a chemical combination of a substance with oxygen. He also demonstrated that, in burning something (or in any chemical transformation), the total mass of the reacting substances is conserved. There was no need to invoke phlogiston as a hypothetical element to understand burning. 

Still, the nature of heat remained obscure. We know that heat flows from hot to cold. A hot bowl of soup will cool off if we stop heating it. Lavoisier proposed that heat was some sort of invisible fluid called caloric that would flow naturally from a hot substance to a cold one. Since Lavoisier had shown that the total mass in any chemical reaction remains constant, he proposed that this caloric fluid was not just invisible but also massless. It also couldn’t be created or destroyed, just transferred from one substance to another. The challenge, then, was to prove that something invisible and massless existed. Or not. 

Benjamin Thompson (1753-1814), an American expatriate later to be known as Count Rumford, was a professed opponent of the caloric hypothesis. After serving as an officer in King George III’s army fighting with the loyalists in America, Rumford eventually ended up in Munich, where he was promoted to general by the elector of Bavaria. While in Munich, he oversaw the boring of cannons, a perfect laboratory to study the generation of heat by friction. Using water to cool the drill and the cannon, he marveled at the tremendous amount of heat being liberated, which would quickly bring the water to a boil and keep it boiling for as long as the boring continued. He pointed out that the amount of heat being generated by friction “appeared evidently to be inexhaustible.” That being the case, heat couldn’t be made of caloric, since at some point the substance would run out of it. Only decades later, it was shown that heat is actually a form of motion, due to the agitation and collisions of molecules. So much for invisible substances explaining the nature of heat.

Luminiferous ether

Next on the list comes the luminiferous ether — the substance that allegedly supports the propagation of light waves. During the mid-19th century, most physicists were convinced that light was a wave. This being the case, they reasoned, it needed to move on a medium. After all, water waves move on water and sound waves move on air. So, it was reasonable to propose that light waves move on some medium, too. The fact that this ether had truly magical properties (like the Aristotelian ether) — filling all space yet being imponderable (weightless), being rigid as a hard solid yet never offering any resistance to the motions of planets and Earth, and being perfectly transparent so we could see far away celestial objects — didn’t seem to worry most physicists. But it should have. Hidden in the mysterious ether was a serious flaw of classical physics. In 1905, Einstein showed that light ether wasn’t needed by demonstrating that light waves have the remarkable property of propagating in empty space, with no support. Another invisible substance hits the dust.

Dark matter and dark energy

There are other strange substances — too many to mention here. But today we are dealing with two invisible substances of a different nature: dark matter and dark energy. Dark matter has been around for about 90 years, and dark energy since 1998. Both have been suggested to exist due to very compelling astronomical observations. Both have very strange properties: Dark matter only interacts with normal matter by gravity. It pulls the stuff we see around and that’s how we presume it exists; an invisible hand moving stuff that shines through space. 

Dark energy acts only at huge cosmological scales, making the very fabric of space stretch out faster than we had anticipated. In other words, it accelerates cosmic expansion. To do that, it must have what we call negative pressure — something we don’t see every day in the laboratory. (Dark energy, pervading all of space, looks uncomfortably like an ether kind of medium.) So, do dark matter and dark energy exist? Will they be found as new invisible substances that are part of reality? Or will they be discarded like the caloric and the luminiferous ether?

We don’t know, although most physicists and astronomers would bet on them existing. But then again, most 19th-century physicists were also convinced that the ether existed. Fortunately, science has a way of moving forward by consistently checking which speculations come true and which don’t as we edge into those parts of reality we don’t know. In a few decades, we should know one way or the other.

This article From “apeiron” to dark energy: Science’s long quest to decode invisible forces is featured on Big Think.

What’s really the problem with quantum mechanics? Why, after 100 years of the most profound success describing nature, are people still arguing over what that description means — that is, how to interpret quantum mechanics? Even more to the point, if we can understand that essential problem, could we tell which of quantum physics’ multiple interpretations addresses the problem best?

In the first post of this series, I introduced the notion of quantum interpretations and QBism (Quantum Bayesianism) as one of the options. Now, we are going to dive a bit deeper into the structure of quantum mechanics itself to see exactly what quantum physicists are arguing about.

Classical physics vs. quantum mechanics

Quantum physics is the science of the nanoworld: molecules, atoms, and subatomic particles. At the turn of the 20^th century, physicists tried to bring concepts from what we now call “classical physics” (that is, Newtonian physics) to bear on experiments probing this nanoworld. The concepts underlying classical physics, however, spectacularly failed to explain the results from those experiments.

In particular, the classical concept of the “state” of a system no longer made sense. The state is a core concept in physics, which represents the description of a system’s properties. In classical physics, those properties — such as position and velocity — were assumed to exist independently of anything else, particularly anything involving us. The properties were seen as real attributes of the system, which could be anything from a particle to a planet. Philosophically, we would say the properties and the system were ontological. (Ontology is the branch of philosophy having to do with “being.”)

Quantum mechanics, however, changed the nature of the state. Instead of just a single set of numbers associated with a particle’s properties, the quantum state allowed for a range of possible numbers that existed simultaneously. Imagine we had a particle with the property “color” that could take values white (W) or black (B). The quantum mechanical state for that particle, before anyone made a “color” measurement, would look like this:

|Ψ > = a |W> + b |B>

Here, Ψ is the Greek letter “psi” and |Ψ> is the symbol physicists use for the quantum state. In this equation, |W> represents the particle having the color white, and |B> represents the particle having the color black. The terms a and b are associated with the probability that once a measurement is made the result will either be white or black.

So why is all this a problem? According to the equation above, before a measurement is made, the particle is neither white nor black — nor is it not-white or not-black. The quantum state |Ψ> seems to imply that before a measurement is made, the particle doesn’t have the property of color at all. Instead, the particle is in a weird “superposed” state whose philosophical implications are very muddy. It’s only after the measurement, when we see either a white particle or a black particle, that we can say the particle has the property of having color.

Now you can see why physicists feel like they need an “interpretation” to understand the most basic element of quantum physics: the quantum state |Ψ> (also called the state vector or the state function).

Psi-ontology vs. Psi-epistemic

In general, there are two different quantum interpretations. One prominent class is called psi-ontology. (Whoever came up with that deserves a medal.) These interpretations reify the mathematics. They make the state function something real, existing “out there” in the Universe in the same way classical physicists thought the classical state was something real and independent. 

The Many Worlds Interpretation (MWI) is a famous example of a psi-ontological interpretation.  To preserve the reality of the quantum state |Y>, fans of the MWI argue that, when a measurement is made, the Universe splits off into two separate parallel branches. In one branch, the particle has the color white, and in the other branch, the particle has the color black. For real systems, you end up with a multitude (maybe an infinite number) of unobservable branching universes for every quantum measurement. If that seems like a steep price to pay to keep the metaphysical biases of classical physics, then I’m with you.

The second class of quantum interpretations are classified as psi-epistemic. While ontology is about what really and truly exists, epistemology is about our knowledge. For those who favor a psi-epistemic perspective, the quantum state is not about stuff floating around out there in some perfect, platonic Universe. Instead, it’s a description we have about the particle as we interact with the world. As Joe Eberly, a senior quantum researcher in my department puts it, “It’s not the electron’s state vector; it’s your state vector.”

The famous Copenhagen Interpretation favored by the founders of quantum mechanics is most definitely psi-epistemic. Niels Bohr, Werner Heisenberg, and others saw the state vector as being related to our interactions with the Universe. As Bohr said, “Physics is not about how the world is; it is about what we can say about the world.”

QBism is psi-epistemic

QBism is also definitively psi-epistemic, but it is not the Copenhagen Interpretation. Its epistemic focus grew organically from its founders’ work in quantum information science, which is arguably the most important development in quantum studies over the last 30 years. As physicists began thinking about quantum computers, they recognized that seeing the quantum in terms of information — an idea with strong epistemic grounding — provided new and powerful insights. By taking the information perspective seriously and asking, “Whose information?” the founders of QBism began a fundamentally new line of inquiry that, in the end, doesn’t require science fiction ideas like infinite parallel universes. That to me is one of its great strengths.

But, like all quantum interpretations, there is a price to be paid by QBism for its psi-epistemic perspective. The perfectly accessible, perfectly knowable Universe of classical physics is gone forever, no matter what interpretation you choose. We’ll dive into the price of QBism next time.

This article QBism and the philosophical crisis of quantum mechanics is featured on Big Think.

We are living on the cusp. Within the next few decades, we may well have hard evidence for the existence of alien life on worlds light-years distant from Earth. That was my takeaway from new results that the James Webb Space Telescope released a couple of weeks ago. While there was some controversy that swirled around the announcement, it really had nothing to do with the science itself, which was (to my mind) quite beautiful. So, let’s dig in to see how JWST is revealing the path humanity will take to resolving the age-old question: Are we alone?

Atmospheric characterization

The JWST press release came following a new paper by Nikku Madusudhan of the University of Cambridge and his collaborators titled “Carbon-bearing Molecules in a Possible Hycean Atmosphere.” The basis of their science was the revolutionary technique called “atmospheric characterization.”

When a distant exoplanet passes between us and the star it orbits, some of the starlight passes through the planet’s atmosphere. Interaction with chemicals in the atmosphere leave a kind of spectral fingerprint in the starlight that allows astronomers to detect what is in that alien planet’s air. (It is a method that I unpack in more detail in The Little Book of Aliens, my new tour of all-things ET coming out next month. In the book I couldn’t help gushing about how stunning it is that human beings can now sniff out the atmospheric constitution of alien worlds.)

So, what did Madusudhan and his colleagues discover? Two molecules in particular were detected with high degrees of confidence: methane (CH₄) and carbon dioxide (CO₂). As you can see from the chemical formulas (and the paper’s title), these are molecules with the element carbon in them. Why was that important? To answer that question, we need to look at the planet the astronomers were focusing on.

Hycean worlds

K2-18b is what’s called a “sub-Neptune” with a mass about 8.6 times that of Earth. We do not have sub-Neptunes in our Solar System. There are no planets orbiting the Sun with masses between 1 Earth mass (that is, Earth) and about 14 Earth masses (Uranus). That means we don’t know much about what these planets really look like. What kinds of worlds are they? 

In earlier papers, Madusudhan suggested that K2-18b might be a Hycean world, a planet with a thick atmosphere made of hydrogen covering a liquid water ocean. That is a pretty radical idea. Most of us in astrobiology believe that liquid water is the key to life. That is why we focus so much on Earth-like planets in the so-called “Habitable Zone” — the band of orbits not too far or too close to the home star where liquid water exists on the planet’s surface. 

If Hycean worlds exist, however, then they might represent an entirely new kind of habitable world. They would not be Earth-like at all, but still warm and very wet. And that brings us back to the methane and carbon dioxide. These chemicals, and their abundances implied by the JWST data, support the conclusion that K2-18b is a Hycean world — a whole new kind of planet where life might form. That’s very exciting.

The game is afoot

Now for the controversy. In the paper, the authors noted that they found very weak evidence for the presence of dimethyl sulfide (DMS). DMS is the kind of chemical that plankton belch into the atmosphere on Earth. Finding a clear signal of DMS would mean finding a potential biosignature — a signature of alien life. If true, that would be world changing. However, the authors were very clear that the evidence was so weak that no one should take it seriously. They raised the issue only to say, “Hey, maybe someday we will find better evidence for something like this.” The way the result got handled in the press in some cases made it seem like JWST had just found life. Nope.

But should we be excited about the JWST results? Yes. They beautifully demonstrate how far we have come in the hunt-for-life game. They also revealed evidence for a whole new class of habitable planet, and they showed what finding a biosignature in the future could look like. 

The game, as Sherlock Holmes once said, is afoot!

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Life is one of those things that you know when you see it, but it is hard to pin down in words. You know a rock is not alive and an earthworm is. You see the earthworm moving, going somewhere, as if on a mission. And it is on a mission, as are most living creatures. Its number one mission, the central purpose of its life, is to remain alive — as is yours and of all living creatures.

When you think of it, this urge is even more powerful than the other essential activity of living creatures: to reproduce genetically. Living matter eats and makes copies of itself. Dead matter does not, at least not on purpose. This we know just by looking, even if some life forms look barely alive. (Think, for example, of an animal in deep hibernation, with barely enough metabolism to remain alive and no reproductive action.) To metabolize and to reproduce genetically are things that life does. That’s not where the mystery lies.

The mystery lies in the why, or to be more specific, on the strange transition from nonliving matter to living matter, which happened on this planet some 3.5 billion years ago. The challenge is to understand this transition — this imbuing of dead matter with the spark of life — through current scientific approaches. This is absolutely no descent into creationism, or into some sort of life force mysticism. It’s a bare bones scientific question that is really hard to even pose properly. But the best formulation is: “How did nonliving matter become living matter?” — all by itself, through physical and biochemical processes.

The hardest question in biology

Our language is permeated with terms that evoke the supernatural. Even what we call living creatures, “animals,” comes from the Latin word anima, which means “soul.” So, it is natural to think of living matter as matter with a soul, at least within the etymological context of the word “animal.” We can say, quite generally, that life is matter with intentionality. And that is what’s so hard for science to pin down. How do you include intentionality into a science designed to describe matter as the result of cause-and-effect relations between inanimate bits of stuff?

For a comparison, think of fires. To sustain themselves, fires spread and feed on their environment. They consume oxygen to keep on burning and are thus thermodynamically open systems, as are living creatures. Given the right conditions, fires multiply. But we know that fires are not alive. We wouldn’t consider the spreading of a fire as a form of reproduction. We wouldn’t call oxygen combustion a metabolic process.

Why? For starters, fires do not have a history. They do not have a gene storage mechanism to transmit their characteristics as they spread. They also don’t have survival strategies or repairing mechanisms. If a fire is burning down a ravine toward a creek, it will keep on burning until it stops by the water and eventually dies out. It doesn’t forage intentionally for more fuel or strategize in any way to keep on burning.

Now, consider hurricanes. Like fires, they are persistent, far-from-equilibrium complex systems (as are living creatures) that need the right environmental support to exist and to maintain themselves. They “move” and are tightly coupled to local humidity, pressure, and temperature conditions. If favorable atmospheric conditions hold, they maintain their basic shape. Jupiter’s Great Red Spot is a giant anticyclonic storm that has endured for at least 400 years. But as with fires, we would not equate these properties of hurricanes with being alive.

Life is inherently unpredictable

We are so imbued with life that we tend to see it everywhere. But one essential difference is that living systems have an unpredictable aspect during reproduction, a random variability that is absent in nonliving systems. For physical systems, if we repeat initial conditions to a very high precision, a fire would always burn the same way, a hurricane will spin the same way, and a star would evolve the same way, even if small details vary. It is as if nonliving systems have an information content that is nearly frozen (that is, a repeatable history from inception to end), while living systems have an information content that is fluid (that is, an unpredictable history from inception to end). Fires and hurricanes don’t evolve from ancestors.

Another essential difference is the passivity of nonliving dissipative structures when contrasted with the active behavior of living systems. Life strategizes to find nutrients even at the bacterial level (chemotaxis), sensing the best path forward through a yet unknown interplay of bottom-up and top-down causation. We use words like volition, urge, autonomy, and control to describe living systems, but we would not use such words to characterize fires, hurricanes, or stars.

Though we recognize these differences, the puzzle of how life emerges from nonlife remains as mysterious as ever. How does an agglomeration of inanimate matter, beyond an unknown level of biochemical complexity, become a living creature?

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We are witnessing a revolution in our knowledge of other worlds, planets orbiting stars far away from our Solar System. Once the stuff of imagination and speculative fiction, we now can state with confidence that most stars have planets orbiting them. That we can do this is no small feat: Finding a tiny planet around bright stars dozens or hundreds of light-years from Earth is extremely difficult.

Planet hunting

Planets don’t shine, of course, and are overwhelmed by their star’s brightness. So, the techniques to hunt for exoplanets rely on indirect methods. Because planets affect the stars they orbit, we can look for those effects to find them.

First, planets tug at stars gravitationally, making them wobble; second, a planet blocks a tiny fraction of the star’s light when passing in front of it. The bigger the planet and the closer it is to its star, the larger these effects are. To measure a star’s wobble, we use the the radial-velocity or Doppler method, and to measure the dimming of its light, we use the transit method. We then work backward to deduce the kinds of planets that could cause such effects on their host stars.

These indirect imaging techniques require incredible precision and care. But they work phenomenally well. To date, we have confirmed observations of more than 5,500 exoplanets, each with its own properties, an amazing diversity of worlds. In my recent book, I give more details about this extraordinary new window into these other worlds. Today, I’ll focus on one of the two most popular techniques, the radial-velocity method, as it was the first to be wildly successful in our search for exoplanets.

Dancing with the stars

As a planet orbits its star, the star wobbles ever so slightly due to the gravitational tug from the planet. The radial-velocity (Doppler) method detects this. Since the more massive the planet the stronger the tug, this technique tends to favor finding stars with big planets with nearby orbits.

The important concept here is the center of mass. If two bodies have the same mass, the center of mass of this two-body system is exactly at the midpoint between the two. Someone sitting at this midpoint won’t feel pulled in either direction, since the equal and opposite pulls cancel each other. If the two bodies spin around each other, they will spin about this midpoint.

This changes if the bodies don’t have equal mass. The center of mass is closer to the more massive body. When one body is much more massive than the other, like a star and a planet, the center of mass is almost at the center of the more massive body — but not quite. For example, the center of mass of the Sun-Jupiter system (forgetting the other planets) is at one-thousandth of the Sun-Jupiter distance, just outside the solar surface.

What astronomers observe is not the wobbling itself but variations in the starlight shining in our direction due to the star’s wobbling, which is caused by the Doppler shift, the variation in light’s frequency due to motion of the source or the observer. Think of how an ambulance siren changes as it approaches you and then goes away from you; that’s a result of the Doppler effect. Similarly, when the star approaches us, its light shifts slightly toward the blue (higher frequency) end of the spectrum, and when it moves away from us, its light shifts slightly toward the red (lower frequency) end of the spectrum. When it falls within detection range, this alternating dance of light allows astronomers to detect the planets causing their host star to wobble.

Finding Dimidium

The first exoplanet detected using the Doppler method was discovered in 1995 orbiting the star 51 Pegasi, a G-type star like our Sun orbiting 50.6 light-years away. The discovery earned Swiss astronomers Michel Mayor and Didier Queloz the 2019 Nobel Prize in Physics. (The third winner that year was James Peebles, a pioneering theoretical cosmologist from Princeton University who influenced a whole generation.) The planet, now called Dimidium, is a “hot Jupiter” orbiting its star every 4.2 days. This means the giant planet is very close to its host star, making it very hot — hence the name hot Jupiter. Compare that to our Jupiter, which takes 12 years to orbit the Sun — or even Mercury, which takes three months.

This discovery caused tremendous excitement in the astronomical community, not only for being the first exoplanet found using the Doppler method, but for forcing us to rethink what planetary systems look like. No one would have guessed that gas giant planets could orbit this close to their host stars.

The lesson here is clear: We must be very careful using inductive thinking when trying to generalize properties of stars and their orbiting planets. The fact that our Solar System has the opposite structure, with giant gas planets orbiting the farthest from the Sun, shows the incredible diversity of planetary systems spread around our galaxy and, surely, all galaxies across the Universe.

A question that follows, then, is whether there are very stringent conditions for a planetary system to have planets with life. Surely, Dimidium is a dead world. How common, then, is our Solar System among billions of others? Estimates from 2010 indicate that around 10% of planetary systems are arranged like ours, with gas giants far from their host stars.

Still, we need more data to determine how odd our Solar System is. Current estimates place it as the rarest kind of planetary system in the galaxy, but it’s still early to quantify how rare. Further studying the architecture of planetary systems will reveal secrets of whether we are the odd system with heavy gas giants on the outside and life on one of the rocky planets on the inside.

This article To find a new world, watch how a planet dances with its star is featured on Big Think.

Human beings need origin stories, which is why every human culture has an origin “myth,” a narrative of how the Universe was born and how it came to be the way it appears today. We moderns, however, developed science, which is a particularly powerful way to enter into dialogue with the world.

Our scientific origin story is something called the standard model of cosmology. It is justifiably seen as a triumph of reason and human imagination. Recently, however, in light of new data and other theoretical considerations, the idea of a “crisis in cosmology” has been getting attention. This essay, the final in a series I’ve been doing here at Big Think, is meant as a kind of summation of where we stand right now in that question. 

Is there a crisis in cosmology?  

This attempt at summation also comes in the wake of a very recent New York Times op-ed Marcelo Gleiser and I wrote on the subject. It received a lot of attention (mostly favorable, I’m happy to say), but the point is that it was driven by and informed through the topics I have been exploring in this series. Today, I want to do a deeper dive into some of the issues we raised there and connect them to what we have been unpacking here in our exploration of the state of the standard model.

Let’s start with the 10,000-foot (or maybe the 10,000-parsec) view. I began this series based on a really interesting paper by astrophysicist Fulvio Melia entitled “A Candid Assessment of Standard Cosmology.” Melia’s actual assessment is pretty negative. As he puts it, “The standard model needs a complete overhaul in order to survive.”

I was actually led to this paper via a nice essay on it by Ethan Siegel who, while he disagreed with Melia’s pessimism, reviewed the questions Melia raised favorably, saying that, “There are incontrovertibly very real problems within the concordance model of cosmology, whether you think it needs a complete overhaul or not… It’s important to recognize that the gaps in our understanding are substantial, and some of them could offer clues that lead us to a better understanding of our universe as a whole.”

In his paper, Melia listed a set of problems both observational and theoretical associated with the standard model that he thinks pose major challenges. These include: the now famous and very challenging Hubble tension; the question of too-early black hole and galaxy formation; the question of initial conditions and entropy; and problems with inflation and the cosmic microwave background. In the previous posts in this series, I have tried to explore some of these issues. In the wake of their totality, Melia acknowledges that the standard model does show some spectacular successes in terms of the match between data and theory. But, he argues, some of this success comes because the model has so many knobs (free parameters) that refining their values via observations is not teaching us anything fundamental. 

So, the question, “Is there or is there not an actual crisis in cosmology?” seems to be a matter of commitment to the standard model in its current form. It does seem to me that there are some “incontrovertibly very real problems.” But what happens next is where things get interesting. That’s what Marcelo and I were exploring in in our op-ed and what I want to unpack a bit deeper here as a way of closing our series.

Cosmology is unlike the other sciences

Marcelo and I wanted to explore a question which might be phrased: What happens if we do have to overhaul cosmology? The thing to note here is that cosmology is not like other sciences. Back in the 15th and 16th centuries, the founders of the scientific method were keen to show how you could take parts of the world, isolate them, and then probe them in controlled experiments. Francis Bacon called this “vexing” a phenomenon. Basically, you isolate the thing you want to study and then poke it. The method works great for lab studies of everything from particle physics to chemistry to biology. Even when you cannot isolate or even control your subject of study, as in geology or astronomy, you can look at many different examples of it to draw statistical conclusions. If you are interested in how volcanoes work, look at lots of different volcanoes. If you are interested in how stars work, look at lots of different stars.

Cosmology, however, is an entirely different ball game. We define the Universe to be all there is. So, unless you want to imagine a bunch of unobservable universes that allow you to pretend you can do statistics on them, you are stuck with the one we live in that includes all space, time, matter, and energy. The “all” in that last sentence is what really makes the consequences of having to reboot a cosmological model so consequential. As Marcelo explored in his book The Dancing Universe, there are only a limited set of logical options for dealing with the origin and evolution of everything. Each one of these has its own philosophical issues, like what it means to start a Universe from “nothing.” What do we even mean by nothing? Can there really be nothing? This is why any big change to cosmology could take us headlong into some profound philosophical questions, the kind that have been floating around inside human heads for millennia.

But there is another possibility, one which Marcelo and I were careful to address multiple times and which we can unpack here too. The problems with the standard model may be solved by simply finding adjustments in the model. That, in a sense, is what has been happening for the last 40 years. The classic Big Bang model showed a number of paradoxes associated with the link between the early and modern Universe, so cosmologists added inflation. The luminous matter we could see was moving in ways we could not understand, so we added dark matter. The Universe was unexpectedly accelerating, so we added dark energy. These were big adjustments to the classical Big Bang model, which is built on the Universe’s expansion and its evolution from a hot dense soup of particles (two things that are absolutely not in doubt). Maybe some of the problems we are seeing today can be handled by smaller adjustments. If that happens, then what people are calling the “crisis in cosmology” will turn out to be something far less dramatic.

In science, a crisis is exciting

So, what’s it going to be? As of this moment, I think it is too early to tell. The standard model has been successful enough that it makes sense for most astrophysicists to stick with it. But if the Hubble tension cannot be resolved, if no dark matter particle shows up after another decade or more of searching, and if the issues with inflation that Melia raised remain, then things may change. Over time, astrophysicists will begin exploring alternatives more seriously.

And that leads us to our final point. The whole idea of a “crisis” gives the wrong impression of what happens when a paradigm (in this case, the standard model of cosmology) begins to show problems. It is not a disaster filled with dread and anxiety. Instead, it’s really exciting! What could be cooler than standing at a frontier where nature is trying to show you something new and dramatic?

This article How to understand all the talk about a “crisis in cosmology” is featured on Big Think.

That Earth is unique we all know. Otherwise, we wouldn’t be here asking questions about other worlds. But nature never ceases to amaze, and recently the James Webb Space Telescope just confirmed once again that reality is stranger than fiction.

An exoplanet extravaganza

We now know that most stars have planets orbiting around them. As of today, we have confirmed the existence of 5,514 exoplanets in 4,107 planetary systems, with 928 systems having more than one planet. So roughly, 25% of stars host planetary systems containing 2+ planets and, quite possibly, with moons going around them.

These exoplanets are truly amazing, each different, each with its own composition and history. There are no two worlds exactly alike. Even when astronomers refer to “Earth-like” or “Neptune-like” planets, they mean worlds with masses and radii similar to Earth or Neptune, not duplicates of Earth or Neptune. Enormous variability ensues as planets form, which dictates their chemical composition, geological activity, and atmospheres. So, when discoveries point to worlds with chemicals related, even if superficially, to life, we pay attention.

K2-18 b

This week, NASA announced that the James Webb Space Telescope (JWST) captured the atmospheric spectrum of planet K2-18 b with excellent precision. K2-18 b is a “sub-Neptune” planet — that is, a world with a mass about 8.9 times that of Earth but below that of Neptune, orbiting the cool dwarf star K2-18 (hence the planet’s name) located 120 light-years from Earth in the constellation Leo. Since our Solar System doesn’t have any sub-Neptune planets, this kind of world is poorly understood, even if it is the type most often found in exoplanet searches. Excitingly, K2-18 b orbits within its star’s habitable zone, implying that if there is water on its surface, it could be liquid. And the first guideline when looking for life in other worlds is “follow the water.”

The measured spectrum is good enough for scientists to identify chemical compounds that indicate active chemistry and, if the initial hints are confirmed, even the possibility of some biological activity. The main compounds that stand out in the spectrum are methane, carbon dioxide, and — the most interesting one — dimethyl sulfide, a compound that (at least on Earth) is only produced by life.

It is a familiar and stinky chemical, produced for example when cooking cabbage, beetroots, and seafood. It is also produced by marine phytoplankton. In fact, dimethyl sulfide is often called the “smell of the sea.” If you ever took a walk on a rocky shore during low tide, you know the smell. Also, and I am a fan, it is the main volatile chemical released by truffles, which pigs and dogs use to detect the delicious (and very expensive) fungi. Life is often smelly, including the good stuff.

With the new spectrum and orbital information, scientists are exploring the possibility that K2-18 b could be a Hycean world, with an atmosphere that could be rich in hydrogen and a surface covered by an ocean of water. If all this is confirmed, the discovery would expand our search for life in other worlds to very exotic habitats, huge planets orbiting very close to small and cool stars.

Expect to be surprised

When dealing with potentially very exciting data such as this, scientists must be extra careful to draw conclusions. The signal from dimethyl sulfide is not very robust and will require further observations from Webb’s mid-infrared instrument for validation. Being very close to its parent star means the planet’s surface is likely subject to a high amount of radiation, which is often hostile to life. The ocean, if it exists, may be too hot to be habitable. But life as we know it here on Earth is resilient and creative. And even if no life out there will be as it is here, it’s a safe bet that if it exists elsewhere, it will also be resilient and creative. And it will, no doubt, surprise us in unexpected ways.

This article James Webb Space Telescope finds possible signs of life chemistry on a strange world is featured on Big Think.

Quantum mechanics, the most potent theory physicists have developed, doesn’t make sense. What I mean by that statement is that quantum mechanics — which was developed to describe the microworld of molecules, atoms, and subatomic particles — leaves its users without a common-sense picture of what it describes. Full of what seem to be paradoxes and puzzles, quantum physics demands, for most scientists, an interpretation: a way of making sense of its mathematical formalism in terms of a concrete description of what exists in the world and how we interact with it. Unfortunately, after a century not one but a basketful of “quantum interpretations” have been proposed. Which one is correct? Which one most clearly understands what quantum physics has been trying to tell us these past 100 years?

In light of these questions, I’m beginning a series that explores the most radical of all the quantum interpretations, the one I think gets it right, or at least is pointed in the right direction. It is a relative newcomer to the scene, so you may not have heard of it. But it has been gaining a lot of attention recently because it doesn’t just ask us to reimagine how we view the science of atoms; it asks us to reimagine the process of science itself.

Welcome to the world of “QBism”

The term “QBism” was shorthand for “Quantum Bayesianism” when this idea/theory/interpretation was first proposed in the late 1990s and early 2000s. The name hit the nail on the head because “Bayesianism” is a radical way of interpreting probabilities. The Bayesianist approach to what we mean by probability differs strongly from what you learned in school about coin flips and dice rolls and how frequently a particular result can be expected to appear. Since probabilities lie at the heart of quantum mechanics, QBism zeroed in on a key aspect of quantum formalism — one that other interpretations had missed or swept under the rug — because it focused squarely on how we interpret probabilities. We’re going to dig deep into all of this as we go along in this series, but since today’s column is supposed to be the introduction, let’s start with a 10,000-foot view of what’s at stake in the great “Quantum Interpretation Wars” so we can see where QBism fits in.

The most radical departure that quantum physics makes from its classical physics predecessor is its treatment of what’s called “the state.” To be explicit, let’s think about a particle of matter.  Classically, the particle’s state refers to its position and momentum (think “velocity”).  In classical physics, we also have “dynamical” equations, like Newton’s laws, which describe how the particle’s position and momentum (the state) change with time. In this view, the state is considered to be a property that the particle has independent of anything else (like the person making measurements on the particle). Properties are self-existing and “objective.” In addition, classical physics says that particles can have exactly one state at any moment in time, and it’s only the dynamical equation that sets how that state changes. Objective states and the rule of dynamical equations are what classical physics is all about.

However, things are very different in quantum mechanics. Quantum states can be “superposed,” meaning a particle can have many values of position and momentum at the same time (like a coffee cup being in many places at one time). Worse, the quantum mechanical dynamical equation (called the Schrödinger equation) does not describe the particle for all time. Instead, it is exactly at the moment when a measurement is made that the Schrödinger equation gets a pink slip. At that moment, the state is determined not through the deterministic dynamical equation but through what’s called the Born rule and its specifications of probabilities for the different outcomes in the superposed state.

Many quantum interpretations have recoiled in horror from this situation. Their goal is to try to preserve the classical view where physics equations are kind of like “the thoughts in God’s mind.” These interpretations take an ontological view of the quantum state, including its superpositions. The quantum state is really real. It is “out there,” as a real thing in the real world, independent of us. But given the superpositions, there is a price to pay for this kind of ontological commitment: the addition of things into the Universe for which there is zero evidence, such as parallel universes splitting off every time a quantum measurement is made. Parallel universes sound cool for science-fiction movies, but really they’re an extravagant price to pay for holding on to the metaphysical preferences of classical physics.

A radical conclusion

QBism takes an entirely different stance. It looks at the changes that the inventors of quantum mechanics were forced to make and draws a truly radical but also radically level-headed conclusion: The quantum state, with its simultaneous superposed possibilities, is not something that exists out there by itself. A state is not something a particle “has” as a property, like the way a house has the property of being painted blue. Instead, quantum states are about our knowledge of the world. They are descriptions encoding our interactions with particles. QBism would say it’s not the particle’s state — it’s your state about the particle. QBism leads not with ontology — a story about what fundamentally exists independent of us — but with epistemology: a story about our information about the world. That change makes all the difference. By refusing to force an old philosophy that came prepackaged with classical physics to be retained no matter what the cost, QBism doesn’t have to force us to accept science-fiction stories about parallel realities (or other such unobservable “entities”) into science. Instead, QBism leads with experience. What, it asks, actually happens when human beings do quantum physics?

The answer QBism produces is as radical as it is mundane. By turning away from an impossible (and paradoxical) God’s-eye view of the Universe, QBism puts human beings squarely in the middle of the scientific enterprise. In this way, I believe, it “gets” what quantum mechanics has been trying to tell us since its invention a century ago. To do physics is not to gain some mythical and supreme perspective but to watch as subjects (people like you and me) gain knowledge about the world. What’s more, and what’s more exciting than that mythical supreme view, is that really understanding quantum mechanics means understanding how we and the world are always woven together as an inextricable whole. Unpacking that perspective is what’s at the heart of QBism’s ambitious research program, and it’s what we’ll be unpacking as this series progresses.

(Just a note: I’ll be filling out this series over the course of the next few months, so stay tuned!)

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When Nicolaus Copernicus published his famous book in 1543, he couldn’t have guessed that it would start a revolution. Copernicus went against what everyone had thought for thousands of years, proposing that the Sun and not the Earth was the center of the cosmos. (One exception was Aristarchus of Samos in ancient Greece, but his ideas didn’t get much traction due to the power of Aristotelian philosophy in people’s minds.) There was no Copernican revolution, at least not immediately, for fascinating (but also tragic) reasons. The first serious proponents of heliocentrism were Johannes Kepler and Galileo, some 60 years after Copernicus’ book was published.

Since then, Copernicanism came to signify much more than the correct arrangement of our Solar System, becoming a symbol of our cosmic insignificance — namely, that the more we learn about the Universe, the less relevant our planet, life, and us humans become. This kind of thinking is predominant in the astronomical sciences and cosmology, based on what we can broadly call the dogma of large numbers: There are hundreds of billions of stars in our galaxy, most of them with planets. This brings the number of planets and moons in our galaxy alone to the trillions. Hence, there will be Earth-like planets in abundance. Hence, we are not special in any way. Furthermore, since the laws of physics and chemistry are the same across the known Universe (which is true), we must conclude that we are not special at all. Hence, if life emerged here, it should be ubiquitous in the Universe.

Everything in the above paragraph is correct, except for two things: (1) What we mean by “Earth-like,” and (2) the last sentence, “If life emerged here, it should be ubiquitous in the Universe.” Let’s take each separately.

What do we mean by “Earth-like”?

When astronomers refer to an “Earth-like” planet, they mean a planet with similar (within a small margin) mass and radius as Earth that also orbits its parent star within the so-called habitable zone. The habitable zone is usually defined as the region around the star where a planet will have liquid water on its surface, if it has water at all.

This operational definition of Earth-like is very useful for astronomers to quickly qualify whether a planet could host life. But it has nothing to say about whether the planet actually hosts any life. From water to biology is a huge and still very mysterious step (in fact, many steps.) So, in astronomy, Earth-like really means a rocky world with similar density as Earth and with liquid water, possibly. To be sure, that’s not another Earth.

An unjustified leap of logic

We cannot use inductive thinking to say anything certain about biology and the emergence of life in another world. There is nothing connecting a rocky world with water to a world like ours, with a thriving biosphere. So, to generalize from “there are many Earth-like worlds” in the astronomical sense to “there are many worlds with life” using large numbers to argue for the ubiquity of life in the Universe is an unjustified logical step. Copernicanism, as an astronomical statement about the non-centrality of Earth in the Solar System, has nothing to say about life, here or anywhere else in the Universe. Biology calls for a very different set of rules, as Stuart Kauffman and others have stressed recently.

This leaves us with a paradox. If we don’t really know what life is or how it emerged on Earth some 3.5 billion years ago, it becomes very hard (if not impossible for now) to quantify the existence of life elsewhere. We have no life metric. Physical scientists love to extrapolate from limited data, and sometimes this works quite well, especially when we have a statistical hold on the subject and can compare probabilities of events. But life is different, and we must accept the fact that we don’t know how to quantify its cosmic frequency.

Beyond Copernicanism

The consequences of this fact are profound, as I recently argued in my book, The Dawn of a Mindful Universe: A Manifesto for Humanity’s Future. If we must move beyond Copernicanism when it comes to arguing for abundant life in the Universe, we must also accept our cosmic loneliness and rethink how we relate to our planet and life on it.

Given the current state of our world, the critical point of our climate crisis looming, this change of mindset becomes an existential safeguard. We take care of what we judge precious, of what we value. Looking at our planet with post-Copernican eyes has the power to change how we relate to it — not as just another world, but as a true marvel of cosmic evolution, a rare oasis where matter can assemble itself and becoming a living, thinking thing that ponders about its future.

This article Post-Copernicanism: How the great mystery of life can save us from ourselves is featured on Big Think.

Dr. William Egginton is the Decker Professor in the Humanities and Director of the Alexander Grass Humanities Institute of the Johns Hopkins University. I spoke with him recently about his new book, The Rigor of Angels: Borges, Heisenberg, Kant, and the Ultimate Nature of Reality.

Marcelo Gleiser: Your book brings together three of the greatest Western minds from physics, literature, and philosophy, subjects that aren’t often presented together. There is a plan here, one that I am sure speaks to the very soul of this project. Can you elaborate on why these three, and how their fictional encounter illuminates your goals in writing this book?

William Egginton: This book is the fruit of several decades of reading, teaching, and thinking about the intersections between literature, philosophy, and physics. Obviously that trajectory encompassed so many more writers, thinkers, and scientists than these three. So when the time came to wrangle the project into a book, the question became: How to organize it? Who are the best characters through whom to tell this story, and how many should there be?

My first stabs at a structure were more expansive. I liked the idea of telling stories about specific human beings and distilling their insights out of those stories. But at first there were simply too many stories there — I believe I outlined a 12-chapter book with a different central character for each chapter — and the book felt scattered, even if the core intellectual project was the same. After that I reigned it in, but perhaps a little too much.

I sketched out what would have been a literary biography of one man. It was Boethius, believe it or not, who still plays a minor role in one of the chapters. But Boethius was too far away historically from some of the major innovations of 20th-century physics that I wanted to engage with. Then it hit me. Some years ago, I had published a little article on what would become the topic of the book in The New York Times. It had three central characters: [Jorge Luis] Borges, [Werner] Heisenberg, and [Immanuel] Kant. They had been there all the time! Returning to those specific figures I realized that among them, they had all the elements I needed.

The core idea was always to show how thinking deeply about a problem can lead to profound insights independently of the specific field of the thinker. In other words, “soft” humanistic approaches can enlighten “hard” scientific ones, and vice versa. In these three I believed I had found my proof of concept, since reading Borges, and then using Kant to think through some of the questions provoked by Borges, had over the years led me to a deeper understanding of what Heisenberg had actually discovered than had just reading Heisenberg and explanations of his discovery.

To be a bit more specific, Borges’ story about a man who becomes incapable of forgetting anything, incapable of any slippages or gaps in his perception of the world, when read through Kant’s analysis of the synthesis required for any experience in time and space to take place in the first place, lay bare in clarion (albeit non-mathematical) logic what Heisenberg had proven in his 1927 paper: An observation, say of a particle in motion, can’t ever achieve perfection because the very essence of an observation depends on there being a minimal difference between what is observed and what is observing.

It’s not about agency; it’s not about brain science; it’s a logical necessity built into the very nature of an observation. It wasn’t until the quantum revolution that the instruments became powerful enough for humanity to run into this limit. And it wasn’t until Heisenberg that anyone could put a number to it (even if Planck’s constant had been popping up for some time!), or, as he did, derive it as a fundamental principle.

Marcelo Gleiser: How does your book speak to the perplexities of being human, our existential angst of being aware of time’s passage and our mortality?

William Egginton: Part of what I wanted to keep at the forefront of the project is what you could call the existential dimension of what these thinkers were drawn to and what they discovered. “Existential” should here be understood in a quite specific way; precisely how [Jean-Paul] Sartre meant it when he glibly spoke of existentialism as reversing the traditional binary of essence and existence. Each of these thinkers — whether through storytelling, confronting philosophical shibboleths, or trying to use mathematics to explain experimental results — was inexorably drawn to what we could call a confrontation with existence.

In Borges’ case, this confrontation emerges as characters he creates explore some widely held presumption we tend to have about the world, push that presumption to its absolute limit, and then find that it fails them. In Kant’s, it came from his struggle with Humean skepticism, which wouldn’t allow him to rest on the rationalist certitude that we are able to know the world because our ideas and the world are of the same substance. In Heisenberg’s case, it shows in his willingness to cast aside anything but the observation itself, and insist, as he did to his dying day, that with science we seek not to explain nature itself, but “nature exposed to our method of questioning.”

What I then try to do in the book is follow how this realization manifests in their lives; what kind of consequence it must have had for people who took their art, their philosophy, and their science so seriously, to realize and hold true to the realization that we do not discover the world as it is but rather must create the very framework that allows us to understand it. Time, in such an understanding of the world, ceases to become a secondary effect, something that we can try to stave off, avoid. To avoid time would be to avoid the very condition of possibility of experiencing the world in the first place. We can only have the world because we can lose it, because we are losing it, every second of every day. Likewise, every choice we make involves the irrevocable loss of other possibilities. And those possibilities, those “roads not taken,” in your fellow New Hampshirite Robert Frost’s great poem, only exist because we have not taken them; they exist as and only as roads of regret.

Marcelo Gleiser: An underlying theme that seems to weave your narrative is the tension between our urge to know — of reaching some sort of “final” answer to our deepest questions about existence — and the impossibility of ever finding these answers. Are we to find some level of consolation in the very act of trying, or are we doomed to an existential dead-end?

William Egginton: Here I really think the least poetic of the three (well, okay, would that be Heisenberg or Kant? —well, here I mean Heisenberg) put it most powerfully. In his “1942 Manuscript” he wrote, “The ability of human beings to understand is without limit. About the ultimate things we cannot speak.”

I think Heisenberg was articulating here something about what I take to be the “internal” or “intrinsic” limitations of knowledge. The quest for knowledge cannot come to an end because our knowledge is intrinsically lacking. To know the world perfectly, in its totality, would be to have access to those “ultimate things” — it would be to stand outside of all existence, outside of time and space, the way that Augustine and the Neo-Platonists imagined God, as capable of grasping the Oneness of being in its entirety, its eternity. And obviously such a knowledge is absolutely, utterly incompatible with anything we can conceive of as human knowledge, which is precisely why our absolute inability to know absolutely, in this sense of “ultimate things,” is a wonderful, hopeful truth! It’s the very opposite of a dead-end because it’s the realization that by its very nature knowledge can never, ever meet such a dead-end.

Marcelo Gleiser: All three of your “characters” had to come to terms with loss. Love and loss, the loss of certainty and objectivity, the loss of a sort of platonic innocence related to the boundless powers of the mind. Loss seems to be an unavoidable part of being human, perhaps even a necessary one. Is loss, then, our greatest teacher of how to find meaning in life? If so, is it fair to say that your book is an optimistic take on the human condition, a guide to self-knowledge and growth?

William Egginton: It is very fair to say that. As I gestured above, their stories, philosophy, and science had existential implications, which each delved into in his own way. There can be no love without the ever-present possibility of loss; no truth without the foil of error and falsehood; no goodness without the possibility of choosing evil. While they labored in creating fiction, philosophy, and science, the unified implication of their work is a view of the world that demands our investment, our commitment, and ultimately our responsibility.

But unlike Sartre, for whom freedom was something we humans are condemned to, my take is, as you say, optimistic. For me, as someone who has learned at the feet of Borges, Kant, and Heisenberg, as well as many others who make appearances in this book, the truth that the rigor we find in the world is a rigor of chess masters, not of angels (as Borges so beautifully put it), still allows that it is a rigor, nonetheless. What we encounter when we study the world, when we deal with relations between us and other people, when we judge the beauty of a work of art — of course these are human perceptions, human codes, human values! But that doesn’t make them any less real, any less shared. In the philosophy I distill from these thinkers, neither AI nor neuroscience can take away one iota of our freedom to choose or our responsibility to each other and the planet — and I think that’s a good thing. In fact, I think it’s the only thing that can possibly save us.

Marcelo Gleiser: Every choice involves loss, the loss of what you have not chosen. Can you address the question of choice and free will in the light of your arguments?

William Egginton: One of the big philosophical discussions that the book opens up is how there can be free will in a mechanistic universe. The first thing to say here is that what I absolutely don’t advocate for is the idea that quantum uncertainty somehow leads to free will because it undermines determinism. Heisenberg correctly said that his discovery overturned Laplace’s demon, because at the quantum level it becomes impossible to know simultaneously the exact location and momentum of a particle, and hence the very presupposition of Laplace’s thought experiment ceases to hold. But the fact that mechanistic determinism is replaced by quantum indeterminacy doesn’t help save free will.

Rather, what I argue for in the book is a thoroughly compatibilist understanding of free will, one that was worked out by Kant but that has its roots in Neo-Platonist thought. We can fully embrace the idea that the human agent is a material entity in a material world ruled by the laws of physics, both quantum and classical, and at the same time find no contradiction at all in the notion that the human agent finds itself at a crossroads where it more or less freely, depending on the situation, chooses what to do. The fact that the choices take time and involve physical processes doesn’t make them any less free. The notion that they can’t be free because the trajectory of the deciding agent is knowable from beginning to end and hence somehow already decided for it is false, because it imports into a temporal spatial reality a presumption of non-temporal, non-spatial knowledge.

Early philosophers like Boethius could imagine a far more powerful foil to human freedom than mere neuroscience — namely an omniscient God — but were still able to see that God’s omniscience would easily coexist with human freedom, because God’s knowledge is outside of time and space and all human decisions take place inside time and space. So how much easier should it be to see that our extrapolations of knowledge about, say, neural processes are just as incapable of making serious arguments about an existential reality that we all live, all the time, namely, the obligation to choose.

Marcelo Gleiser: We tend to want to be sure, to be certain of everything we do, of the choices we make in life. But you are saying that this is not a realistic expectation. Why is uncertainty a good thing?

William Egginton: Because our presumptions of certainty lead to arrogance, to closed-mindedness, and to shutting down new avenues of thought. Science is about observing, experimenting, and coming up with provisional explanations. Those explanations are vetted by communities and, if they are upheld by evidence, accepted as the best explanation we have so far. But science doesn’t get where it’s gotten by deciding the game is up, that we have the ultimate solution and there’s no sense in thinking any more about this.

Yes, resources and time are limited, and obviously problems are put aside when a satisfactory solution has been obtained and seems to work to everyone’s satisfaction. But that is not the same as saying that a final, certain, and never-to-be-questioned answer has finally arisen. There always can come a time when a prior theory is upset by new evidence, and this is precisely how we continue to learn and grow as a species. In the end, this position is a version of what Socrates said in the Apology, that “what I do not know I do not think I know either.” Words justifiably held up as a kind of model of wisdom, and the kind of intellectual humility that should guide not only the scientific method, but how we go about judging the actions of others, and ourselves.

This article A meeting of the greatest minds in science, philosophy, and literature is featured on Big Think.

“At the very beginning of history, we find the extraordinary monuments of Paleolithic art, standing as a problem to all theories of human development, and a delicate test of their truth.”
—R.G. Collingwood

This quote and the problem it describes drives The Entanglement by Alva Noë, a new book on art, philosophy, and what it means to be human. Almost as far back as we want to go in the story of humanity, there is art standing in a central, pivotal location. The question that Noë, a philosopher at the University of California-Berkeley, wants to understand is simple: Why? Why is art so central to our development that we cannot tell the story of humanity without it?

The centrality of art

In the modern world, we tend to view science and technology as the most important achievements — the true pinnacles of human ability. While we acknowledge that art is something only humans do, it tends to get relegated to the domain of “mere” beauty or pleasure. In this view, art is important, in its own way, but it simply does not have the same sort of cosmic relevance as the theory of general relativity or the standard model of particle physics. 

The key point of The Entanglement, however, is that this kind of hierarchy is a profound mistake. Art is just as much about revealing the essential as science is. You might even say that the making of art comes before science in reaching down to our very roots — those deep philosophical underpinnings that allow human beings the ability to unveil hidden truths.

The fact of art’s central place in human development speaks to the problem Collingwood identifies in the quote above. We are physically embodied. That is the central fact of our lives. We don’t start off as brains in a vat contemplating the perfect platonic abstractions of mathematical physics. Instead, we begin with the constraints of being in bodies. But being human also means we are constrained by our cultures. By this, I mean the simple fact that we emerge into the world as part of a community of other language users from whom we are given the shape of our world of experience. This includes the norms of social behavior and the tools that shape the material facts of daily life. From our earliest origins as Homo sapiens living in small tribes, we both have been made by the world as much we make it. And that is why art has always been central to human experience. 

As Noë puts it: “To say that art and life are entangled is to propose not only that we make art out of life — that life supplies art’s raw materials — but further that art then works those materials over and changes them. Art makes life new” [emphasis added].

Freedom from constraints

What Noë means here is that while we are given the world and constrained by it, we always have pushed back against those constraints in a way that seeks to free us from them. Noë points to the example of language. We can use language to “speak plainly,” meaning to describe things and make plans that further our project of surviving in the world. But then comes the possibility of irony, the ability to use language in a way that subverts itself. In that subversion, what was plain, ordinary, and even habitual suddenly stands out on its own. The use of irony — one form of many that can be used in art — is a kind of attempt at emancipation from the brute facts of our embodiment. In this way, it is a key step that opens an entirely different way of encountering the world. As Noë says, art requires that “we work ourselves over and make ourselves anew, individually and ensemble.”

That “making ourselves anew” is why I find Noë’s ideas so compelling and relevant for science. For me, science is not simply the picking up of “facts” that are lying around. Instead, it’s a kind of sympathetic creative exchange with the world in which we are enmeshed through embodiment. The world is not simply “out there,” and science is not simply a view through “God’s eyes.” Instead, we are always entangled with the world.

What Noë shows is how that essential act of “making” art is more than just an act of pleasure. What it really encompasses is a radical act of inquiry into our entanglement. It’s the first recognition of the inescapable fact that it’s always us and the world. We recognize that fact by understanding that we have the possibility of re-seeing the world and remaking it through the making of art. For me, it’s only through that kind of recognition that true science and its abstractions become possible.

This article Why the truth of art is greater than the truth of science is featured on Big Think.

A Universe without life is a dead Universe. A Universe without minds has no memory. A Universe without memory has no history. The dawn of humanity marked the dawn of a mindful Universe, a Universe that after 13.8 billion years of quiet expansion found a voice to tell its story. Before life existed, the Universe was confined to physics and chemistry, stars forging chemical elements within their entrails and spreading them across space. There was no purpose to any of this, no grand plan of Creation. Through the unfolding of time, matter interacted with itself, as gravity sculpted galaxies and their stars. The emergence of life on Earth changed everything. Living matter doesn’t simply undergo passive transformations. Life is “animated” matter, matter with purpose, the purpose of surviving. Ecotheologian Thomas Berry wrote, “The term animal will forever indicate an ensouled being.” Life is a blending of elements that manifests as purpose. This sense of purpose, this autonomous drive to survive, is what defines life at its most general.

And in our world, the mountains, rivers, oceans, and air sustain every living being. Life elsewhere may be very different from life here. But if it exists, it must share the same urge to survive, to perpetuate itself in deep communion with its environment. The alternative, of course, is extinction. When life exists, it will struggle to remain existing. Life is matter with intentionality.

Life without higher levels of cognition doesn’t know itself as living. It knows it needs to survive and will do what it can to remain alive, developing survival strategies with varying levels of complexity. It will search for food, eat when hungry, and sleep when tired; it will find or build shelter; it will protect itself and its young; it will fight to remain alive through force or strategy, as even plants are believed to do. Species evolved all sorts of remarkable tricks and weaponry to stay alive. Different animals have a range of emotions that may be quite expansive, although it is hard to truly understand what goes on in their psyches. Some may feel joy or sadness; some may help members of their species and even of other species, developing a true sense of companionship and caring. (Why else would we have pets?) But deep as their emotions might be, animals don’t ponder the meaning of their existence. They don’t have the urge to tell their stories and wonder about their origins. We do.

And what have we done with this remarkable ability? We became expert hunters and warriors, we became artists and storytellers, we worshipped gods and coveted love and power. We became a paradox, half beasts, half gods, capable of the most beautiful creations and the most atrocious crimes. We became the greatest lovers and the greatest murderers, thinking ourselves masters of this planet. We have turned our backs to the teachings of our ancestors and Indigenous cultures, who worshipped the land as their mother and the animals as their peers. We can tame much of what we fear, from fire to lions, and this power makes us giddy. But our ancestors knew, as we do, that we can’t tame Nature. We can bend the course of rivers and raze forests, we can bring whole species into extinction, but we can’t control the emergence of new diseases or stop cataclysmic events from killing us. We can kill wolves and tigers but not stop volcanoes from erupting. We are big and we are small, powerful, and limited. 

Our success has lulled us into a false sense of confidence, leading us to believe that we are above Nature. But our planet, vast as it is, is limited, and it is responding to our voracity in ways that might destroy us or, at the very least, compromise the future of our species and countless others. We coevolve with Nature and can’t extricate ourselves from its dynamics. To believe we can is our biggest mistake. Still, this is what we have attempted to do, creating a chasm separating us from the rest of Nature. We built huge cities and factories and country-sized mechanized agricultural monocultures, pushing wilderness to the unreachable fringes of the land. We consumed the planet’s entrails, the oil and gas and coal, to feed our industrial growth. We lost touch with our evolutionary origins, with our roots in the wild, and we have forgotten who we are and where we came from. We have desecrated the land that sustains us, treating the world as our property.

This old narrative of the human has reached its end. The time has come for new humans, humans who understand that all forms of life are codependent, who have the humility to position themselves alongside all living creatures, and not above them. We have seen that this new narrative for humanity is founded on a confluence of cultures, merging Indigenous traditions with our growing scientific knowledge of the trillions of worlds around us. This new vision for humanity combines reason and spirituality, the material and the sacred, refusing to objectify the natural world. The fundamental tenet of this biocentric view is that a planet that holds life is sacred. And what is sacred must be revered and protected. A planet that holds life is profoundly different from the countless barren worlds spread across the vastness of space, marvelous as they might be. A planet that holds life is a living planet, and a living planet is where Cosmos and life embrace each other and create an irreducible wholeness. And of all the planets that may hold life in this galaxy and others, ours is a beacon of hope for being home to a species of storytellers.

The more we look to other worlds in search of signs of life, the more we realize how rare Earth is, how rare life is, how rare we are. We are the cosmic voice, capable of telling the cosmic story, and we need to rise above our destructive urges and our greed for immediate gratification to reorient our future. The story we have been telling until now, the Copernican narrative that we don’t matter in the big scheme of things, that Earth is just a planet among trillions of others, is simply wrong. We matter because we are the only life-form that knows what it means to matter. We matter because we now understand how we are evolutionarily connected to every other life-form on this planet, descended as we are from the same bacterial ancestor. We matter because we know that life here is contingent on the whole cosmic history, from the properties of subatomic particles to the expansion of the Universe. We matter because we are how the Universe ponders its own existence. We matter because the Universe exists through our minds.

Moral rules are hardly universal. Those that to one group are terrorists, to another are freedom fighters. Values esteemed in one culture are criminalized in another. Different religions and political philosophies have different moral codes, and these differences have led to war and destruction across millennia. But the new understanding of how rare life is in this solar system and probably in most others should elevate one moral rule above all others. We no longer should think of the Universe only as a physical system. We must think of the Universe as home to life. The sacredness of a living planet is the central tenet of our post-Copernican narrative. We protect what is rare and precious. Life on Earth is rare and precious, planet and biosphere entangled in a single wholeness.

There is no life without Earth, but there is Earth without life. To transform Earth into one of our barren solar system neighbors would be the greatest crime humankind could commit against itself, against all life, against the Cosmos. Biocentrism is a vision for a morally aware humanity that celebrates and protects all forms of life as the only way to secure a healthy future for our project of civilization. It reaches beyond pre-Copernican human exceptionalism (we are the center of all Creation) and Copernican nihilism (we are nothing in the cosmic vastness), given that it weaves humankind into the web of life, the irreducible wholeness that enshrines the planet. Biocentrism presents humankind with a collective purpose, since, barring Earth experiencing a cataclysmic collision with a large asteroid, we alone have the power to preserve or destroy the biosphere. The alternative — inaction and neglect — will bring great suffering to all sectors of the population, especially — but certainly not exclusively — to those of weaker economic means and to our children and subsequent generations. The choice should be obvious.

This article “Biocentrism”: A scientific answer to the meaning of life is featured on Big Think.

There are ten billion trillion planets in the visible Universe where life might form. Given that spectacularly large number, most people would argue that we cannot be the only intelligent self-aware creatures in the cosmos. And from that conclusion, there sometimes comes a profound sense of our insignificance. How can we humans matter at all in the face of such a vast Universe brimming with planets and, potentially, life?

That conclusion is, however, just as profoundly misguided. This is the major thrust of my colleague and fellow 13.8 writer Marcelo Gleiser’s new book The Dawn of a Mindful Universe: A Manifesto for Humanity’s Future. Gleiser has written a broad and sweeping argument for a fundamental shift in how we understand ourselves and our cosmic setting with equally fundamental consequences for the future (if we are to have one). Here, I want to focus on one particular point that lies at the heart of his argument.

There can be only one Earth

With his usual mix of a poet’s ear and scientist’s acumen, Gleiser gives us a grand tour of astronomy, physics, and astrobiology to set the stage for asking the question: How can we matter in such a vast Universe? Detailed descriptions of the evolution of planets and life lead him to a startling conclusion: There can only be one Earth. It is from that vantage point that a new perspective on ourselves and our future emerges.

That ten billion trillion number certainly tells us that the cosmos has had a lot of planets on which to run experiments with life and civilization. But what it does not reveal is how specific the outcome of those experiments will be. The details of evolution on each world will be extraordinarily contingent on so many accidents that no two worlds will have the same history. That might seem like a small point, but when we add the evolution of life into the mix, those accidents start to matter.

Take the balance of land and water. Earth is approximately two-thirds covered by oceans. Why only two-thirds and not more or less? It turns out the delivery of water to the planet came through its early bombardment by comets and asteroids. The exact number of those planetary interlopers was a complete accident. In fact, we should expect that most planets will lie on the extremes of water delivery. Either they got so much water through comet impacts that all basins are entirely filled, and the water rises above whatever continents exist, or they got almost no water at all. This means most planets will either be water worlds or desert worlds. The almost half and half mix we ended up with may be very improbable. This has huge implications for the specifics of life’s evolutionary trajectory on each world. On Earth, tidal regions at the intersection between ocean and land played an important role in our world’s biological linages.

What all this means is we will not find another Earth. Our planet’s history is unique, and as a result, so is its life. There may be other planets with life, but they will have their own trajectories — including the possible development of minds. The origin of self-awareness on Earth is likely to have attributes that reflect our planet’s specific history. That means we are likely to be utterly and particularly unique in all the Universe.

Beyond the Copernican principle

It is from this vantage point that Gleiser makes his radical proposal. It is time to go beyond the “Copernican Principle” — sometimes called the “principle of cosmic mediocrity” when it comes to humanity. In his view, we need to tell a new story about ourselves that acknowledges how and why we are unique, even if there are other inhabited planets. The kind of “biocentrism” he argues for puts humanity back into the center of a story of a singular planet and its singular history. Only then, he says, will we be able see how precious, and even sacred, is the world upon which we find ourselves.

Human civilization faces profound challenges, ranging from nuclear war to climate change to unchecked AI. I think Gleiser is right that the worldview we have been living with is not up to the task of dealing with these challenges. We need a different kind of story, and the one he offers is both grounded in science and rooted in wisdom.

This article Beyond the Copernican principle: A radical idea rethinks humanity’s place in the cosmos is featured on Big Think.