74. Astrobiology, natural laws of the universe, confronting bias.

Hi, everyone. It's another episode of Tom Psycast, where we explore the universe. And today, we are going to really explore the universe. Every fall semester, I have started teaching a class in astrobiology. So this podcast today is going to basically be my first lecture in my class of astrobiology. So I call it, of course, an introduction to astrobiology. And it's a field that is really fun for me to study. In fact, it's been one of the most intellectually challenging things I've done in my career as scientists. It's pretty amazing. And in fact, I'm going to slowly move into this field as I start to publish more papers on astrobiology. But the question is, what is astrobiology? Well, I look this question up because there's a lot of really smart people that do astrobiology. And I went to NASA. Where else could you go? Right? And NASA defines astrobiology as a study of the origins, the evolution, distribution, and future of life in the universe. I'll tell you what, that gives us a lot to talk about any single semester. But in addition to that NASA definition, I have to add in what is life? You see, that's a question that we don't think about a lot. And I'm going to do yet another podcast on my current views of life, because I have changed the way I think about what is life so much in the last four years. I mean paradigm shifting. But that's the case for another podcast later on in the semester. And it's hopefully one of the papers that I hope to put out soon. So in addition to, you know, the origins of life, you need to understand what is life and come up with a unified theory of life, something we're still working on. But the other one, origins of life, that's a very important question. It's like, how did life emerge? Where did life emerge? When? And why did life begin? Now, that's an interesting question. Why is it a fluke? Is, are we literally a one and trillion trillion chance in the universe? The only chance of life, the only example of life or is universe teaming with life? Is there some type of deterministic process that drives the origins of life across the universe? I don't know. We're going to find out, hopefully, I'm going to make some predictions about that, of course. Now, once life begins anywhere, it's most likely going to evolve. And it's going to evolve along with its planet and its planetary system. And there are physical laws of nature that life must follow. And we'll get into those natural laws of the universe that are important for life, because life is going to follow them. So there are going to be convergence across the universe. There's going to be, I would imagine some deterministic or preordained outcomes. And that's interesting. And also the role of contingency, how important are random events in the, in the evolution of life in the universe, along with what, what does it take for major evolutionary transitions? And I define a transition is basically the way that you use information in a very different way, along with key biological innovations, like photosynthesis. That was really important. And then how does all of this lead to complexity? And if you're like me, I really wonder, are there other advanced civilizations out there? And for an advanced civilization to evolve on a planet, there has to be some things that happened in this evolutionary history leading to that level of evolutionary complexity. So for me, that's a very interesting question, you know, the evolution of life and what it takes. Now next is the distribution of life. Like where are we going to potentially find a life in the universe? And once we have a good definition of life or a theory of life, then we can start to make predictions about where we might find a life. Now, of course, when we start talking about the distribution of life, I love going into the Fermi Paradox, biosignatures, tech signatures. So I really like thinking about Kardashev scale, Drake equations, stuff like that. Those are just really fascinating topics. And if you're not familiar with the Kardashev scale, that's what Nikolai Kardashev came up with a type 1, a type 2, or a type 3 civilizations, that we call planetary stellar and neglected civilizations. Based on energy usage, and it's a way that we could look for science of a technologically advanced civilization. And then lastly, I love the idea that we can be a bit speculative about life in the universe. You know, this, our imaginations, philosophy, and science all kind of come together here to ask a question, well, how long can life persist in the universe? All stellar systems have a life cycle. And believe it or not, there's only about a hundred or no, sorry, a thousand trillion years left of this de la Fris era of the universe. Now that might sound like an unfathomable amount of time, like something we just can't even really understand. But in the total age of the universe, time is just beginning when the last star dies out. So how long can life persist in the universe? Can it survive past the age of stars? Because that is really the beginning of what's happening in the universe. So as you can imagine, we get a lot to discuss in a semester of astrobiology, right? And I always like to walk in right as class begins and go, you know what, we're going to talk about aliens in this class. And what class in college do you get to have a serious and philosophical conversation about aliens in the universe? Okay, this is to me just so fascinating. Even though my friends had the giggle factor when I talk about astrobiology, they're like, is that even a real science? And it is absolutely a real science. And that begs the question, if we've never discovered life yet, or if we haven't discovered life yet, why do we study astrobiology? And honestly, I like to brag a little bit. I've got 80 students in this class. And that's a 400 level senior class and also graduate class and one of the largest 400s in our in our university, even in our department with a lot of med students. So clearly, there's a reason why people are taking this class. And I think it really comes down to curiosity. It really shows that our students and myself, and I think it's a reflection of our own society. There's a lot of curiosity about astrobiology. And there's an age old question. Are we alone in the universe? And we don't know the answer yet, but we are in a golden age of exploration. I mean, we're just really getting started. Now, I've called biology, the apex of science. But in reality, astrobiology is the apex of science in almost every single way. And for me, that's another reason why I really like astrobiology. It's so integrative. You need to know not just biology. Biology is a very, very broad field. It's important to know things about physiology, ecology, and evolution. It's important to know about geology, atmosphere, science is important to know about, guess what, astronomy, stellar processes, those lead to the origins of all the elements. Life on this earth is largely tied to the output of energy from our sun. However, it's also a planetary phenomena. So we need to know geology. It's one of my geology friends once told me he goes, "Eenatom, um, biology is really just a subset of geological processes." I'm like, "Well, you're right. It's a very important subset of geological processes because most of the minerals formed on the surface are there because of life." Oxygen in the atmosphere, for example. So not only does astrobiology depend on astrophysics, geology, various branches of biology, and atmosphere science. It also depends, of course, on chemistry. The biology of life is dependent on a bunch of chemical reactions. It's also dependent on physics and, believe it or not, it's also important to understand information theory to understand life as well. So biology sits on top of all the other sciences. Let me think about that, right? Astrobiology incorporates basically every branch of science. Not only is astrobiology the apex of science, it's also what we call a pre-paradematic field, and it is rapidly growing. Now, what I mean by pre-paradematic field is, well, of course, the Giggle factor is we've never discovered life outside of Earth. That means the field is wide open. We don't really have a full-on theory of life. We don't have a paradigm. This is an overarching theme of our construct to understand life in the universe yet. We haven't figured that out. Now, if you're wondering what a paradigmatic field it looks like, think about biology, where I come from. The central paradigm of biology is basically nothing in biology makes sense except in the light of evolution because evolution explains both the unity and diversity of life. Evolution explains why we have millions of different species because they're constantly evolving. That's the diversity of life, and then the unity of life arises from the fact that if you go back further and further in time, all life shares common ancestry. You share common ancestry with all of their mammals. The unity of mammals is we have mammary glands. We're endothermic. We have hair. You guys get the idea. That's the central paradigm of biology, but astrobiology is pre-paradematic because we don't exactly have a paradigm explaining what life is, why it originates, where we might find it, how it complexifies over time. This is an exciting time to be in a pre-paradematic field. Now, here's a place in the podcast where this is kind of to my students, but I think it's also helpful for other people that just want to listen in and see what a college class is like, and also get a view of my goals of a class and sort of my teaching philosophy. I get a fancy term for that as pedagogy, but in every class I set up some goals, right? And the goals of astrobiology is of course the science. I mean, astrobiology is grounded in science because that's how I see my world. So, of course, we're going to study the definitions of life. I'm trying to get an idea of what life is, the origin, evolution, distribution, and future of life in the universe. Because astrobiology is grounded in the natural laws of the universe. I want to make some predictions. What predictions might we make about life in the universe by integrating physics, chemistry, earth and planetary sciences, biology, and even information theory. And then of course, I mean, what happens if we discover life? So what would be the scientific, the societal, and the philosophical implications of finding life in the universe? What would we learn from that? What would it impact us? And then in every class I teach, not only do I have goals, I also have some takeaway messages because I'm aware that we're going to forget a lot of what you learn in a class. You're going to forget a lot of what you learn in a podcast. You're going to forget what you watch in a YouTube documentary. We forget stuff. But I always like people to take away something from a podcast I have or a class lecture or even an a an entire course. And so my my major takeaways, the themes that I like to to have underlying my classes, but it's specifically astrobiology here is that life anywhere in the universe is going to follow the same natural laws. And because of that, I think we can make predictions about life in the universe. So one of my things that I always want to challenge everybody on is a very common statement you hear in astrobiology is life as we know it or we have no idea what life in the universe would look like. And my question to them is what do you mean that we have no idea what life in the universe would look like? What does that mean to you? And why do we keep saying that? Because I think we can actually use the natural laws of universe and convergence evolution and figure out like, hey, we might be able to put some boundaries on what life looks like. We can put some boundaries on it and we can make some predictions. Now, as I say that, I don't want to sound like a no-it-all here. I mean, I don't want to sound arrogant or, oh, I know what life is going to look like because I'm going to discuss exactly like there's a big sandbox for life to play in, right? And as my imagination kind of takes me away into the distance reaches of the universe. Unfortunately, there are limitations to what we know and what can be known. Now, we can learn a lot about the universe through making all these observations, but we will likely never know if there's another multiverse. Maybe we will. Maybe we won't. We might not really ever know how life got started on this planet. We might figure out ways it could have happened, but we may never know exactly how it happened. We may never know the full extent of life in the universe. Okay? So there are things that we know and things that may not be known because we don't have the evidence, the information, the data, or some way of testing for the limits of science, right? Now, so we have to come with astrobiology with a bunch of humility, right? Even though I say we can make predictions about life, there's still a lot we don't know and how often have we been wrong in making our predictions. Okay, here's my third one. Never underestimate the complexity of the universe or a life or anything. In our world of YouTube shorts and TikTok videos and sound bites from the news, we distill these very complex topics and subjects and phenomena into very short sound bites. And the reality is our world is often much more complex, much more nuanced than what we often see. And a great example of that is life. And we have very simple definitions of life like like NASA's definition of life that says life is a self-sustaining chemical system capable of Darwinian evolution. Maybe that might be good and it does capture a lot, but life as a universal or sorry as a planetary phenomena might be more complex than that and that simple definition may not capture this phenomena that we call life, right? So things are usually more complex and as a biologist, all right, I'm going to go into my biases here. As a biologist, I find beauty in complexity. Now a physicist might find beauty in simplicity. They love their beautiful equations that describe the universe, E equals MC squared, for example. Me, somebody goes, well, what is an organism or what is an ecosystem and say, well, an organism is a bunch of cells interacting together. I'm like, really? Is that all an organism? Is a mammal just that? Am I just my brain? My consciousness is just my brain or my personal? No, there's more to it than that. It's more complex. And that view of the universe, finding beauty in complexity, finding beauty in simplicity. Those are our worldviews. Those are our own biases and understanding your biases and how I form my worldview, why I find the beauty in complexity and why I think that life is very complex and simple definitions of life may not work very well. But those biases in our worldview are going to bias and they're going to influence how we interpret evidence. Right? So understanding your biases is very important for understanding your worldview and how you come about looking at evidence and drawing conclusions from that. And that is not just for astrobiology, but almost everything we do. So there it is. That's why I want to study astrobiology. I mean, this is one of the most fascinating fields of science. Let's switch gears here. And let's talk about the universe that we live in. This to me is very important, understanding the basics of our universe. Because even though life is a planetary phenomena, well, guess what? Planetary phenomena, life, solar system, stars, galaxies, we are all part of this universe. I mean, whereas integrated into it as you can possibly imagine, right? And so understanding the universe is important for understanding maybe why there's life in the universe, how it got started, where we might find it. So let's talk about the age and scale of the universe. And I like to call it the comprehensible universe. I get that from I'm inspired from that by Einstein. And he goes the most incomprehensible thing about the universe is that is comprehensible. And that's of course going back to we can describe the universe based on these natural laws. Now, I don't want to get into a philosophical discussion about the difference between laws and theories and facts right now. But what I want to do is come up with the basic principles under which we believe the universe works. Now, we don't fully understand all of the natural laws of the universe. But nonetheless, they are there. And we have this concept called uniformitarianism. And in uniformitarianism, it basically means that these natural laws of the universe operate the same everywhere in the operate the same in the past for the most part and in the future for the most part. Yes, there are times way, way, the beginning of the universe or things are acting kind of weird. We're not going to really get into that or way far in the future near the heat death of the universe. We don't exactly know what's going to happen. But either way, in our universe today, and at least for the last 13 billion years, uniformitarianism has been an integral part of our universe. And it helps us understand it. And then the last thing I will talk about is just understanding the biases that we have. And we think of this biases as a bad thing. But I think if you can peg down your biases, understand them. Know where they're coming from, identify them and embrace them or change them. If you need to, but that can help give us more empathy and a better understanding of other arguments that may challenge the way we think things work. We can start with the agent scale of the universe. And let me be clear, there are a number of excellent YouTube videos on the universe. There are so many good ones. There's a lot out there with Brian Cox, there's StarTalk. These are excellent videos. I watch a few others and they do a really good job. Dr. Becky, I like her too. She's really good. But in your rate, there's a lot of videos and a lot of podcasts that have covered this in depth. So I'm just going to give it a very superficial treatment here. Because like I said, other people that are experts in this field have covered this very well. But for our purposes, you know, the age of the universe, it began in a hot dent state about 13.77 billion years ago. So you often hear the term, the universe is about 13.8 billion years. Now this hot dent state, I mean, imagine taking the universe and squeezing it down is something like the size of a proton, right? And then within, I don't know, 10 to the minus 34 seconds to 10 to the minus 32 seconds, they went to the size of a grapefruit. And they call that inflation where the size of the universe expanded incredibly rapidly. And yeah, and then it's been expanding ever since. And the reason why we believe the universe began in this hot dent state is when we look at the galaxies across the universe, we noticed that they are moving away from us. And we can see that by understanding how light works as you move away from something light becomes red shifted. And basically the further away a galaxy is the more that light becomes red shifted, which means the faster it's moving away from us. So as we go forward in time, the universe is expanding. Well, if you run it backwards in time, the obvious answer is it's contracting. So that's one of the really leading pieces of evidence for the big bang that we began in a hot dent state. And the other evidence is the cosmic microwave background radiation. So if the universe began in a hot dent state, as it expands, it has cooled, there should be some residual energy across the universe. And that's exactly what we find. If you look anywhere in the universe, there is this basically uniform or nearly uniform microwave background radiation, which is basically the after glow of the big bang. And this part of the understanding of our universe is very interesting to me, because that really shows, you know, what we know and the limitations of what might be known. It is very hard for us to know what the universe is expanding into. We don't really know. We don't know if there's other universes out there. We don't know if the universe is expanding into something this infinite or not. So we don't know. So we don't know what came before the big bang. And we have hypotheses about these and we have hypothesis about what the fate of the universe is. But like I said, there's just a lot that we don't know. But in our current known universe, and I like to use the term known universe, I used to just say the universe is everything that we can see. No, that's not true, actually. We don't know what the universe is expanding into. We don't know what was before it. So when we talk about the known universe, the known universe is what we can observe. And we know that to be about 93 billion light years in diameter. So the edge of the known universe, we can see all the way back to the very first galaxies. Maybe even the first stars like a Lindyel, a Lindyel may actually be a little cluster of big stars. And then we have the cosmic microwave background radiation that is the afterglow from the big bang. That's around 375,000 years after that occurred. Okay. That's a limitations of what we can see to basically. Now we've got models that predict what happened before that. But before the big bang 13.77 billion years ago, we don't know. So the known universe is these things that we see. Now inside this 93 billion light year diameter sphere. There are an estimated, this estimate ranges all over the place from around 300 billion galaxies to a trillion galaxies to approximately two trillion galaxies. That's a big range isn't it? We don't actually know the full extent of galaxies in the universe with the advent of Hubble and James Webb more recently. Of course, we are discovering that as you look further back in time or further into the distant universe, we look further back in time. Galaxies are also they are more concentrated, but they're a feinter. So what we're discovering is, yeah, you know, we have to keep revising our number of galaxies upward. Because we keep making more discoveries. So the number of galaxies, I was suspect is probably closer to two trillion galaxies. I always think that there's more because we keep revising those numbers upward. That's a hint into my bias right there. Now a galaxy, these are collections of stars. So while there's, you know, one to two trillion galaxies in the universe. These galaxies can be very small, like little satellite galaxies with maybe a few million stars all the way up to the Milky Way, which has once again, there is an estimated 300 billion to one trillion stars. When you look out into the night sky and you see between five and 7,000 stars, they are only within a few thousand light years away. We're looking at a very tiny part of our galaxy, but not only that, not only that, you're seeing like only about 10 or 15% of all the stars within that thousand light years. You can't see the vast majority of stars because they're all red doors. So once again, we're constantly revising our numbers upward as we learn more about our own galaxy. And some galaxies have trillions of stars that are much larger than our Milky Way. Our Milky Way is about a hundred thousand light years across and about 3500 light years and with. And when you look up in the night sky and you see what we call the Milky Way, what you are actually seeing is a minor spiral arm of our galaxy called the Orion arm or the Orion spur. Now let's take a step back out now that we know that there's you know one to two trillion galaxies in the universe. There's you know anywhere between 300 billion to a trillion stars in our own galaxy. We live in a universe with a lot of stars. There are more stars in the known universe. Then there are sand grains on all the beaches of the world. And if you're an against guy walker, that is really bad news for you because you hate sand, just kidding. It's been. estimated the upward estimate is what I'm going to go with that we live in a universe with a trillion trillion stars That is a boatload of stars and what we've learned in the last couple of decades Is that most stars likely have planets? So there's potentially habitable planets out there in the universe. There's estimated to be a lot And we'll get into that when we start talking about planet habitability just a sheer number of Potentially stars with habitable planets out there and that's not even Ice oceans rogue planets and small rogue systems either they could also be potentially habitable. So what I'm telling you There's a lot of chance out there for a life in the universe Now for unfortunately the vast majority of it will never be able to study But within a few thousand light years of our own solar system we have a good chance of finding something Okay, so there's a lot of possibilities in the universe and in my classes. It's really fun to talk about the multiverse Sean Carroll in his podcast of mindscape does an excellent review of the philosophy of the multiverse And he is a physicist that does philosophy as well And it's a little bit different than like our views of Rick and Morty or the Star Trek or the Marvel comic universe With their multiverse. There's an actual like real scientific theories About the multiverse to explain Some of the evidence that we have some of the data we have, okay I'm not gonna go into it here because it's not something that I am feeling very confident to talk about So our universe is big it's old. So the possibility of life in the universe Don't know But I like to quote Arthur C Clark on this one. He says you know two possibilities exist Either we are alone in the universe Or we are not and both are equally terrifying When I get to the end of my semester here and the end of the podcast for these You know we'll we'll talk about why that is equally terrifying And for me I'm biased. I've been raised on science fiction my whole life from Star Trek of course and Star Wars Yes, I like them both But we live in a universe That could be teaming with complex life. There could be advanced alien civilizations wandering the stars that are being billions of years old Maybe I like to think so The more I studied it the more I become skeptical that the universe is teaming with technologically advanced civilizations But it could be I like to think that it is Maybe that's too terrifying. I don't know We could live in a universe where life is common But it's mostly microbes I strongly suspect that that's actually the case and there's reasons why I believe that Life is probably common in the universe and it's probably just microbes and I will definitely get into that this semester The other possibility is won't you know we we could be alone in the universe We are that one fluke We're a life originated on a planet And you know this makes me think about Carl Sagan right when he The early 90s. I think 91 or maybe late 80s. I can't remember the exact same the exact date right now But he had the Voyager spacecraft turn around And take a picture of the earth from billions of miles away And basically the earth is this tiny blue dot Caught in a sun beam Norea of Sun a flare on the lens And he says That's us That's home the only known place in the universe with a life Maybe that's true. Maybe it's not Whether or not it is there's a lot of philosophical implications about Whether or not we are alone in the universe For example if we are alone Should we spread life Throughout the universe so that it persists because it would be a totally unique Universal phenomena. I know life is a planetary phenomena, but we're still part of the universe And the implication of that is that all life is going to follow the natural laws of the universe That's a pretty profound statement right? So this goes back to Einstein's the most incomprehensible thing about the universe Is that it's comprehensible So one of my underlying themes in astrobiology Is that Everything in the universe is going to follow the same laws the same laws of the universe Okay, so we can use those to make predictions or hypotheses about life across the universe And this goes back to the principle of uniformitarianism You know these natural laws of the universe are going to operate the same everywhere in the past the present in the future Now that being said as I said earlier in the podcast. I don't want to get into a semantic or philosophical conversation about the difference between laws and theories and facts But what I want to do is just say hey look there are these principles that the universe follows So let's take a look at some of these what I'm talking about here these natural laws of the universe Things like Newton's laws of motion Newton's laws of gravitation The laws of thermodynamics or Maxwell's equations unifying electricity and magnetism or coulombs law and chemical bonding Gas laws and then of course there's things like relativity quantum mechanics and dare I say Darwinian evolution Hmm it does explain a lot of life on this planet doesn't it So what are the importance of these natural laws One of them in astronomy is of course the Kepler's laws of planetary motions And basically there's these three laws of planetary motion to say one planets orbit in ellipses To a line connecting a planet and the Sun sweep out equal areas During equal intervals of time as a planet orbits its Sun which basically means that planets move faster when closer to the Sun And that's a consequence of angular momentum And then three the square of the orbital period is directly proportional to the cube of the semi major axis of its orbit And those are the three laws of planetary motion and there's a lot of implications here first of all those laws of planetary motion I helped Newton discover the law of gravitation And it provides a framework for understanding planetary motion Not just in our solar system but in any solar system Okay, and it can also help predict the size of planets it can help predict whether or not they're in the habitable zone Especially the third law and we used Kepler's laws all the time for space exploration like how do we get the Juno probe Out to Jupiter how do we get the Voyager to go by all of the All of the planets in the solar system right so we have to use these Kepler's laws of motion And of course this led into Newton's laws of gravitation And he basically said Every particle in the universe attracts every other particle with a force that is proportional to the product of their masses And second inversely proportional to the square of the distance between their centers And that's a Newton's law of gravitation And that works really well There's of course as you're probably thinking wait there's general relativity that involves some of this Yes, general relativity does explain how gravity works And of course it makes understanding the laws of gravity a little bit more tricky But the importance for astrobiology is that If life is a planetary phenomena life is originating and evolving on a planet Every organism experiences gravity now if it's in water it's gonna probably experience very little gravity But it's still gonna experience pressure from the water As it gets deeper and deeper in its ocean which has important physiological uh Consequences but especially on land Gravity is very important for things like allometric scaling What that means is there's a non-linear scaling In the organisms as they get bigger and bigger and bigger In plain English basically I can't take a mouse Or a lizard and scale it proportionally to the size of an elephant it would crush itself You have to get the bones thicker quicker right And then other physiological adaptations are important for Things as they move on to land and experience gravity okay, so even plants Even plants for them to grow at all had to have support system To deal with the force of gravity so Bigger planets there's gonna be more gravity smaller planets will have less gravity That's gonna have huge implications for the organisms that live on those planets And also the atmosphere on those planets as well. Then of course there's Maxwell's equations. This describes electric and magnetic fields in their interactions. This is why this explains how we get magnetic fields around planets, which is apparently fairly important for maintaining atmospheres and maintaining life on the planet. And also it helps us understand the electromagnetic spectrum of light so we can understand things like how far away distant objects are by understanding redshift. We can also understand how organisms create and/or detect electric fields. Another organism can actually detect magnetic fields as part of what organisms can sense in their environment. And our visible light that we see is part of the electromagnetic spectrum. It obeys those Maxwell equations. And if we were to go throughout the universe, we could probably make predictions like, hey, if you're going to detect electromagnetic radiation, you're probably going to detect something around visible light. And there are reasons for that. Okay. Also in our universe, this same fundamental building blocks make up all the matter in the universe. Protons, neutrons, electrons, they form atoms. We change the number of protons in the nucleus of an atom and you get a new element. And the way that we get new elements in the universe, is through a process called nucleosynthesis. And this process occurs through nuclear fusion inside of stars. And it also occurs when you get a supernova explosion. And those also create the heavier elements beyond iron. So like gold was created in a supernova explosion. And it scatters these elements out. So you wouldn't get planets. You wouldn't even get life if it weren't for these nuclear processes. Now, there are 92 elements. I always laugh when somebody goes, elements we have never seen on earth. No, there are 92 elements. Yes, there are trans uranium elements that we have created in the lab. And I'm sure somewhere in the universe, they're created inside enormous explosions. Some of the hypernovas or something like that probably create trans uranium elements. But they don't last very long anywhere from a few hundreds of years to nanoseconds. Now, these elements bond together. So atoms combine to form molecules. Anywhere you look in the universe, if you see hydrogen gas, it's actually a molecule because there's two hydrogens held together by a covalent bond. We look out in the universe, we see water. Water is H2O. The hydrogen and the oxygen are held together by a covalent bond. So anywhere we find water in the universe, no matter how distant it is or how old that water is, it is the exact same water on this planet. So chemical bonding, covalent bonds help make molecules. We also have compounds through ionic bonds. And there's also things like hydrogen bonds, which help hold water together, because it's a weak electrostatic attraction. And it's also very important for a lot of life's processes. And there's a bit of energy in those bonds, right? It takes energy to break them. And this chemistry is going to be universal. Now, it might change under different parameters, but we can predict that, okay? So for instance, you know, if I take carbon and bond it to oxygen, that bond energy is 360 kilojoules of mole. But if I take silicon and bond that with oxygen, it's now got 798 kilojoules of mole. And what that tells you is that if you have silicon dioxide, that's a really stable molecule. It's really hard to break. It takes an enormous amount of energy to break it. Yeah. And that also means that it's not used very often by a life. Whereas something like carbon and oxygen is stable, but not so stable that you can't break it. So these these bond energies are going to be similar throughout the universe. Awesome. And we look at life on this planet. There are these building blocks of life. And we find them throughout the universe. You probably will hear chinops, carbon, hydrogen, nitrogen, oxygen, phosphorus. And these form organic molecules, like methane, pyruvate, acetates, amino acids. And of course, we also see water. And we find these things throughout the universe. We even find them on rocks. We find them in our solar system. So these building blocks of life are found everywhere. That's going to have some interesting implications. I don't know what the most important law of physics are for understanding life. I don't know. I mean, everybody will have their case. I'm biased. And I'm going to say it's the laws of thermodynamics. And the reason why I say that is because the laws of thermodynamics govern energy in this universe. And you've probably heard them. There's a conservation of energy. Basically, you can change energy, move it, transform it, transfer it. But you're not going to create it or destroy it. There's always total equal energy and ecosystem. And the second law says entropy of an isolated system will always increase. And the third law says the entropy of a system approaches this constant-- a constant is temperature approaches absolute zero. And of course, there's a zero-th law about equilibrium. But is that second law of thermodynamics that I used to say was a real sucker punch, the gut punch, the kick in the teeth? Because the universe is grinding down. The second law of thermodynamics says this entropy, this measure of disorder, is always increasing. The universe wants to be in equilibrium with no free energy, no ability to do work. And I'm like, man, that government, too bad, we don't have an unlimited amount of free energy. However, on my journey of studying extrabiology, I have come to love the second law of thermodynamics, especially at this point in the universe, right? Because this is why things happen. Yes, gravity is important, too. But the second law matters. It's about energy flows, entropy, and equilibrium. You see, the universe wants to be maximum state of entropy. That is equilibrium. That is no free energy, no ability to do work. But the early universe, the universe began in a low entropy state. And it's going to end, we think, with the heat death of the universe, which sounds weird, because it actually be cold. But when the last black hole is gone, there's no more free energy. Entropy is at maximum. This point time has no meaning because nothing is happening. Nothing happens at the end of the universe. It's just done. It's just all the energies in heat. OK. But that path, that path, the maximum entropy, that's why we exist in the universe. And this is part of why we need to come up with a law of life, a universal or a theory of life, to explain why life arises. Because we can start looking at the universe, when we see stars, we see galaxies. And these are actually what we call dissipative structures and dissipative structures like planets, stars, galaxies, crystals, hurricanes, tornadoes. These are dissipative structures. So what they do is they take and exploit energy gradients and dissipate that energy gradient. So it speeds up the production of entropy, right? By exploiting these energy gradients and dissipating them. But while it does so, it temporarily creates an ordered structure like a hurricane or a tornado or a crystal. So for example, when water freezes to form a crystal, it's creating a dissipative structure that is self-organizing into repeating pattern of water molecules. But as those water molecules lock into place, they release energy. They're exploiting energy gradients. And interestingly, organisms are dissipative structures. All life uses energy and it creates order. Interesting, isn't it? Might be budding a case for a theory of life here. Now this being said about the laws of physics, the laws of chemistry. I didn't really get into quantum theory or general relativity or even special relativity. And you might be thinking of other laws of the universe that are very important gas laws, fix laws, stuff like that. But the point is those laws, even if we don't understand them, like we don't understand how relativity would work at very tiny scales. We've got to combine the universe at very small scales of atoms to the very large scales of our size and upward. So maybe string theory will combine quantum mechanics with relativity. Even though I said there's 92 elements in the universe, we understand chemical bonding fairly well. We still-- don't know all the possibilities of chemicals and chemical reactions in the universe. We do not, by any stretch of the imagination, know the full scope of planets and their geologies. So we don't know what geology on a Haitian world would look like or a super-earth, where planet, frozen moons, we don't know all the scope of, you know, their geologies or anything. So there's this white open and this universe is full of planetary systems and rogue planets. And in fact, our solar system seems to be anomalous. And based on that, we also, you know, we don't have this universal theory of life that incorporates all of these things we've been talking about. And there may be new physics out there, new physics that explains and links relativity with quantum mechanics that explains life, that explains the multiverse. Don't know either way it's out there. But despite that, we have a pretty good idea of most of what's happening in the universe and those laws of nature are the foundation from which we study life on earth. And one of the underlying themes that I'm going to teach this semester is that it can make predictions about life in the universe. Okay, so we might not understand the relation between quantum physics and and relativity, but we do understand chemical bonding. We do know what the chemical elements are. We do understand the laws of gravitation fairly well. We do understand fixed laws, gas laws, all of those are very important for understanding life. Okay, so what can we know? Well, we can look at distance galaxies billions of light years away for this known objects in the universe. We can look at their light spectrum. We can use laws of gravitation, relativity, and we can understand how these galaxies are working. Now, because we can understand how a galaxy works, billions of light years away, based on the universal laws that we understand in our own solar system, there's that property of uniformitarianism going on. Could we use a life on earth as a template for life in the universe? Some of you are immediately shaking your head. No, no, we, we, life is, we have no idea what life in the universe would look like. We'd be arrogant to think that we can make predictions about life or know what it might look like. But I do think that there are ways that we can use life on earth as a template. Okay, first, life as a planetary phenomena is going to arise from geological processes on a planet. And then what about the molecular level? I told you the building blocks of life basically found everywhere. So would life be similar at the molecular level? Neclic acids, proteins, carbohydrates, lipids, would they have cellular memories made of phospholipids? I don't know. Maybe it works for very well for a life on earth for multiple reasons. Would life be carbon-based in water chemistry? Most likely, there are other scenarios that people talk about like in methane or in ammonia, but those systems are rare and there's some problems with that. I mean, I'm not saying that we, I'm going to just rule it out, but I would say it'd be less likely than life on earth. And there's, like I said, there are these physical and chemical reasons why we would want to think that. So what about metabolic pathways? Electron transport, Krebs cycle, could that be universal? I'm probably really taking a leap here, but according to Nick Lane, who's a biochemist, he said, he predicted or speculated, I should say, that maybe the first metabolic pathway was something like the Krebs cycle. Wow, pretty crazy, isn't it? Can we make predictions that life is cellular? Are there pro-carriers in the equivalent of eukaryotes out in the universe? You know, is there multi-cellular life? Are they going to be animal like? What I mean by animal like? Are they going to have symmetry? Are they going to have a nervous system and muscles that can move around responding to stimuli? Do they have excitable cells? I don't know. I would say probably so, right? So this comes into question about how much of life would be deterministic? Do the laws of nature drive convergence evolution across the universe? So for example, if you live in water, you're going to be fish like. So think of a shark, think of a dolphin, think of an ichthyosaur. They all look fish like. And I've heard astrobiologists say, well, you know, all those are vertebrates. They're all related to each other. So of course, there's going to be convergence evolution where they look similar. And my response is, yeah, sure, you're all right. They are related to each other. This is life on earth. However, when you look at the physical structure of these animals living in water, there's a reason why they look fish like, and that has to do with the ability to move through water. And in fact, there's convergence on body shape and fin shape based on how fast or how slow these organisms move through the water. So when we make a torpedo, it looks a lot like a tuna. And the reason why is because that allows you to move through the water with maximum efficiency. Okay. So this is where these natural laws of understanding something like viscosity of water Reynolds number, you're going to converge on similar solutions if you have a similar problem. Okay. Now, I got to ask some humility here. I'm not trying to sound arrogant. But I do think that there are bounds that we can put on life. And there are some predictions that we can make about life at various scales from simple pro-carotid cells, simple ecosystems to complex ecosystems, and complex organisms that live within those complex ecosystems. I know that's a lot of complexity, isn't it? But I think that's important. And lastly, this really comes up to confronting our own biases, our world views, and the limitations of science. I'm over here saying, you know, I think we can make predictions about life in the universe. And that's in a response, a direct response to people that keep saying, we have no idea what life in the universe would look like. And I disagree with that. And why do I think that? Where did I form my world view? Because I could be totally wrong here. And I think that's important. And in class, I always like to show this image of Obi-Wan Kenobi, telling Luke, "You tell me my father was dead." And Obi-Wan's backtracking, of course. But he goes, "Well, from a certain point of view, he was." Okay. So for me, acknowledging our biases helps us understand our world of view and how we might interpret information. And also how somebody else, how you might interpret somebody else's interpretation that might be different from yours. And I'm going to come into some examples of that in a few minutes. But let me talk a little bit about how I form my views of life in the universe and where I'm drawing from. Because in that can help you understand my biases and understand how I'm working and gives you ways to either agree or disagree with me. Like I said, "Preparadigmatic field. Gotta have some humility, but I am going to throw out some of my ideas here." Okay. First, my very first love in science was astronomy. I was influenced by Carl Sagan. Carl Sagan was an astronomer and he was a strong science advocate. He really put into me what a biologist or a scientist is and what science can do for us. And to me, that's important. You know, science is a way of thinking and it can challenge our preconceptions about things. And I really taken that to heart. Sagan is also very famous for saying things like extraordinary claims require extraordinary evidence. And that is now permeated. I feel astronomy and I'm going to come back to this. But more about me here a little bit is I'm a biologist. I'm a trained biologist. So even though I wanted to be an astronomer, I was still outketching lizards and learning birds at a very early age. But I also love science fiction and star wars as well. So I do like some some fantasy there, but I grew up on Star Wars and Star Trek and other sci-fi. My modern day influences outside of Carl Sagan and Isaac Asimov. I am, you know, he's a great sci-fi writer who envisioned robots, galactic civilization, city-wide planets. Like Arthur C. Clark, he's a science fiction writer that pushes the boundaries of what's possible. And of course, one of my favorite scientists these days is Nick Elaine on the origins of life and importance of evolutionary innovations. I mean, this guy I read his books and I'm like mitochondria now my favorite organelle. And he's made me re- think about the way I understand life. And I mean, the guy wrote a book on the Krebs cycle that I couldn't put down. Yes, I am a bit of a nerd, but to write a popular science book about the Krebs cycle is pretty remarkable, right? So, Nick Lane really has been the latest of my paradigm shifts and I'm, and I'm in the process of another one now with my understanding of, or at least what I think is my understanding of life. Now, because I'm a biologist and with astronomy envy basically, not so much physics envy, but I love astronomy and I love imagination and science fiction. And my imagination, I see the universe teaming with life. You know, are there great, galactic civilizations out there or at the very least it's teaming with microbial life? I think that making contact with an advanced race would probably be good for humanity. And of course, think about the Vulcans meeting the earth and bringing us into this, you know, the federation that we formed. I also admit that, hey, every time we've had a more technologically advanced civilization run into a less technologically advanced civilizations doesn't go well for the ones that aren't as technologically advanced. And we have seen that time and time again on our own planet. So maybe it could be really bad for us. Think V, the final battle. Yes, that's a 1980s mini series. And wow, I watched it not too long ago. Yes, the special effects and the acting are a tad bit dated but the concepts are spot on. Okay. So from a certain point of view, feel free to challenge me if you want. You can disagree. I'm not gonna hold that against anybody. In fact, I need to understand why people don't believe the same thing or don't think the same thing I do. But I'm optimistic the life is abundant in the universe and I believe that we can use life on earth to serve as a template for understanding life in the universe. Okay, so I believe in some level of determinism and reasons for an optimistic view of life being abundant in the universe. And here's this, so determinism is I'm saying if you have the right conditions and the right ingredients is going to happen. I don't know how fast is going to happen but it will likely happen. Okay, so for me, I'm gonna say life will arise if you have the right ingredients, circumstances and sufficient time. So for me, if you have a geologically active planet with a rock water interface and sufficient time, you will likely get life occurring on that planet. Okay, now if you think about this, a rocky planet with a water interface has got to be geologically active, right? Because you got to have a source of energy to push systems out of equilibrium. When we look at earth, here's reasons to be optimistic. We keep pushing back the date of first life on this planet. When I was in college, 3.5 billion years ago, later on, 3.8 billion years ago. Now there's compelling evidence, 3.2 billion years ago, 4.2. That is right after the surface cooled enough to have liquid water on it. Life arose quickly, which had the right conditions. Okay, so I don't think it's an improbable fluke of nature. Here's another thing. This is gonna get you. Life is thermodynamically favored. Now I'm not talking about morally favored or anything like that. But in thermodynamics, basically, if you have a system that is increasing, the rate entropy is generated, which means you're speeding up the rate you get to equilibrium by using free energy that is thermodynamically favored. That's why a carbohydrate won't last forever. It will eventually oxidize forming carbon dioxide and water and release energy, because that is closer to equilibrium. Life also dissipates energy. It generates entropy. So it's thermodynamically favored. And like I said, life, we think has arisen very quickly. Okay, here's another view for optimistic, or another reason for optimistic view of life. In 1990, we didn't know of any except planets. 1992 got the first one. By eight years later, we knew of 100 planets outside of our solar system. By 2024, there's 5,750 confirmed planets. 59 rocky planets confirmed in the habitable zone, with an estimated 300 million estimated rocky planets in the habitable zone. And that's a distance from a star that you could have liquid water on the surface. Remember that other thing they said about the universe is more complex. I will get into habitable zones. And it is way more complex than just that, same with habitability. We look in our own solar system. We have icy moons in the outer solar system, far away from what we call the habitable zone. We have Europa and cellulitis, Titan, Genamine, Triton, series, Pluto, other trans and Neptuneian objects have evidence of liquid water, especially Europa and Enceladus. And Titan's another one that people are really interested in as well. That's a lot of liquid water, even in our own solar system. And we were to find life in our own solar system. I would say that definitely life is going to be abundant for life in the universe. Okay, so that's why I think life could be abundant. Other reasons why I think we can use Earth as a template for understanding life in the universe, okay? Life is a planetary phenomena. It arises from geological processes and is subjected to the same natural laws everywhere. So through convergence evolution, life will evolve similar solutions to similar problems. For example, if you live in water, you're gonna look fish-like. If you're gonna move on land, if you're using water-based chemistry, guess what? You gotta prevent desiccation. You've gotta deal with gravity. So I've got a lot, I've gotta say about that. So I think our n equals one of life is more informative than is often given credit. But the question is, how informative? We're incredibly limited in our knowledge. We don't know the full extent of chemistry and geology in the universe. You know, even on Earth, we have whales, octopus, and ants. I'm not sure you could predict that those would evolve on any other planet, but I can't predict things like, if you're gonna swim in the water and the water call them a lot, I gotta look like a fish. But within these boundaries, I think there's an incredible room for variation. And I think that's where we can ground the, we don't know what life would look like. Within these boundaries. Now remember this, biases, right? Okay, from the essays of hazards of prophecy, the failure of imagination, Arthur C. Clark has three laws here. He goes, when a distinguished, but elderly scientist says this something is possible, he is almost certainly right. When he says this something is impossible, he is very probably wrong. Now, I'm not an elderly scientist by any stretch of the imagination. I'm mid-career, supposedly at my peak right now. I'm saying that I think we can put these parameters on life, but I could be wrong. The only way of discovering the limits of the possible is to venture a little way past them into the impossible. And I think that's what astrobiology is doing right now. And then his third law is any sufficiently advanced technology is indistinguishable from magic. So that's always a science fiction trope there that was explored very well. And one of my favorite shows called Babylon 5. Now, I'm not the only one that's biased. I, you kind of see where I'm biased. I think that there's reasons to believe that life is abundant in the universe because there's a lot of rocky planets. There's a lot of water. There's a lot of geologically active planets. And the ingredients for life on Earth are found everywhere else. One of my recently, one of my favorite scientists has become Avilome. And if you've ever read somewhere about Harvard scientists says that a Muammuah is of alien origin. OK, that's a little bit hyped up. But he is an astrophysicist. And he is an alien hunter. He is also the chairman of the astronomy department at Harvard. He is not a quack scientist. He is a very good scientist. And he makes an interesting case about bias and astronomy. And that bias is against life as an explanation for observable phenomena. And I think that bias and modern day astronomy against life as an explanation comes from Carl Sagan. Extraordinary claims require extraordinary evidence. So right now, finding life. would be an extraordinary claim. It would be an extraordinary finding if we confirmed it. And right now we have not found life. We have potentially some evidence of life that lived on Mars. That is contentious. We'll find out. We don't know yet. If we were on Earth, we would look at some of those same structures we found, some of the same phenomena. And we would say, yeah, life probably did that. But on Mars, we don't know. So we're coming up with lots of abiotic reasons to explain what we're finding. Case in point, a mu-a-mu-a. Okay. It's almost certainly just a fragment from another star that got ejected out of its system because it collided with something else or blah, blah, blah. I don't know the reason why, but it's almost certainly of a natural origin. And same with this, I think the new one is Axis 3i or something like that. It's even bigger than a mu-a-mu-a coming in in a really fast pace. And so Avilub goes, you know what? These could be alien probes. Why not? Earth, if you were an alien and you were observing Earth for millions of years, you would notice that we're an oddball. We're different. We have an atmosphere that's completely out of equilibrium with where you would expect it to be because of the amount of oxygen in it. That's almost certainly caused by life. If you have an incredibly powerful telescope, you could see that it's got some green on it and it changes over time. So the Earth would be a great candidate to send a probe to to see what it's like. Okay, so Avilub goes, you know, a mu-a-mu-a could be an alien artifact. It could be an alien probe. Same with, I forget, Atlas 3i or something. So as Avilub speculating that it could be or hypothesizing, we don't know. There's a paper that comes out, I believe it was a nature or something, and it says, "Reasons why a mu-a-mu-a could not be an alien artifact." Here's the point that Avilub made. He pointed out correctly that several of the explanations used to disprove it being of alien origins, right? Non-natural origins. We also have never observed in the universe either. We've never observed life. And we've also never observed these other explanations to explain a mu-a-mu-a. Okay? So I think Avilub is right. But let me be clear about when I say it could be. I would say it's highly unlikely. I'm with the Carl Sagan camp. I would really want to know, right? I'd want to like, I was captured or sent another probe to it and look at it and just show disprove that it's not. But he does make the very important point. It could be, this is not science fiction, this is not outside of the realm of science. He's proposing a testable hypothesis. If we could send a probe to it, if we could capture it, then we could directly observe it, and we would know if it was just of natural origin or of biotic origin. Okay? And like I said, you know, that's also an explanation for these interstellar objects. Also, as we observe phenomena on Mars or Europa or Enceladus, we have to be very open to yes, life could be a potential explanation for the observations we're seeing, but it might not be. And I do agree that we need to explore all possible explanations for the phenomena that we are seeing. And in my optimistic point of view, I'm hoping that one day we realize or we discover that life is abundant in our own solar system. We find it on multiple planets or moons and that when we look out in the universe and we see evidence of life, we're like, yeah, that's probably life. So for example, a recently discovered exoplanet called K2 18 B. It reminds me of K2SO, but K2 18 B had dimethyl sulfide. Now, it wasn't a really strong signal. It could be something like just methane that they're seeing as well. For this, let's entertain the notion that maybe K2 18 B does have dimethyl sulfide. Let's say we do some more research on it, get some more data. Well, dimethyl sulfide on Earth is produced by plankton. It's a biotic origin and we really don't have a way to produce it abiotically. But remember when I said we don't know the scope of all chemistries in the universe, we don't know if there are abiotic processes that could produce dimethyl sulfide, but on our planet is produced by plankton. So if we see it elsewhere right now, we need to come up with a list of all the different mechanisms that could produce dimethyl sulfide. And maybe in the future, when we've discovered life elsewhere in our own solar system and we find dimethyl sulfide on another planet, we'll be like, yeah, that's probably good evidence for life on that planet. And we'll go along and say likely has life on that planet, like K2 18 B. So there you have it. That's a my take on an introduction to astrobiology, why we want to study it, what the universe is we live in, why I think we can use Earth as a template and understanding our biases and how that can affect our world view and how we interpret data. So there was a lot in this podcast and we will explore these themes in a lot deeper as I go through this semester. So stay tuned. I can't wait to update my podcast again on what is life. It's been quite the ride thinking about it. And here I am in my 50s. Now, I can say to everyone out there is stay curious. Until next time, this is Tom Sykes.