Martin Rees: Black Holes, Alien Life, Dark Matter, and the Big Bang | Lex Fridman Podcast #305

There's no reason to think that the ocean ends just beyond your horizon. And likewise, there's no reason to think that the aftermath of our Big Bang ends just at the boundary of what we can see. Indeed, there are quite strong arguments that it probably goes on about 100 times further. It may even go on so much further that all combinatorials are replicated. And there's another set of people like us sitting in a room like this.

The following is a conversation with Lord Martin Reese, Emeritus professor of Cosmology and Astrophysics at Cambridge University and co founder of the center for the Study of Existential Risk. This is the Lex Friedman podcast to support it. Please check out our sponsors in the description. And now, dear friends, here's Martin Reese. In your 2020 Scientific American article, you write that today we know that the universe is far bigger and stranger than anyone suspected. So what do you think are the strangest, maybe the most beautiful, or maybe even the most terrifying things lurking out there in the cosmos?

Well, of course, we're still groping for any detailed understanding of the remote parts of the universe. But of course, what we've learned in the last few decades is really two things. First, we've understood that the universe had an origin about 13.8 billion years ago in a so called Big Bang, a hot, dense state whose very beginnings are still shrouded in mystery. And also we've learned more about the extreme things in it. Black holes, neutron stars, explosions of various kinds. And one of the most potentially exciting discoveries in the last 20 years, mainly in the last 10, has been the realization that most of the stars in the sky are orbited by retinues of planets, just as the sun is orbited by the Earth and the other familiar planets. And this, of course, makes the night sky far more interesting. What you see up there aren't just points of light, but they're planetary systems. And that raises the question, could there be life out there? And so that is an exciting problem for the 21st century.

So when you see all those lights out there, you immediately imagine all the planetary worlds that are around them. And they potentially have all kinds of different lives, living organisms, life forms, or different histories.

Well, that we don't know at all. We know that these planets are there. We know that they have masses and orbits rather like the planets of our solar system. But we don't know at all if there's any life on any of them. I mean, it's entirely logically possible that life is unique to this Earth, exist anywhere. On the other hand, it could be that the origin of life is something which happens routinely given conditions like the young Earth, in which case there could be literally billions of places in our galaxy where some sort of biosphere has evolved. And settling where the truth lies between those two extremes is a challenge for the coming decades.

So certainly we're either lucky to be here, are very, very, very lucky to be here.

I guess that's the difference.

Where do you fall, your own estimate, your own guess on this question? Are we alone in the universe, do you think?

I think it would be foolish to give any firm estimate because we just don't know. And that's just an example of how we are depending on greater observations. And also incidentally, in the case of life, we've got to take account of the fact that, as I always say to my scientific colleagues, biology is a much harder subject than physics. Most of the universe that we know about could be understood by physics. But we've got to remember that even the smallest living organism, an insect, is far more complicated with layer on layer complexity, than the most complicated star or galaxy.

You know, that's the funny thing about physics and biology. The dream of physicists in the 20th century, and maybe this century, is to discover the theory of Everything. And there's a sense that once you discover that theory, you will understand everything. If we unlock the mysteries of how the universe works, would you be able to understand how life emerges from, from that fabric of the universe that we understand?

I think the phrase theory of everything is very misleading because it's used to describe a theory which unifies the three laws of microphysics, electricity, magnetism, and weak interaction with gravity. So it's important step forward for particle physicists. But the lack of such a theory doesn't hold up any other scientists. Anyone doing biology or most of physics is not held up at all through not understanding sub nuclear physics. They're held up because they're dealing with things that are very complicated. And that's especially true of anything biological. So what's holding up biologists is not a lack of the so called theory of Everything. It's the inability to understand things which are very complicated.

What do you think we'll understand first? How the universe works or how the human body works deeply, like from a fundamental deep level?

Well, I think perhaps we can come back to it later that there are only limited prospects of ever being able to understand with unaided human brains the most fundamental theories linking together all the forces of nature. I think that may be a limitation of the human brains. But I also think that we can, perhaps aided by computer simulations, understand a bit more of the complexity of nature. But even understanding a simple organism from the atom up is very, very difficult. And I think extreme reductionists have a very misleading perception. They tend to think that, in a sense, we are all solutions at frothing's equation, etc. But that isn't the way we'll ever understand anything. It may be true that we are reductions in the sense, if we believe that that's the case. We don't believe in any special life force in living things. But nonetheless, no one thinks that we can understand a living thing by solving Schrodinger's equation. To take an example, which isn't as complicated, lots of people study the flow of fluids like water, why waves break, why flows go turbulent, things like that. This is a serious branch of applied mathematics and engineering. And in doing this you have concepts of viscosity, turbulence and things like that. Now you can understand quite a lot about how water behaves and how waves break in terms of those concepts. But the fact that any breaking wave is a solution of Schroding's equation for 10 to the 30 particles, even if you could solve that, which you clearly can't, would not give you any insight. So the important thing is that every science has its own irreducible concepts in which you get the best explanation. So it may be in chemistry it's things like valence in biology, concepts in cell biology and in ecology there are concepts like imprinting, et cetera, and in psychology there are other concepts. So in a sense the sciences are like a tall building where you have basic physics, the most fundamental, then the rest of physics, then chemistry, then cell biology, et cetera, all the way up to the, I guess, economist in the penthouse and all that. And we have that. And that's true in a sense, but it's not true that it's like a building in that it's made unstable by an unstable base. Because if you're a chemist, biologist, or an economist, you're facing challenging problems, but they're not made any worse by uncertainty about sub nuclear physics.

And at every level, just because you understand the rules of the game, or have some understanding of the rules of the game, doesn't mean you know what kind of beautiful things that game creates, right?

So if you're interested in birds and how they fly, then things like imprinting the baby on the mother and all that, and things like that are what you need to understand. You couldn't even in principle solve this vertical equation, how an Albatross wanders for thousands of miles of the Southern Ocean and comes back and then coughs up food for its young. That's something we can understand in a sense and predict the behavior, but it's not because we can solve it on the atomic scale.

You mentioned that there might be some fundamental limitation to the human brain that limits our ability to understand some aspect of how the universe works that's really interesting. That's sad actually, if to the degree it's true, it's sad. So what do you mean by that?

I would simply say that just as a monkey can't understand quantum theory or even Newtonian physics, there's no particular reason why the human brain should have evolved to be well matched to understanding the deepest aspects of reality. And I suspect that there may be aspects that we are not even aware of and couldn't really fully comprehend. But as an intermediate step towards that, one thing which I think is very interesting possibility is the extent to which AI can help us. I mean, I think if you take the example of so called theories of everything, one of which is string theory. String theory involves very complicated geometry and structures in 10 dimensions. And it's certainly in my view on the cards, that the physics of 10 dimensions, very complicated geometry, may be too hard for a human being to work through, but could be worked through by an AI with the advantage of the huge processing power which enables them to learn world championship chess within a few hours just by watching games. So there's every reason to expect that these machines could help us to solve these problems. And of course, if that's the way we came to understand whether string theory was right, it would be in a sense frustrating because you wouldn't get the sort of aha insight which is the greatest satisfaction from doing science. But on the other hand, if a machine churns away a 10 dimensional geometry, figuring out all the possible origamis wound up in extra dimensions, if it comes out at the end, spews out the correct mass of the electron, the fact that there are three kinds of neutrinos, something like that, you would know that there was some truth in the theory. And so we may have a theory which we come to trust because it does predict theory, things that we can observe and check, but we may never really understand the full workings of it to the extent that we do more or less understand how most phenomena can be explained in a fundamental way. Of course, in the case of quantum theory, many people would say, understandably there's just some mystery. If you don't quite understand why it works. But there could be deeper mysteries when we get to these unified theories where there's a big gap between what a computer can print out for us at the end and what we can actually grasp and think through in our heads.

Yeah, it's interesting that the idea that there could be things a computer could tell us that is true. And maybe you can even help us understand why it's true a little bit. But ultimately it's still a long journey to really deeply understand the whys of it.

Yes. And that's an imitation of our brain.

We can try to sneak up to it in different ways, given the limitations of our brain. I've gotten a chance to spend the day at DeepMind, talk to Demis Las Habas. His big dream is to apply AI to the questions of science, certainly to the questions of physics. Have you gotten a chance to interact with him?

Well, I know him quite well. He's one of my heroes, certainly.

And I remember, I'm sure he would say the same.

And I remember the. The first time I met him, he said that he was like me. He wanted to understand the universe, but he thought the best thing to do was to try and develop AI. And then with the help of AI, he'd stand more chance of understanding the universe. And I think he's right about that. And of course, although we're familiar with the way his computers played GO and chess, he's already made contributions to science through understanding protein folding better than the best human chemists. And so already he's on the path to showing ways in which computers have the power to learn and do things by having ability to analyze enormous samples in a short time to do better than humans. And so I think he would resonate with what I've just said that it may be that in these other fundamental questions, the computers will play a crucial role.

Yeah. And they're also doing quantum mechanical simulation of electrons. They're doing control of high temperature plasmas. Fusion reactors.

Yes, that's a new thing, which is very interesting. They can suppress the instabilities in these tokamaks better than any other way. Yeah.

And it's just the march of progress by AIs. And science is making big strides. Do you think an AI system will a Nobel Prize in this century? What do you think? Does that make you sad?

If I can digress and put in a plug for my next book, it has a chapter saying why Nobel Prizes do more harm than good. So on a quite separate subject, I think Nobel Prizes do a great deal of damage. To the perception of the way science is done. Of course, if you ask who or what deserves the credit for any scientific discovery, it may be often someone who has an idea, a team of people who work a big experiment, et cetera. And of course, it's the quality of the equipment which is crucial. And certainly in the subjects I do in astronomy, the huge advances we've had come not from us being more intelligent than Aristotle was, but through us having far, far better data from powerful telescopes on the ground and in space. And also, incidentally, we benefited hugely in astronomy from computer simulations, because if you are a subatomic physicist, then of course, you crash together the particles in a big accelerator like the one at CERN and see what happens. But I can't crash together two galaxies or two stars and see what happens. But in the virtual world of a computer, one can do simulations like that. And the power of computers is such that these simulations can yield phenomena and insights which we wouldn't have guessed beforehand. And the way we can feel we're making progress in trying to understand some of these phenomena, why galaxies have the size and shape they do. And all that is because we can do simulations tweaking different initial conditions and seeing which gives the best fit to what we actually observe. And so that's a way in which we've made progress in using computers. And incidentally, we also now need to analyze data, because one thinks of astronomy as being traditionally a rather data poor subject. But the European satellite called Gaia has just put online the speeds and colors and properties of nearly 2 billion stars in the Milky Way, which you can do fantastic analyses of. And that, of course, could not be done at all without just the number of crunchy capacities.

Computers and the new methods of machine learning actually love raw data, the kind that astronomy provides, organized, structured, raw data.

Yeah, well, indeed, because the reason they really have a benefit over us is is that they can learn and think so much faster. That's how they can learn to play chess and go. That's how they can learn to diagnose lung cancer better than a radiologist, because they can look at 100,000 scans in a few days, whereas no human radiologist sees that many in a lifetime.

Well, there's still a magic to the human intelligence, to the intuition, to the common sense reasoning.

Well, we hope so.

For now. What is the new book that you mentioned?

The book I mentioned? It's called if Science is to Save us. It's coming out in September, and it's on the big challenges of science, climate, dealing with Biosafety and dealing with cyber safety. And also it's got chapters on the way science is organized, you know, universities and academies, etc. And, and the, the ethics of science and.

And perhaps the limits.

And the limits, yes. Yeah.

Well, let me actually just stroll around the, the beautiful and the strange of the universe. Over 20 years ago, you hypothesized that we would solve the mystery of dark matter by now. So unfortunately we didn't yet. First, what is dark matter and why has it been so tough to figure out?

Well, I mean, we learned that galaxies and other large scale structures which are moving around but prevented flying apart by gravity, would be flying apart if they only contain the stuff we see, if everything in them are shining. And to understand how galaxies formed and why they do remain confined the same size, one has to infer that there's about five times as much stuff producing gravitational forces than the total amount of stuff in the gas and stars that we see. And that stuff is called Dark Matter. That's leading name. It's not dark, it's just transparent, et cetera. And the most likely interpretation is that it's a swarm of microscopic particles which have no electric charge. And the very small cross sections were hitting each other and hitting anything else, so they swarm around and we can detect their collective effects. And when we do computer simulations of how galaxies form and evolve and how they emerge from the Big Bang, then we get a nice consistent picture. If we put in five times as much mass in the form of these mysterious dark particles, and for instance, it works better if we think they're non interacting particles than if you think they're a gas, which would have shock waves and things. So we know something about the properties of these, but we don't know what they are. And the disappointment compared to my guess 20 years ago, is that particles answering this description have not yet been found. It was thought that the big accelerator, the Large Hadro Collider at cern, which is the world's biggest, might have found a new class of particles which would have been the obvious candidates. And it hasn't. And some people say, well, dark matter can't be there, et cetera. But what I would argue is that there's a huge amount of parameter space that hasn't been explored. There are other kinds of particles called axions, which behave slightly differently, which are good candidates. And there's a factor of 10 powers of 10 between the heaviest particles that could be created by the Large Hadron Collider and the heaviest particles which on theoretical grounds could exist without turning into black holes. So there's a huge amount of possible particles which, which could be out there as remnants of the Big Bang, but which we wouldn't be able to detect so easily. So the fact that we've got new constraints on what the dark matter could be doesn't diminish my belief that it's there in the form of particles, because we've only explored a small fraction of parameter space.

So there's this search you're literally upon unintended, are searching in the dark here in this giant parameter space of possible particles you're searching for. I mean, there could be all kinds of particles.

There could be, and there's some. It may be very, very hard to detect. But I think we can hope for some new theoretical ideas because one point, which perhaps you'd like to discuss more, is about the very early stage of the Big Bang. And the situation now is that we have a outline picture for how the universe has evolved from the time when it was expanding in just a nanosecond up to the present. And we could do that because after nanosecond, the physics of the material is in the same range that we can test in the lab. After a nanosecond, the particles moving around, like those in the Large Hadro Collider, if you wait for one second, they're rather like in the centers of the hottest stars. And nuclear reactions produce hydrogen and helium, et cetera, which fit the data. So we can, with confidence, extrapolate back to when the universe was a nanosecond old. Indeed, I think we can do it with as much confidence as anything a geologist tells you about the early history of the Earth. And that's huge progress in the last 50 years. But any progress puts in sharper focus new mysteries. And of course, the new mysteries in this context are why is the universe expanding the way it is? Why does it contain this mixture of atoms and dark matter and radiation? And why does it have the properties which allow galaxies to form, being fairly smooth, but not completely smooth? And the answer to those questions are generally believed to lie in a much, much earlier stage of the universe when conditions were much more extreme and therefore far beyond the stage where we have the foothold in experiments? Very theoretical. And so we don't have a convincing theory. We just have ideas. Until we have something like string theory or some other clues to the ultra early universe, that's going to remain speculative. So there's a big gap. And to say how big the gap is, if we take the observable universe out to bit more than 10 billion light years, then when the universe was a nanosecond old, that would have been squeezed down to the size of our solar system or compressed into that volume. But the times we're talking about when the key properties of the universe were first imprinted were times when that entire universe was squeezed down to the size of a tennis ball or baseball, if you prefer, and to emerge from something microscopic. So it's a huge extrapolation and it's not surprising that since it's so far from our experimental range of detectability, we are still groping for ideas.

But you think first theory will reach into that place and then experiment will perhaps one day catch up?

Well, I think simulation in a sense, it's a combination. I think what, what we hope for is that there'll be a theory which applies to the early universe, but which also has consequences which we can test in our present day universe, like discovering why neutrinos exist or things like that. And that's the thing which, as I mentioned, we may perhaps need a bit of AI to help us to calculate. But I think the hope would be that we will have a theory which applies under the very, very extreme early stage of the universe, but which gains credibility and gains confidence because it also manages to account for otherwise unexplained features of the low energy world and what people call a standard model of particle physics where there are lots of undetermined numbers. So it may help with that.

So we're dancing between physics and philosophy a little bit. But what do you think? What do you think happened before the Big Bang? So this feels like something that's out of the reach of science.

It's out of the reach of present science because science develops and as the frontiers advance, then new problems come into focus that couldn't even be postulated before. I mean, if I think of my own career, when I was a student, the evidence for the Big Bang was pretty weak, whereas now it's extremely strong. But we are now thinking about the reason why the universe is the way it is and all that. So I would put all these things we've just mentioned in the category of speculative science. And I don't see a bifurcation between that and philosophy. But of course, to answer your question, if we do want to understand the very early universe, then we've got to realize that it may involve even more counterintuitive concepts than quantum theory does, because it's a condition even further away from everyday world than quantum theory is. And remember, Our lives, our brains evolved and haven't changed much since our ancestors roamed the African savanna and looked at the everyday world. And it's rather amazing that we've been able to make some sense of the quantum microworld and of the cosmos. But there may be some things which are beyond us, and certainly, as we implied, there are things that we don't yet understand at all. And of course, one concept we might have to jettison is the idea of three dimensions of space and time just ticking away. There are lots of ideas. I mean, I think Stephen Hawking had an idea that talking about what happened before the Big Bang, it's like asking what happens if you go north from the North Pole? It somehow closes off. That's just one idea. I don't like that idea, but that's a possible one. And so we just don't know what happened at the very beginning of the Big Bang. Were there many Big Bangs rather than one, et cetera. And those are issues which we may be able to get some foothold on from some new theory, but even then, we won't be able to directly test the theories. But I think it's a heresy to think you have to be able to test every prediction of a theory. Let me give you another example. We take seriously what Einstein's theory says about the inside of black holes, even though we can't observe them, because that theory has been vindicated in many other places in cosmology and black holes, gravitational waves, and all those things. Likewise, if we had a theory which explains some things about the early history of our Big Bang and the present universe, then we would take seriously.

The.

Inference, if it predicted many Big Bangs, not one, even though we can't predict the other ones. So the example is that we can take seriously a prediction if it's the consequence of a theory that we believe on other grounds. We don't need to be able to detect another Big Bang in order to take it seriously.

It may not be a proof, but it's a good indication that this is the direction where the truth lies.

Yeah. If the theory has gained confidence in other ways. Yes.

Where do you sense. Do you think there's other universes besides our own?

There are sort of well defined theories which make assumptions about the physics at the relevant time. And this time, incidentally, is 10 to the power, minus 36 seconds or earlier than that. So this tiny sliver of time. And there are some theories, a famous one due to Andrei Linde, the Russian cosmologist now at Stanford, called eternal inflation, which did Predict an eternal production of new Big Bangs, as it were. And that's based on specific assumptions about the physics. But those assumptions, of course, are just hypotheses which aren't vindicated. But there are other theories which only predict one Big Bang. So I think we should be open minded and not dogmatic about these options until we do understand the relevant physics. But there are these different scenarios or very different ideas about this, but I think all of them have the feature that physical reality is a lot more extensive than what we can see through our telescope. I think even most conservative astronomers would say that because we can see out with our telescopes to a sort of horizon which is about, depending on how you measure it, it's about maybe 15 billion light years away or something like that. But that horizon of our observations is no more physical reality than the horizon around you. If you're in the ocean and looking out at your horizon, there's no reason to think that the ocean ends just beyond your horizon. And likewise, there's no reason to think that the aftermath of our Big Bang ends just at the boundary of what we can see. Indeed, there are quite strong arguments that it probably goes on about 100 times further. It may even go on so much further that all combinatorials are replicated. And there's another set of people like us sitting in a room like this.

Every possible combination of, yeah, that could.

Happen, that's not logically impossible. But I think many people would accept that it does go on and contain probably a million times as much stuff as what we can see within a horizon. The reason for that, incidentally, is that if we look as far as we can in one direction and in the opposite direction, then the conditions don't differ by more than one part in a hundred thousand. So that means that if we're part of some finite structure, the gradient across the part we can see is very small. And so that suggests that it probably does go on a lot further. And the best estimates say must go at least 20 times further.

Is that exciting or terrifying to you? Just the spans of it all, the wide everything that lies beyond the horizon, that example doesn't even hold for Earth. So it goes way, way farther. And on top of that, just to take your metaphor further, on the ocean, while we're on top of this ocean, not only can we not see beyond the horizon, we also don't know much about the depth of the ocean nor the actual mechanism of observation that's in our head.

Yes. No, I think the rook was inhalation is all Those points you make. Yes, yes, but I think even the solar system is pretty vast by human standards. And so I don't think the perception of this utterly vast cosmos need have any deeper impact on us than just realizing that we are very small on the scale of the external world.

Yeah, it's humbling though. It's humbling in depending where your ego is, it's humbling.

Well, if you speak very unhumble indeed, it may make a difference, but for most of us, I don't think it makes much difference. Well, there's a more general question, of course, about whether the human race as such is something which is very special, or if on the other hand, it's just one of many such species elsewhere in the universe, or indeed existing at different times in our universe.

It, to me it feels almost obvious that the universe should be full of alien life, perhaps dead alien civilizations, but just the, the vastness of space and it just feels wrong to think of Earth as somehow special. It sure as heck doesn't look that special when you. The more we learn, the less special it seems.

Well, I mean, I don't agree with that as far as life is concerned, because remember that we don't understand how life began here on Earth. We don't understand, although we know Darwinian evolution of simple life to complex life, we don't understand what caused the transition between complex chemistry and the first replicating metabolizing entity we call alive. That's a mystery, and serious physicists and chemists are now thinking about it. But we don't know. So we therefore can't say was it a rare fluke which would not have happened anywhere else? Or was it something which involves a process that would have happened in any other planet where conditions were like they were on young Earth? So we can't say that. Now. I think many of us would indeed bet that probably some kind of life exists elsewhere. But even if you accept that, then there are many contingencies going from simple life to present day life. And some biologists, like Stephen Jay Gould, thought that if you reran evolution, you'd end up with something quite different and maybe not with an intelligent species. So the contingencies in evolution may militate against the emergence of intelligence, even if life gets started in lots of places. So I think these are still completely open questions and that's why it's such an exciting time now that we are starting to be able to address these. I mean, I mentioned the fact that the origin of life is a question that we may be able to understand. And serious people are working on it. It's usually put in the sort of too difficult box everyone knew was important, but they didn't know how to tackle it or what it's going to do. But it's not like that now. And that's partly because of clever experiments, but I think most importantly because we are aware that we can look for life in other places, other places in our solar system and of course on the exoplanets around other stars. And within 10 or 20 years, I think two things could happen which would be really, really important. We might, with the next big telescope, be able to image some of the Earth like planets around other stars.

Image like get a picture?

Well, actually let me caveat that it'd take 50 years to get a resolved image, but to actually detect the light. Because now of course these exoplanets are detected by their effects on the parent star. They either cause their parent star to dim slightly when they cause transit across in front of it. And so we see the dips, or their gravitational pull makes the star wobble a bit. So most of the 5,000 plus planets that have been found around other stars, they've been found indirectly by their effect in one of those two ways. On the pair you can still do.

A pretty good job of estimating size.

All those kinds of things, the size and the mass you can estimate. But detecting the actual light from one of these exoplanets hasn't really been done yet, except in one or two very bright big planets.

So maybe like James Webb telescope would be.

Well, James Webb may do this, but even better will be the European ground based telescope called unimaginatively the Extremely Large Telescope, which has a 39 meter diameter mirror, 39 meters mosaic of 800 sheets of glass, and that will collect enough light from one of these exoplanets around a nearby star to be able to separate out its light from that of the star, which is millions of times brighter, and get the spectrum of the planet and see if it's got oxygen or chlorophyll and things in it. So that will come. James Webb may make some steps there, but I think we can look forward to learning quite a bit in the next 20 years. Because I like to say, supposing that aliens looking at the solar system, then they see the sun as an ordinary star, they'd see the Earth as in Carl Sager's nice phrase, a pale blue dot lying very close in the sky to its star, our sun, and much, much, much fainter. But if they could observe that dot they could learn quite a bit. They could perhaps get the spectrum of the light and find the atmosphere. They'd find the shade of blue was slightly different, depending on whether the Pacific Ocean or land mass of Asia was facing them. So they could infer the length of the day and the oceans and continents and maybe something about the seasons and the climate. And that's the kind of calculation and inference we might be able to draw within the next 10 or 20 years about other exoplanets. And evidence of some sort of biosphere on one of them would, of course, be crucial, and it would rule out the still logical possibility that life is unique. But there's another way in which this may happen in the next 20 years. People think there could be something swimming under the ice of Europa and Enceladus, and probes are being sent to maybe not quite go under the ice, but detect the spray coming out to see if there's evidence for organics in that. And if we found any evidence for an origin of life that happened in either of those places, that would immediately be important, because if life has originated twice independently in one planetary system, the solar system, that would tell us straight away it wasn't a rare accident and must have happened billions of times in the galaxy. At the moment, we can't rule out it being unique. And incidentally, if we found life on Mars, then that would still be ambiguous because people have realized that this early life could have got from Mars to Earth or vice versa on meteorites. So if you found life on Mars, then some skeptics could still say if it's a single origin.

But I think Europa is far enough.

That's far enough away statistically, because. Yes, so. So that's why that would be especially.

It's always the skeptics that ruin a good party. But, but we need them. Of course we need them at the party. We need some skeptics at the party. But, boy, would that be so exciting to find life on one of the moons.

That'll just be any kind of vegetation or life. The question of the aliens of science fiction is a different matter.

Intelligent aliens, yeah. But if you have a good indication that there's life elsewhere in the solar system, that means life is everywhere.

Yep.

And that.

Yep, that's. That's.

I don't know if that's terrifying or what that is. Because if life is everywhere, why is intelligent life not everywhere? Why? I mean, you've talked about that most likely alien civilizations, if they are out there, they would likely be far ahead of us. The ones that would actually communicate with us. Yes, and that again, one of those things that is both exciting and terrifying. You've mentioned that they're likely not to be of biological nature.

Well, I think that's important. Of course, again it's a speculation, but in speculating about intelligent life, and I take the search seriously. In fact, I chair the committee that the Russian American investor Yuri Milner supports looking for intelligent Life. He's putting $10 million a year into better equipment and getting time on telescopes to do this. And so I think it's worthwhile, even though I don't hold my breath for success. It's very exciting. But that does lead me to wonder what might be detected. And I think, well, we don't know. We've got to be open minded about anything. We have no idea what it will be. And so any anomalous objects or even some strange shiny objects in the solar system or anything we've got to keep our eyes open for. But I think if we ask what about a planet like the Earth where evolution had taken more of the same track, then as you say, it wouldn't be synchronized. If it had lagged behind, then of course it would not have got to advanced life. But it may have had a head start. It may have formed on a plant around an older star. Okay, but then let's ask what we'd see. It's taken nearly 4 billion years from the first life to us and we've now got this technological civilization which could make itself detectable to any alien life, aliens out there. But I think most people would say that this civilization of flesh and blood creatures in a collective civilization may not last more than a few hundred years. More. I think that the people may, some people say it will kill itself off, but I'm more optimistic and I would say that what we're going to have in future is no longer the slow Darwinian selection, but we're going to have what I call secular intelligence design, which will be humans designing their progeny to be better adapted to where they are. And if they go to Mars or somewhere, they're badly adapted and they want to adapt a lot. And so they will adapt. But there may be some limits to what could be done with flesh and blood. And so they may become largely electronic, download their brains and be electronic entities. And if they're electronic, then what's important is that they're near immortal. And also they won't want to be on a planet with an atmosphere or gravity. They may go off into the blue yonder. And if they're near immortal. They won't be daunted by interstellar travel taking a long time. And so if we looked at what would happen on the Earth in the next millions of years, then there may be these electronic entities which have been sent out and are now far away from the Earth, but still sort of burping away in some fashion to be detected. And so this therefore leads me to think that if there was another planet which had evolved like the Earth and was ahead of us, it wouldn't be synchronized. So we wouldn't see a flesh and blood civilization, but we would see these electronic progeny as it were. And then this raises another question, because there's the famous argument against there being lots of aliens out there, which is that they would come and invade us and eat us or something like that. You know, that's a common idea which Fermi is attributed to have been the first to say, and I think there's an escape clause to that, because these entities would be say that they evolved by secular intel to design designed by their predecessors and then designed by us. And whereas Darwinian selection requires two things, it requires aggression and intelligence. This future intelligent design may favor intelligence because that's what they were designed for, but, but it may not favor aggression. And so these future entities, they may be sitting deep thoughts, thinking deep thoughts and not being at all expansionist. So they could be out there and we can't refute their existence in the way the Fermi paradox is supposed to refute their existence, because these would not be aggressive or expansionist.

Well, maybe evolution requires competition, not aggression. And I wonder if competition can take forms that are non expansionist, dimensionary, so you can still have fun competing.

Yeah, yeah.

In the space of ideas, which may.

Be primarily Adobe philosophers perhaps. Yeah.