#808 - Dr David Kipping - Black Holes, Alien Civilisations & How The World Ends
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Hello friends, welcome back to the show. My guest today is Dr. David Kipping. He's an astronomer, a professor at Columbia University, and a YouTuber. Expect to learn David's thoughts on Terence Howard's appearance on Joe Rogan, what actually happens as you approach the speed of light, if there is any chance of finding intelligent life out there in the universe, how big the universe really is, the biggest questions we still have about black holes, how the moon was created,

whether time is infinite or if the universe will ever end, and much more. David is fantastic.

phenomenal. His YouTube channel, Cool Worlds, is one of my favorites. And he's just great. He's talking about all of the interesting space stuff that you always want to know about, about alien civilizations and exomoons and the history of the solar system and what happens in the future. It's great. He's phenomenal at what he does. And the two and a half hours of me harassing him about all of the weird questions I have about how the universe works, it is...

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Yeah.

Dude, I love your YouTube channel. The number of airplane flights that I've been on, delays, sat somewhere where I wish that I wasn't listening to your YouTube channel has been insane. So thank you very much for what you do. Likewise. I've been listening to your podcast for a while and you have so many great guests, so much wisdom on the channel as the name suggests. So I really appreciate being on here as well. You got tenure. Congratulations. Yeah, that's a big deal for me personally to hit this landmark. Yeah.

I don't know if too many people know what it means though. I think tenure is a term which maybe outside of academia, it's unclear what that really means. Yeah, but it's like you're allowed to research whatever you want now and no one can tell you no. Right. Ultimate freedom. That's kind of one way to think about it. It's supposed to be, I think, ideally that it gives you the ability to pursue much more high-risk endeavors. So maybe as a tenure track faculty, which is what I was before,

you're kind of living like day to day. Each project has to deliver something within the next quarter, the next year, and everything's kind of very short term, which is how a lot of corporations work, of course. But when you get tenure, you get to think about going truly long term for something which is 10, 20 years for the rest of your career. And that's exciting. I'm still trying to figure out exactly what I want to do with my tenure, but it's an amazing gift to have.

Speaking of high-risk, explorative conversations, did you listen to Terrence Howard on Joe Rogan? I did. I was actually listening this morning. I was in the gym and I was listening to Neil deGrasse Tyson's video, which was a response to it. And I think Neil did a great job in being very...

respectful and thoughtful and polite, but at the same time forcefully pushing back about many of the things which were questionable in this treatise that Terence had come up with.

What did you make of the conversation with Joe? Because there's been a lot of, I think it caused a lot of ripples. A lot of people were very excited and, you know, it seems like it's upended or some people believe that it was able to upend mathematics and, you know, this sort of a narrative it's personified there keeping the real information from us type thing. What did it feel like as someone who kind of lives in the world of maths and physics listening to that conversation?

Yeah, I only saw snippets of the conversation, but I will say that it's not unusual to see a reaction like this. I know it's kind of blown up on social media, and in the social media world, perhaps it's unusual. But in my world, I receive letters every day coming through my postbox,

with theories and ideas i get of course many many blind emails cold emails saying here's my theory of everything please check it out you know i've proved that einstein is wrong this kind of stuff it's very very common to not just myself but many academics we are used to this and i think neil is in the same boat i'm sure he gets tons of those kinds of pet theories sent to him as well

And so they range from some of them are just a complete crapshoot to some of them there's some serious thought in it. I think Terence actually did try to put some thought into it, despite the fact there was many missteps and misrepresentations of other information that predates his ideas.

However, I think it is true what Neil said, that it is really important that we don't kill that, that idea, that, that love and that passion, because I was that person once. I remember when I was probably 11 years old, I wrote a theory, uh,

I gave it to my physics teacher at school and I said to him, "I think I've proven there's a new relativity theory that I've proven." It was something about clocks ticking at different rates to different observers. It was kind of like a proto-relativity. I'm not claiming I independently invented relativity or anything, but I wasn't aware of relativity and it just struck me that somebody approaching a clock

close to the speed of light would see the rate at which it ticks be very different to someone flying away from the clock.

clock. And so does that have some interesting implications about time? And so I wrote one of those crazy, not crazy, but not well-informed, I should say, speculative theories down, because I wasn't crazy, and I don't think Terence Howard's crazy. And I think you write down these ideas, and it gets you impassioned and excited about physics. And part of me is a little bit embarrassed about doing that as a kid, but I also think

whether you're a kid whether you're an adult whether you're whatever stage you're coming at when you first start diving into this world it's

it's natural to have lots of ideas and questions and want to put them down into paper and have other people look at them and want to talk about them. Physics and science is like being in love. When you're in love, you just want to sing it to the world. I think that's just where he is right now. He's just at that stage where he's getting really thick and heavy into it and enjoying it. Hopefully, we can direct him towards some other truths along the way as well. And peer review

guides, a combination of guides and beats it out of you and sort of moves you toward what's more accurate.

It can do. Peer review is not a perfect system. I think this is why people like Terence are gaining traction, because we all recognize that having one or two people who are so-called experts in that field sway judgment about whether your idea is right or wrong has its own flaws. There are political reasons why someone might want to squash your ideas, or simply because they might not like it because it's so

fundamentally different to everything they're used to. Hold on, this isn't what I was taught in the textbook. I don't like this because it's going to force me to have to reteach the way I've been taught everything for years and years. So there is resistance to new ideas. And I think that came up in the podcast with Joe, and that's right. There is definitely resistance to new ideas. However, if

If you have a great idea and it disseminates to the community, which is the way it works these days, you can put it on social media, you can put it on an archive posting is how scientists typically do this, or on Twitter, or on X.

You can put it out there and hopefully if it's a good idea, it will sustain, it will survive that process of not just academic peers, but a much broader peer community looking at it. So peer review, I mean, it's kind of obvious that that has to be the way you do it. You have to have lots of people look at an idea and...

It's like a meme. If it hits, if it tracks with people, if there's something in it which appeals and explains phenomena in a way which we previously couldn't explain, then it's going to survive and in Darwinian evolution sense, persist. And hopefully the key with science is that we're using evidence to make that assessment as to whether it's correct or not. As the assessment criteria. Yeah, and not just an emotional appeal. How sexy is this?

Yeah, which is the thing. Which has its own aspects. And certainly scientists also appeal to that as well. Sexiness, sexy scientists. There's definitely the string theory or multiverse.

Well, perhaps in a physical sense too, but I was really thinking about just the ideas can be attractive and alluring. And I think when people talk about, for example, the multiverse, that's something very alluring about that idea that there could be other versions of you who were more successful or maybe less successful and that imagination kind of runs wild. I think a lot of us get drawn into that idea as well. And so it's hard to sometimes stop yourself and say,

hold on, I think I'm getting deceived by what I want to be true rather than what is really true. A pretty sexy idea that's been floating around, continues to sort of resurface all the time, is that quantum entanglement allows for faster-than-light communication. What's the scientist's perspective on that? Yeah, it really doesn't work. It seems like it should work when you first hear about the idea. Let me try and just break this down a little bit. So

You can imagine that you have a pair of particles which are what we call 'quantumly entangled' to each other. What that really means is that their state is in a superposition together. The idea of superpositions in quantum theory is very familiar. Whenever you have a single particle whose spin could be up or spin could be down, for example, until you measure it, it really is in a superposition of those two states. We don't know. Then once you measure it, it collapses down and makes a choice essentially to one of those variables.

With a pair of particles, if they are created together in a certain set of conditions, you can create them such that they are entangled, which really means that the combined sum and combined nature of their state is entangled to one another. So for example, the total of their spins could be zero. So in that case, one would have to be up and one would have to be down, but you don't know which one is which.

So this is very similar to having a box of shoes. So you can have a left shoe and a right shoe. They're in the box and you kind of blindfold yourself and you take one of the shoes and you give it to your friend. He goes on an aeroplane, he keeps himself blindfolded and you don't feel the shoe so you don't break the illusion as to what it really is. But then once you get to the other side, one of you opens the box and when you open the box it collapses the uncertainty you might say.

And so the question is, can that be used for communication? And the answer is, well, no. Because if I open my box and I discover that it's a left-footed shoe, then that instantaneously tells me the other shoe must be right-footed. And not only does it tell me that, but in the quantum world it actually does force that state to be right-footed as well. It really is a physical effect that it forces it into that state. But nevertheless, there's no way to use this for communication.

Since I can't force my shoe to be left or right, if I could, then we could use it for communication. If I could push it to be not just a 50-50 probability, but rather a 60-40 probability even, just slightly nudge the probabilities, there would be a way to use it for communication. But as long as it's inherently random, which it is from my perspective when I open that box as an inherently random process,

All I can ever do is just get a string of, if I had a whole box of these things, many, many boxes of just left, right, left, right, right, left. It'd just be random sequences. There's no way we can use these shoeboxes to send a message to each other. And manipulating the one that you have doesn't change the one that your friend has?

Well, there is no way to manipulate it. The only manipulation you really have is that you can open the box. You can measure it. That's it. That's the only manipulation you can do. If someone could invent a way to manipulate the quantum state without measuring it, which seems like an oxymoron to me, then there would be a path forward for communication. Because the act of measuring causes it to collapse, and then after that there is no such thing as changing it.

Once the states have collapsed, they're no longer entangled to each other. So then the link has been broken. So once the measurement's been made, that's it. They both collapse into their state and the entanglement's gone. So it's not persistent past that point. Right. That makes the quantum entanglement communication thing seem quite

simple as why it's not going to work. Yeah, I mean, it is fairly simple. Obviously the way I'm describing it is a little bit simplified, but in a nutshell that's kind of the basic principle. I obviously have a video if you want to go much deeper that gets into all the nuts and bolts of how this works and kind of looks at the superposition states and things. But essentially that is the problem. And it's a shame because in, you know, I think there's a game Mass Effect 2,

which has a quantum communicator in it. I actually used a scene from one of my videos about this. I think the character comes up to this computer and it says, "I have a quantum entangled state particle. As long as there's one back on Earth and there's one on the ship, we can communicate with this particle." But of course, that doesn't make any sense. The moment you interact with that particle,

and measure it, the state collapses. And so the entanglement's gone. Entanglement is actually a very delicate state of affairs. It's hard to maintain entanglement. And basically any interaction with the real world will collapse it, including and especially you trying to measure that thing. Wow.

That's so interesting. Well, I remember reading, this was in college, this must be nearly 20 years ago. I read that gravity moves quicker than the speed of light. Is that true to gravitational waves? If the sun disappeared now, would we start flying off immediately or would it take us four minutes? No, it would take, well, eight minutes. Yeah, it would take eight minutes. It actually does turn out it

In general relativity, it is assumed that it travels at the speed of light. It's kind of built into the theory. And there have been some measurements that have attempted to measure this or at least constrain it. And although we don't have a super precise measurement like we have for the speed of light where we can pin it down to fractions of a metre per second,

for the speed of gravity, it does appear to be at least consistent with the speed of light. But one of the ways we can actually do better with this is looking at what we call electromagnetic counterparts to gravitational wave sources. There are these black holes which are smashing into each other and combining out there, and we've been detecting those, hundreds of them now, using a telescope or really an instrument I should say called LIGO. It's not really a telescope in the conventional sense, it's just giant laser beams essentially.

But using these laser beams, we've been able to detect as gravitational waves ripple past, they squish and squash the Earth just a fraction of a proton in diameter. No way. It's a tiny, tiny disturbance. But these lasers are so sensitive, they can tell when they've been squished and squashed by that tiny amount using a technique called interferometry. So we've been able to tell there's these gravitational waves that black holes merge.

In some cases, we've even seen neutron stars merge. Neutron stars are not black holes, they're kind of like failed black holes if you like. They didn't quite have enough mass to collapse all the way down to a black hole. The Sun will also not turn into a neutron star. It's not heavy enough to get into that regime either, but some massive stars will collapse down to a neutron star.

These are things which are about the same size as New York City, Manhattan even, and they're almost the same mass as the sun, maybe a little bit heavier. So incredibly dense objects. And these, because they're not black holes, when they collide with each other, they shine. They do produce a huge amount of energy. So

So we have two things. It's like a race happening. You have the gravitational wave racing towards you from that collision, and you also have the light that was emitted during that smash. Oh, of course, it is literally like a race. Yeah, so we can actually time when those two events arrived, and we can use that to test how similar they are. For all accounts so far, they've been pretty consistent, but it's still fairly early days. We only have a handful of neutron stars. Most of the events we've detected have been black holes.

but we're getting to the point where we should have hundreds of these things coming online in the next few years. So I expect we will be able to pin that number down really precisely as going forward. Would there be anything special? Would it be unbelievably shocking if the speed of gravity was less than the speed of light? Would that cause some oddities?

For sure. It would basically mean general relativity was wrong. We'd have to go back to the drawing board a little bit with the ideas of general relativity. I think you'd have to speak to some theorists about the wild ideas about what that could mean, but it might imply some kind of foam or some kind of resistance to spacetime itself for the propagation of gravitational waves in a way that is not expected in simple general relativity. It would be a very exciting result. It's important to remember that despite scientists

for one aspect, not being often resistant to new ideas. On the other hand, they love new ideas. And so I think if we discovered that,

theorists would be very, very excited because it kind of gives theorists, at least, and observers, an excuse to do a lot more science. Because now we've got this mystery to explain, so we can plan either more observations to try and explain that mystery, or we can come up with lots of ideas and speculations about what might be going on, see how it lines up, hypothesize about what future observations will make. So scientists do actually really

enjoy a mystery. And so I think if we discovered that most of us would be celebrating. Right. Yeah. Lots of work to do, lots of research and grants and new, exciting things to focus on.

Yeah, I think the most boring outcome is that we understand everything. That's actually what put me off when I was studying physics at school. I remember being kind of put off physics because the way it's taught at schools feels like everything's been figured out. Like, here's Newton's laws of gravity, here's the atomic structure, here's the electromagnetism, how that works. And it kind of feels like, well, what's left to do? I wish I was born 200, 300 years ago when it felt like back then all you had to do was throw

some wooden water and pointed it and say it floats and you could get the Nobel Prize or something. Now it's so hard. What's happened? It does feel like that, but then that's why I got attracted to astronomy because in astronomy it really is like an

a multitude of things that we can discover out there. The galaxy alone has 100 billion stars in it, and there's 100 billion at least galaxies out there. There's only 10,000 astronomers on Earth. We are never going to run out of stars and planets and galaxies to study. There'll be millions each for us. That was always the appeal for me. If I'm going to choose a subject to study,

and I don't want to run out of things to be surprised and amazed about. Astronomy has got to be the one. Wow, you're hopelessly outnumbered stars to astronomers. For now. We're going to try and pull it back. Yeah, I seem to remember reading an article about how

the number of kangaroos that exist on the planet compared to the population of Czechoslovakia. It was like that it would result in each Czech citizen having to fight 11 kangaroos, and that was a really important stat that we weren't talking about. It's kind of the same with you and the astronomy. I can't believe there's only 10,000 astronomers. Where did you go to school? What was your academic comeuppance?

So I grew up in the UK, and people get confused by that because of my accent. I think I've been in the US for a while, and sometimes even people get confused about where I grew up. But I grew up in Warwickshire in the UK. I went to a little school near Twycross, it was called. And then eventually I went to Cambridge University and I studied physics there. Well, really, natural sciences was the name of the degree, but primarily I studied physics.

They're kind of a little bit pompous that way. They won't let you have a physics degree. No, this is Cambridge. It has to be called something else, so it's called Natural Sciences. Then once I got that, I decided to go to London and study astronomy for my PhD and eventually came stateside during that process. I really loved being in the UK. I miss the UK quite a lot, but I do feel the direction, especially scientifically,

with the Brexit and the reduction in science funding, the state of the economy, it doesn't feel like the future is bright, at least for me sat here in the US. And there's problems in the US for sure as well, but certainly looking at what's going on in the UK, there's nothing about this drawing me back in a career perspective. But I'm very fond of the UK. I love the people. I have so many great friends there. My family is still all there. I love the countryside and

There's something special about being back in the UK. I feel the same. It's an odd sort of push and pull where you go somewhere because it's a better environment for the work that you do and there's more opportunity and then there's sort of this wistful cultural...

departure that you make from uh from the place that you know so well so yeah yeah i feel you with that uh just as a side point totally unrelated i just got before we started talking an email from dominic cummings remember dominic yes yes so i'm gonna bring him on just after the results of the general election in july okay great and uh i think that's going to be

really fascinating insight about exactly what's going on. I don't really care that much about politics, but I'm very interested in the social dynamics of what's happening and why people behave the way that they do. And I think that he has some amazing insights, regardless of what you think about sort of how he contributed to anything. He just knows what Whitehall's like from the inside out. So I'll have a

I'll have some interesting stuff to go through. I look forward to that. It's a crazy world over there. I think with everything going on with the election right now, I know everyone in the UK keeps asking me, everyone on the phone, they're like, what do you think of what's going on in the election? I'm like,

My head's pretty exploding with what's going on in November over here right now. So I don't know if I can handle all the elections happening in the world right now. It's pretty distracting as a scientist, actually, to try and sit down and focus on doing some serious work. And then you open your phone and it's just crazy headline after crazy headline. And yeah, I think I'm starting to think I need to unplug as November approaches. Hmm.

Yeah, I wonder how many people, smart people, are having their precious mind cycles captured by stuff that is sexy and interesting and newsworthy, but totally unrelated to their primary pursuit. And I wonder how much that's holding back human progress across the world. I would guess an awful lot.

Massive, massive. I've never felt personally so distracted by what's going on in the world. And I'm trying to be, you know, I feel like there's a responsibility to be a good citizen and be engaged because this is a democracy and

this nation and the world will be what we make it as participants in it. And so it feels wrong to just stick your head in the sand and ignore what's going on. But at the same time, my effectiveness and my productivity crashes the more I open that New York Times app or CNN or Twitter or whatever it is. You're being bombarded with these

these, these headlines that just take you down these rabbit holes. And before you know it, it's 2pm and you haven't done anything yet. So I think I'm seeing with lots of people, I've seen with lots of my colleagues that students and young people, especially, I think are really being heavily affected by what is happening and their studies and their focus is being almost stolen from them because of the state of the world.

Especially for you, being captured by things that's happening on Earth when the entirety of your job occurs outside of Earth. The only place that you shouldn't be looking really is here. Everything is up there. Yeah. We do lots of work in looking out in the universe, but in a way that's almost like a reflection of us as well.

People say this often beautifully about SETI, the search for extraterrestrial intelligence, that the things that we choose to worry about and look for. So for instance, there are ideas that we should look for planets which are undergoing nuclear war.

because we're on the precipice of that potentially. So you could make the argument that other civilizations will do this, and therefore it's our responsibility and our opportunity to detect them using neutrinos or using bright flashes from the explosions on these other planets. That really is a reflection not so much of what aliens are doing, but of ourselves. It's a mirror.

of us, a dark mirror of our own fears and hopes for the future. And I think that's very much true in SETI. But I think when you look expansively out even beyond searching for aliens, just trying to get a sense as to who we are in the universe is still very much an inward journey as much as an outward one of trying to figure out what is the point of my life. If the universe is so vast and so big, where do I fit in it? Where do our lives

cue into this line. And so for me, looking for answers out in deep space is as much a process of looking for answers inward as beyond. Did you get to watch The Three-Body Problem? Yeah, I did. And I'd read the first couple of books and I thought the show was really intriguing. It was pretty well done, actually, I thought. I like all the actors from the game, because it's kind of the Game of Thrones mop.

version two or something, right? Just put into the modern world or something with aliens. So I kind of enjoy seeing all those actors again doing well and getting jobs because I thought they did a great job with Game of Thrones. The story was done well. Obviously the physics is a bit spoofy. I think one of my biggest gripes with it was the idea that the nearest star, because they never actually name the star, but they keep saying it's four light years away. So there's only one star that's four light years away and that's Proxima Centauri.

there is a triple star system there, but it's nowhere near compact enough to have this chaos that they have in the story. So they've taken some artistic license there to make things a little bit more interesting. But I think the idea that the nearest star system would have an intelligent civilization on it is a little bit contrived. Because if the nearest one has it, then basically every single star should really have intelligent civilizations on it. And then that just

That just seems very curious because for the vast majority of Earth's history, four and a half billion years, there was basically no intelligent species on this planet until very, very recently. It would seem an enormous coincidence that all the planets which have completely different ages - some were born very recently, some were born billions and billions of years before the Sun was - and yet they all just happen to line up so that civilizations just kind of queue up at the same time.

That's always a little bit contrived to me, that every single star system is going to have civilizations on it. But I could let that go. When I watch a show, be it fantasy or sci-fi, I can let go of those things just to sit down and enjoy it. A bit of artistic license. Can you explain it to me? Can you explain the three-body problem? The physical idea of the three-body problem, essentially it's a chaotic system. If you have a single...

It's obviously fairly trivial to predict its path in the future. If you know what direction it's moving and you know its current location, then you should be able to predict at any point in the future where it will be. It will just basically travel along a straight line.

However, if you have two particles, it's a little bit more complicated and they have mass and they're going to gravitationally interact with each other and circle around one another. But it was shown by Newton and many others that this is also a completely determinable system as well. So if you give me the starting positions of those two particles and you give me the momenta in which they're moving, then again, we should be able to calculate for a billion years into the future to exact precision where they will be.

But this all kind of breaks down when we get to three bodies. So when you have three, same situation, just three particles, you know their initial positions, you know their initial trajectories. Now you can predict where they will be, but if you very, very slightly deviate one of those particles, so you just say I'm going to shift one of those particles a millimeter over to the left,

and redo that calculation, you will get a wildly different answer for the final outcome. So this is kind of like the butterfly effect. So if a butterfly flaps its wings and you think, "What difference does that make?" But if you propagate it over a long enough time, it can have enormous implications. People playfully say it could cause a hurricane, the flaps of a butterfly. That's maybe a little bit exaggerated, but in this case, certainly a very slight nudge to one of these particles will give a wildly different answer. So whenever you have a system like this, we call it a chaotic system,

Because it basically means we cannot make predictions that are reliable about their final position in a million years, a billion years from now, because we can never know the position of a planet to absolute precision. There's always going to be some slight uncertainty. And if you nudge it within that uncertainty, you get a very different answer. So it's not the same as being random, because there's not randomness. It's still fully determined, but...

so chaotic and complex that it's unpredictable? Is that a way to say it? Yeah, I think unpredictability is the key word. It's that you can't forecast with any meaningful, accurate prediction where it will be. You can actually make distribution. So you can say, I'm going to run this simulation

a thousand, a million times over and over again, and just slightly nudge it around and see what the spread of results are. Then that can help you to place your bets as to where you think is most likely to land, like going to the casino and gambling where you think the ball will land on the roulette table. You can make that kind of statistical analysis, but you certainly can't make a good prediction. Even for the solar system, this is true. For the solar system, it's been shown that if you go forward about a billion years into the future,

Mercury is not necessarily stable. In about 1% of simulations, I think it is, this is work done by Konstantin Batygin during his PhD, he showed that about 1% of the time the solar system will become unstable. So in one billion years. That's before the Sun actually will long engulf the Earth. What tends to happen is I think Mercury gets ejected from the solar system altogether,

and Earth and Venus swap positions. No way! Earth becomes the Venus, and Venus gets a chance to cool down and could potentially become habitable, I suppose, if it was far enough away from the star. It's pretty wild that even the solar system, which we think of as incredibly ordered and structured and long-lived, as not just a three-body system but a many-body system, also has instability. The real question is for any multi-body system, not whether it's chaotic or not, they're all chaotic.

The question is, how long does that chaos timescale start to creep in? For the solar system, the chaos timescale is called the Lepinov number technically. It's around about 5 billion years or so. Whereas for some solar systems that we look at, the chaos timescale is very, very short, of 100 million years. For those, we're really looking at them thinking, "That thing might not even be around here much longer because it just seems like it's balanced on a knife edge of instability."

Dude, that's so cool. Chaos timescale being how long will the current system remain similar in terms of what we would expect to see?

I think it's better to think of it as when do your predictions diverge? Almost like in a multiverse scenario of living different lives, like in the film Sliding Doors, whether you get on the train or don't get on the door, over what timescale do the outcomes diverge? Meaningfully. Because presumably there's a 0.000001% chance that Mercury gets ejected tomorrow. Correct. Yeah, there's a definition of exactly what that means, of how quantitatively large it has to be. But typically it's of order of sort of a fraction

an exponent number, so that's a power of about 2.5 in terms of the semi-major axes, the orbital periods, things like that. So if they change by a factor of two or three, then that's definitely a very major change to the order of the system. How is it the case that there's so many bodies in the Solar System and yet were relatively stable, at least maybe for the next half billion to a billion years? Why is

There seems to be so much going on. How is it that orbits get settled into kind of reliably? Why is there not more play in the system?

It is kind of a miracle. It's a miracle of stability that we should be thankful for, because if it wasn't so, then we wouldn't be here. But on the other hand, perhaps that's the answer right there, that if it wasn't so, we wouldn't be here to talk about it. And it's not a guaranteed situation. So when we look at other exoplanet systems, which we have been cataloging now over the last 20 years, it's actually quite rare that we see a solar system that looks like ours. There's something

not necessarily completely unique, but rare about the structure and architecture of our solar system. For example, we often see planets in highly elliptical orbits going around their star. In our solar system, if you had a planet like that, if Jupiter entered a highly elliptical orbit for whatever reason, it would completely destabilize the rest of the planets.

We also have lots of hot Jupiters. These are Jupiter-sized planets which are orbiting very, very close to the star. And again, in order to get Jupiter, which passed a form far out in the star system, to migrate inwards, it's like a bulldozer coming through the planetary system. It just knocks everything else out.

But it's possible that the solar system had instabilities. It's thought that at one point in the past, there may have been another planet similar to Uranus and Neptune that we lost. So there could have been what's called the fifth gas giant in the solar system.

The reason why we think this is true is that when you do these simulations and you put the eight planets in and you let them all interact with each other and you speed it up over time, you very often find that Uranus or Neptune get ejected out of the solar system in half of the simulations. Therefore, it seems odd.

If Uranus and Neptune are so unstable, why are they so stable when we look at them today? The explanation for this, and David Nesvornia, one of my colleagues at the Southwest Research Institute suggested this, he said, "Look, if you put in an extra planet on the back end of that solar system, it's the one that often gets ejected and it sacrifices itself to save Neptune and Uranus. And then everything makes sense if you do that." So even though we don't have direct evidence for this fifth giant planet,

it kind of neatly explains why the outer solar system seems coherent and stable, because it wasn't always coherent and stable, and it's only got that way as a result of basically chucking out the unstable stuff. So we don't just have a rare Earth hypothesis, we have a rare solar system hypothesis as well. Yeah, I think about this a lot. This is one of those thoughts that really bother me as an exoplanet scientist, is understanding how special and unique we are. It's like the driving question.

question I have as a scientist is, is our home, is there something special about not just the Earth, but maybe the Earth-Moon system, the solar system, even our sun, even our part of the galaxy, maybe even our galaxy itself, like where, which aspects of this are special and which aren't.

For example, the Sun is not a typical star. Only about 10% of stars in the universe look like the Sun. And amongst those, our Sun is unusually quiet. Most stars have lots of flaring and activity, lots of star spots. Our Sun is curiously very, very stable as well in terms of its luminosity output.

So that's also kind of odd. You look at the solar system, we have a gas giant. As far as we can tell, just having one gas giant is kind of unusual. Certainly less than 20% of exoplanet systems have that, possibly as low as 10%. So just having a Jupiter around your star is weird.

And Jupiter is thought to be potentially a good thing because it could hoover up all the asteroids, for instance, that's been suggested. Maybe that protects the Earth from getting bombarded early on in its lifetime. You put something in one of your videos. When was it? 2001? When did Jupiter take one for the team recently? The Schumacher-Levy comet that hit it? Yeah, big boy. Yeah.

Yeah, that was a huge impact. That happened when I was a kid. It wasn't when I was a professional astronomer. I think this was when I was 13 or 14, I think, that was happening. I remember seeing it in the news and seeing the images. But that was a situation that obviously happens very often. If it happened in a human lifetime, it's happening probably every few decades or so to a plant like that. So that's not surprising. And if that had hit the Earth, it would have definitely extinguished life on Earth, no doubt about it. It was a massive, massive impact.

worked. So having Jupiter take that over a team was one that we were pretty grateful for. Have we got any idea about the odds of life and intelligence? That's something that is definitely right up my street. I've been thinking about my whole career, I'd say. There's something to say there are two types of astronomers: the ones who want to understand how the universe works

They want to understand the mechanisms, what was the Big Bang, how does space-time work? And there are astronomers who just want to have this itch, "Are we alone?" And it just drives you, and you can't help thinking about it. And I've probably fallen into that latter category. I find both questions very interesting, but that latter one really bothers me. Calculating on odds is very difficult because there's only us that we know of. So you have 100 billion stars potentially,

And so a lot of people would say, therefore the probability of life somewhere in the galaxy is very high. Because if the probability is, say, 0.1%, then that would mean there's millions and millions of civilizations out there in the galaxy.

Fine, but we don't know that the probability is 0.1%. So there's 10 to the 11, 100 billion stars, let's say 100 billion potentially Earth-like planets out there. But if the probability of life starting on each one of those Earth-like planets is less than 1 in 100 billion, then it's just us.

That's it. And that's just life. Then you could add on, well, what about multicellular life? What about eukaryotes? What about photosynthesis? What about getting all the way up to intelligence and technology even? Because intelligence and technology are not the same thing. You have intelligent species on Earth which do not have technology, such as crows or humpback whales and dolphins and things. So just being intelligent isn't enough either. We have no idea what the outcome of all those steps would be.

But what we do know is that life started pretty quickly on the Earth, and that's interesting. We can look at the time scan, and we can say it happened within about the first maybe 200-300 million years as evidence for life on Earth since when the oceans formed. Whereas intelligent life took a lot longer. It took intelligent life four, four and a half billion years, depending on when you make the start date.

That's a long time, and the Earth will not be habitable that much longer. I just think this is kind of an amazing fact. The Earth will probably be uninhabitable to complex life in less than a billion years. About 900 million years is the estimate. If it had taken only a little bit more,

we would have been just about getting to the stage of intelligence just about when we would be uninhabitable. Yeah. There's a really interesting idea called the hard locks idea that Brandon Carter wrote about. His idea was

It's kind of odd that we have these major evolutionary transitions such as the development of combigenesis , the development of eukaryote cells, photosynthesis, all these major evolutionary developments. They seem to be uniformly spaced in time. From the start date of Earth to the end date of Earth, they seem to be uniformly spaced. He said, "Look, that's actually similar to trying to pick a lock."

a very hard lock. So imagine you had a sequence of doors in front of you and the lock on average would take, let's say, 100 hours to pick.

But I only give you 30 minutes to pick all six, and you've got to get through these six locks to get to the end. Now, the vast majority of people, of course, will not get through the six locks, and we just never hear from them. They never become an intelligent civilization in this picture. But very, very rarely, someone will be fortunate enough, just very lucky, that they'll get through those six locks, despite the fact the odds are against them. And when you look at the distribution of how long it took them to get through those locks...

they end up being uniformly spread in time, even if the locks are grossly different in difficulty. So the first lock could take maybe an hour to break, the next one could be a thousand hours, the next one could be ten hours. They could be completely different numbers. As long as they're all hard, the final distribution is always uniform, which is what we see. So he suggested this is consistent with each of these steps being incredibly unlikely events,

and that would naturally explain why they seem to be almost coincidentally evenly spread in time in the evolutionary record. Which is obviously bad news for intelligent life. If that's true, then there's not going to be many people out there. Yeah, because the hurdles to get over are all really, really high. Yeah. So I'm receptive to that argument. The only real thing I feel confident saying anything about on this--I've done a paper about this a few years ago--is

where I said, well, intelligent life is hard to deal with, but let's look at the early life situation. And despite the fact life did start early, when we did this full basic analysis of the timing and the chronology of Earth's history,

It is a good sign for life starting again if we kind of re-ran the clock, if we could go in a time machine and we did what we did for the chaos theory. We kind of pushed things around a little bit, we just nudged things around, and we re-run the tape and we see how often would life start again. And the outcome was that about nine out of every ten simulations, we would expect life to start again.

given that situation. So that's just purely looking at the chronology and how fast life started. But it's not a guaranteed outcome, so it is possible that you could have plants that do not form life as well. Whereas when it comes to intelligence, we try to do the same thing for intelligence. It actually slightly disfavored intelligence. It said that when you look at the numbers, it looks kind of unlikely that intelligence would happen again, but it was a very marginal result. And so

Really, what that's telling us is we need more data. Whenever you come to a point where your statistical significance is kind of weak as a scientist, that's a point to reflect that we need better data. And certainly for intelligent life, and for life as well, we need more data. And my analysis was only restricted to running the Earth's tape backwards. I mean, who knows if Earth is common either? Earth might be special out there as well. What are the planetary conditions required for life, as far as we know it?

For life as we know it, the basic condition is liquid water. Every single living organism on this planet has to have living water in order to survive. There are some animals and some creatures which can go without water for extended periods of time, but they can't go forever without liquid water. That seems to be a basic requirement. You also need an energy source. All of life metabolizes, so there has to be some source of energy.

For most life on Earth, that essentially comes from the sun. Obviously, we get our food from eating animals and plants, but all of that essentially still derives from the sun if you go far enough back down the food chain. And then there's some things like chemotrophs, which get the energy from chemical gradients or from deep down, near to the bottom of the ocean, there are some volcanic vents that could be a source of energy.

So you have to have an energy source, you have to have water, and I think a lot of us think that you need some kind of information storage system as well. So for us that's DNA, some life uses RNA. Whether there's other versions of that on other planets is an open question, and something that's very interesting to explore. RNA seems to be a popular idea that it could be almost a common precursor for life out there that we might find. It's very difficult to form RNA spontaneously.

So it doesn't seem like it's easy to make RNA, but somehow it must have got started. And once you get it, it's autocatalytic, so it can make more of itself. It does reproduce. But getting that first one is kind of the chicken and egg problem with life, quite literally.

And then you probably also want to have some kind of cell structure, something to bind the organism together. It can't just be diffuse and just dilute across the entire ocean. It probably needs some physical structure. So that could be, for instance, like an oil droplet can actually form almost a natural vessel without having to have an organism already around. You could have the oil do that job for you.

It's also been suggested that in clays, they can form these little bubbles as well. If you have wet clay and air cycling through it, you can form these bubbles. Those clay bubbles could also be potentially little pockets that form protocells as well. There's lots of interesting ideas about getting the precursors to life going, but of course that's just life on Earth. It is possible that life elsewhere does not require liquid water.

But I think there are very good arguments as to why it probably would. You want some kind of solvent, and there are alternatives that you could imagine, such as alcohols for instance. But

In general, it's difficult to argue that water is both extremely common in the universe - it's one of the most abundant things out there. We see it in many, many planetary atmospheres that we've been studying over the last couple of decades, so we know this stuff is all over the place. It's just hydrogen and oxygen, two of the most obvious and common things in the universe, and it has so many advantages for life. So if you want to have liquid water as your basic requirement, then that all comes down to the surface temperature

or the subsurface temperature of the object, you want to have it in that temperature range where it's not too cold, so it's not freezing to ice and not too hot that it's boiling to steam. Why do you need the lubricant? The solvent. Solvent.

Yeah, so you need the solvent to basically carry nutrients around the organism. If you have a completely solid object, it's difficult to imagine how it would transfer energy from different organelles and different components of the cell. So a solvent is just useful for keeping... I mean, I'm not a biologist, but my understanding is it's just to keep a way of moving stuff around inside the cell.

What else about the planet, stuff like the magnetosphere and plate tectonics and a big moon and stuff like that, what else is sort of rare about where we are? I mean, possibly the part of the galaxy could be rare as well. People have suggested that where we live in the galaxy may be itself special. We live in a spiral arm, and we live sort of like halfway to two-thirds of the way out from the center of the galaxy to its edge. Yeah, so the suburban district.

And we certainly think that if you were too close to the galactic centre, that would be bad. As you get closer and closer towards the galactic core, the density of stars increases. There's more and more stars, which means the spacing between stars decreases. Now that's problematic because you can have exposure to supernovae and gamma-ray bursts, which can be essentially life-extinguishing events. So if you get too close, that's a problem. We also did some work in my team

with Moya McTeer, where we showed that actually the instability we talked about earlier, the three-body problem type effect, also gets worse as you get closer in. Because stars themselves often not collide with each other, but come very close to each other. And when that happens, the gravity of a nearby star can actually rip off and destabilize the planets that you're trying to form.

So this is bad, and we think that certainly once you get within that inner core, you actually lose the majority of your planets this way. This is why I always get a little bit bothered. Sometimes you hear astronomers say - this is a pet heave I have with my colleagues - that locally, we know this is true, nearby to the star, that about let's say 10% of Sun-like stars have planets of similar kind of size to the Earth. Not necessarily habitable planets, but similar size to the Earth.

Therefore, there are 100 billion stars, therefore there's a billion of those, 10 billion of those in the entire galaxy. Now the problem with that is that we just don't know that we can extrapolate what happens locally in our neck of the woods to the entire galaxy and especially to that galactic core. It seems very unlikely that in a region

Unlike Star Wars, and Star Wars, that inner region is where all the activity is going. Everyone wants to live in Coruscant, which is right in the center of the galaxy. In the real world, you do not want to live in the center of the galaxy. That's actually a hellhole place to be living. So I don't think we can generalize these numbers elsewhere. So when you look out to the outer suburbs of where we live, there are some reasons why it seems useful. We're far enough away from all that behavior, but we're in a region that's dense enough to be forming stars and dense enough to be forming planets.

The metallicity gradient's good. We also happen to move around the galaxy, orbit around the galaxy. It's comparable to the speed at which the galactic arms themselves rotate around. And so people have- So we're not crossing streams and other lanes of traffic.

Right, exactly. So the spiral arms are basically compression waves of gas that are moving through the galaxy. And those compression waves, as they push through, they lead to star formation increases. So you have this compression wave, suddenly you get more and more stars being born. And that's generally hazardous to have lots of stars being born because that means you're going to have some stars which are going to go supernovae. It's not common, one in a thousand stars will go supernovae, but if you have a star-forming

surge, a few of them will. That's going to be bad if you live in that neck of the neighbourhood. It's like having a swarm of migrants or something swarming through your neighbourhood and some of them just explode randomly as they come through. You don't really want that. You'd rather be in a place where there

There's no visitors, and it's a fairly stable place environment. That seems to be the neck of the woods that we live in. In that sense, it may be fortuitous that we live where we are. But this is an open question. I don't think we've really established this, but we have some ideas as to why it might be so. But ultimately, this is something we hope to test. If we can detect planets right down the centre of the galaxy, that would disprove what I'm saying.

and prove that actually planets can form in these bizarre places, which would be, again, interesting to discover. Or maybe we'll even discover that there's Earth-like planets in that region and life in that region, which would again upend a lot of what I'm saying. So it's a testable theory, but it is the only idea we've got right now prior to having any data that it does seem like there's some advantages to being where we are in the galaxy.

Rare Earth, rare solar system, rare suburb. It's so interesting to think about that number of this is how many billion stars

stars there are and this is how many planets we think are on average around each star. Therefore, if you run the numbers forward, but what it doesn't account for is that not all star localities are created equal and presumably as you get closer toward the center of the galaxy, that accounts for a very large number of the number of stars, but at a much lower...

appropriateness, the environment within which those planets inhabit isn't sufficiently stable and long-lasting to actually allow life. Yeah, that's so cool.

Yeah, I mean one of the strange things, not just location but star type, is the most common type of star in the universe is a red dwarf. So 75% of all stars are red dwarfs. And immediately you might think, well how come we don't live around one if they're so common? But it gets even worse than that because as far as we can tell, they seem to have more Earth-sized planets around them than sun-like stars do.

And yet more, we know that they live for far, far longer. So the sun, as we talked about earlier, will eventually burn out and die. It'll probably take another 5 billion years before it turns into a giant. But even within a billion years from now, it will become hot enough that it will make the Earth uninhabitable. So this is climate change forced from the sun over billion year timescales. They'll just basically...

mean there's no way for us to adapt to that and we will die. However, these red dwarfs, it's like everything happens in slow motion for a red dwarf. Their lives are extended to trillions of years because they're so small, it takes them a lot longer. They're much less efficient at burning that nuclear fuel in their centre.

And so that means that if you lived around a red dwarf, you could have a civilization which lasts far, far, far longer than we ever will. And so all of this is intriguing. There's more of them, they have more Earths, and they last for far longer. So they seem to have everything going for them, and yet we don't live around one. And that has also kind of bothered me in the past. And I called this the red sky paradox. Why don't we have a red star in our sky rather than a yellow star in our sky?

And one possible resolution is that there is something wrong with red dwarfs that we don't yet understand. Maybe the radiation they spew out is just hazardous to forming life in the first place. They have these very prolonged--I say they do everything in slow motion--that includes their adolescence. So the Sun went through its adolescence pretty quick. In order of like 10 million years, it kind of settled down, it chilled out, it stopped spewing flares out all the time. What happens during adolescence?

It's just a very active star. It's very unstable, it's very volatile, its luminosity is changing dramatically, it's spewing out high-energy radiation. It is not a nice place to be living during that time.

For red dwarfs, that adolescence extends for a billion years in some cases. The problem with that is that it can actually eradicate the planets of their water. Let's say the Earth happened to be a water-rich world born around a red dwarf, but then it's being bombarded with this high-energy radiation.

It can actually remove the atmosphere completely off the planet. They're so powerful, these events. When you remove the atmosphere, the water then just escapes. It boils off, it forms maybe clouds at a high altitude, but then the ultraviolet radiation, which these stars also produce, splits water up into hydrogen and oxygen. So it's like fission of the molecule into hydrogen and oxygen, and the hydrogen will escape into deep space.

So an Earth-like planet does not have enough gravity to hold on to hydrogen. If you let out hydrogen in the air into a balloon or something, minus the weight of the film itself of the balloon, the hydrogen will just float off into deep space and not come back. The Earth does not have enough gravity to hold on to it. So once you lose your hydrogen, you've now just got oxygen by itself. You can't make water with just oxygen. And so the planet loses all of its water this way. This is thought to have happened to Venus, actually, in its past.

And so this is a very dry planet, and we can see that. So this is potentially an explanation as to why, despite the fact red dwarfs are everywhere, they may not be as hospitable as we hope. But perhaps civilizations go there eventually. They might be like the retirement homes, like the Florida of the universe. Because I think a civilization like us would recognize that

there's something here for our future. Even though there's no water, maybe we could bring water with us. We could have a huge settlement program. We eventually have huge ships and we can move over there and bring everything we need. And these stars will be energy sources, stable energy sources, for the future trillion years of the rest of the universe. When all the other stars go out, it will just be the red dwarfs left shining. And so it seems obvious that that's where civilizations would be drawn to one day live.

It's a reliable retirement home, reliable long-term goods, stable property prices throughout. I've seen Sunshine. I've seen that movie. How much truth is there in what we can do to stars to prolong them, to control them?

Yeah. We actually have an idea in my team where we've been working on some of these ideas. One immediate threat in our solar system is, of course, the Sun. So the Sun is evolving, which means as it's maturing, it's becoming more luminous over time. When the Earth was first born, the Sun was about 20% to 30% less luminous than it is today.

That's a big drop-off: 30% less luminous over 4 billion years. So if you go another billion years into the future, that's another 10% increase in luminosity, even a bit more than that. And then that will wreak havoc to the climate at this point. So you have to do something. One option that one of my colleagues suggested, Greg Laughlin, was to try and push the Earth back into a wider orbit.

So what you could do is you could actually hurl an asteroid directly just off center of the Earth. And as it hurls towards it, it will swing around or do like a gravitational slingshot around the Earth and it will fling off in the other direction. But every time that you have one of these gravitational interactions, if it does a slingshot, it basically steals a bit of speed and it will steal that speed and go off faster than it was before. And

and that means the Earth will change speed, it will lose speed. So you can actually modify the orbit of the Earth by having these interactions. So in this case we'd actually want to increase the Earth's angular momentum, we want to increase its speed, and as you do so it would push it out into a wider orbit

So you'd have to throw thousands and millions of asteroids at the Earth to do this. And every time, you'd have to do it very close, but not just too close. It's a high-risk strategy. It seems like a very high-risk strategy. It's a high-risk strategy for an advanced civilization that really knows what they're doing. But that's where you can move the Earth back at just the right rate to keep the temperature the same. I guess you could do this for climate change as well in the near term, but I wouldn't recommend it. I think there's probably safer solutions.

The other solution that is, I think, more feasible, or at least less risky for this, is actually to remove mass off the Sun. But maybe this is a bit more sci-fi. Even more sci-fi than throwing asteroids at the Earth. You could actually have some kind of way, most simply like a ram scoop or something off the surface of the Sun, but you could actually probably do it with lasers as well. You could actually excite certain modes on the surface of the Sun and get material to be ejected out this way.

If you make the Sun lose mass, that reduces its gravitational pressure in the center. And so the core of the Sun is where all the energy is produced, and it's like a thermostat. The greater the gravitational pressure from the outside squeezing down on that core, the hotter it gets. So if we take some mass off the top, it'll reduce the pressure and the oven will cool down a little bit. And so we can actually reduce the output of the Sun. Would that not cause it to expand if it's got less gravity?

It would cause it to slightly change in radius, but it would not be a dramatic effect. So when we're modifying the radii of these stars, it would actually end up probably overall net decreasing the radius of the Sun because as you cool down the core of the Sun,

there's less outward radiation pressure. So that radiation pressure is basic. If that wasn't there, the sun would collapse into a black hole. The sun wants to collapse into a black or to a very small object, maybe not a black hole because of electron degeneracy pressure, but it wants to collapse all the way down. The only thing stopping it from collapsing down is radiation pressure, like energy

spewing out in all directions and pushing back against that force. If we reduce the power in the oven, we make that core less powerful, the radiation pressure will decrease and will actually net shrink very slightly. That's why if you look at stars with lower masses, they tend to have smaller radii. They don't actually

get bigger as a result of the level of gravity, which you might think of. So overall this would slightly decrease the radius of the Sun, and the net effect would be to decrease the luminosity. So we calculated a rate of doing this, and it turns out to be something like one asteroid's worth. Like Vesta is one of the largest asteroids. There's one asteroid's worth of material off the Sun every year. So not very much. That's how much you have to remove off the Sun.

to basically keep it cooling down gradually over the next billion years, such that it basically doesn't change temperature. It'll basically stay exactly the same luminosity as it is today. So we did this calculation in my team, and we think it's an intriguing idea. And we think that if somebody was ever going to move to another star and potentially colonize it for a trillion years, this would be an obvious thing that they would do. And there are actually signatures that we could look for potentially to detect this.

So we call this starlifting. I was thinking about solar landscaping, like a solar landscaper would be a future job. Solar gardening, almost, yeah. And another idea was that my student had this idea that you could also use this in the neighbourhood. So we talked about supernovae being potentially dangerous, like Betelgeuse is nearby and people are worried about Betelgeuse one day going supernovae and potentially...

It's too far away to actually really affect us, to be honest. But you could have a star like this nearby. We could potentially, or a civilization more advanced than us, could potentially fly there, do this mass removal process almost as a pruning technique. So this star is kind of like a weed in your garden, like a pest that you want to get rid of. And so by stripping mass off the top,

you could remove that threat and de-claw it and mean that your neighborhood is safe again. So it's really fun to imagine this is all what physics allows, right? There's nothing about the laws of physics which prevents somebody from doing any of this. And so if the laws of physics allow it, and there's a good motivation for why a civilization might want to do it, then it's interesting to ask whether somebody is actually trying this right now.

Given the requirement for water that's needed for life in any form, at least as far as we know it, uh,

What is the likelihood of underwater civilizations? And if you have an underwater civilization, I seem to remember learning that there's a few restrictions that those kinds of species would have. They can't smelt iron and materials that they would be able to use to build things in the same way to be able to go to other planets. Is that something you've considered?

Yeah, I mean, this is super intriguing. One of the most interesting aspects of this is the communication aspect of dolphins and whales as our sea intelligent companions that live in the ocean.

And for years and years, we've been trying to just communicate with them. If we want to communicate with an alien civilization, we should at least be able to communicate with dolphins and whales and have a conversation with them. But we haven't really succeeded very well at that. Although there has recently been breakthroughs in this. There was a wonderful podcast on The Daily, a daily podcast The New York Times does that talked about some recent breakthroughs in this area.

So there are some advances happening, but in terms of a whale or a dolphin or anything analogous to that ever becoming a civilization, it does seem like there's obvious hurdles. My colleague Adam Frank has been thinking about this a little bit harder than I have, and he pointed out that oxygen is not just a problem in the ocean, but it could be a problem in the atmosphere as well. You could be on an exoplanet that has no oxygen.

But you could still be a creature with thumbs and opposable thumbs and hands and things and a smart brain that you might have the idea of developing technology. But similarly, you wouldn't be able to really do any industry if you couldn't burn. If you didn't have access to combustion, that seems to prohibit a huge range of technologies that were foundational to us getting started. And people often say this about fossil fuels as well. Fossil fuels are clearly...

a poison to our atmosphere. But had they had not been on our planet at all, it's questionable whether we would have got to a point where we'd even be developing solar panels, right? Because that requires some pretty advanced technology compared to Stone Age tools. You can't go from Stone Age tools to solar panels. You need something in between to bridge that. And combustion was certainly a pivotal filling in step for us in our own development.

We're getting a little bit speculative as to whether other civilizations could use other things. I think Adam Frank has been interested in alternatives to oxygen for combustion. I think he talks about hydrofluoride as a possible alternative, but that's a very toxic alternative.

molecule. So it's unclear if anything could actually survive and not be intoxicated by having such a poisonous fume for its one combustion thing. Also, that doesn't just combust, but it combusts way harsher than oxygen does. It would really explode basically every time you tried to use it. So it'd be very difficult maybe to imagine combustion. Similarly, it does seem like having an oxygen-rich atmosphere could be

requirement to potentially developing a technological civilization. But subsurface intelligences and subsurface life more broadly is

One of the most interesting things we can do in the near term to look for, because we have Europa and we have Enceladus, these moons in our solar system, which almost certainly have liquid water beneath their icy crusts. And we know we can visit them and we know we could think of ways of getting down to that surface and probing and looking for life in them.

it's going to be very difficult to do so, but I think the investment is worth it because we could answer this most profound question as to whether life started in a completely different environment to that of the Earth. I think if we found that there,

it would resolve the question I brought about earlier as to how often does life start in general. If there's two instantiations of it in the same solar system but under completely different independent circumstances, that essentially proves that life is easy and life could therefore start everywhere. So having that second data point will be incredibly important for us in our understanding of life in the universe.

even if it's not intelligent. I doubt we're going to find the city of Atlantis on the bottom of Europa. We might have Europa and sushi in a few centuries, and the billionaires will be shipping over some Europa and sushi and selling that at a premium, I'm sure. But it's a possibility that I think is to be taken very seriously, that there could be life in our own solar system. And for me, that is the most likely place we're going to find it beyond the Earth.

I suppose one of the potential pushbacks there would be what if there was some sort of cross-pollination? How do you know that we're in the same solar system, something hit us, there was something carried on that which seeded this other moon

moon or some other area of the solar system with the same original sort of genesis of this? Yeah, that's a great question. And that's an idea called panspermia. So panspermia is the idea that life couldn't transfer between planets, between moons, and spread out within a solar system, but potentially even beyond into other solar systems as well. So

The nice thing about Europa and Seldes is that they're pretty much sealed behind this prison of this thick ice sheet, which is at least a kilometre, probably several kilometres thick for both of those objects. It's very difficult to imagine. Let's say a rock got knocked off the Earth in an impact, and on that rock was a tardigrade or a whole bunch of them, a whole bunch of extremophiles clinging on for dear life. They somehow survived the journey of space, which I think is actually feasible.

they survive the impact. But even so, unless that impact is extremely massive, it's not going to crack all the way through many kilometers of ice and penetrate through into that ocean water. Also, not only this, but it's further out in the solar system.

So you're going from, imagine like a well, you know those coin drops that you throw a coin, it circles down, it circles down, it circles down, it circles down. Now you can have two coins hit each other fairly deep down in the well, that's the Earth. The Earth is pretty deep down in the gravitational well, it's pretty close to the Sun. Jupiter's pretty far out, it's 5.2 further times out than the Earth is from the Sun.

And that's where the nearest one of these moons is, Europa. So you have to have a collision that is impactful enough that that rock can then circle all the way back up five times higher and then still have enough energy to strike Europa and break through the ice. It's not impossible, I don't think, but it would be pretty unlikely that you would have the circumstances to create something like this. For Mars, for Venus, and the Earth, there we can imagine interchange of material much more readily.

And it is intriguing to ask, maybe life started on Venus or maybe life started on Mars and moved over to the Earth and there's some transfer between us. But I think Europa and Celeridus, they're almost like sealed boxes. Yeah, that's exactly what I had in mind. But then that does raise the question that we might break that seal, right? Because if we deliberately drill down into it,

whether we want to or not, some extremophile is going to cling onto the side of that spaceship. It's basically impossible to completely clean the spacecraft. Sterilize your spaceship out in space, yeah. There's always something. And then it's going to penetrate into that ocean and potentially be a source of contaminant. So you get that one chance of doing the experiment correctly. And if you screw it up, you've potentially introduced an entire new biosphere that could be

fairly dangerous, in fact, to an existing biosphere there. Talking about large impacts, can we talk about the importance of the Moon and its creation and stuff? Yeah, the Moon's a puzzle that we still wonder about today, despite the fact it seems like it's a sealed story. We think the Moon formed from a huge impact

It's thought that there was a Mars-sized planet which smashed into the proto-Earth billions of years ago, just after the solar system formed. So the Earth would have actually been larger had this impact not occurred. It would have been maybe 50% more massive than it is today, maybe twice as massive. This impactor came along, smashed into the Earth, and knocked off a huge amount of material. It's thought that that impactor, which we normally give it the name Theia,

would have been almost completely obliterated and vaporized in this collision. Then some chunk of the Earth was knocked off, and that chunk of the Earth is ultimately what formed the Moon, or maybe even multiple moons that then coalesced later into a single moon.

So there's a huge amount of interest about why you might come up with a speculative idea and still people are challenging this idea. The thing we know for sure is that the Moon rocks that were collected by the Apollo astronauts have almost the exact same isotropic ratio of oxygen-18 to oxygen-17, I think it is, as Earth rocks do. This is thought to be a fingerprint that the rocks

formed in the exact same place around the sun. We look at rocks from Mars, we look at rocks from Venus, these are basically meteorites we've collected that land on the Earth. They have distinct isotropic ratios, but the Moon and the Earth have exactly the same. So that tells us that they formed from the same inherent clump of material.

That's challenging with this impactor. If this thing really did have its own unique origin, this impactor Theia, why didn't it contaminate that then and have its own distinct signature that gets mixed in? That has been a challenge. One idea that has been suggested to Cataract - this is called synestia, I think I'm pronouncing that right - and that's when the impact happened

It was so extreme that it formed basically one giant donut-shaped planet for a while. The Earth and the Moon would have smashed together, formed basically a ball of lava that was shaped like almost a donut in space, spinning very rapidly because of all the angular momentum from the impact, and then gradually have peeled off and formed a Moon and the Earth separately from this giant impact.

The reason why this is attractive is because it allows for this material to mix in thoroughly. So this impact of whatever it was, Theia, and the Earth completely mix into one single object, and then it separates that into the Earth and the Moon separately.

That seems to explain some of the mysteries, but not everybody accepts that idea. There's still a lot of controversy about the Moon. The Moon's far side has a very different appearance and thickness to the near side. Have you ever seen a picture of the far side of the Moon? It looks radically different to the near side. The near side has these Maria

these beautiful lava flows that happened millions of billions of years ago that kind of smooth out and it has these more cratered areas whereas the far side is almost completely cratered there's very very few maria

That's because the crust, the actual lithosphere of the Moon, is much thicker on the far side than the near side. And again, that's weird. Why should that be? Why is there a dichotomy like that? And so one idea there is that actually two moons formed in this process, and then one kind of pancaked onto the back of the Moon today. No way. And it's that pancaking that then formed a thicker shell on the far side of the Moon. So

I wish we had a time machine because this would have been the greatest fireworks show in the universe to have seen the formation of the Moon. And again, it raises so many questions like how

How unique was that? Does that happen in other exoplanet systems? Are we special that this happened here? We don't really have any observational evidence either way, but obviously my team and I, one of the things we've been trying to do over the last few years is to try and detect moons around other planets to try and ultimately answer this question. Because at the end of the day, the moon has a huge influence on our planet.

It stabilizes the obliquity of the earth. It gives us the tides. It gives us the rise and the fall of the tides, which potentially are a useful thing for life. They create rock pools on the coastlines, especially when the moon was closer in. It would have formed rocks

continent-covering tides, basically. The entire continent would have been covered in a massive tide that would have formed all these rock pools all over the place. It also potentially stripped off the upper lithosphere of the Earth. What's the lithosphere? Basically, the crust. The crust may have been much thicker of the Earth when it first formed, and then the impact could have ripped off some of that thick crust

And had that not had happened, the crust may have been too thick to have allowed for plate tectonics. So plate tectonics, we think, are absolutely crucial for life, as light life as we have it on the Earth, because they allow for something called the carbon cycle. So when an animal dies in the bottom of the ocean, its carbon is locked up in its bones and its shell, whatever it is, and it settles down to the bottom of the ocean. It just stays there.

If that was just the way it was, the world would run out of carbon, basically, and there'd be no way for animals to grow on the surface anymore because there'd be no carbon left. But instead what happens is these plates subduct and they go under each other, and so that carbon recycles. It comes back out in CO2 in volcanoes, and that allows access for photosynthesis to happen in plants, for instance. So without the carbon cycle, it's difficult to imagine how we'd have the biosphere we have today. And the moon...

may actually be the reason why we have a carbon cycle. For if it had not stripped off that upper layer

that upper crust, the crust would have been so thick that it would have formed what we call a stagnant lid. A stagnant lid seems to be the case for Venus. Venus seems to have a very thick lithosphere which basically prevents plate tectonics as we have them on the Earth. So yeah, very intriguing. You look at all the things the Moon does and you think, "Wow, are we a product of the Moon?"

The idea of plate tectonics kind of tilling, like doing global tilling, is so, so fascinating. And yeah, I mean, the moon being tidally locked or rotationally locked, what's that called? Yeah, tidally locked. Tidally locked. Yeah, so we only ever see. How rare is that?

to have something that doesn't rotate at all. That seems bizarre. That's actually pretty common. A lot of millions, that's true. We think we understand why this should happen. Whenever you get fairly close to a planet or a star, the gravitational effect obviously increases as you get closer and closer, and it kind of locks in the shape of that object to always have one side facing it.

So, especially if you have some kind of fluids like the Earth does, these tides can be quite effective at slowing things down. It happens for many moons around Jupiter, Saturn, so we think this is pretty common. It's thought that this should be common for exoplanets as well, which is interesting but again, unproven. But we think that there are some stars which have very close-in planets, and those planets are so close that they should tidally lock to their star.

We've measured many of these hot Jupiters and we've watched them whizz around their star. We can even see thermal maps. We can thermally map the distribution of energy on these planets, and they look indeed like they are tidally locked, as we would expect them to be. Everything about exoplanets seems to support this idea that tidal locking should happen. But there are also mysteries with tidal locking. We don't really know exactly when it stops.

The theories of tidal theory that we use are fairly primitive, to be honest. They kind of parameterize things in a very basic way. Ideally, you would just simulate an entire planet, like every single atom, but we just don't have computers powerful enough to simulate every single atom. So we use these simplified models. And we know these simplified models don't always work. So for instance, for Mercury...

It was predicted that Mercury should be tidally locked to the Sun, but it's not. It's in a pseudo-synchronous orbit. Probably the reason why that's happening is because of general relativity, because actually there's general relativistic effects that come into play when you get close to a star as well. So it's thought that

Tidal locking should happen, but in some instances it's more complicated than just a simple formula. You really need to think about the composition of the star, the composition of the planet, what it's made out of, does it have a core, what's its density profile like, how much general relativity is kicking in here. The calculation is quite non-trivial, but it does seem like it's common in the solar system and expected to be common elsewhere. Are there any other interesting rotations of planets in our solar system?

Yeah, I mean, one of the things I think is interesting is Uranus is tilted on its side, which is kind of confusing. So even though its spin isn't particularly unusual, it's somehow been knocked over. So it's just spinning in a sideways configuration. Like it's rolling forward?

It's like it's axis in which it spins. The Earth's axis is basically pointed orthogonal to its orbital plane, so normal to its orbital plane, pointed up if you like, whereas for Uranus it's kind of tilted so that its north pole is pointed at the Sun.

It's like it's rolling forward on a surface that doesn't exist. Yeah, kind of. Yeah. And as it goes round, what's kind of weird is that the moons have also tilted over alongside it. So this has been curious how we can imagine maybe the planet getting knocked over on its side.

but then why are all the moons also on its side as well? We don't really understand what happened there. So very strange to understand what happened to Uranus. One of the cool things we're thinking about, a lot of my team at the moment in my research group, the Cool Words Lab, is the rotation of Jupiter and Saturn, which are rotating pretty fast, once every 10 hours. We think this is to be expected pretty much for all giant planets once you get far enough away from the star. So if the

If Jupiter came too close to the Sun, that tidal locking thing would kick in and it would slow Jupiter down. It would put the brakes on Jupiter's spin and slow it down to days rotation rate, basically whatever its orbital period was. But Jupiter is far enough away that it still retains what we would call its primordial spin. Jupiter and Saturn don't really have any way of getting rid of that spin.

For the Sun, it does lose spin. It was probably spinning much faster when it was young, and it's been losing it through its very strong magnetic fields. Jupiter has magnetic fields, but nowhere near strong enough that it can lose spin the same way that the Sun does. And it's so far away from the Sun that it's not going to be slowed down by being closer. Yes, correct. So it doesn't really have any way to shed this spin.

That's interesting because we have some observations coming up with the James Webb Space Telescope in October where we're going to basically measure a Jupiter analog, so a planet, an exoplanet around a different star. It's over a thousand light years away, but we're going to measure very precisely its shadow as it passes in front of another star. And we think that this planet should have similarly a fast spin.

And why that's interesting is that that fast spin causes Jupiter to bulge out at its equator more than its pole. So it's actually 5% wider than it is tall and Saturn's 10% wider than it is tall through this spinning effect.

We think we can measure this. It's never been measured before. If we can measure it, it will tell us basically what the planet is made out of, how fast it's spinning, and even its tilt angle. So as I said, Uranus is tilted right over. Jupiter and Saturn are not very tilted compared to that, but we should be able to actually measure that angle for the first time and really get a deeper insight as to how these planets are forming. So I'm just excited that we might have access for the first time, thanks to James Webb, to a completely new observational technique

learning about exoplanets we have their mass we have their radius but now we can get their their spin their bulginess their tilt angle and really just complete the picture as to how these things formed are most solar systems and galaxies on a kind of a plane like why why is why are things not spheres why is there not sort of three dimensions of movement

Yeah, that's a great question. You might think of that as being an obvious possibility. And certainly there are actually some planets which do that, Chris. It does happen sometimes that you have planets in these wild, chaotic orbits. If you look at Jupiter as a mini solar system, it has these four inner moons, the Galilean moons as they're called. That's Io, Europa, Callisto, Ganymede. And they look like a mini solar system, like a pizza.

like a flat disk. But then around that you have this nebula of spherical orbits basically, as you say, just stuff in all kinds of crazy directions. We think that all of that stuff in the wild orbits is what we call irregular moons, and the stuff that's close in and formed like a disk we call a regular moon. So we think the regular moon's formed basically from a disk of material that was around Jupiter when it first formed. So as it was forming, it was

spinning and collecting material. Just like spinning a piece of dough, it naturally wants to form a disk through that angular momentum. Then from that disk, the moons just coalesced and popped out. But the irregular moons, they can't have formed that way. We think those are probably asteroids and even minor planets that were captured by Jupiter's

Jupiter's gravity. So that's more like the three-body problem type stuff. That's instabilities that kicked in, then Jupiter gone in the way and kind of dragged them into these wild orbits around themselves. And we do see in some exoplanets

planets doing very strange things like that. There's even many cases of planets orbiting backwards around the stars. So the stars spinning, say, in a clockwise sense, and the planet goes round, sometimes even in a plane, but in the complete opposite direction. We don't have that in the solar system at all. That's very, very odd. That has been a big headache for lots of people trying to understand how these things form. How on earth do you get a planet to go around in the complete opposite direction?

Is angular momentum the explanation for why most things seem to be on a plane? Yeah. I mean, disks happen all over the universe. Think about Saturn's rings. It's in a disk. Think about the galaxy. It's in a disk. When we look at young stars, we see disks around them. We've taken photos of them. We see these disks forming. Essentially, as they spin, that angular momentum wants to spread material out into a white disk.

Is it possible to know the size of the universe outside of the observable universe? Is that something that we can answer? That's a hard question to answer because of the fact we can only see so far. When we look out into the universe, basically the greatest distance we can see is just how long light has had to travel given the age of the universe.

So you might naively think if the universe is about 13.8 billion years old, the furthest distance we could see would therefore be 13.8 billion light years away. However, the distance is actually much greater than that because the universe is expanding. So during the time this distant object produced a particle of light, a photon towards you, and it travels that distance, that that

origin point has itself moved further and further away from you. And so due to the rate at which we think the universe is expanding, the most distant point that we could possibly see, which would be 13.8 billion light years of travel, would actually be probably something like 45 billion light years away due to that expansion effect.

So therefore you have 45 billion light years in one direction. You could do the other direction, another 45. So that gives you a diameter of about 90 billion light years. So we can say the universe must be at least this big because when we look out in that region, we don't see repetitions. So we don't see...

If the universe was like on a sphere and you just traveled round and round the sphere over and over again, you'd see the same stuff happening over and over. But everything in the universe seems unique. Every patch seems a different patch to everywhere else. So the universe seems to be at least 90 billion light years in size.

But it's probably much larger than that, because when we look out at that distant speck, there's nothing fundamentally different about it. Presumably, from its perspective, it could see another 45 billion light years again in the other direction. The question is: how many times can this go before there is some kind of wraparound? Or perhaps there is no wraparound, it just goes on forever. This really speaks to the curvature of spacetime. What is the shape of it? Is it indeed totally flat?

If it was perfectly flat, then the universe would essentially be infinite in every direction. You could just travel and travel and travel and you'd never come back to the same point.

It doesn't mean necessarily that the universe in terms of matter is infinite. There may be a region where all the matter and energy lives, and then eventually you just exit that region. You're still in space-time, but there's just no stuff anymore. And then eventually you might travel far enough away and you'd hit another universe, if you like, another region of mass and energy that's completely separate from that of our own.

But generally, I think we assume that that's not the case, that it's just kind of homogenous everywhere. By the cosmological principle, as we call it, we kind of assume that where we are is typical of everywhere else. There are some measurements trying to constrain the curvature of spacetime.

especially using Gaia, you can essentially draw triangles on the sky and add the angles up of those triangles. If you draw a triangle on a flat piece of paper, the angles should add up to 180 degrees. But if you imagine drawing a triangle on a balloon or on a football that's curved, the angles will actually add to an angle greater than 180. You could therefore tell that there's some curvature based off some of those angles. We can do a similar kind of experiment in astronomy

And as far as we can tell, the angles do add up to 180. The flatness of the universe is very, very flat. It may just be though that like our early ancestors who looked out at the horizon and they saw what seemed to be the flat Earth. The Earth does look flat, but if you travel far enough and you get a tower big enough, you will eventually see the curvature. So it may simply be that the curvature evades us and there is a curvature, but we just are not able to see it yet.

But it does imply the universe is very, very, very large, much larger than that which we see, and it is potentially and mind-bogglingly infinite. What would the implications of that be? An infinite universe? In a sense, there's no implication. In another sense, there's profound implications. So in a sense, there's no implication. It doesn't really affect anything outside of this barrier as far as we can see.

13.8 billion years of light travel time, or 90 billion years when you convert to the diameter of this physical scale, anything outside of that Hubble volume, as we call it, can have no interaction or effect on us in any way. So there's no way, if there was a malevolent alien out there, who could ever affect us. There's no supernova which could ever go off. There's nothing which can ever happen there, ever, in the past or the future, which can influence us.

And so in that sense, it doesn't really matter what's happening out there. So it's like if a tree falls in a forest and no one's around to hear it, does it really make a sound? Does it even really matter? Philosophically, does it matter whether this stuff is out there? And if you think about quantum interpretations of the universe, some interpretations would basically say it doesn't even exist. If it's not observable, its superposition is basically completely ill-defined and you can't

even talk about it being a physical object in a sense. So there's that kind of perspective of it. But another perspective is profound because if the universe is infinite and not just infinite in scale but there's mass and energy all over the place, then there would be an infinite number of Chris's and an infinite version of David's out there. And with enough monkeys typing on a typewriter, infinite opportunities, everything will happen

again and again and again and again an infinite number of times and sometimes they'll be slightly different sometimes they'll be exactly the same and that's a a strange concept it means none of us ever really die right there is someone who has the exact same life experience as you who is you in every measurable sense of the word down to the atom down to the electron they are the same as you

And yet they could be offset 100 years into the future or 100 years into the past, whatever this really means in terms of time, because we're such wide separations at this point. But we would all basically be alive forever somewhere. So you can get into kind of like

metaphysical, philosophical aspects of it which are very strange to ponder as well. Yeah, I'm right in saying that there is - I don't know what the cubic metre space that I inhabit is - but there's only so many ways that matter can be arranged inside of the space that I occupy. And if you have an infinite universe, therefore there must be at least at some point this. Is this not

Boltzmann brains? Is this not something else as well that kind of ties in with that? Yeah, it's a similar argument to the Boltzmann brains. The Boltzmann brains argue that it's really thinking about the far future typically when people talk about Boltzmann brains. But if you imagine time running forever and ever into the distant future, then random particles will sometimes coalesce in random ways to eventually form a conscious brain.

And what's kind of strange about that idea is that the conscious brain doesn't even have to exist for very long. It could exist for just a microsecond and then fall apart. But in that microsecond, it could have all of your memories. Every experience you've ever had would be hard-coded into its wiring. And so it would believe it was in this room. It had had all the experiences we had had. And it would be indistinct. There'd be no way to disprove that. And in fact, when you...

really think about the infinities involved, there's far more Boltzmann brains than there are rational human brains. It's far harder to have a human go through all the steps of actually living a life than it is just to emulate the life.

And so by that account, it's much more likely you'd be a Boltzmann brain. It's the original simulation hypothesis. Dear God. Right. It is kind of like a simulation hypothesis. But a lot of astronomers have turned very sour to this idea. And a lot of the arguments against it fall into entropy camps. And if you really look at the far future of the universe and look at the heat death, you can't just...

have entropy reversed like this, even in spontaneous ways in a probabilistic sense. It just really shouldn't happen once you get to these kind of extreme times where the particle density drops down so much that each particle eventually will just be in its own universe. So it can't possibly coalesce into these balls from brains if it's the only particle around. So when you think about the practical implications of the cosmological model that we think is the most likely answer for the future of the universe,

The Boltzmann brain's idea starts to fall over a little bit. Have you read The Five Ages of the Universe? I haven't, no. That's the Fred Adams, Greg Laughlin book. Oh, I know. I probably know the paper because...

they wrote a paper which is The Deep Time of the Universe. That's a classic paper that I've given to my students many, many times. It talks about the decay of the proton, the far future of how the last stars all go out, and the possibility of forming new stars. I know the paper quite well. I haven't read the book. This is like the normie translation, probably, of that paper. It's just a

I think it's maybe 25 years old now. It's in the 90s, I think, that the book was written. It's written excessively, but it's still heavy going for a muggle like me. But I love thinking about far futures. I absolutely... There's something so...

awe-inspiring and sort of dreadful about it. And it's in the same way as spatially looking up at the night sky makes you feel small and insignificant. This is the same, but doing it with time, like you're temporally insignificant. And yeah, just thinking about how much further they go ahead. You had that beautiful story. I must've listened to it

five or ten times the one about the civilization that waits until the very, very final stars are going to die. That stuff to me, far future's thinking is one of the coolest thought experiments to do. Yeah, it's a bizarre concept to think that we are at the beginning of the story. It kind of feels...

Everything is often presented to us as we should treat ourselves as mediocre. So if you're born in a random country, it's pretty unlikely you're going to be born in a tiny country like the Virgin Islands or something because it's just the population is so tiny there versus being born in a country like United States or China or India or something. You're much more likely to be born there. So that's the mediocrity principle.

But when we apply the mediocrity principle to time, it just doesn't work. So the history of the whole universe should stretch out for trillions and trillions and trillions of years, even 10 to the 10 to the 10 type years we're talking about here. And we live in not just the first chapter and not just the first page, but the very first letter of that

whole story. And that feels really odd. It feels incongruous with our expectation that we should be typical and we shouldn't expect to be special. And yet when we look at our timing, it is clearly very special. And there's no reason why

In all of that vast, deep future, we couldn't arrive much, much later in the story. You can imagine, as I said, these red dwarfs, which will live for trillions of years. Why shouldn't they have planets and life around them for a very long time? In that paper, and I'm sure the book as well, Greg Laughlin talks about the idea of brown dwarfs

colliding together and birthing new stars. That would be a very rare event, but over the vast, vast epoch of time, they actually form a significant population of stars which form. In all of that deep, deep future, Boltzmann brains, it seems odd that we would live right at the very, very beginning of the story. I think about that a lot. I'm trying to make sense as to what it means. It seems to suggest that either our idea of mediocrity is fundamentally wrong,

that we should not assume we're in the middle, that maybe it's okay to assume we're special in this sense, which is strange as that sounds. Or perhaps there is something about the deep future which is inhospitable. There's two ways out. The universe could just become inhospitable over time. And it may be not necessarily through stars, because we think there'll be plenty of stars, but maybe a roaming civilization, just like a virus. Povering up.

hoovers up all planets which could potentially have life. That would actually work really well as an explanation. If a roaming AI went around the universe

It happened spontaneously in many different parts of the universe at a certain amount of time, and AI just arrives and it spreads off and it just knocks off everything. It just converts everything into computers. Paying everyone. Yeah, that would actually make sense as to why we lived when we did in the history of the universe. Or if there was another catastrophic event, like the universe went through a false vacuum decay event,

Which essentially means the universe itself becomes unstable, and we have almost like another Big Bang-type event in the next 10, 20 billion years. It's kind of improbable when you do the math that should happen, but that again would rationally explain why we live when we live. And so the mediocrity principle does seem in strong tension with this chronology. And I think that's probably why you and many others, and myself included, get so alluring this idea and so...

There's something about it, something profound here. There's a lesson, and we just can't quite see what the lesson is, but there's something here for us to pick apart, and there's some deep truth that we're missing that this is telling us. Is there not something to be said about the rate at which new stars and therefore planets are being born, that that will sort of drop off over time, therefore being shunted toward the start is more likely? It's a kind of more fertile ground?

That's only true. So certainly star formation rate is already in decline in our galaxy. It's already in decline. So the peak of star formation rate has passed, which is already kind of sad, right? The good times have peaked in terms of the economy of the galaxy. I was going to say we're in a stellar depression. Yeah, right. It's kind of depressing to think of it that way. But despite that, there's just so much time ahead of us that even if you reduce the rate to...

10% of that which is now, that if you have a trillion times longer to go, you're still going to have a lot of stars. So even though there is a peak, it's not a symmetric peak. I guess that's the thing to get your head around. It's a very, very long-tailed peak.

and it takes a long time to decline all the way down to zero star formation. And so if you actually add up how many stars live in the tail of that distribution, there's far more stars and planets born in the tail of the distribution than there are born at the peak of the distribution. And so then it gets really curious, like why therefore shouldn't civilizations also be correlated in their birth rate to planets? You might expect that naively to be true.

How right is it to say that we would be one of the first civilizations to come about, assuming this sort of mediocrity principle? But then also I've heard that, you know, stars and planets have been born, lived and died many times over before ours was even created. Therefore, we should see some civilizations out there that they've had chance to get to where we are and way beyond.

Yeah, it's certainly a way of resolving many puzzles. Like, why do we not see a galactic empire spanning the galaxy that has done this starlifting thing we talked about earlier, or just converted stars into giant machines, or

built infrastructure or have starship lanes across the galaxy. We don't see any of this. We have been doing SETI for 50, 60 years and we don't hear any radio signals from other parts of the galaxy either. I mean, it is possible there's someone out there, but they're very quiet. It's not a chattery, loud galaxy out there. And this raises a puzzle. Like it may be one explanation. This is really the Fermi paradox we're talking about now is one explanation is that we are the first.

And not only would we be the first, that would necessarily imply that intelligent civilizations are very, very rare, right? Because the galaxy is already 13 billion years old, almost the same age as the universe. So that implies that it's a one per 13 billion year event, which is incredibly unusual then, if that was the case. So

It is possible with firsts. I tend to lean more on the idea that if there is life out there and civilizations out there, I think getting to this point is not that hard. I think it probably does happen. But the real question is the future for us, the future of humanity, whether we can

continue on this path that we've been continuing on in this unsustainable trajectory that we've frankly been living in over the last few centuries, certainly. It seems questionable that we can keep doing this. One way to resolve this is to try and live in balance with your planet, of course, and try to be a more sustainable civilization. I think having

I always worry about nuclear weapons. Having nuclear weapons is just immediately unsustainable because as long as there's a 0.00% risk of someone clicking the red button each year, given enough time, it will happen. It's just the same thing. Given enough time, there will inevitably be a nuclear war as long as nukes exist. It's just a question of when, not a question of if. It's just going to happen. So that's already kind of terrifying.

And really, what we're doing to our planet is kind of similar. We are affecting the habitability of our planet by this huge experiment of modifying the chemical composition of our atmosphere. And that's also kind of concerning. I don't think it's going to cause an extinction event for humanity. I'm not a doomist in that sense, but I do think it would probably put pressure on our economy.

It'll mean we'll probably take resources away from science, from exploring space, and I think we'll become more and more insular. Then you can kind of imagine why a civilization would never spread between the stars, because they get so distressed and so hung up on just

keeping alive basically and trying to maintain some level of comfort level to what they're used to, that the idea of spending 10% of your income on something which might seem frivolous, like building a Moon base or a Mars base, just becomes a lower and lower priority. And certainly that's happening with our own budgetary

definitions over the last five, 10 years or so. We're seeing less and less money go to basic sciences in the United States. And so this is also a worry that it could be that very, very slow decline. And I think that could be a possible explanation for the Fermi paradox that this happens quite often. Civilizations, they're inherently unsustainable, and they run up into themselves. And it's themselves that are the ultimate threat to their own growth.

But on the other hand, that means that if someone cracks this and they do become sustainable, we probably would never see them because someone who is completely sustainable would be invisible. If you're in complete equilibrium with your planet...

then there's nothing to look for. If we want to look for a civilization, what do we look for? We look for the solar panels because that's in disequilibrium with the planet. That's not the natural material on the surface of the planet. Or you would look for a nuclear bomb going off. That's in disequilibrium with the natural state of the planet. But if a civilization truly reaches a completely 100% sustainable state,

there is no signature to look for that would be indistinguishable from a perfectly natural biosphere. That's intriguing. We may not be able to actually detect those civilizations because they're so good at looking like a natural planet. Given the time that you spend thinking about potential futures for civilizations, the ways that they may or may not be in equilibrium, does it give you a

an additional sense of seriousness and trepidation sort of about what, whatever we do here on earth, the fact that you kind of can see cosmically, galactically, this sort of knife edge of just how easy it would be to not end up keeping going the way that maybe we would like to. Yeah. I think it's such an awesome responsibility when you think about

the pressure of just existing in a way as a species. It is, you know, I think about this in my own life a lot, and maybe you do as well, that if you've played computer games growing up, as I did, it does feel sometimes that life is a bit like a computer game. Like it's kind of wild. And

In a computer game, you realize there's certain rules and you realize what you're allowed to do and what you're not allowed to do. Once you know what you're allowed to do, it's sometimes a little bit crazy that you actually could complete the game. I could basically finish the whole thing. I could build this massive city or massive empire, whatever it is you're playing in the game. Life is kind of like that. When you realize the rules of the game,

you realize there's nothing really stopping you from completing everything you want to complete in the thing. And I think as a species, it's wild to think that we have that. As far as we can tell, the rules of this game that we're playing do not prohibit us from one day

colonizing the entire galaxy if we wanted to. There's nothing in the game that prevents us from doing that, as far as we can tell. There's nothing that prevents us from having a civilization which would last for a trillion years, of building wonders that would light up the universe essentially. And yet, none of that has happened. It is interesting that we have this awesome power

as we still have free will, I believe. I still believe in free will and choice. And so I believe that we have the opportunity, if we decide to take our civilization wherever we want to take it and become that dream civilization that maybe whatever it is we have, for me maybe it is a civilization that spans the galaxy, maybe for you it's something else, but whatever that dream is, we can achieve it. And

And so that just reframes for me a little bit the power we have. I think we often feel powerless, but when you realize it's just these rules and there's nothing in the rule that prevents this, it's exciting. It means it's up to us what we do. It's still our choice what we do with this planet, what we do with our society. It's all up to us. There's a lot of responsibility that comes along with that. Yeah, it can feel sometimes...

paralyzing and crushing the weight of that. If you were told you were a child prodigy and therefore you're expected to become the greatest genius since Einstein, that could feel like an enormous pressure on your shoulders. You can only fail from there. Yeah, to live up to your father's expectations, as many of us have felt that pressure. But

There is no father. This is just us. No one's expecting us to do anything because it is just us. We're in a game. It's a one-player game. It's just us in the game. There's no one else out there, as far as we can tell. So we can do whatever the hell we want to do. And if we want to

destroy our planet. We are totally capable of destroying our planet. If we want to live in squalor and have a terrible economy and society and burn the environment down, it is within our power. But it's equally within our power to do something completely different and have the future that we dream of. That's what I believe. And so I've always found that uplifting, actually, that we have the agency—that's the

to be whoever we want to be both personally as individuals, I think, but also especially as a civilization. But it's a collective agency to work together to form whatever we want to form. Yeah, that's the coordination problem, right? It would be, what a shame it would be if we jump through all of these evenly spaced, insanely unlikely,

suburb of the galaxy into having the moon that's tidally locked into having the sun that's the right size and we're the right distance and then the prokaryotic life into the eukaryotic life and then all the way up, all the way up, all the way up and then tribal biases and in-group, out-group signaling and what feels like the final hurdle before you go. I'm going to guess, this would be an interesting question, I suppose that

um if we were to get ourselves to something close to multi-planetary life how much of a how big of a step change in our long-term survivability odds do you think that that makes i think a significant one um

It's hard to put a number on that. I think it would obviously save us from certain threats that we could either put ourselves into the Earth or could come from outward forces. So an outward force might be an asteroid impact, most obviously. Inward forces could be some kind of massive conflict or a virus or something like this. So it certainly provides some fencing off of that kind of danger. But of course, there are other threats beyond that. I mean, we all know that with

COVID, it wasn't self-contained to a single country. And so if there was a virus, whether it's a mind virus or a physical biological virus, it still would most likely have vectors to spread to our neighboring colonies, even in the solar system. It seems quite plausible that the entire solar system would still be in danger of suffocating by such a threat.

And of course, an outward threat could be a supernovae or a gamma-ray burst, which would equally put the whole solar system at risk. So it's definitely an advantage, but it's not enough. If your sole priority is to perpetuate the flame of consciousness, as Musk would say, then you'd want to not just be interplanetary but interstellar to truly achieve that, and even eventually intergalactic to achieve that. But then you have to question

you know, why hasn't a civilization done that? Because as we said, we don't see evidence for regions of the Stagai which have been colonized in this way. Although perhaps they're just doing it in such a way they don't want to be detected or hiding from us in some way. But as far as we can tell, this kind of empire building doesn't seem to happen very often. But I would hope

I would hope that we can continue to keep this consciousness going because I think there's so much. It's such a boring universe without it. I think it lights up the universe to have some thought and some agency in there. Yeah, I agree. Again, every time that I think of the potential far-flung futures of what we could be really helps to give perspective. It really is kind of the

sort of philosophical, imaginative equivalent of looking up at the night sky and making yourself feel small and putting your problems into perspective and realizing just how much you should probably be thinking of a broader horizons in all directions, in all different types. And it's oddly existentially reassuring, I think, in some ways, or at least I find it is. Yeah. Yeah. One of my colleagues says about time a little bit as well. And he said to me,

I think with our lives sometimes as individuals we feel this way that I'll get to this point and then I'll be happy. I'll get to this point and then I'll do this. There's always that thinking of the future as a point of rest or a point of achievement. And one of my good friends, he said to me, this is it. You're in your 30s. This is life right now. Don't let life slip you by.

because you're so focused on the future. I think as astronomers, I tend to live especially in the future because we think about this deep time. But don't live your whole life thinking about making sure… Obviously, it's important to have enough money for retirement and be comfortable with things like this, but don't obsess your whole life about that because you'll miss out on what's happening right in front of you. Somehow being present

and seizing what's in front of you is an equally important lesson because at the end of the day, life is incredibly short and I'm turning 40 this year and that's making me think, wow, where's the last 10 years just gone? They just disappeared under the abyss. And you do start to realize that...

This is it. You only get this one life and it's going by pretty fast and you don't want to mess around. There should be a sense of urgency, I think, in your life. That's how I try to live my life, with a sense of urgency that every day is kind of precious and matters and you're not going to get a second chance at this. Yeah, I love that. Can we talk about my new favorite pet obsession, which is ton 618? It's this massive galaxy or massive star? It's a black hole.

Oh, the black hole. Yeah. I don't know too much about this black hole though, to be honest. I think it's just the biggest one that's been logged. But when you look at the size of this thing, I think it's,

It's event horizon is larger than the orbit of... It's basically larger than our entire solar system. Like this thing's just beyond... It's like Gargantuan from Interstellar, basically. Yes, yeah, yeah, yeah. Yeah, it's just beyond obscene. And the more that I learn about the, again, far futures and then looking at black holes and kind of the very...

odd way that they break much of the intuitions that even someone that knows as little about me as me about physics has. They're just so fascinating. The unanswered questions about black holes are just beyond fascinating.

Well, they're such bizarre objects. They really seem like a nightmare that's come to real life. They're so strange, like a hole in space-time. Many people, including Einstein, didn't believe they were possible until we really started to see more and more direct evidence for their real existence.

They're very strange, and I think the massive ones have been a puzzle mostly in context of what research astronomers are talking about. The most common thing I hear about with massive black holes is the puzzle of how they got so big, especially as fast as they seem to have got that big. When we look at the images from the James Webb Space Telescope, we do see evidence of massive black holes, what we call quasars, these active galactic nuclei which are basically

So there's material falling into the black hole and it forms these very powerful jets. We can see these jets and that allows us to weigh how heavy the black hole likely is. We see evidence for black holes which are just so large in the early universe that it doesn't seem possible that there was enough time, given the age of the universe then, to have built something that big, that massive. That has been a puzzle. It's similar for galaxies as well. Galaxies and black holes tend to go together for the supermassive black holes.

It's kind of an open question, like a chicken-egg problem as to what comes first. Is it the galaxy that first forms and in the center you end up with a black hole? Or does the black hole come first and that leads to a seed to the rest of the galaxy? Or maybe a bit of both. Maybe a bit of both is going on. But certainly when we look at these early images, we're seeing evidence of both unusually massive black holes and galaxies in the early universe. And it's

puzzling that the universe can form stuff this fast. There are some ideas around this that are maybe a bit more exotic that people are floating around. One idea is a primordial black hole. So this is something which could have actually formed from essentially the conditions of the Big Bang itself. So very soon after the Big Bang,

It's a very dense soup, the universe when it first formed. It gets less and less dense as it expands. Maybe some of those densities are a little bit denser than others, little pockets. Those pockets could collapse down and form black holes directly straight after. No stars involved, just from the raw material of what came out of the cosmic soup of the Big Bang. Those things could be potentially both very big and very small.

They could even be Earth-sized, Earth-mass black holes, or they could form things all the way up to the kind of tonne 618 gargantuan-style black holes as well. People are struggling and they're reaching a little bit for some of these more exotic theories right now. We have many surveys still planned with JDUST. It's still only two years into its 20-year mission.

that's hopefully got ahead of itself. And so this is definitely an area of active research right now. And I don't really want to

predict what the answer will be at this point because it's hard to tell. I think a lot of people are saying we should rip up our models of cosmology, and I don't agree with that. I don't think the Big Bang theory is fundamentally wrong, or the models we use we call the 'standard model of cosmology' essentially is fundamentally at issue. I don't think you have to throw that out to explain these things, at least not yet. And I think astronomers have very good reasons to not want to do that because then

how do you explain the fact that it explains 999 other things perfectly? How do you explain all that other stuff so well, so perfectly well, if you throw out this model? I think it's probably issues of some of the early galaxies, especially, that were being discovered. It was actually the star formation models were probably in error. So we take the rate of how we think stars form, and we take a look at the local star formation rate,

of what we see around us as kind of a proxy for that. So you say if you have a certain amount of density, a certain amount of gas, you expect to form this number of stars. And we see that around the solar system locally. And then we take those models and we extrapolate them onto these very, very distant galaxies on the other side of the universe.

Reasonably, astronomers have pointed out that's probably not a good idea because why should we expect the way in which stars form from this mature, metal-rich, very old glass cloud to at all be similar to the way the very, very first primordial stars formed? When you modify your models to account for those differences, you actually can explain where these early galaxies came from.

So I think it's probably an issue of not the fundamental cosmology being wrong, but the way in which we think that stars and black holes form within that cosmology probably needing updating. At least I hope that's the case, because if we have to throw out cosmology completely

It's both exciting, but it'd be a big headache to explain all the other stuff that it works so well for. Do you class yourself as an experimentalist? Is that sort of the camp within which you sit? Yeah. You know what? I don't like labels at all. Maybe I'm a bit controversial in a sense, but a lot of astronomers - maybe an astronomer isn't a label I'm okay with - but a lot of astronomers would split themselves up into categories of theorist,

modeler or observer. They'd probably be your three categories of astronomers, theorist, modeler, or observer. A modeler kind of sits in between those two. The theorist who do pen and paper math and they're working stuff out on the blackboard, the observers who are going to the telescope collecting data, and the modelers who are trying to connect the two worlds to each other. I do all three. That's why I don't really like a specific label. I also just think, in general, advice I give to students is

is that it's not useful or conducive to work with such a label. If you tell yourself you're an observer, then it's like someone saying, I can't do math. I hear this all the time. So many students who come into the classroom and say, I've never been able to do math. I can't do math. It's all gobbledygook to me. And if you approach the world with that mindset, then of course you won't be able to do math. It's a self-fulfilling prophecy. You've predestined that you can't do math. And so I think calling yourself an observer is

can have negative self-connotations that you think, "Therefore I can't do X, Y, or Z." So I prefer personally to really not work with those labels. Not because I'm trying to be pretentious, but just because I think it doesn't serve any purpose for me thinking about the things that I can and can't do. And even with astronomy, I'd prefer not even to really be an astronomer because I like a bit of philosophy, I like thinking about

astrobiology. I like thinking about the connections to biology and the chemical world as well. And statistics. I write a lot of just almost pure statistics papers, so I don't want to be in any one camp. I think that's how it was back in the day. There were just these polymaths that just worked on everything. That was beautiful because they could see connections between things that you would miss.

And we live in an academic world right now that really promotes extreme specialization. Not only are you an astronomer, you are an exoplanet astronomer. And not only are you an exoplanet astronomer, you're an exoplanet atmosphere astronomer. And not only are you an atmosphere astronomer, you're a cloud astronomer. It gets more and more niche. And literally, I'll bump into students at meetings and postdocs who will say,

you know, "Oh, I'm a cloud specialist." And that's great, but don't you think about other aspects as well? Because if you're not thinking about the chemistry and the surface, how can you possibly connect that to the chemistry in the atmosphere? All these things are connected to each other in some way. So yeah, a bit of a rant there, but I just don't think it's particularly useful personally to operate with a label. It's kind of one of my

pet heaves that in the world of academia we have become overly specialized and niche in our interests. Yeah, that specialization being for insects. I spoke to Eric Weinstein twice about this. I remember I spoke to Sabina Hossenfelder a while ago about this too.

It seems to me that the theoreticians, less maybe so on the astronomy side, but as I'm hearing you speak today, it's so evident that there's just tons of cool, interesting stuff that's being found out, that's being tested. And you have a sort of vim and vigor about, it's so cool. Your passion's infectious. That's why I love your YouTube channel. But then I look over to kind of

M theory, string theory, hardcore theoretician side of stuff. And it just seems like, I can say this because I'm not a physicist and I'm not getting you in trouble, but it just seems like this weird, boring Groundhog Day circle jerk of people not really making legitimate progress in any one direction, right?

From what I know, it's incredibly sort of tribal and quite politically kind of driven. Oddly, the people that are trying to sort of transcend or helping us transcend humanity are some of the ones that are the most captured by it. It just must be, of all of the different areas that you could have found yourself in in physics, it seems like there's lots to do, lots of new territory and ground to cover, very much a kind of like...

captain cook new worlds sort of let's go find some cool stuff out over here mentality as opposed to yeah this very slow moving quicksand that may be going backward maybe going in the wrong direction who knows uh on the like hardcore theoretician side yeah i think academia is littered with many issues many problems it is by far away from a perfect idyllic system i mean when i

was a kid, I actually did want to be a professor. I thought about that. I never thought I'd be doing it, to be honest. I never thought I'd get to that point. It seemed like you'd have to be some kind of super genius or something to become a professor. But

um it seemed idyllic in that i imagine you just sat in your office and thought about this you know the universe all day and that's not really sometimes you get moments to do that but most of the job is not doing that and people don't act with pure intents people aren't all driven just by this pure scientific ideology like any industry like any corporation any field there's personalities there's cultures there's

people trying to play politics, trying to protect their little area and trying to shoot down your little area. That

That's distressing. A lot of academics do become disenfranchised and disillusioned with the whole game and eventually leave the field and go on to become much more successful working in a hedge fund company or finance, especially my colleagues. That's very popular to basically just cash out. You've got all these math skills. Why not use it to make bank? Because it's actually not that hard to do so. Finding all of these stupid planets. We can't make money off the back of those. Yeah, right. And I think

I know very clearly there was a colleague of mine who was brilliant and he felt this way. He said, "Look, I wrote this package, this software package, this statistical package that everybody in the whole community is pretty much using at this point. It's been cited thousands of times. There were entire conferences organized about his paper and about his work, and yet he could not

navigate his way to a successful faculty job despite that. People would say, "Well, you're just a software engineer in the field. You're not a real astronomer." So there was that kind of pretentiousness of you're not doing the kind of hardcore string theory, M-theory, pen and paper stuff that maybe people might imagine when they think about a physicist looking like

And so those stereotypes have been problematic. It frustrated him enormously, of course. And he said, "I just don't know what I'm supposed to aim for. I just want to know what is it that I am supposed to do? Is it supposed to get citations? Because I've got that. Is it because I'm supposed to be invited to talks? Because I get... So what am I supposed to do?" And he was so frustrated and eventually said, "I'm done with this." And just left the field. And I think that's a different example, but software engineers

We are now trying to promote that actually. So the Simons Foundation, which is down the road from us here, they're now starting up faculty jobs that are supported privately just in software engineering, in astronomy and other sciences as well. But they're really putting money to support these types of positions because they are so important.

But even in my own little world of exomoons, which is the most niche thing in the world you could imagine working on, I spend not all my time working on that, but I spend a significant fraction of my time working on that. But as I said, I don't want to do one thing. But when in that little world, there's probably only a few dozen of us on the planet who are thinking about exomoons in a professional setting. And even within that little world, it's been not always the most pleasant experience amongst colleagues. Because

I think sometimes when it is a very small field, people do get very competitive. If it is a small pond, the temptation is to have one big fish. Whereas if it's a big pond, people maybe play a little bit more easily together, or maybe a large collaboration tries to become the big fish that takes over. But certainly if you're in a niche field, and I think string theory and M-theory have become… there's not many students we recruit now that are interested in working on that topic.

But I think whenever you have a field that does become fairly insular, politics and the darker side of human behavior does inevitably play out. And that happens in all fields. I don't think it's necessarily isolated to theoretical physics, M-theory, string theory. I think it happens in every aspect of science to just different degrees. And it is something which I hate, and I always try to

avoid as much as I can but even doing stuff like this

Like doing YouTube videos, podcasts, even that will create friction, right? Because people are like, "Well, you're not doing real science. All your time should be dedicated to just doing pure research," which obviously I disagree with. If we don't talk about our research, we don't talk about the universe and get people excited about what's out there, what the hell is the point of this? We're not training the next generation. We're not inspiring anyone. We're not ultimately bringing in funding to support our activities.

And also it makes me a better scientist when I do this kind of work. But everything you do, there's always going to be that side that wants to downplay it and pour cold water on it. But

I think just having a thick skin is probably the best advice I can give anyone. If you just get to a point where you just don't care, which is kind of eventually where I've got to, then you're just like, I know this is the right thing for me. I'm just going to do it. I know this is the right thing. And I think that's hard to get through. But when there's politics playing out, that's the only advice I have is just try to keep your head down and just push through those headwinds.

Yeah, it's strange that Puritans and politics exist even in physics, which we would hope are kind of above that or outside of that, maybe in a different dimension. I did want to ask about how your YouTube channel, which is nearly a million subscribers, all of the different things that you do, how balancing that with...

tenure track? I mean, have you got people that just purposefully take your modules and your courses because they love your YouTube channel and they want to be near Professor Kipping? How have those streams sort of crossed over? Has it helped you get access to really phenomenal grad students to come into your lab? It must be a big usefulness there. It has been, yeah. It's always weird to me. When I make the videos,

I always make them assuming nobody watches them. At least nobody I know watches them, that's for sure. I kind of make them in a sense that I want them to be high quality and the highest product I can, the best I can do with it. But I always assume that no one in New York watches it. And so it's always very strange to me when someone talks to me about it and, you know,

bumps into you because sometimes it's in the street someone will ask you about it not that often i'm not super famous or anything but and especially odd when i go to an astronomy conference and other astronomers say i watched your video and that's always a surprise to me because i was like well

I almost feel bad because that video wasn't meant for you. It's cool that you watched my video, but that video was not meant for a professional astronomer. Not that there's anything wrong in the video, but you were just not the audience that I was gearing that to when I made that video. I almost feel bad when they watch my videos, that they see a presentation style

speaker, which is not reflective of how I would give a colloquium or a seminar or something in a way. But it has been useful. One of the major ways it's been useful is actually through donations to my team.

So we have a research account called the Cool Worlds Lab Research Account here at Columbia University. And people donate anywhere from five bucks a month up to, I think our maximum is 500 bucks a month. We have a few of those. Where can people go? If they want to donate to your lab, where should they go? Yeah, it's coolworldslab.com is the website. And then there's a link called support in there you can hit.

So if you head over to there, you can support us. And the amazing thing is that you are, you know, this isn't money that I get. So this isn't like a Patreon. You've not got some golden throne in your office somewhere at Columbia? No, no. I don't see any of this money directly. It all just supports research. That's it. So we're supporting like paying for...

The students stipends to keep them, to hire them, to recruit them. We're paying for supercomputer time, cluster time, for disk space, publication costs, travel costs to conferences. We're supporting bridge program students. So we're doing all this activity with it. And especially it's been great because it's allowed us to get off this academic wheel that we've sort of been alluding to of...

How do you pursue your research passions? One of my research passions is, as we've talked about, searching for life in the universe. But believe it or not, that's very hard to find funding for, especially for intelligent life in the universe. It's still kind of got a giggle factor aspect a little bit to it.

It's pretty hard to persuade NASA or the National Science Foundation to hand over much money to do research in that area, but it's, I think, one of the most interesting questions we can do. Many people agree. The funding we get from the public has allowed us to basically pursue the questions that we think are the most interesting, rather than the questions which we know are most likely to get funded.

When I'm writing a grant, that's typically how we have to write grants. You typically have to write the grant to be, "This isn't what I'm interested in. This isn't even particularly interesting to anybody, but I know this is the boring science that they will likely fund." And it's usually boring because it's low risk. It's something that you just know you can do, and anyone could frankly do it who's a professional astronomer.

It's just arduous and it's not even, frankly, half the time particularly that interesting, half the stuff that you get done with these grants. But you know it's kind of a guaranteed slam-dunk hit that you will have a guaranteed science product at the end of this work. Whereas high-risk work is, by nature, you don't know where it's going to go, what the product's going to be, but you're asking much bolder, ambitious questions. And if we stop, if we just always cut short and just go for the simplest answer,

stuff with the guaranteed results, we're never going to really advance the field and advance our ambitions in space. So I've been very proud and honored to have those donations to support our work. And that's been a big influence. And of course, it has been useful for recruitment to some extent as well. What is this satellite time, this observation time that I know that you just got a big allowance for? I saw your video about it.

Yeah, so it's telescope time on the James Webb Space Telescope. So James Webb is the success of that. The big one. This is like playing Glastonbury, right? Main stage. Oh yeah, this is the pyramid stage. Yeah, this is big. So the James Webb Space Telescope, six and a half meter telescope, is an infrared telescope. It was launched a few years ago now. It's in its second year of science operations. And we proposed...

For the previous two years, we had proposed as well to search an exoplanet for an exomoon. We had previously claimed evidence, tentative evidence, of exomoons in two of the systems, but we hadn't really got to the point where the evidence was overwhelming. To do that, you really want something with a precision of the best telescope, which is James Webb.

So we put in this pitch, but the problem is, as I said, there's hardly anyone working on exomoons. So it's very unlikely this gets peer-reviewed, that the peer reviewer is going to be someone who's particularly fond of exomoons. So there's a little bit of politics there in terms of getting selected time. And so I have to say, we were very pessimistic. We had this planet

I actually discovered this planet myself in 2016. It's called Kepler-167e. I knew it was the perfect planet to look for an exomoon, just coincidence that I found it. But the planet is as similar to Jupiter as you could possibly want. It has the same temperature as Jupiter, the same mass within 1%, the same radius, the same orbital eccentricity. Everything about it is just Jupiter, Jupiter, Jupiter.

So if this planet is like Jupiter, it should have the same kind of moons that Jupiter has, and we could prove that JWST could detect those moons. So this was why it was so exciting. It was the only system this was true of. So we actually went through all 5,000 exoplanets that had been discovered to date,

and we calculated for each one of them what's the biggest Moon it could have, could JVST detect that, and there was only about half a dozen or a dozen of planets that came out as potentially doable. This one was by far the best, by far the best at the top. But it only transits, which is the event we use when it eclipses its star, it only does that every three years. So if we didn't get the telescope time in the next cycle, which is in October,

we would have to wait three more years, to 2027, just to have another shot at doing this again. I hope it should still be around 2027, but you never know. It's been hit by a meteor already once and damaged one of the mirrors, so we just don't know for sure.

we want to see this thing happen over and over again to get shored up evidence of its existence. So we were surprised but very excited that they granted us a huge wallop of telescope time. We asked for 60 hours of telescope time.

And they gave us it. And we need 60 hours because this planet is so far from its star that it takes a long time for it to eclipse over its star. Remember the total eclipse we had when the Moon passed in front of the Sun that we had in America just recently? That's a four-minute transit, basically. Whereas the event we're looking at lasts for about 20 hours, I think. So it's a 20-hour eclipse that you have to stare at. And then you want to have 20 hours either side to calibrate your data and look for the exomoons.

What would happen if you found exomoons? I think the hope is that this is just the start of what happened in the field of exoplanets. So go back 25 years ago, we're at 1995, a little bit further, 30 years ago, you have the first exoplanet being discovered, 51 Pegasi b. Before that, hardly anyone was working on exoplanets. It was considered fringe, it was considered like looking for alien life, and not a serious science. And

Despite that, most people thought, well, they should be out there. It seems obvious that plants should be out there, but it's intrinsically risky to try and claim you're the first person in anything in a scientific discipline. So I think...

With exomoons, I see an analogy that we will hopefully be able to make the first one. And now cycle forward 25, 30 years after that first discovery, you have 5,000 plus exoplanets being used, being found. Now exoplanets represents probably about a quarter of all astronomy funding, depending on how you count it. But about a quarter of all astronomers and astronomy funding goes to exoplanetary science. 30 years ago, that was zero.

So there's been a blossoming of an entire field. And it's not just for the sake of a field. We've learned so much about it. It's completely revolutionized our understanding of planetary systems. We thought the solar system was the way it happened everywhere. We thought that was it. And that's totally wrong. That's totally wrong. The solar system is, if anything, like a weirdo on the block.

It has just profoundly altered our worldview of who we are in the universe, and it has now opened up the door to potentially detecting life in the next 10 years or so using these next generations of telescopes. Exomoons will surely offer up so many surprises that we can't even anticipate yet.

They may be seats for life in their own right, as we've already talked about. They may influence the possibility of life on the planets they orbit. The Moon and the Earth, remember, there's a connection there as to how that could be interacting with one another. And then finally, if we want to eventually take a photo, which I think we do, we want to take a photo of an Earth-like planet one day,

We have to know about the moons around them. If I take a photo of a pale blue dot of light, a distant image, I will be able to resolve the planet from the star with these impressive next generations of telescopes we're planning, but I will not be able to resolve the moon from the Earth. They will be too close together for the telescope to resolve. So that pale blue dot of light will actually be a pale blue-grey blob of light.

It will be the mixture of light from the Moon and the Earth. And when we look at that light, if we don't understand there's a Moon in there, we're going to completely misinterpret what the hell that light even means if you don't recognise that there's a Moon in there. In fact, it could even cause us to think we've detected life when we haven't. So I think this is a very, very important question to figure out, both for our scientific goals, but also for our goals of trying to

understand our uniqueness and origins in the universe. How exciting, man. David, I love your stuff. I love your YouTube channel. Let's bring this one into land. Where should people go? They want to check out everything that you do and follow you and support you.

Yeah, so you can head to my YouTube channel. That's called The Cool World's Lab, at Cool World's Lab, and you can find that channel over there. We also have The Cool World's Podcast, which we started out over the last year. Again, just grab that on YouTube or iTunes, wherever you are. And finally, you can also just check out my Twitter handle, David underscore Kipping, and head to my website, coolworldslab.com, if you want to learn more. Hell yeah. David, I really appreciate you. Thank you. Thank you.