Janna Levin: Black Holes, Wormholes, Aliens, Paradoxes & Extra Dimensions | Lex Fridman Podcast #468

Black holes curve space and time around them in the way that we've been describing.

Things follow along the curves in space. If the black holes move around, the curves have to follow them right?

But they can't travel faster than the speed of light either.

So what happens is black holes, let's say, move around.

Maybe I've got two black holes in orbit around each other.

That can happen. It takes a while. A wave is created in the actual shape of space.

And that wave follows the black holes.

Those black holes are undulating.

Eventually, those two black holes will merge.

And as we were talking about, it doesn't take an infinite time, even though there's time dilation because they're both so big.

They're really deforming spaceime a lot. I don't have a little tiny marble falling across an event horizon.

I have two event horizons.

And in the simulations, you can see it bobble and they merge together.

They make one bigger black hole.

And then it radiates in the gravitational waves.

It radiates away all those imperfections and it settles down to one quscent perfectly silent black hole that's spinning.

Beautiful stuff. And it emits E= MC² energy.

So the mass of the final black hole will be less than the sum of the two starter black holes.

And that energy is radiated away in this ringing of spaceime.

It's really important to emphasize that it's not light.

None of this has to do literally with light that we can detect with normal things that detect light.

X-rays form of light. Gamma rays are a form of light. Infrared, optical, all this whole electromagnetic spectrum.

None of it is emitted as light.

It's completely dark. It's only emitted in the rippling of the shape of space.

A lot of times it's likened closer to sound.

Technically, we've kind of argued.

I mean, I haven't done an anatomical calculation, but if you're near enough to two colliding black holes, they actually ring spaceime in the human auditory range.

The frequency is actually in the human auditory range that the shape of space could squeeze and stretch your eardrum even in vacuum.

And you could hear literally hear these waves ringing.

The following is a conversation with Jenna Levan, a theoretical physicist and cosmologist specializing in black holes cosmology of extra dimensions, topology of the universe, and gravitational waves in spaceime.

She has also written some incredible books including how the universe got its spots on the topic of the shape and the size of the universe a mad man dreams of touring machines on the topic of genius madness and the limits of knowledge. Black hole blues and other songs from outer space on the topic of LIGO and the detection of gravitational waves and black hole survival guide all about black holes.

This was a fun and fascinating conversation.

This is a Lexman podcast.

To support it, please check out our sponsors in the description.

And now dear friends, here's Jenna 11.

I should say that you sent me a message about not starting early in the morning, and that made me feel like we're kindred spirits.

You wrote to me, "When the great physicist Sydney Coleman was asked to attend a 9:00 a.m. meeting, his reply was, "I can't stay up that late." Yeah.

So, classic. Sydney was beloved.

I think all the best thoughts, honestly, maybe the worst thoughts, too, are all come at night.

There's something There's something about the night.

Maybe it's the silence. Maybe it's the peace all around.

Maybe it's the darkness and you just you could be with yourself and you could think deeply.

I feel like there's stolen hours in the middle of the night because it's not busy. Your gadgets aren't pinging.

There's really no pressure to do anything but I'm off and awake in the middle of the night and so it's sort of like these extra hours of the day.

I think we were exchanging messages at 4 in the morning. Okay. So in that way many other ways were kindred spirits. M.

So, let's go in the one of the coolest objects in the universe, black holes.

What are they? And maybe even a good way to start is to talk about how are they formed?

Yeah. In a way, people often confuse how they're formed with the concept of the black hole in the first place.

So when black holes were first proposed Einstein was very surprised that such a solution could be found so quickly but really thought nature would protect us from their formation. And then nature thinks of a way nature thinks of a way to make these crazy objects which is to kill off a few stars. But then I think that there's a confusion that dead stars, these very very massive stars that die are synonymous with the phenomenon of black hole.

And it's really not the case. Black holes are more general and more fundamental than just the death state of a star.

But even the history of how people realize that stars could form black holes is is is quite fascinating because the entire idea really just started as a thought experiment.

And if you think of it's 1915 1916 when Einstein fully describes relativity in a way that's the canonical formulation.

It was a lot of changing back and forth before then.

And it's World War I and he gets a message from the Eastern Front from a friend of his Carl Shortfield, who's who solved Einstein's equations, you know, between sitting in the trenches and like cannon fire.

Um, it was joked that he was calculating ballistic trajectories.

He's also perusing the proceedings of the Prussian Academy of Sciences as you do.

and he was an astronomer um who had enlisted in his 40s and he finds this really remarkable solution to Einstein's equations and it's the first exact solution.

He doesn't call it a black hole.

It's not called a black hole for decades.

But what I love about what Schwarz shield did is it's a thought experiment.

It's not about observations.

It's not about making these things in nature.

Um it's really just about the idea.

He sets up this completely untenable situation.

and he says "Imagine I crush all the mass of a star to a point." Don't ask how that's done because that's really absurd.

Um, but let's just pretend and let's just imagine that that that's a scenario.

And then he wants to decide what happens to spacetime if I set up this confounding but somehow very simple scenario.

And really what Einstein's equations were were telling everybody at the time was that matter and energy curve space and time and then curved spacetime tells matter and energy how to fall once the spacetime shaped.

So he finds this beautiful solution and the most amazing thing about a solution is he finds this demarcation which is the event horizon which is the region beyond which not even light can escape. And if you were to ask me today all these decass crushed to a point.

The black hole is the event horizon.

The event horizon is really just a point in spaceime or or a region in spaceime.

It's actually in this case a surface in spaceime.

And it marks uh a separation in events which is why it's called an event horizon.

Everything outside is causally separated from the inside in so far as what's inside the event horizon can't affect events outside.

What's outside can affect events inside.

I can throw a probe into a black hole and cause something to happen on the inside.

But the opposite isn't true.

Somebody who fell in can't send a probe out.

And this oneway aspect really is what's profound about the black hole.

Um, sometimes we talk about the black holes being nothing because at the event horizon there's really nothing there.

Uh, sometimes when we when we think about black holes, we want to imagine a really dense dead star. But if you go up to the event horizon, it's an empty region of spaceime. It's it's more of a place than it is a thing.

And Einstein found this fascinating. He helped get the work published, but he really didn't think these would form in nature.

I doubt Carl Schwarz shield did either.

Um I think they thought they were uh solving theoretical mathematical problems. Um but not describing this what turned out to be the end state of gravitational collapse.

And maybe the purpose of the thought experiment was to find the limitations of the theory.

So you you find the most extreme versions in order to understand where it breaks down.

Yeah. And it just so happens in this case that might actually predict these extreme kinds of objects.

It does both. So it also describes the sun from far away.

So the same solution does a great job helping us understand the Earth's orbit around the sun.

It's incredible. Does a great job.

It's almost overkill. You don't really need to be that precise as relativity.

Um and yes, it predicts the phenomenon of black holes, but doesn't really explain how nature would form them. But then it also on top of that does signal the breakdown of the theory. I mean, you're quite right about that.

It actually says, "Oh, man." But you you go all the way towards the center and yeah, this doesn't sound right anymore.

Um sometimes I liken it to, you know, it's like a dying man marking in the dirt that something's gone wrong here, right?

it it it's signaling that that there's some culprit there's something wrong in the theory and um and even Roger Penrose who did this general work trying to understand uh the formation of black holes from gravitational collapse he thought oh yeah there's a singularity that's inevitable it's in every there's no way around it once you form a black hole but he said this is probably just a shortcoming of the fact that we've forgotten to include quantum mechanics and that when we do we'll understand this um differently. So according to him the closer you get to the singularity the more quantum mechanics comes into play and therefore there is no singularity there's something else.

I think everybody would say that.

I think everybody would say the closer you get to the singularity for sure you have to include quantum mechanics.

You just can't consistently talk about magnifying such small scales, having such enormous uh ruptures and and curvatures and energy scales and not include quantum mechanics that that's just inconsistent with the world as we understand it.

So you've described the brainbreaking idea that a black hole is uh not so much a super dense matter as it's sometimes described, but it's more akin to, you know, a region of space time, but even more so just nothing.

Yeah, it's nothing. That that's a thing you seem to like to say. I do I do like to say that black holes are no thing.

They're nothing. Okay. So what what what does that mean? That's that's what I mean.

That's the more profound aspect of the black hole. So you asked originally um how do they form? And I think that that that even when you try to form them in messy astrophysical systems, there's still nothing at the end of the day left behind.

And um this was a very big surprise.

Even though Einstein accepted that this was a true prediction, he didn't think that that they'd be made.

And it was quite astounding that that people like Oppenheimer actually it's probably Oenheimer's most important theoretical work um who are thinking about nuclear physics and quantum mechanics but in the context of these kind of utopian questions why do stars shine um why is the sun radiant and hot and this amazing source of light and it was people like Oenheimer who began to ask the question well could stars collapse to form black holes Could they become so dense that uh eventually not even light would escape? And that's why I think people think that black holes are these dense objects.

That's often how it's described. But actually what happens these very massive stars they're burning thermonuclear fuel.

You know, they're earthfuls of thermonuclear fuel.

They're burning um and emitting energy in E= MC² energy. So it's fusing.

It's a fusion bomb. It's a constantly going thermonuclear bomb.

And um eventually it's going to run out of fuel.

It's going to run out of hydrogen helium, stuff to fuse. It hits an iron core.

Iron to go past iron with fusion is actually energetically expensive.

So it's no longer going to do that so easily.

So suddenly it's run out of fuel.

And if the star is very very very massive, much more massive than our sun maybe 20, 30 times the mass of our sun it'll collapse under its own weight.

And that collapse is incredibly fast and dramatic and it creates a shock wave.

So that's the supernova explosion. So a lot of these they rebound because once they crunch they've reached a new critical uh capacity where they can reignite to higher elements, heavier elements and that sets off a bomb essentially.

So the star explodes helpfully because that's why you and I are here because stars send their material back out into space and you and I get to be made of carbon and oxygen and all this good stuff.

We're not just hydrogen.

So, the suns do that for us.

And then what's left sometimes ends at a neutron star, which is a very cool object, very fascinating object, super dense, uh, but bigger than a black hole meaning it's it's it's not compact enough to become a black hole.

It's an actual thing. A neutron star is a real thing.

It's like a giant neutron.

Literally, electrons get jammed into the protons and make this giant nucleus and this superconducting matter.

Very strange, amazing objects. But if it's heavier than that the core and that's you know heavier than twice the mass of the sun um it will become a black hole and Oenheimer was wrote this beautiful paper in 1939 with his student uh saying that they believed that the end state of gravitational collapse is actually a black hole.

This is stunning and really um a visionary conclusion.

Now, the paper is published the same day the Nazis advance on Poland and so it does not get a lot of fanfare in the newspapers.

Yeah, we think there's a lot of drama today on social media.

Imagine that. Like here's a guy who predicts how actually in nature would be the formation of this most radical of object that broke even Einstein's brain while one of the most evil if not the most evil humans in history starting a uh the first steps of a global war. What I also love about that lesson is how agnostic science is because he was asking these utopian questions as were other people of the time about the nuclear physics and stars.

You might know this play Copenhagen by Michael Fra.

There's this line that he attributes to Boore and Boore was the great thinker of early foundations of quantum mechanics, Danish physicist, where Boore says to his wife "Nobody's thought of a way to kill people using quantum mechanics." Now, of course, then there's the nuclear bomb.

And what I love about this was the pressure scientists were under to do something with this nuclear physics and and to enter this race over um a nuclear weapon.

But really at the same time 1939 really uh Oenheimer's thinking about black holes. There's a there's even a small line in Chris Nolan's film.

It's very hard to catch.

There's a reference to it in the film where he they're sort of joking well I guess nobody's going to pay attention to your paper now you know because uh because of the Nazi advance on Poland that's the other remarkable thing about Oppenheimer is he's also a central figure in the construction of the bomb right so it's theory and experiment clashing together with the geopolitics exactly so of course Oppenheimer now known as the father of the atomic bomb um he talks about destroyers of worlds um But it's the same technology and that's what I mean by science is agnostic, right?

It's the same technology overcoming a critical mass um igniting thermonuclear fusion.

Eventually there was a fision the original bomb was a fision bomb and fision was first shown by Le Mitner who showed that a certain uranium when you bombarded it with protons broke into smaller pieces that were less than the uranium.

Right? So some of that mass that E= MC² energy had escaped and it was the first kind of concrete demonstration of this Einstein's most famous equation.

So all of this comes together but the story of um they still weren't called black holes.

This is 1939 and they had these very long-winded ways of describing the end state the catastrophic end state of gravitational collapse.

But what you have to imagine is as this star collapses. So now, so what's the sun? The sun's a million and a half kilometers across. So imagine a star much bigger than the sun.

Much bigger radius. And it's so heavy it collapses.

It supernovas. What's left is still maybe 10 times the mass of the sun.

Just what's left in that core.

And it continues to collapse. And when that reaches about 60 kilometers across, like just imagine 10 times the mass of the sun citys sized. That is a really dense object.

And now the black hole essentially has begun to form.

Meaning the curve in spaceime is so tremendous that not even light can escape.

The event horizon forms. But the event horizon is almost imprinted on the spacetime because the star can't sit there in that dense state any more than it can race outward at the speed of light because even light is forced to rain inwards.

So the star continues to fall and that's the magic part.

The star leaves the event horizon behind and it continues to fall and it falls into the interior of the black hole.

Where it goes, nobody really knows. But it's gone from sight.

It goes dark.

There's this quote by John Wheeler who's like granddaddy of American relativity and he has a line that's something to the effect. Um, the star like the Cheshire cat fades from view.

One leaves behind only its grin, the other only its gravitational attraction.

And he was giving a lecture.

It's actually above Tom's restaurant, you know, from Seinfeld near Colombia in New York.

Nice. There was a a place or there still is a place there where people were giving lectures about astrophysics.

And it's 1967.

Wheeler is exhaustively saying this loaded term, the end state of catastrophic gravitational collapse.

And rumor is that someone shouts from the back row, well, how about black hole?

And um apparently he then foists this term on the world. Wheelerhead way of doing that.

Well, I love terms like that.

Big bang, black hole.

There's some I mean, it's just pointing out the elephant in the room and calling it an elephant.

It is a black hole.

That's a pretty uh accurate and deep description.

I just wanted to point out that the just looking for the first time at a 1939 paper from Oppenheimer. It's like two page.

It's like three pages.

Oh yeah it's gorgeous. The simplicity of some of these that's so gangster.

Just revolutionize all of physics with this with you know Einstein did that multiple times in a single year. Mhm.

When all thermonuclear sources of energy are exhausted, a sufficiently heavy star will collapse.

That's an opener. Mhm.

Unless fision due to rotation, the radiation of mass or the blowing off of mass by radiation reduce the stars mass to orders of that of the sun, this contraction will continue indefinitely.

And it goes on that way. Yeah.

Now, I have to say that Wheeler, who actually coins the term black hole, uh gives Oenheimer quite a terrible time about this.

He thinks he's wrong.

and they entered what has sometimes been described as kind of a bitter I don't know if you would actually say feud but there were bad feelings and um Wheeler actually spent decades uh saying Oenheimer was wrong and eventually with his computer work that early work that Wheeler was doing with computers when he was also trying to understand nuclear weapons and in peace time world found themselves returning again to these astrophysical questions uh decided that actually Oenheimer had been right.

He thought it was too simplistic, too idealized a setup that they had used and that if you you looked at something that was more realistic and more complicated that it it just simply it just would go away. And in fact, he he draws the opposite conclusion.

There's a story that Oppenheimer was sitting outside of the auditorium when Wheeler was coming forth with his declaration that in fact black holes were the likely end state of gravitational collapse for very very heavy stars and um when asked about it Oppenheimer sort of said well I've moved on to other things because you've written in many places about the human beings behind the science I have to ask you about this about nuclear weapons where is the greatest of physicists coming together to create this most terrifying and powerful of a technology.

And now I get to talk to world leaders for whom this technology is part of the tools that is used perhaps implicitly on the chessboard of geopolitics.

What what can you say as a person who's a physicist and who have studied the physicists and written about the physicists the humans behind this about this moment in human history when physicists came together and created this weapon that's powerful enough to destroy all of human civilization.

I think it's an excruciating moment in in the history of science and um people talk about Heisenberg who stayed in Germany and and uh worked for the Nazis in their own attempt to build the bomb.

There was this kind of hopeful talk that maybe Heisenberg had intentionally derailed the nuclear weapons program.

But I think that's been largely discredited that he would have made the bomb could he had he not made some really kind of simple errors in his original estimates about how much material would be required or how they would get over the energy barriers.

And that's a terrifying thought.

Um, I I don't know that any of us can really put ourselves in that position of imagining that we're faced with that quandry, having to take the initiative to participate in thinking of a way that quantum mechanics can kill people and then making the bomb.

I think overwhelmingly physicists today feel we should not continue in the proliferation of nuclear weapons. Very few um theoretical physicists want to see this continue.

that moment in history, the Soviet Union had incredible scientists.

Nazi Germany had incredible scientists and the United States had incredible scientists.

And it's very easy to imagine that one of those three would have created the bomb first, not the United States.

And how different would the world be? The game theory of that I think say the probability is 33% that it was the United States. If the Soviet Union had the bomb, I think I think they would have used it in a much more terrifying way in the in the European theater and maybe turn on the United States.

And obviously with Hitler, he would have used it.

I think there's no question he would have used it to to to kill hundreds of millions of people. In the game theory version, this was the least harmful outcome.

Yes. Yes. But there is no outcome with no bomb that that any game theorist would uh I think would play.

But I I think if we just remove the geopolitics and the ideology and the evil dictators all of those people are just scientists.

I think they don't necessarily even think about the ideology.

And it's a it's a it's a deep lesson about the connection between great science and the annoying sometimes evil politicians that use that science for means that are either good or bad. Mhm. And the scientists perhaps don't boy do they even have control of how that science is used.

It's hard. They don't have control.

Right. once it's once it's made, it's no longer scientific reasoning that dictates the use or um it's restraint.

But I will say that I do believe that it wasn't a 30 one-third down the line because America was different and I think that's something we have to think about right now in this particular climate.

So many scientists fled here.

They fled to here.

Americans weren't fleeing to Nazi Germany.

they came here and and they were motivated um by uh it's more than a patriotism, you know, it was um I mean it was a patriotism obviously, but it was sort of more than that.

It was really understanding the threat of Europe, uh what was going on in Europe and um and what that life, how quickly it turned, how quickly this freespirited Berlin culture, you know, was suddenly in this repressive and terrifying uh regime.

So, I think that it was a much higher chance that it happened here in America.

Yeah. And there's something about the American system, the you know it's cliche to say but the freedom all the different individual freedoms that enable a very vibrant at its best a very vibrant scientific community and that's really exciting absolutely to scientists and it's very valuable to ma maintain that right the the vibrancy of the debate of the funding those mechanisms absolutely the world flocked here and that won't be the case if we no longer have intellectual freedom yeah there's there's something interesting to think about the tension the cold war between China and the United States in the 21st century you know some of those same questions some of those ideas will rise up again and we want to make sure that um there's a vibrant free exchange of scientific ideas I believe most Nobel prizes come from the United States right oh yeah I don't have the number but I disproportionately so disproportionately so in fact a lot of them from particle physics came from the Bronx [Laughter] and they were European immigrants.

How do you explain this? Fled Europe um precisely because of the geopolitics we're describing.

Yeah. And so instead of being Nobel Prize winners from the Soviet Union or from the Eastern Block they were from the Bronx.

And that's the thing you write about and we'll return to time and time again that you know science is done by humans.

And some of those humans are fascinating.

There's tensions. There's battles.

There's some are loners. Some are great collaborators.

Some are tormented, some are easygoing, all this kind of stuff.

And that's the beautiful thing about it.

We forget sometimes is it's humans and humans are messy and complicated and beautiful and all of that. Yeah.

Uh so what were we talking about? Oh, the star is collapsing.

Okay. So can we just return to the collapse of a star that forms a black hole?

At which point does the super dense thing become nothing? if we can just like linger on this concept. Yeah.

So if I were falling into a black hole and I I I tried really fast right as I crossed this empty region but this demarcation I happened to know where it was.

I calculated because there's no line there.

There's no sign that it's there.

There's no signpost. Um I could emit a little light pulse and try to send it outward exactly at the event horizon.

So it's racing outward at the speed of light. It can hover there because from my perspective, it's very strange.

The spaceime is like a waterfall raining in and I'm being dragged in with that waterfall.

I can't stop at the event horizon. It comes, it goes.

It's behind me really quickly.

That light beam can try to sit there because it's like it's like a fish swimming against the Niagara, you know swimming against the waterfall.

It's like stuck there. But it's like stuck there.

Um, and so that's one way you could have a little signpost.

You know if you fly by, you think it's moving at the speed of light. It flies past you at the speed of light, but it's sitting right there at the event horizon.

So you're falling back, cross the event horizon.

Right at that point, you shoot outwards a photon. Yes. And it's just stuck there.

It just gets stuck there.

Now, it's very unstable. So, the star can't sit there is the point. It It just can't.

So, it rains inward with this waterfall.

But from the outside, all we should ever really care about is the event horizon because I can't know what happens to it. It could be pure matter and antimatter thrown together which annihilates into photons on the inside and loses all its mass into the energy of light.

Won't matter to me because I can't know anything about what happened on the inside. Okay. Can we just like linger on this? So what models do we have about what happens on the inside of the black hole at that moment?

So I guess that one of the intuitions, one of the big reminders that you're giving to us is like, hey, we know very little about what can happen on the inside of a black hole. And that's why we have to be careful about making it's better to think about the black hole as an event horizon. But what can we know and what do we know about the physics of of space time inside the black hole?

I don't mind being incautious about thinking about what the math tells us.

So I'm not such a an observer. I'm very theoretical in my work.

It's really pen on paper a lot.

Um these are thought experiments that I think we we can perform and contemplate.

Um whether or not we'll ever know is another question.

And um so one of the most beautiful things that we suspect happens on the inside of a black hole is that space and time in some sense swap places.

So while I'm on the outside of the black hole, let's say I'm in a nice comfortable space station.

This black hole is maybe 10 times the mass of the sun, 60 kilometers across. I could be a 100 kilometers out. That's very, very close.

Orbiting quite safely.

No big deal. You know, hanging out. Uh I don't bug the black hole. Black hole doesn't bug me.

It won't suck me up like a vacuum or anything crazy. But uh some my my astronaut friend jumps in.

Um, as they cross the event horizon what I'm calling space, I'm looking on the outside at this spherical shadow of the black hole cast by maybe light around it.

It's a shadow because everything gets too close, falls in.

It's just this um uh just contrast against a bright sky. I think, oh there's a center of a sphere and in the center of the sphere is the singularity.

It's a point in space from my perspective, but from the perspective of the astronaut who falls in, it's actually a point in time.

So their notions of space and time have rotated so completely that what I'm calling a direction in space towards the center of the black hole, like the center of a physical sphere, they're going to tell me, well, they can't tell me, but they're going to come to the conclusion, oh no, that's not a location in space.

That's a location in time.

In other words, the singularity ends up in their future and they can no more avoid the singularity than they can avoid time coming their way. So there's no shenanigans you can do once you're inside the black hole to try to skirt it the singularity.

You can't set yourself up in orbit around it. You can't try to fire rockets and stay away from it because it's in your future and there's an inevitable moment when you will hit it.

Usually for a stellar mass black hole, we think it's micros secondsonds.

Micros secondsonds to get from the event horizon to the to the singularity.

To the singularity. Oh boy. Oh boy.

So that's describing from the your astronaut friend's perspective. Yes.

From their perspective, the singularities in their future.

But from your perspective, what do you see when your friend falls into the black hole and you're chilling outside and watching?

So, one way to think about this um is to is to think that as you're approaching the black hole, the astronaut's spaceime is rotating relative to your spacetime.

So, let's say right now my left is your right.

We're not shocked by the fact that there's this relativity in left and right.

It's completely understood.

And I can perform a spatial rotation to align my left with your left. Right now I've completely rotated left out. Right.

Um if I just want to draw a a a kind of uh compass diagram, not a compass diagram but you know at the top of maps there's a northsoutheast west. But now time is up down and one direction of space is let's say east west. As you approach the black hole it's as though you're rotating in spaceime is one way of thinking about it. So what is the effect of that?

The effect of that is as this astronaut gets closer and closer to the event horizon, part of their space is rotated into my time and part of their time is rotated into my space. So in other words, their clocks seem to be less aligned with my time. And the overall effect is that their time seems to dilate.

the spacing between ticks on the clock of their watch, let's say, um on the on the face of their watch, uh is is elongated, dilated relative to mine.

And it seems to me that their watches are running slowly, even though they were made in the same factory as mine.

They were both synchronized beautifully and they're excellent Swiss watches.

Um, it seems as though time is elapsing more slowly for my companion and uh likewise for them it seems like mine's going really fast.

So years could elapse in my space station.

My plants come and go.

They die. I age faster. I've got gray hair.

Um, and they're falling in and it's been minutes in their frame of reference.

Um, flowers in their little rocket ship haven't rotted.

They don't have gray hair.

Their biological clocks have slowown down relative to ours.

Eventually at the event horizon, it's so extreme.

It's so slow. It's as though their clocks have stopped altogether from my point of view. And that's to say that it's as though their time is completely rotated into my space.

And this is connected with the idea that inside the black hole space and time have switched places.

Um, so I might see them hover there for millennia.

Other astronauts could be born on my space station.

Generations could be populated there watching this poor astronaut never fall in.

So basically the time almost comes to a standstill, but we still they do fall in, right?

They do fall in eventually.

Now that's because they have some mass of their own. Yeah. So they're not a perfectly light particle and so they deform the event horizon a little bit.

You'll actually see the event horizon bobble and absorb the astronaut.

So in some finite time the astronaut will actually fall in. So it's a it's like this weird space-time bubble that we have around us. Mhm. And then there's a very big space-time curvature bubble thing from the black hole and they there's a nice swirly type situation going on.

That's how you get sucked up.

Yeah. So if you're a perfect like uh infinitely small particle, you would just be take longer and longer and probably just be stuck there or something.

But no, there's quantum mechanics.

Mhm. Eventually you'll fall in there.

Any perturbation will only go one way.

It's unstable in one direction.

In one direction only. Um, but it's it's really important to remember that from the point of view of the astronaut, not much time has passed at all.

You just sail right across as far as you're concerned and nothing dramatic happens here.

You might not even realize you've come to the event horizon. You you might not even realize you've crossed the event horizon because it's there's nothing there.

Right? This is an empty region of spaceime. There's no marker to tell you you've reached this very dangerous point of no return.

You can fire your rockets like hell when you're on the outside and maybe even escape right?

But once you get to that point there's no amount of energy.

All the energy in the universe will not save you from uh this demise. You know, there's different size black holes. Mhm.

And maybe can we talk about the experience that you have falling into a black hole depending on what the size of the black hole is?

Yeah. cuz um as I understand if the the the bigger it is, the less drastic the experience of falling into it. Yeah, that might surprise people.

The bigger it is, the less noticeable it is that you've you've crossed the event horizon. One way to think about it is um curvature is less noticeable the bigger it is. So, if I'm standing on a basketball, I'm very aware I'm I'm balancing on a curved surface.

I my two feet are in different locations and I really notice. But on the Earth you actually have to be kind of clever to deduce that the Earth is curved.

The bigger the planet, the less you're going to notice the curvature. Um the the global curvature.

And it's the same thing with a black hole, a huge huge black hole.

It just is kind of feels like just flat. You don't really notice.

I'm trying to figure out how the phys because if you don't notice and there's nothing there but the physics is weird in your frame of reference.

No. Well, so another cool thing.

So I'd like to dispel myths.

Yeah. Do you need a minute?

You're holding your head.

There's a sense like you you should be able to know when you're inside of a black hole when you've crossed the event horizon.

But no, from your frame of reference, you might not be able to know.

Yeah, at first at least, you might not realize what's happened.

There are some hints. For instance, black holes are dark from the outside, but they're not necessarily dark on the inside.

So this is uh a kind of fascinating that your experience could be that it's quite bright inside the black hole because all the light from the galaxy can be shining in behind you and it's focusing down because you're all approaching this really focused region in the interior.

And so you actually see a bright white flash of light as you approach the singularity.

Um, you know, I kind of uh I joke that it's a, you know, it's like a near-death experience. You see the light at the end of the tunnel.

So, you would see millennia pass on Earth.

You could see the evolution of um the entire galaxy, you know, one big bright flash of light.

So, it's like a near-death experience, but it's a definitely a total death experience. It goes pretty fast.

But you looking out, you looking out, everything's going super fast.

Yeah.

the clocks um on the earth on the space station seem to be progressing very rapidly relative to yours. The light can catch up to you and you get this bright beam of light as you see the evolution of the galaxy unfold and um I mean it sort of depends on the size of the black hole and how long you have to hang around. The bigger the black hole the longer it takes you to expire in the center. Obviously the human uh sensory system we're not able to process that information correctly right it would be a microcond in a right that would be too fast. Yeah but it would be wow it' be so cool to get that information but a big black hole you could actually you know hang around for some months.

So yeah what's uh how are small black holes versus super massive uh black holes formed just so people can kind of load that in. Are they are they all is it always a star? No. So this is also why it's important to think of black holes more abstractly.

They are something very profound in the universe and there are probably multiple ways to make black holes.

Um making them with stars is most plentiful.

There could be hundreds of millions maybe even a billion black holes in our Milky Way galaxy alone.

that many stars. It's only about 1% of stars that will um end their lives in in in a death state that is a black hole.

But we now see and this was really quite a surprise that there are super massive black holes.

They're billions or even hundreds of billions of times the mass of the sun and um uh millions to to tens of billions maybe even hundreds of billions.

So extremely massive.

We don't think that the universe has had enough time to make them from stars that just merge.

We know that two black holes can merge and make a bigger black hole and then those can merge and make a bigger black hole.

We don't think there's been enough time for that. So, it's suspected that they're formed very early, maybe even a hundred few hundred million years after the big bang and that they're formed directly by collapsing out of primordial stuff.

Mhm. that there's a direct collapse right into the black hole.

So like in the in the very early universe, these are primordial black holes from the stars. Not quite Wait how how do you get from that soup black holes right away, right? So it's odd but it's weirdly easier to make a big black hole out of something that's just the density of air if it's really really as big as what we're talking about.

So in some sense, if they're just allowed to directly collapse very early in the universe's history, they can do that more easily.

Um, and it's so much so that we think that there's one of these super massive black holes in the center of every galaxy. So, they're not rare and we know where they are.

They're in the nuclei of galaxies.

So, they're bound to the very early formation of entire galaxies in um in a really surprising and deeply connected way.

I wonder if the like the chicken or the egg is it uh like how critical how essential are the super massive black holes to the formation of galaxies?

Yeah, I mean it's ongoing, right?

It's ongoing. Which came first, the black hole or the galaxy? Um probably um big early stars which were just made out of hydrogen and helium from the big bang.

Um there wasn't anything else, not much of anything else. um those early stars were forming and then maybe the black holes and kind of the galaxies were like these gassy clouds around them.

Um but there's probably a deep relationship between the black hole powering jets these jets blowing material out of the galaxy that that shaped galaxies maybe kind of curbed their growth. Um and so I think the mechanisms are still are still ongoing attempts to understand exactly the ordering of these things. Can we get back to spacetime? Just going back to the beginning of the 20th century.

How do you imagine spacetime? How do we as human beings supposed to visualize and think about spacetime where you know time is just another dimension in this 4D space that combines space and time?

Because we've been talking about morphing in all kinds of different ways.

is a curvature of spacetime like how do you how are we supposed to conceive of it?

How do you think of it?

Yeah, time is just another dimension.

There are different ways we can think about it.

We can imagine drawing a map of space and treating time as another direction in that map.

But we're limited because as three-dimensional beings, we can't really draw four dimensions, which is what I'd require. three spatial because I'm pretty sure there's at least three.

I think there's probably more, but um I'm happy just talking about the large dimensions, the three we see up, down right, east, west, uh north, south three spatial dimensions and time is the fourth.

Nobody can really visualize it.

Um but we know mathematically how to unpack it on paper. I can mathematically suppress one of the spatial dimensions and then I can draw it pretty well.

Now the problem is that we'd call it a ukitian spacetime.

A uklitian spacetime is when all the dimensions are orthogonal and are treated equally.

Time is not another ukitian dimension.

It's actually a manowskian spacetime.

But it means that the spacetime, we're misrepresenting it when we draw it, but we're misrepresenting it in a way that we deeply understand. I can give you an example.

The Earth, I can project onto a flat sheet of paper. I am now misrepresenting a map of the Earth.

And I know that, but I understand the rules for how to add distances on this misrepresentation because the Earth is not a flat sheet of paper.

It's a sphere. And um and as long as I understand the rules for how I get from the north pole to the south pole that I'm moving along really a great arc and I understand that the distance is not the distance I would measure on a flat sheet of paper then I can do a really great job with a map and understanding the rules of addition multiplication and the geometry is not the geometry of a flat sheet of paper. I can do the same thing with spacetime. I can draw it on a flat sheet of paper but I know that it's not actually a flat uklidian space.

And so my rules for measuring distances are different than the rules I would use that for instance cartisian rules of geometry.

I I would know to use the correct rules for manovski spacetime and and that will allow me to to to to calculate how long uh time has elapsed which is now a kind of a length a space-time length on my map um between two relative observers. and I will get the correct answer. Um but only if I use these different rules. So then what does according to general relativity does uh objects with mass due to the spacetime?

Right. Exactly.

So Einstein struggled for this completely general theory not a specific solution like a black hole or an expanding spaceime or galaxies make lenses or those are all solutions.

That's why what he did was so enormous.

It's an entire paradigm that says over here is matter and energy.

I'm going to call that the right hand side of the equation. Everything on the right hand side of Einstein's equations is how matter and energy are distributed in spaceime.

On the left hand side tells you how space and time deform in response to that matter and energy.

And it can be impossible to solve some of those equations.

What was so amazing about what Shell did is he found this very elegant simple solution within like a month of reading um this final formulation.

But Einstein didn't go through and try to find all the solutions.

He sort of gave it to us right?

He shared this and then lots of people since have been scrambling to try to ah I can predict the curvature of the spaceime if I tell you how the matter and energy is laid out. If it's all compact in a spherical system like a sun or even a black hole, I can understand the curves in the spaceime around it.

I can solve for the for the shape of the spacetime.

I can also say, well, what if the universe is full of gas or light and it's all kind of uniform everywhere and I'll find a different and equally surprising solution, which is that the universe would expand.

In response to that, that it's not static, that the distances between galaxies would grow. This was a huge surprise to Einstein. Um, so all of these consequences of his theory, you know, came with revelations that were not at all obvious when he first wrote down um the general theory and he was afraid to take the consequences of that theory seriously which is aen the theory itself in its scope and grandeur and power is scary.

So I can understand.

Then there's, you know, the the edges of the theory where it falls apart.

The consequences of the theory that are extreme, it's hard to take seriously.

So you can sort of empathize. Yeah.

He very much resisted the expansion. So if you think about 1905 when he's writing these sequence of unbelievable papers as a 25year-old who can't get a job, you know, as a physicist and he writes all of these remarkable papers on relativity and quantum mechanics. Um and then even in 191516 he does not know that there are other galaxies out there. This this was not known.

People had mused about it.

Um there were these kind of smudges on the sky that people contemplated what if there are other island universes. You know going back to Kant thought about this.

But it wasn't until Hubble it really wasn't until the late 20s um that it's confirmed that there are other galaxies.

Wow. Yeah.

He didn't obviously there's so much we think of now that he didn't think of.

So there's no big bang static universe.

But these are all connected.

Wow. Yeah. So he's operating on very little information.

Very little information. That's absolutely true.

Actually, one of the things I like to point out is the idea of relativity was foisted on people in this kind of cultural way.

But there's many ways in which you could call it a theory of absolutism.

And um the way Einstein got there with so little information um is by adhering to certain very strict absolutes like the absolute limit of the speed of light and the absolute constancy of the speed of light which was completely bizarre when it was first uh discovered.

really that was observed through experiments trying to figure out um you know what would the relative speed of light be? It's the only really only massless particles have this property that they have an absolute speed and if you think about it it's incredibly strange.

Yeah, it's really strange.

Incredibly strange. And so so from from a theoretical perspective he he's he takes that seriously.

He takes it very seriously and everyone else is trying to come up with models to make it go away.

Um to make uh the speed of light be a little bit more reasonable like everything else in the universe.

Um you know if I run at a car, two cars coming at each other, they're coming at each other faster than if one of them stops.

It's really a basic observation of reality right here. This is saying that if I'm racing at a light beam um and you're standing still relative to the source, uh we'll measure the same exact speed of light. Very strange.

And he gets to relativity by saying, well what's speed?

Speed is distance.

It's space over time. It's how far you travel.

Um it's the space you travel in a certain duration of time. And he said "Well, I bet something must be wrong then with space and time." So this is an enormous leap.

He's willing to give up the absolute character of space and time in favor of keeping the speed of light constant.

How was he able to intuitit a world of curved spaceime?

Like I think it's like one of the most special leaps in human history, right?

Cuz you're it's amazing. like it's very very very difficult to make that kind of leap.

I I'll tell you it took me I think a long time to I can't say this is how he got there exactly. It's not as though I studied the historical accounts of or his description of his internal states.

This is more having learned the subject how I try to tell people how to get there in a few short steps. Um, one is to start with the equivalence principle which he called the happiest thought of his life.

And the equivalence principle comes pretty early on in his thinking.

And and um it starts with something like this.

Like right now I think I'm feeling gravity because I'm sitting in this chair and I feel the pressure of the chair and it's stopping me from falling and um lie down in a bed and I feel heavy on the bed and I think of that as gravity.

Ein has a beautiful ability to remove all of these extraneous factors, including atoms. So let's imagine instead that you're in an elevator and you feel heavy on your feet because the floor of the elevator is resisting your fall, but I want to remove the elevator. What does the elevator have to do with fundamental properties of gravity? So, I cut the cable.

Now, I'm falling, but the elevator is falling at the same rate as me.

So now I'm floating in the elevator.

And if this happened to me, if I woke up in this state of falling or floating in the elevator, I might not know if I was in empty space just floating um or if I was falling around the earth.

There would actually equivalent situations.

I would not be able to tell the difference.

I'm actually when I get rid of the elevator in this way by cutting the cable, I'm actually experiencing weightlessness.

And that weightlessness is the purest experience of gravity.

And um and so this idea of falling is actually fundamental.

It's how we talk about it all the time.

The earth is in a free fall around the sun.

It's actually falling. It's not firing engines, right?

It's just it's just falling all the time, but it's just cruising so fast. So actually Yeah.

God you said so many profound things.

So one of them is really one of the ways to experience spaceime is to be falling. To be falling that is the purest experience of gravity.

The experience of gravity uh unfettered uninterrupted by atoms is weightlessness.

Yeah. That observation no it has an unhappy ending.

the elevator story right?

Because of atoms. Again, that's the fault of the atoms in your body interacting electromagnetically with the crust of the earth or the bottom of the building or whatever it is. Um, but this period of freeall, so the first observation is that that is the purest experience of gravity. Now, I can convince you that things follow along curved paths because I could take uh you know, a pen and if I throw it, we both know it's going to follow an arc and it's going to follow an arc until atoms interfere again and it hits the ground.

But while it's in freef fall experiencing gravity at its purest, what the Einsteinian description would say is it is following the natural curve in spaceime inscribed by the earth.

So the earth's mass and shape curves the paths in space and then those curvatures tell you how to fall, the paths along which you should fall when you're falling freely.

And so the Earth has found itself on a free fall that happens to be a closed circle, but it's it's actually falling.

The International Space Station uses this principle all the time.

They get the space station up there and then they turn off the engines. Can you imagine how expensive it would be if they had to fuel that thing at all times? Right.

They turn off the engines.

They're just falling. Yeah, they're falling.

And they're not that far up. Um there there are certainly people sometimes say, "Oh they're so far away they don't feel gravity.

" Oh, absolutely. If you stopped the space station, it's going like 17,500 m an hour, something like that.

If you were to stop that, it would drop like a stone right to the earth.

So they're in a state of constant freefall and they're falling along a curved path.

And that curved path is a result of curving spacetime and that particular curved path's calculated in such a way that it curves onto itself.

So, you're orbiting, right? So it has to be cruising at a certain speed. So once you get it at that cruising speed, you turn off the engines. But yeah, to be able to visualize at the beginning of the 20th century Mhm.

that not you know that free falling in in in curved spaceime. Mhm.

Boy, the human mind is capable of things.

I mean some of that is um constructing thought experiments that collide with our understanding of reality.

Maybe in the collisions, in the contradictions, you try to think of extreme thought experiments that that uh exacerbate that contradiction and see like, okay, what is actually is there another model that can incorporate this?

But to be able to do that, I mean, it's it's kind of inspiring because, you know, there's probably another general relativity out there.

Yeah. in all not just in physics in all lines of work in all scientific pursuits there's certain theories where you're like okay I just explained like a big elephant in the room here that everybody just kind of didn't even think about there could be uh for stuff we know about in physics there could be stuff like that for the origin of life on earth everyone's like yeah okay everyone's like in polite companies Yeah.

Yeah. Yeah. Yeah.

Somehow it started. Mhm. Right. Nobody knows.

I find it wild that that's so elusive.

Yeah. It's it's strange. And the lab became strange that it's so elusive.

I think it's a general relativity thing.

There's going to be some thing.

It's going to involve aliens and wormholes and and dimensions that we don't quite understand or some some field that's bigger than like it's possible, maybe not.

It's possible that it has it's a field that is different that will feel fundamentally different from chemistry and biology it'll be maybe through physics again maybe the key to the origin of life is in physics and the same there it's like a a weird neighbor is consciousness.

Mhm. It's like all right a weird neighbor. Yeah.

It's like okay so we all know that life started on Earth somehow.

Mhm. Nobody knows how.

Mhm. We all know that we're conscious.

We have a subjective experience of things.

Nobody understands that people have ideas and so on.

But it's such a dark sort of we're entering a dark room where a bunch of people are whispering about like, "Hey, what's in this room?

" But nobody nobody has a effing clue.

Mhm. So, and then somebody comes along with a general relativity kind of conception where like it reconceives everything and you're like ah it's like a watershed moment. Yeah.

Yeah. It's there and until we're living in the mo we're living in a time until that theory comes along and uh it'll be obvious in retrospect, but right now we're right.

Well, this it was obvious to no one that spacetime was curved, but even Newton understood something wasn't right.

So, he knew there was something missing.

And I think that's always fascinating when we're in a situation where we're pressure testing our own ideas.

He did something remarkable Newton did, with his theory of gravity.

Just understanding that the same phenomena was at work with the earth around the sun as the apple falling from the tree.

That's insane. That's a huge leap.

Understanding that mass, inertial mass, what makes something hard to push around is the same thing that feels gravity in at least in the Newtonian picture in that simple way.

Unbelievable leap. Absolutely genius. But he didn't like that the apple fell from the tree even though the earth wasn't touching it.

Yeah, the action at a distance thing.

The action at a distance thing.

That is weird, too. Well, but that is a really weird one. It's really weird.

But see, Einstein solves that.

Relativity solves that because it says the Earth created the curve in space.

The apple wants to fall freely along it.

The problem is the trees in the way.

The tree is the problem.

The tree is actually accelerating the apple.

It's keeping it away from its natural state of weightlessness in a gravitational field.

And as soon as the tree lets go of it, the apple will simply fall along the curve that exists.

I would I would love it if somebody went back to Newton's time and told him all this.

Probably some like some like hippie would be like it's a gravity is just the curvature in space time, man.

I wonder if he would be able to I don't think there's you know every idea has its time.

He might not he might not even be able to load that in.

I I mean that sometimes even the greatest geniuses I mean you can't like you need too out of context. You need to be standing on the shoulders of giants and on the shoulders of those giants and so on.

I heard that Newton used that as an unkind remark to his competitor Hook.

Oh no, the people talk even back then.

Trash talking.

This is one of the hilarious things about humans in general, but scientists too, like these huge minds.

There's these moments in history where you'll see this in this in universities, but everywhere else too. Like you have gigantic minds obviously also coupled with everybody has an ego and like sometimes it's just the same soap opera that played out amongst humans everywhere else and so you're thinking about the biggest cosmological objects and forces and ideas and you're still like jealous and right I know your your office is bigger than my office.

I know this chair this or or maybe uh you got married to this person that I was always in love with the betrayal of something.

The one woman in the department. Yeah.

The one woman in the department. Yeah.

And it's just I mean but that is also the fuel of innovation that jealousy that tension that's well you know the expression I'm sure um the battles are so bitter in academia because the stakes are so low. That's a beautiful way to phrase it.

But also like we shouldn't forget I mean that I love seeing that even in academia because it's humanity the silliness it's there is a degree to academia where the reason you're able to think about some of these grand ideas is because you still allow yourself to be childlike.

Oh yeah, there's a childlike nature to be ask questions but children can also be like children children.

So like you don't I think when um in in in a corporate context and maybe the world gets forces you to behave you're supposed to be a certain kind of way there's some aspects and it's a really beautiful aspect to preserve and to celebrate in academia is like you're just allowed to be childlike in your curiosity and your exploration you're just exploring asking the biggest questions the best scientists I know often ask the simplest questions questions.

Um they're they're really um first of all there's probably some confidence there, but also they're never going to lie to themselves that they understand something that they don't understand.

So even this idea that Newton didn't understand the apple falling from the tree, he had he lived another couple hundred of years, he would have invented relativity because he never would have lied to himself that he understood it. he would have kept asking this very simple question.

Um and uh, I think that there is this childlike beauty to that. Absolutely.

Yeah. Just some of the topics, I don't know why I'm stuck to those two topics of origin of life and consciousness, but there's I'll talk about this.

Some of the most brilliant people I know are stuck just like with Newton and Einstein.

They're stuck on that.

This doesn't make sense. I know a bunch of brilliant biologists, physicists chemists, they're thinking about the origin of life. They're like, "This doesn't I know how evolution works.

I know how the biological systems work.

How genetic information propagates, but like this this part, the singularity at the beginning doesn't make sense.

We don't understand. We can't create in the lab.

They're bothered come every single day.

They're bothered by it.

And that being bothered by that tension, by that gap in knowledge is uh yeah, that's the catalyst.

That's the fuel catalyst for the discovery.

But the discovery yeah absolutely the discovery is going to come because somebody couldn't sleep at night and couldn't rest.

So in that way I think black holes are a kind of portal into some of the biggest mysteries of our universe. So it is a it's a good terrain on which to explore these ideas.

So can can you speak about some of the mysteries that the black holes present us with? Yeah, I think it's important to separate the idea that there are these astrophysical states that become black holes um from being synonymous with black holes because black holes are kind of this this larger um idea and uh they might have been made primordally when the big bang happened and they're there's something flawless about black holes that makes them fundamental.

um unlike anything else. So, uh they're flawless in the sense that you can completely understand a black hole by looking at just its charge, electric charge, its mass, and its spin.

And every black hole with that charge, mass and spin is identical to every other black hole.

You can't be like, "Oh, that one's mine.

I recognize it. It has this little feature, and that's how I know it's mine.

" They're featureless.

They you you try to put uh Mount Everest on a black hole and it will shake it off in these gravitational waves.

It will radiate away this imperfection until it settles down to be a perfect black hole again.

So there's something about them that is unlike and another reason why I don't like to call them objects in a traditional sense unlike anything else in the universe that's macroscopic.

It's kind of a little bit more like a fundamental particle.

So, an electron is described by a certain short list of properties. Charge, mass, spin maybe some other quantum numbers.

That's what it means to be an electron.

There's no electron that's a little bit different.

You can't recognize your electron.

They're all identical in that sense.

Um, and and so in some very abstract way, black holes share something in common with microscopic fundamental particles.

And so what they tell us about the fundamental laws of physics um can be very profound and it's why even theoretical physicists mathematical physicists, not just astronomers who use telescopes, they rely on the black hole as a terrain to perform their thought experiments.

And and it's because there's something fundamental about them.

Yeah. General relativity means quantum mechanics means singularity and sadly heartbreakingly so it's out of reach for experiment at this moment but but within reach for theoretical it's in reach for for thought experiments for thought experiments which are quite beautiful well on that topic I have to ask you about the paradox the information paradox of black holes what is it so this is what catapulted Hawkings fame when he was a young researcher, he was thinking about black holes and wanted to just add a little smidge of quantum mechanics, just a little smidge, you know, wasn't going for full-blown quantum gravity, but kind of just asking, well, what if I allowed this nothing, this vacuum, this empty space around the event horizon, the star is gone, there's nothing there. What if I allowed it to possess sort of ordinary quantum properties just a little tiny bit you know nothing dramatic don't go crazy you know and one of the properties of the vacuum that um is intriguing is this idea that you can never say the vacuum is actually completely empty we talked about Heisenberg but you know the Heisenberg uncertainty principle really kicked off a lot of quantum mechanical thinking it says that you can never exactly know a particle's position simultaneously ly with its motion, with its momentum.

You can know one or the other pretty precisely, but not both precisely.

And the uncertainty isn't a lack of ability that will technologically overcome.

It's foundational. So that there's in some sense when it's in a precise location it is fundamentally no longer in a precise motion.

And that uncertainty principle means I can't precisely say a particle is exactly here, but it also means I can't say it's not. Okay?

And so it led to this idea that what do I mean by a vacuum? Because I can't 100% precisely know.

In fact, there's not really meaningful to say that there's zero particles here. And so what you can say, however, is you can say, well maybe particles kind of froth around in this seething quantum sea of the vacuum.

Maybe two particles come into existence and they're entangled in such a way that they cancel out each other's properties.

So they they have the properties of the vacuum, you know, they don't they don't destroy the kind of properties of the vacuum because they cancel out each other's spin, maybe each other's charge maybe things like that, but they kind of froth around.

They come, they go, they come, they go and that's what we really think is the best that empty space can do in a quantum mechanical universe.

Now, if you add an event horizon, which as we said is really fundamentally what a black hole is, that's the most important feature of a black hole.

The event horizon, if the particles are created slightly on either side of that event horizon, now you have a real problem.

Okay? Now, the pair has been separated by this event horizon.

Now they can both fall in. That's okay.

But if one falls in and the other doesn't it's stuck.

It can't go back into the vacuum because now it has a charge or it has a spin or it has something.

It's no longer the property of that vacuum it came from.

It needs its pair to disappear.

Now it's stuck. It exists.

It's like you've made it real. So in a sense, the black hole steals one of these virtual particles and forces the other to live.

And if it is, it'll escape radiate out to infinity and look like to an observer far away that the black hole is actually radiated a particle. Now the particle did not emanate from inside.

It came from the vacuum. It stole it from empty space from the nothingness that is the black hole.

Now the reason why this is very tricky is because in the process because of this separation on either side of the event horizon.

The particle it absorbs it has to do with the switching of space and time that we talked about.

But the particle it absorbs well from the outside you might say oh it had negative momentum.

It was falling in from the inside you say well this is actually motion and time.

This is energy. It has negative energy and it is absorbs negative energy.

Its mass goes down. the black hole gets a little lighter and as it continues to do this the black hole really begins to evaporate.

It does more than just radiate.

It evaporates away.

And um it's intriguing because Hawking said, "Look, this is going to look thermal, meaning featureless.

It's going to have no information in it. It's going to be the most informationless possibility you could possibly come up with when you're radiating particles.

It's just going to look like a thermal distribution of particles, like a hot body.

And the temperature is going to only tell you about the mass, which you could tell from outside the black hole anyway.

You know the mass of the black hole from the outside.

So, it's not telling you anything about the black hole.

It's got no information about the black hole.

Now, you have a real problem.

And when he first said it, a lot of people describe that not everyone understood how really naughty he was being.

He did. Um, but some people who love quantum mechanics were really annoyed.

Okay, people like Lenny Suskin Jerard, Nobel Prize winner, they were mad because it suggested something was fundamentally wrong with quantum mechanics if it was right. Um, and the reason why it says there's something fundamentally wrong with quantum mechanics is because quantum mechanics does not allow this. It does not allow quantum information to simply evaporate away and poof out of the universe and cease to exist. It's a violation of something called unitarity.

But really the idea is it's the loss of quantum information that's intolerable.

Quantum mechanics was built to preserve information.

It's one of the sacred principles as sacred as conservation of energy.

In this example, more sacred because you can violate conservation of energy with Heisenberg's uncertainty principle a little tiny bit.

um but so sacred that it created what became um coined as the black hole wars where people were saying look general relativity is wrong something's wrong with our thinking about the event horizon or quantum mechanics isn't what we think it is but the two are not getting along anymore and just to tell you how dramatic it is so the temperature goes down with the mass of the black hole heavier a black hole the cooler it is so we don't see Black holes evaporate, they're way too big.

But as they get smaller and smaller, they get hotter and hotter.

So as the black hole nears the end of this cycle of evaporating away, it takes a very long time, much longer than the age of the universe. Um it will be as though the curtain, the event horizon's yanked up, like it'll literally explode away.

Just boom. And the event horizon in principle would be yanked up.

Everything's gone. all that information that went into the black hole, all that sacred quantum stuff gone. Poof. Okay?

Because it's not in the radiation because the radiation has no information.

And um and so it was an incredibly productive debate because in it are the signs of what will make gravity and quantum mechanics play nice together.

You know some quantum theory of gravity.

Um whatever these clues are, and they're hard to assemble. Uh, if you want a quantum gravity theory, it has to correctly predict the temperature of a black hole, the entropy of a black hole.

It has to have all of these correct features.

The black hole is the place on which we can test quantum gravity, but it still has not been resolved.

It has not been fully resolved. I looked up all the different ideas for the resolution.

So, there's the information loss, which is what you referred to.

It's perhaps the simplest yet most radical resolution is that information is truly lost.

This would mean quantum mechanics as we currently understand it specifically unitarity is incomplete or incorrect under these extreme gravitational conditions.

I'm unhappy with that.

I'm I would not be happy with information loss.

I love that it's telling us that there's this crisis cuz I do think it's giving us the clues and we have to take them seriously.

For you the the gut is like unitarity is going to be preserved preserved.

So quantum mechanics is we have to come to the rescue as Lenny Suskin in his book black hole war says uh his subtitle is um my battle with Stephen Hawking to make the world safe for quantum mechanics.

Quantum mechanics I love something to that effect.

So then from string theory one of the resolutions is called fuzzballs.

I love physicists so much.

Originating from string the theory this proposal suggests that black holes aren't singularity surrounded by empty space and an event horizon.

Instead, they are horizonless complex, tangled objects, aka fuzzballs made of strings and brains roughly the size of the wouldbe event horizon.

There's no single point of infinite density and no true horizon to cross.

In some sense, it says there's no interior to the black hole. Nothing ever crosses.

So, I gave you this very nice story that there's no drama. Sometimes that's how it's described at the event horizon and you fall through and there's nothing there.

This other idea says, well, hold on a second. If it's really strings, as I get close to this magnifying quality and the slowing time down near the event horizon, it is as though I put a magnifying glass on things and now the strings aren't so microscopic.

They kind of shmear around and then they get caught like a tangle around the event horizon and they just actually never fall through.

Um, I don't think that either, but it was interesting.

So, it's just adding a very large number of extra complex degrees of freedom.

Yeah, there are no teeny tiny marbles to fall through, but it's similar to what we already have with quantum mechanics.

It's just giving a really saying the interior is just not there ever.

Nothing falls in.

So, the information gets out cuz it never went in in the first place. Oh, interesting.

So, there is a strong statement there.

A strong statement there. Yeah. Okay.

Soft hair challenges the classical no hair theorem by suggesting that black holes do possess subtle quantum quote hair.

This isn't classical hairike charge, but very low energy quantum excitations, soft gravitons or photons at the event horizon that can store information about what fell in.

Worth trying, but I also don't think that that's the case. So the no hair theorems are um formal proofs that the black hole is this featureless perfect fundamental particle that we talked about that all you can ever tell about the black hole is its electrical charge, its mass and its spin and that it cannot possess other features.

It has no hair is one way of describing it and that those are proven mathematical proofs in the context of general relativity.

So the idea is well therefore I can know nothing about what goes into the black hole.

So the information is lost.

But if they could have hair I could say that's my black hole because it have features that I could distinguish and it could encode the information that went in in this way.

And and the event horizon isn't so serious. There isn't such a stark demarcation between events inside and outside and where I can't know what happened inside or outside. And um I don't think that's the resolution either but it was worth a try. Okay.

The pros and cons of that one. The pros, it works within the framework of quantum field theory in curved spaceime potentially requiring less radical modifications than fuzballs or information loss.

Recent work by Hawking Perry Strongly revitalized this idea. The cons is that the precise mechanism by which information is encoded and transferred to the radiation is still debated and technically challenging to work out fully and indeed it needs to store a vast amount of information.

Okay another one. This is a weird one.

boy is uh ER equals EPR. This is probably it though.

Oh boy. So ER equals EPR is Einstein Rosen Bridge equals Einstein Podski Rosen Bridge posits a deep connection between quantum entanglement and space-time geometry.

Uh specifically Einstein Rosen bridge commonly known as wormholes.

It suggests that entangled particles are connected by a non-traversible wormhole.

are tiny wormholes connecting.

Okay, I I can say that this is not uh a situation we can follow the chalk.

We can't start at the beginning and calculate to the end. So, it's um it's still a conjecture. I think it's very profound though.

Um I kind of imagine Juan Maldsina who's part of this with Lenny Suskin, they were kind of like h it's like er equals EPR.

They couldn't even formulate it properly. It was like an intuition that they had kind of landed on and now are trying to formalize.

But to take a step back, one way of thinking about ER equals EPR, you have to talk about holography first.

And holography both Juan Maldina really formalized it, Lenny Suskin suggested it.

The idea of a black hole hologram is that all of the information in the black hole whatever it is whatever you know entropy as a measure of information uh whatever the entropy of the black hole is which is telling you how much information is hidden in there how much information you don't have direct access to in some sense um is completely encoded in the area of the black hole meaning as the area grows the entropy grows it does not grow as the volume this actually turns out to be really really important If I tried to pack a lot of information into a volume, more information than I could pack, let's say, on the surface of a black hole, I would simply make a black hole and I would find out, oh, I can't have more information than I can fit on the surface. So, Lenny coined this a hologram. People who take it very seriously say, well, again, maybe the interior of the black hole just doesn't exist.

It's a holographic projection of this two-dimensional surface.

In fact maybe I should take it all the way and say, so are we. Mhm. The whole universe is a holographic projection of a lower dimensional surface, right?

And so people have struggled, nobody's really landed it to find a universe version of it.

Oh, maybe there's a boundary to the universe where all the information is encoded and this entire three-dimensional reality that's so compelling and so convincing is actually just a holographic projection.

Juan Maldesina did something absolutely brilliant.

It's the most highly cited paper in the history of physics.

It was published in the late '9s. Uh it has a very opaque title that would not lead you to believe it's as revelatory as it is.

But he was able to show that a universe like in a box with gravity in it.

It's not the same universe we observe.

Doesn't matter. It's just a hypothetical called an anti-itter space.

It's a universe in a box.

It has gravity. It has black holes.

It has everything gravity can do in it.

on its boundary is a a theory with no gravity a universe that can be described with no gravity at all. So, no black holes and no information loss problem.

And they're equivalent.

That the interior universe in a box is a holographic projection of this quantum mechanics on the boundary.

pure quantum mechanics purely unitary, no loss of information.

None of this stuff could possibly be true.

There can't be loss of information if this dictionary really works.

If the interior is a hologram, a projection of the boundary.

I know that's a lot. Yeah.

So, there's a there's some mathematics there.

There's physics and then there's trying to conceal what that actually means practically for for us. Mhm.

Well what it would mean for us is that information can't be lost even if we don't know how to show it in the description in which there are black holes.

It means it can't possibly be lost because it's equivalent to this description with no gravity in it at all. No event horizons no black holes, just quantum mechanics.

So it really strongly suggested that that quantum mechanics was going to win in this battle, but it didn't show exactly how it was going to win.

So then comes ER equals EPR. A visual way to imagine what this means. So ER has to do with little wormholes.

EPR Einstein Podski Rosen has to do with quantum entanglement.

The idea was, well, maybe the stuff that's interior to the black hole is quantum entangled, like EPR, quantum entangled with the Hawking radiation outside the black hole that's escaping.

And that quantum entanglement is what allows you to extract the information because it's not actually physically moving from the interior to the exterior. It's it's just subtle quantum entanglement.

And in fact, I can kind of think of the entire black hole.

If I look at it, it looks like a solid shadow cast on the sky some region of spaceime. If I look at it very closely, I will see, oh no, it's actually sewn from these quantum wormholes, like embroidered. And so when I get up close, it's almost as though the event horizon isn't the fundamental uh feature on the spacetime.

The fundamental feature is the quantum entanglement embroidering the event horizon.

The embroidering is is just tiny wormholes.

So the quantum entanglement is when two particles are connected at arbitrary distances and they're connected by a wormhole.

And in this case they would be connected by a wormhole.

Mhm. So the reason why that's helpful, it helps you connect the interior to the exterior without trying to pass through the horizon. The cons of this theory is highly conceptual and abstract.

The exact mechanism for information retrieval via these non-traversible war polls is not fully understood.

Primarily explored in theoretical toy models.

Whoa, Gemini going hard. Uh theoretical toy models like the anti-deitter spaceime rather than realistic black holes. True.

We do what we can do.

in baby steps. So the uh another idea to resolve the information paradox is firewalls proposed by Mary Marov Pchinski and Sully amps.

This is a more drastic scenario arising from analyzing the entanglement requirements of Hawking radiation to preserve unitarity and avoid information loss. They argued that the entanglement structure requires the event horizon not to be smooth, not to be the smooth unremarkable place predicted by general relativity, the equivalence principle.

Instead, it must be a highly energetic region, a quote firewall that incinerates anything attempting to cross it. Okay.

So, yeah that's a nice solution.

Just destroy everything that crosses them. Um, do you find this at all a convincing resolution to the information? would say the firewall papers were fascinating and were very provocative and very important in making progress. I don't even think the authors of those papers thought firewalls were real. I think they were saying, "Look, we've been brushing too much under the rug." And if you look at the evaporation process, it's even worse than what you thought previously.

It's so bad that I can't get away with some of these prior solutions that I thought I could get away with. Um there was a kind of duality idea or a complimentarity idea that oh well maybe one person thinks they fell in one person thinks they never fell in and that's okay you know no big deal.

They sort of exposed flaws in these kind of approaches and it actually reinvigorated the campaign to find a solution.

Um so it stopped it from stalling.

I don't think anyone really believes that the event horizon, at the event horizon you'll find a firewall. But it did lead to things like the entangled wormholes embroidering a black hole, which is um was born out of an attempt to um address the concerns that amps raised. So it did lead to progress. So for you, the resolution would uh I'm going back to the vacuum.

You're going back, the empty space, the beautiful event horizon.

Y I'll give up um I'll give up locality meaning that I will allow things to be connected non-locally by a wormhole. So that is the weirdest thing you're willing to allow for which is arbitrary distance connection of particles through a wormhole.

But quantum mechanics must be preserved.

I'll entertain pretty weird things but I think that's the one that sounds promising.

The implications are so dramatic because this is why you start to hear things like, "Wait a minute.

If the event horizon only exists when it's sewn out of these quantum threads, does that mean that gravity is fundamentally quantum mechanics?

" Not that gravity and quantum mechanics get along and I have a quantum gravity theory and I now know how to quantize gravity.

Actually, something much more dramatic.

Gravity is just kind of emerging from this quantum description that gravity isn't fundamental.

And what is the only thing that we have when we go rock bottom, when we go deeper and deeper, smaller and smaller is quantum mechanics. So all of this like spacetime looks nice and smooth and continuous.

But if I look at the quantum realm, I'll see everything sewn together out of quantum threads and that spacetime is not a smooth continuum all the way down. Now people already thought that, but they thought it kind of came in chunks of spaceime. instead.

Maybe it's just quantum mechanics all the way down.

Quantum threads.

So these entangled particles connected by wormholes.

So that's what that's how you would how would you even visualize a black hole in that way.

So it's all um I mean it's all sort of from our perspective in terms of detecting things the light goes going in it's all still the same.

But when you zoom in a lot when you zoom in a lot to the quantum mechanical scale at which you're seeing the Hawking radiation, you would be noticing that there's there's some entanglement between the radiation that I could not explain before and the interior of the black hole. So, it's now no longer a perfectly thermal spectrum with no features that only depends on the mass.

it actually has a way to have an imprint of the information interior to the black hole in the particles that um escape.

And so now in principle I could sit there for a very long time.

It might take longer than the age of the universe and collect all the Hawking radiation and see that it actually had details in it that are going to explain to me what was interior to the black hole.

So the information is no longer lost.

So yeah so information is not being destroyed.

So in theory, you should be able to get information.

Now I can't do that anymore than I can recover the words on that piece of paper once it's been burnt.

But that's a practical limitation, not a fundamental one.

It's just too hard.

But when I burn a piece of paper technically the information is all there somewhere.

It's in the smoke.

It's in the currents. It's in the molecules.

It's in the ink molecules.

But in principle, if I had took the age of the universe, I could probably reconstru I should be able to in principle reconstruct the piece of paper and all the words on it.

Do you think a theory of everything that unifies general relativity, quantum mechanics is possible? So, we're like uh skirting around it. Yeah, we're skirting around it.

I think that this is the way to find that out. It's going to be on the train of black holes that we figure out if that's possible.

Um I think that this is suggesting that there might not be a theory of quantum gravity that gravity will emerge at a macroscopic level out of quantum phenomena.

Now we don't know how to do that yet but these are all hints emerge.

So a lot of the mathematics of anything that emerges from complex system is very difficult to the transition is very difficult right so if that's the case there might not be a simple clean equation that that connects everything there are examples of emerging phenomena which are very simple and clean like I can just take electromagnetic scattering just um law of physics where particles scatter just by electromagnetically and I have a lot of them and I have a lot of them in this room and they come to some average well I call that temperature right?

And that one number, the fact that there's one number describing all of these gazillions of particles is an emergent quantity.

It's there's no particle that carries around this fundamental property called temperature right?

Um it emerges from the collective behavior of tons and tons of particles.

In some sense, temperature is not a fundamental quantity.

It's not a fundamental law of nature, right?

It's just what happens from the collective behavior.

And that's what we'd be saying.

We'd be saying "Oh, this this emerges from the collective behavior of lots and lots and lots of um quantum interactions.

" So when do you think we would have some breakthroughs on uh the path towards theory of everything showing that it's possible or impossible all that kind of stuff? If you look at the 21st century, say you're move 100 years into the future and looking back when do you think the breakthroughs will come?

So I'll give you some hard problems. I guess my question is how hard is this problem? Your like what does your gut say? Because you know finding the origin of life, figuring out consciousness, solving some of the major diseases.

Then there's the theory of everything, understanding this resolving the information paradox.

So these puzzles that are before us as a human civilization physics, this feels like really one of the big ones. Of course, there could be other breakthroughs in physics that don't solve this.

Yeah, we could discover dark matter, dark energy.

We could discover extra spatial dimensions.

We could discover that those three things are linked, that there's like a dark sector to the universe that's hiding in these extra dimensions.

And that's something that I love to work on.

I think is really fascinating.

All of those would also be clues about this question, but they wouldn't solve this problem.

Um I think there I think it's impossible to predict.

There has been real progress and the progress as we've said comes from the childlike curiosity of saying "Well, I don't actually understand this.

I'm going to keep leaning on it because I don't understand it." And then suddenly you realize nobody really understood it.

Um so I don't I don't know.

Do I think it's a harder problem than the problem of the origin of life?

I think it's technically a harder problem.

Um, but I don't know.

Maybe maybe the breakthrough will come.

So when you mentioned discovering extra dimensions, what do you mean?

What could that possibly mean?

Well, we we know that there are three spatial dimensions.

We like to talk about time as a dimension. We can argue about whether that's the right thing to do, but we don't know why there are only three.

It very well could be that there are extra spatial dimensions that there's like a little origami of these tightly rolled up dimensions.

Um, not all of them, not all the models require that they're small, but most do.

String theory requires extra dimensions to make sense.

But even if you uh feel very um hostile towards string theory, there are there are lots of reasons to consider the viability of extra dimensions.

And we think that they can trap little quantum energies in such a way that might align with the dark energy.

And the numerology is not perfect.

It's a little bit subtle.

it's hard to stabilize them.

Um, it's possible that there are these kind of quantum exitations that look a lot like dark matter.

It's kind of an interesting idea that in the Big Bang, the universe was born with lots of these dimensions.

They were all kind of wrapped up in the early universe.

And what we're really trying to understand is why did three get so big and and why did the others stay so small?

Is it possible to have some kind of natural selection of dimensions kind of situation?

There is actually and people have worked on that. Is there a reason why it's uh easier to unravel three?

Some people think about strings and brains wrapping up in the extra dimensions causing a kind of constriction but preferentially loosening up in three. Um, sometimes we look at exactly models like that which have to do with the origami uh being resistant to change in a certain way that only allows three to unravel and keeps the others really taught.

But then there are other ideas that we're actually living on a three-dimensional membrane that moves through these higher dimensions.

And so the reason we don't notice them isn't because they're small.

Maybe they're not small at all.

But it's because we're stuck to this membrane.

So, we're unaware of these extra directions.

Is it possible that there's other intelligent alien civilizations out there that are operating on a different membrane?

Is is this a bit of an out there question?

But I I ask it more kind of seriously like is it possible do you think from a physics perspective to exist on a slice of uh what the universe is capable of?

I think it is certainly mathematically possible on paper to imagine a higher dimensional universe with more than one membrane.

And if things are mathematically possible, I often wonder if nature will try it out. Yeah. Um, which is how people get into the the strange territory of talking about a multiverse.

Because if you start to say one of the aspirations was in the same way that we identified the law of electroeak theory of matter that it was a single description and exactly um landed on the description that matched observations.

People were hoping the same thing would happen for a kind of theory that also incorporated gravity.

there would be this one beautiful law, but instead they got a proliferation, all of which did okay or did equally badly.

Um, they suddenly had trouble finding not only finding a single one, but sort of that would just beg a new question, which is well, why that one? And if if nature can do something, won't she do anything she can try?

And so maybe we really are just one example in an infinite sea of possible universes with slightly different laws of physics. So if I can do some of these things on paper, like imagine a higher dimensional space in which I'm confined to a brain and there's another brain or maybe a whole array of them. Maybe nature's tried that out somewhere.

Maybe that's been tried out here.

Um, and then yes, is it possible that there's life and civilizations on those other brains?

Yeah, but we can't communicate with them.

They'd be like in a shadow space.

Can you seriously say we can't communicate with them? No, that's fair.

I there I'm limited in my communication cuz I'm glued to the brain.

But some things can move. We call the bulk through the bulk. Gravity, for instance a gravitational wave. So I could design a gravitational communicator communication system and I could send gravitational waves through the bulk and how SETI is doing with light into space. I could um send signals into the bulk. Nice.

Telling them where we are and what we do and of course singing songs.

Sending gravitational waves is very expensive.

We don't know how to very expensive very hard to localize. They tend to be long wavelength and very hard to do.

lot of energy moving around. A lot of energy.

Uh, so is it possible that the membranes are quote unquote hairy in other ways like some kind of weird? It is possible that there's other things that live in the bulk.

I mean, last night I was calculating away looking at something that lives in the bulk. Okay, this is fascinating.

So, I mean, okay, can we take a little bit more seriously about the the whole when I look out there at the stars? Mhm. I from a basic intuition cannot possibly imagine there's not just alien civilizations everywhere.

Yeah. Life is so damn good.

Like you said, nature tries stuff out.

Yeah. Nature's an experimentter.

And I just can't just basic sort of uh observation life uh you said somewhere that you like extreop files life just figures out it just finds a way to survive.

Now there could be something magical about the origin of life the first spark but like I can't even see that it's over and over and over.

I bet actually once once the story is fully told and figured out, life originated on Earth almost right away and did that.

So like billions of times uh in multiple places just over and over and over and over.

Uh that seems to be the thing that just whatever is the life force behind this whole thing seems to uh seems to create life seems to be a creator of different sorts.

Yeah. the the the very from the very original primordial soup of things.

It just creates stuff. So, I just can't imagine, but we don't see the aliens.

So, right. Yeah. We don't even have to go to something as crazy as extra dimensions and brain worlds and all of that.

What's happening right now in the past 30 years in astronomy looking at real objects is that the number of planets, exoplanets outside our solar system has absolutely proliferated.

There are probably more planets in the Milky Way galaxy than there are stars.

And now we have a real quandry.

Not I don't think it's quandry. I think it's really exciting.

It becomes impossible.

What you just said, I totally agree with.

It becomes impossible to imagine that life was not sparked somewhere else in our Milky Way galaxy and maybe even in our local neighborhood of the Milky Way galaxy, maybe within a few hundred lighty years of the Milky of of of our solar system.

So my my my gut says like some crazy amount of uh solar systems have life bacterial life somewhere at some point in their history had some bacterial type of life something like bacterial maybe it's totally different kinds of life so then I'm just facing with a question it's like why have we not clearly seen alien civilizations and there the answer I I just I I don't find any great filter answer convincing.

There's just no way I can imagine an advanced alien civilization not avoiding its own destruction. I can see a lot of them getting into trouble. I could see how we humans are really like 50/50 here.

Well, isn't that kind of appalling?

I mean, just take that statement.

We've only been around for like I mean couple hundred thousand years tops, you know? Um, that is not very long and we're at a 50/50.

I mean that's unbelievable. I mean, it's indisputable that we have created the means at least potentially for our own destruction.

Will we learn from our mistakes?

Will we avert course and save ourselves?

One hopes so, right?

But but even the concept that it's conceivable whales have not invented a way to kill themselves to wipe out all whales and earth and life on earth. That's one way to see it. But I I actually see it as a feature not a bug when you look at the entirety of the universe because uh it does seem that the mechanism of evolution constantly creates you want to operate on the verge of destruction.

It seems like I mean the predator and prey dynamic is really effective at creating a at accelerating evolution and development.

It seems like us being able to destroy ourselves is a really powerful way to give us a chance to really get our together and to flourish to develop to innovate to to uh go out amongst the stars or 50/50 destroy ourselves.

But like, which I think me as a human is a horrible thing.

But if there's a lot of other alien civilizations, that's a pretty cool thing.

You want to give everybody nuclear weapons half of them will figure it out, half of them won't.

And the ones that give everyone all these civilizations, all these civilizations, and then the ones that figure it out will figure out some incredible technologies about how to expand, how to develop, and all that kind of stuff, right? You could use a kind of evolutionary Darwinian natural selection on that where in survival isn't just in a harsh naturally induced climate change but is because of a nuclear holocaust and so but and then and then something will will be created that is now impervious to that that now knows how to survive. Yep. Exactly.

So why haven't we seen them? Right.

Well because that's a pretty big bar.

So if you look at the just to say for a comparison dinosaurs you know 250 million years I mean maybe not very bright um didn't invent but fire didn't write sonnets they didn't contemplate the origin of the universe but they they lived and um in a benign situation without confronting their own demise at their own hands pause um so It's just a sheer numbers game.

That's a long time, 250 million years.

I do think though that life can flourish without wanting to manipulate its environment.

And that we do see many examples of species on Earth that are very longived, very very longived.

Um and have very different states of consciousness.

They have the jellyfish does not even have a localized brain.

Um, I don't think they have a heart or blood.

I mean, they're really different from us.

Okay? And that's what I think we have to start thinking about when we think about aliens. Those, uh, species have lived for a very, very long time.

They even show some evidence of immortality.

You can wound one badly and there are certain jellyfish that will go back into a kind of pre-state and start over. So, I think we're very attached to imagining creatures like us that manipulate technology. Um, and um and I think we have to be way more imaginative uh, if we're going to really take seriously life in the universe. Yeah.

They might not prioritize conquest and expansion.

Mhm. They might not be violent.

They might not be violent like us humans.

They might be solitary.

They might not be social. They might not move in groups.

They might not want to leave records.

Um, uh, they might again not have a localized brain or have a completely different kind of nervous system.

I think all we can say about life is it has something to do with moving electrons around and um, like neurologically we move electrons through our nervous system.

Our brain has electrical configurations.

We metabolize food and that has to do with uh getting energy electrical energy in some sense out of um what we're eating. You we organisms on the earth that can eat rocks.

It's quite amazing. Minerals. I mean, talk about extreophiles.

They can metabolize things that I would have thought uh were impossible to metabolize. And so, again I think we we have to kind of open our minds to how strange that could be um and how different from us. And we are the only example even here on earth that that does manipulate its environment in that extreme way. I mean can you think of life as cuz you said electrons is is there some degree of information processing required?

So like it does something interesting in quotes with information.

I think there are arguments like that. um how entropy is changing from the beginning of the universe to today. How life uh lowers entropy by organizing things but it costs more as a whole system.

So the whole entropy of the whole system goes up.

But um but of course I I organized things today and reduced the entropy of certain things in order to get up and get here.

um and even having this conversation organizing thoughts um out of the cloud of information but it comes at the cost of the entire system increasing um entropy so I do think there's probably a very interesting way to talk about life in this way I'm sure somebody has yeah yeah it creates local pockets of low entropy and then the kind of mechanism the kind of object the kind of life form that could do that probably can take arbitrary forms and you could think now if you you reduce it all to information.

Now you can start to think about physics and in the realm of physics with with the multiverse and all this kind of stuff.

You could start to think about okay how do I detect those pockets of low entropy?

Mhm. Yeah. I mean people have tried to make arguments like that like can I look for entropic arguments that might suggest we've done this before?

the big bang has happened before.

So, is it possible that there's some kind of physics explanation why we haven't seen the aliens? Like we said membranes, I don't think membranes is going to explain why we don't see them in the Milky Way. I think that is just a problem we're stuck with. whether or not there are extra dimensions or whether or not there's life in another membrane.

Um I think we know that even just in our galaxy which is a very small part of the universe um 300 billion stars something like that a whole kind of variety of possibilities to be explored by nature in the same way that we're describing.

And I think you're absolutely right when when life was kicked off first sparked here on Earth it was voracious.

Now, it took a really long time though to get to multisellularity.

I think that's interesting.

That's weird. It's weird.

It took a really really long time to become multisellular.

But it it did not take long just to start. Yeah. What do you think is the hardest thing on the chain of leaps that got to humans? I would say multisellularity, which is strictly an energy problem.

I I think again it's just like can electrons flow the right way?

Uh and is it energetically favorable for multisellularity to exist?

Because if it's energetically expensive, it's not going to succeed. And if it's energetically favorable, it's going to take off.

It's really just and that's why I also think that going from inanimate um to animate is probably gray.

Like the transition is gray. At what point we call something fully alive?

Famously it's hard to make a nice list of bullet points that need to be met in order to declare something alive. Is a virus alive?

I mean, I don't know. Was a PON alive?

Those are they seem to do some things, but they kind of rely on stealing other DNA and replicating.

And I don't know. I guess they're not alive.

But I mean, the point is is that it really at the end of the day, I really think it's just, you asked if it's just physics.

I mean, I think it's just this these rules of energetics. And the gray area between the non-living and the living is way simpler just on Earth.

And you said it's already complicated on Earth, but it's probably even more complicated elsewhere where the chemistry could be anything.

Carbon is really cool and really useful because it finds a lot. It's nice. It finds a lot of ways to combine with other things.

And that's complexity. And complexity is the kind of thing you need for life.

You can't have a very simple linear chain and expect to get life. But I don't know, maybe sulfur would do. Okay. Okay.

As we get progressively towards crazier and crazier ideas. So, we talked about these microscopic wormholes, which you know, my mind is still blown away by that.

But if we talk about a little bit more seriously about wormholes in general, also called the Einstein rose and bridges, to what degree do you think they're actually possible as a thing to study, creeping towards the possibility, maybe centuries from now of engineering ways of using them, of creating wormholes and using them for transportation of humanlike organisms. I think wormholes are a perfectly valid construction to consider.

They're just they're just a curve in spaceime.

Um the topologically, which has to do with the connectedness of the space, is a little tricky because we know that Einstein's description is completely in terms of local curves and distortions expansion, contraction.

But it doesn't say anything about the global connectedness of the space because he knew that it could be globally connected on the largest scales. This kind of origami that we're talking about that you could travel in a straight line through the universe, leave our galaxy behind, watch the Virgo cluster drift behind us and travel in a straight line as possible and find ourselves coming back again to the Virgo cluster and eventually the Milky Way and eventually the Earth that we could find ourselves on a connected compact spaceime.

And so topologically um there's something we know for sure something beyond Einstein's theory that has to explain that to us.

Now wormholes are a little funky because they're topological.

You know they create these handles and holes in these sneaky by topological I mean these connected spaces and yes it's like Swiss cheese or something.

like Swiss cheese and they right and they so I could have you know I I could have two like flat sheets that are connected by a wormhole but then wrap around on the largest scale you know all this cool stuff um there's nothing wrong with it as far as I can see there's nothing abusive towards the laws about a wormhole but we can reverse engineer you we were saying oh look if I know how matter and energy are distributed I can predict how spaceime is curved I can reverse engineer I can say I want to build a curved spaceime like a wormhole. What matter and energy do I need to do that? It's a simple process and it's kind of thing Hip Thorne uh worked on very imaginative creative person.

Um and the problem was that he said, "Oh, you know, here's the bummer.

The matter and energy you need doesn't seem to be like anything we've ever seen before. It has to have like negative energy.

" And that's that's not great.

Um there are some conjectures that we shouldn't allow things that have that kind of a property that have negative energies.

U only things that have positive energies are going to be stable and longived. But we actually know of quantum examples of negative energy.

So it's not that crazy.

There's something called the Casmir effect.

You have two metal plates and put them really close together. You can see this kind of quantum fluctuation between the plates.

It's called a kasmir energy.

And that can have a negative energy can actually um cause the place to attract or repel depending on how they're configured.

And and so you could kind of imagine doing something like that, like having wormholes propped up by these kinds of quantum energies.

And people have thought of imaginative configurations to try to keep them propped up.

Is it are we at the point of me saying, "Oh, this is an engineering problem.

" I'm not saying that quite yet but it's certainly plausible.

Yeah. So, you have to get a lot of this kind of weird matter. You need a lot of this weird matter to send a person through, right?

That's going to be really telling.

So, I'm not saying we're it's simply an engineering problem, but it's all within the realm of plausible physics.

I think I I think that's super interesting.

I think it's obviously intricately deeply connected to black holes.

H is is it fair to think of wormholes as just two black holes that are connected somehow? Is that people have looked at that? They tend to be non-traversible wormholes.

They're they're not trying to prop them open.

Um but yeah, I mean some of this er equals EPR, quantum entanglement they're trying to connect black holes.

Um you know, it's it's really cool.

It's not quite again it's not quite following the chalk.

And by that I mean we can't exactly start at a concrete place calculate all the way to the end yet.

So if I may read off some of the ideas that kept throwing his head about how to artificially construct wormholes.

So the first method involves quantum mechanics and the concept of quantum foam.

And this is the thing we've been talking about.

Now to create a wormhole these tiny wormholes would need to be enlarged and stabilized to be useful for travel.

But the exact method of doing this remains entirely theoretical.

No You think so? So this these tiny wormholes that are basically um for the quantum entanglement of the particles somehow enlarged.

Man, playing with the topology of the Swiss cheese would be so interesting.

Even to get a hint. Mhm. That would be like top three if not one of maybe even number one question for me to ask if I got a a chance to ask an omnicient being.

omnicient being of like a question that I can get answer to. Mhm.

Maybe with some visualization. Mhm.

Like the shape the topology of the universe.

Yeah. Like but like I need some details.

Unfortunately, I'll get an answer that I can't possibly comprehend. Right.

It's a hyperbolic manifold that's identified across Exactly.

You need to be able to ask a follow-up question.

Exactly. Yeah. That would be so interesting.

Anyway, um classical quantum strategy.

The second approach combines classical physics with quantum effects.

This method would this method would require an advanced civilization to manipulate quantum gravity effects in ways we don't yet understand.

There's a lot of in ways we don't understand.

Yeah, there's a lot of And then there's exotic matter requirements.

There's a lot of But I can tell you I'm pretty sure all of them have in common the feature that they're saying here's what I want my wormhole to look like first.

So it's like saying I want to build a building first.

So they ar they construct there's an architecture of the spaceime that they're after and then they reverse the Einstein equations to say what must matter and energy uh what are the conditions that I impose on matter and energy to build this architecture which is unfortunately a very early step of figuring out but it's important because it's how they realized oh wow they have to have these negative energies they have to violate certain uh energy conditions that we often assume are true and then you either say, "Oh well then all bets are off they'll never exist or you uh look a little harder and you say, "Well, I can violate that energy condition without it being that big a deal." And um and again, quantum mechanics often does violate those energy conditions.

So, do you think the studying of black holes and some of the topics we've been talking about will allow us to travel faster than the speed of light or travel close to the speed of light or do some kind of really innovative breakthroughs on the propulsion technology we use for traveling in space? Yeah.

I mean sometimes I assign in an advanced general relativity class the assignment of inventing a warp drive and it's kind of similar.

So the idea is uh here's a place you want to get to and can you contract the spaceime between you with some some kind of some something antithetical to dark energy the opposite and skip across and then push it back out again.

That's all can you can do that in the context of general relativity.

Now I I can't find the energy that has these properties but I also can't find dark energy.

So, so we've already been confronted with something that we look at the spaceime.

The spaceime is expanding ever faster.

We say, "What could possibly do that?

" We don't know what it is. But I can tell you about its pressure. I can tell you certain features about it. And I just call it dark energy, but I actually have no idea.

It's just that name's just a proxy for what this it should be called invisible because it's not actually dark.

It's in this room. It's not hard to see through. It's not dark.

It's It's literally invisible. Um, so maybe that was a misnomer. But the point being, I still don't fundamentally know what it is.

That's not so terrible.

That's that's the state of the world that we're actually in.

So maybe warp drive is just kind of like a version of that.

I I don't know what form of matter can do that yet, but at least I can identify the features that are needed.

So figuring out what dark energy is might land some clues. Yeah, it actually it might.

Um, it it is it is positive energy.

Um um and a negative pressure which is kind of like a rubber band sort of quality.

We think of pressure as pushing things outward and dark energy has a very strange sort of quality that as things move outward you feel more energy as opposed to less energy.

The energy doesn't get lower, it gets more.

And um but it so it doesn't have the right features for the wormhole.

But those are some pretty surprising features.

And we we again can conjecture like oh hey you know the quantum energy of the vacuum kind of behaves that way.

That would be a great resolution to the dark energy problem. It's just the energy of empty space and it's the quantum energy of empty space.

That's an excellent answer. The problem is is by all our methods and all the understanding we have that energy is either really really huge huge um way bigger than what we see today or it's like zero.

So that's a numbers problem.

We can't naturally fine-tune the energy of empty space to give us this really weird value so that we just happen to be seeing it today.

But again we can think of a kind of dark energy that exists. Um so the question is just why is it it becomes why is it such such a weird value.

Um not how is this conceivable because we can't conceive of it. Yeah. But if it's a weird value that means there is a phenomena we don't understand. Yes.

There's absolutely a phenomenon.

Nobody's going to say they're happy with that.

We're all going to say there's something we don't understand.

which is why we look to the extra dimensions because then you can say, "Oh, maybe it has to do with the size of the extra dimensions or the way that they're wrapped up or um and so maybe there it's foisted on us because of the the topology, the connectedness of the higher dimensional space. These are all things that we're exploring.

Nobody's landed one that's so compelling that uh your friends like it as much as you do.

" What what what do you think would lead to the breakthroughs on dark matter and dark energy?

I think dark matter might be uh less peculiar um than dark energy. My hope is that they're tied together. That's that would be very gratifying. These aren't just separate problems coming from different sectors, but that they're actually connected.

um that the reason the dark matter is where it is in terms of how much it's contributing to the universe is is connected with why the dark energy is showing up right now. I would love that.

That would be a solution like no other, right?

And and like I said, if it revealed something about dark dimensions, you know, that's that would be a happy day. Correct me if I'm wrong.

Dark matter could be localized in space.

Yeah, dark matter is localized in space.

So, it clumps. I mean, it doesn't it doesn't clump a lot, you know, but but I mean, it's around the galaxy. It's in a halo around the galaxy. So, people get increasingly more confident that it doesn't Oh, it's really compelling.

Yeah. I mean, you see um these images of uh galaxies that clusters that that pass through each other and you can see where the light is, the luminous matter is distributed.

And then by looking at the gravitational lensing which shows you where the actual mass is distributed so that light bends around the most massive parts in a particular way. So you can reconstruct where the mass is gravitationally quite separate from looking at the luminous matter which is not dark and they are separate because the stuff as they pass through each other the interacting stuff the luminous stuff collides and gets stuck and you can see it colliding and lighting up the dark stuff which by definition it's dark because it doesn't interact passes right through it's right through each other right and this is I mean it's so compelling And there's lots of other um observations, but but that one is just before you just look at it you can see that the mass is distributed differently than the interacting luminous matter.

So, uh dark energy is harder to get a hold of. Dark energy is much harder to get a hold of.

But, you know, I mean, the Higs field could have also explained dark energy. Yeah.

Um, if you've heard of the God particle, I don't know if you know the originally Leon Letterman co-authored a book and he wanted to call it the goddamn particle because I couldn't find it and his his publisher convinced him to call it the God particle.

Uh, and he said he said they managed to offend two groups, those that believed in God and those that didn't.

That's a good line, too.

Oh boy. He was very funny. He was very witty.

So, you know, Higs turned out to be Higs great discovery.

I mean unbelievable. Um, there it was.

Build this massive collider in CERN in Switzerland and there it is.

Unbelievable. Kind of where you expect it to be. Now, the reason I say it could be dark energy is because the Higs particle like a particle of light also has a field like an electromagnetic field.

So light can have this field that's distributed through all space electric magnetic field, and you shake it around and it creates little particles.

So the Higs field is actually more important than the Higs particle the complement to the Higs particle because that's what you and I connect with to get mass in our atoms. So the idea is that our atoms are interacting with this gooey field that's everywhere.

Mhm. And um and that's what's giving us this experience of inertial mass, but we don't actually inter there's not a lot of quanta lying around. There's not a lot of Higs particles lying around cuz they decay.

So it's the field that's really important.

And that field could act like a dark energy.

It's just not in the right place, meaning it's not at the right the energy's too high in to explain this tiny tiny value today.

And again, we're back to this mismatch.

It's not that we can't conceive of forms of dark energy, it's that we can't make one where we where we're finding it.

So, uh I wonder if you can comment on something that I've I've heard recently.

There's some people who say uh people outside of physics say that you know, dark matter and dark energy is just something physicists made up. Yeah.

to uh put a label on the fact that they don't understand a very large fraction of the universe and how it operates. Is there some truth to that?

What's your response to that?

There's some truth to it, but but it's really missing a huge point, which is that if we did not understand the universe as incredibly precisely as we do, it's stunning that there's modern precision cosmology.

It's absolutely incredible.

uh when Kobe which is an experiment that measured the light left over from uh the big bang in the 80s first revealed its observations I mean there was applause you know people were cheering right it was unbelievable we had predicted and measured the light left over from the big bang and because of all the precision that's happened since then that's how we're able to confront that there's things that we don't know and that's how we're able to confront like, "Wow, this is really everything everybody has ever seen and ever will see as far as we understand makes up less than 5% of what's out there.

" Yeah. And and so I would say yes, we're just giving proxy names to things we don't understand.

But to dismiss that as some kind of oh, they just don't know that it is actually quite the opposite. It is a stunning achievement to be able to stare that down and to have that um so precise and so compelling that we're able to to to know that there's dark energy and dark matter.

I don't think those are disputed anymore and they were up until, you know, recently.

They were still disputed.

I think we're still at such early stages where we're not really even at a good explanation. Right.

You've mentioned a few. Well, I can think of examples of dark matter that exist that we really know for sure are real versions of dark matter, like nutrinos.

Right now, they're radiating through us.

That's very well confirmed.

And they're technically dark. They don't interact with light and so we can't see them.

Right now, they're raining through us.

If we could see the dark matter in this room and we absolutely know is coming from the sun, it would be wild.

Be a rainstorm, you know, but they're just invisible to us. Um, mostly they pass through our bodies. Mostly they pass through the earth. Occasionally they get caught in some fancy detector experiment that somebody built specifically to catch solar.

So dark matter is known to exist.

It's just again there's not enough of it. It's not the right mass to be the dark matter that makes up this missing component.

I wanted to say that I was been recently fascinated by the flat earth people because there's been a split in the community. Mhm.

First of all, the community is fascinating study of human psychology.

uh they did um this experiment where I I forgot who funded it, but they sent like physicists and flatearthers Mhm. to Antarctica.

Really? And this split happened because half of them got converted into round earthers.

Wow. Well, good for them.

And then but then the other half just went that it was all a sigh out. Really?

That's fascinating. Did somebody film that?

That'd be a great documentary.

Yeah, it did. They did. I made a whole thing.

This was just at the end of last year.

There was a big I meaning cuz I I I think that's such a clean study of conspiracy theories because like there's so many conspiracy theories have some inkling of truth in them.

Like there's some elements about the way governments operate or human psychology that there's it's too messy.

Flat Earth to me is just clean. It's like spaghetti monster or something like right.

It's just a cleanly wrong thing. So it's a nice way to understand the psychology how a large number of people can believe a thing.

Yeah. And why do they want to believe a thing? What's very interesting is um use trying to use rational arguments.

So I that makes it even more confounding to me. I would understand more somebody who just said, "Look, I have faith and I believe these things and it's not about reason and it's not about logic and okay.

I mean, I don't relate to it, but okay.

" Um, but to say I'm going to use reason and logic and to prove to you this completely orthogonal conclusion that I find really interesting.

So, there's some kind of romance.

There's about reason and logic. Yeah. But also there's a questioning of institutions that's really interesting and important to understand.

Well, I mean I I actually appreciate the skeptics's stance.

I don't scientists also have to be skeptics. We have to be childlike, naive, and somewhat in some sense really open to anything, right?

Otherwise, you're not going to be a flexible.

You're not going to be at the forefront.

But but also to be skeptical.

Um, so I have respect for I guess I that's exactly what I'm saying is more confusing because to invoke skepticism and then to want to use rational argument.

What is the other component that's that's going into this because as you said this is something that's easily verified.

I mean, we have people in space.

So, you have to believe a lot more machinery um that's a lot more difficult to justify explain as a wild conspiracy.

So there's something about the conspiracy that stirs an emo a positive emotion.

I think one of the most incredible things I have to talk to you about this, one of the most incredible things that humans have ever accomplished is LIGO. Hm.

We have to talk about gravitational waves.

And the the very fact that we're able to detect gravitational waves from the early universe is effing wild. It's crazy.

Yeah. Can you explain what gravitational waves are?

And we should mention you wrote a book about the humans about the whole journey of detecting gravitational waves and LIGO Black Hole Blues is the book.

But can you talk about gravitational waves and how the hell we're able to actually do it?

Let's just start with the idea of gravitational waves.

I have to move around a lot of mass to make anything interesting happening in gravity. I mean, if you think about it, gravity is incredibly weak.

I mean, right now, the whole Earth is pulling on me and I can still get out of this chair and walk around.

Like that's insane. The whole Earth, you know, gravity's weak, right? Um, so to get something going on in gravity, I need like big objects and things like black holes.

So the idea is if black holes curve space and time around them in the way that we've been describing things follow along the curves in space.

If the black holes move around, the curves have to follow them, right?

But they can't travel faster than the speed of light either. So what happens is as black holes, let's say, move around maybe I've got two black holes in orbit around each other. That can happen.

It takes a while. a wave is created in the actual shape of space and that wave follows the black holes as black holes are undulating.

Eventually, those two black holes will merge and as we were talking about, it doesn't take an infinite time even though there's time dilation because they're both so big.

They're really deforming spaceime a lot.

I don't have a little tiny marble falling across an event horizon.

I have two event horizons. And in the simulations, you can see it bobble and they merge together and they make one bigger black hole. And then it radiates in the gravitational waves.

It radiates away all those imperfections and it settles down to one quscent perfectly silent black hole that's spinning.

Beautiful stuff. And it emits E= MC² energy.

So the mass of the final black hole will be less than the sum of the two starter black holes. And that energy is radiated away in this ringing of spaceime.

It's really important to emphasize that it's not light.

None of this has to do literally with light that we can detect with normal things that detect light.

X-rays form of light.

Gamma rays are a form of light.

Infrared, optical, all this whole electromagnetic spectrum.

None of it is emitted as light. It's completely dark.

It's only emitted in the rippling of the shape of space. A lot of times it's likened closer to sound.

Technically we've kind of argued, I mean, I haven't done an anatomical calculation, but if you're near enough to two colliding black holes, they actually ring spaceime in the human auditory range.

The frequency is actually in the human auditory range that the shape of space could squeeze and stretch your eardrum even in vacuum. And you could hear literally hear these waves ringing.

[Music] So the idea is that they're closer um to something that you would want to map as a sound than it's something as a picture.

Sorry. So what do you think it would feel like to ride the gravitational wave?

So like to be to exist to exist as you mentioned here would literally bob around like your orbit would change right if you were orbiting these black holes two black holes you'd be on a kind of complicated orbit but your orbit would get tossed about well how would the experience be because you're inside spaceime yes I see so the the the the black hole is experienced within spacetime as a squeezing and stretching. So you would feel it as a sort of squeezing and stretching and you would also find your location change where your where you would fall would be redirected.

Um so it's literally like a squeezing and stretching. That's the way to think about it. And and and it's very detailed the sort of nature of this and um but for many years people thought well these gravitational waves kind of have to exist for these intuitive reasons I've described.

spacetime's curved. I move the curve. The wave has to propagate um through that curved spaceime.

But people didn't know if they really carried energy.

The arguments went on and back and forth and papers written in decades, right? Um but I like this sound an more than an analogy because I I liken the black holes as like mallets on the drum. The drum is spacetime.

Yeah. As they move, they bang on the drum of spaceime and it rings.

Mhm. Remarkably, those gravitational waves do things don't interfere with them very much. So, they can travel for two billion years, light years, you know, in distance, two billion years in time, and get to us kind of as they were when they were emitted, quieter, more diffuse, maybe they've stretched out a little bit from the expansion of the universe, but they're pretty preserved.

And so the idea of LIGO, this instrument, is to build a gigantic musical instrument.

It's kind of like building an electric guitar where the electric guitar is recording the shape of the string and it plays it back to you through an amplifier. LIGO is trying to record the shape of the ringing drum and they literally listen to it in the control room.

just sort of hums and wobbles and they're like trying to play this recording drum back to you as opposed to taking a snapshot.

It's like a in time. Yeah. But to construct this guitar Yes.

gigantic instrument has to be very large and extremely precise.

It's unbelievable. I can't believe they succeeded.

I honestly I can't believe they succeeded.

It was so insane.

It was such a crazy thing to even attempt.

It took them 50 years. Really?

It's people who started in their 30s and 40s who were in their 80s when when it succeeded.

I mean, imagine that tenacity, the unbelievable commitment.

Um, but the sensitivity that we're talking about is we have a this musical instrument the s four kilometers spanning four kilometers in a kind of L-shape with these tunnels where there's this the largest holes in the earth's atmosphere because they pulled a vacuum in these tunnels to build this instrument.

Um, and they're measuring they're they're trying to record the wobbling of spaceime right as it passes this sort of undulation.

Uh, that amounts to less than 110,000th the variation in a proton over the four kilometers. It's an insane insane achievement.

Oh, great engineering.

I don't know how they did I swear I follow them around from so I just for fun I'm I'm very theoretical.

I don't build things. I'm always super impressed that people can translate something on the page and and it looks like wires and I don't know how I'm always surprised at what it looks like and but I walked the tunnels with Ray Weiss who won the Nobel Prize along with Kip Thorne and Barry Barish one of the project managers and I walked the tunnels with Ray. It was a delight.

I mean Ray is one of the most delightful people.

Kip is one of the most wonderful people I've ever known. Um, and uh, Rey said to me, you know, the reason why it was called Black Hole Blues is because about a month before they succeeded, he said to me, if we don't detect black holes, this whole thing's a failure.

And, um, we've led this country, you know, down this wrong path. And, um, he really felt like this tremendous responsibility for this project to succeed.

And it weighed on him, you know, it was uh it was just quite tremendous what the the integrity right, the scientific integrity.

And the first instruments he built, he was building outside of MIT and on a tabletop and his his colleagues said "You're not going to get tenure, you know, you're never going to succeed.

" Um, and they just kept going.

People like that. So huge teams, huge collaborations are just uh is how the world moves forward because it's an example.

It's you know there's building cynicism about bureaucracies when a large number of people especially connected to government can be productive.

You know bureaucracies slow everything down.

So it's nice to see an incredibly unlikely exceptionally difficult engineering project like this succeed.

Oh yeah. So I I understand why there's this weight on his shoulders and I'm great there's I'm grateful that there's great leaders that push it forward like that.

Yeah, it really is. You see so many u moments when they could have stumbled.

Yeah. Um and they built a first generation machine just after 2000 and it wasn't a surprise to them but it detected nothing.

Crickets. Crickets.

And they just, you know, they have the wherewithal to keep going.

second generation. They're about to turn the machine on, quote unquote. You It's a little bit of a simplification, but do their first science run and they decide to postpone um because they feel they're not ready yet. It's September 14th in 2015 and the experimentalists are out there.

They're in the middle of the night, you know, they're working all night long and they're they're banging on the thing, you know, literally driving trucks, slamming the brakes on to see the noise that it creates.

And um so they're really messing with the machine, really interfering with it just to kind of calibrate how much noise can this thing tolerate. And I guess the story is is they get tired.

There's there's an instrument in Louisiana and there's one in Washington state.

And they go home, put their tools down, they go home.

It's um they leave the instrument locked though, mercifully.

And um it's something like within the span of an hour of them driving back to their humble abodess that they have in these remote uh regions where they built these instruments, this gravitational wave washes over, I think it hits Louisiana first.

It travels across the US, brings the instrument in Washington state.

It began, you know, over a billion and a half years ago before multisellular organisms had emerged on the earth.

Just imagine this from like a distant view this collision course, right?

And um it's the centenerary. It's it's it's the year Einstein published general relativity.

That's so it was this, you know, a hundred years. I mean, just think about where that where that signal was when Einstein in, you know, 1915 wrote down the general theory of relativity.

It was on its way here.

It was almost here.

Uh, what do you think is cooler?

Uh Einstein's general relativity or LIGO.

Well, I can't disparage my friends, but of course, relativity is just so all-encompassing.

No, but see, so hold on a second.

All-encompassing, super powerful leap of a theory. Yeah.

And they built it. They built it.

I don't know, man. the greatest engineering on the in the you know cuz I I don't know cuz you know yeah humans getting together and building the thing that's really ultimately what uh what impacts the world right yeah uh I mean I I just as I said my admiration for for Ry and Kip and the entire team is is enormous and you know just imagining Rey had been out there on site he had just left to go back home um wakes up in the middle night and sees it, you know, can you imagine?

And there's a signal, you know, there's something in the log. He's like, "What the hell is that?

" So, speaking of the human story, you uh also wrote the book A Mad Man: Dreams of Touring Machines.

It connects two geniuses of the 20th century, Alan Touring and Girdle.

What specific threads connect these two minds?

Yeah, I was um was really mesmerized by these two characters.

They people know of Alan Turing for having ideiated about the computer being the person to really imagine that.

But his work began with thinking about God's work.

That's where it began and it began with this phenomenon of undecidable propositions or unprovable propositions.

So um uh there was something huge that happened in mathematics which is people imagined that any problem in math could technically be proven to be true.

doesn't mean human beings are going to prove every fact about everything in mathematics but you know it should be provable right I mean it seemed kind of it's not that wild supposition and everyone believed this all the great mathematicians Hilbert was a call of his to prove that and go to a very strange character uh very unusual he he was a platonist he he literally believed that mathematical objects had a existential reality he wasn't so sure about this reality.

This reality he struggled with. He he was distrustful um a physical reality but he absolutely took very seriously a platonic reality and often his own way of thinking and he proved that there were facts even among the numbers that could never be proven to be true. You have to think about that how wild that is that even a fact about numbers seems very simple uh could be true and unprovable could never exist as a theorem for instance in mathematics unreachable um this incompleteness result was very disturbing essentially it's equivalent to saying there's no theory of everything for mathematics it was very disturbing to people but it was very profound and Alan Turing got involved in this because he was you know he was thinking about uncomputable numbers.

So um and that led him what's an uncomputable number? A number like 0.175.

It just goes on forever with no pattern and I can't I can't even figure out how to generate it. There's no rule for making that number. And he was able to prove that there were such things as these uncomputable effectively unknowable numbers.

That might not sound like a big deal was actually was actually actually really quite profound.

He was relating to godal intellectually right in the space of ideas. But he goes a very different path almost philosophically the opposite direction.

He he he builds he starts to to think about machines.

He starts to think about mechanizing thought.

Starts to think what is a proof? How does a mathematician reason?

What does it mean to reason at all? What does it mean to think?

And he begins to imagine inventing a machine that will execute certain orders, you know mechanize thought in a specific way.

Well, maybe I can get a machine.

I can imagine a machine that does this kind of thinking and that he can prove that even a machine could not compute these uncomputable numbers.

But where he ends up is the idea of a universal machine that computes.

Um, essentially can take different software and execute different jobs, right?

We don't have a different computer to connect to the internet than we do to write papers. It's one machine and um, one piece of hardware, but it can do all of these this huge variety of tasks.

And so he really does invent the computer essentially.

Um, and famously he uses that thinking in a very primitive form in the war effort where he's recruited to help break the German enigma code.

Um, which is heavily encrypted and largely believed to be uncrackable code.

and um and and people believe that Turing and his very small group actually turned the tide of the war in favor of the allies precisely um by using a combination of this thinking and just sheer ingenuity and some luck.

Um but uh but the other profound revelation that Turring has is that well maybe we're just machines right and uh just biological machines and this is a huge shift for him.

feels very different from God who doesn't really believe in reality and thinks numbers are are platonic realities and and Turing kind of thinking we're kind of like we're actually machines and we could be replicated.

So of course Turing's influence is still widely felt on many levels. So as to the on many levels yeah in complexity theories theoretical computer science and mathematics but also in philosophy with his famous touring test paper.

So like you said conceiving like what what is the connection that I guess Ger never really made between mathematics and humanity uh touring did but I think there's another connection to those two people is that they're both in their own way kind of tormented yeah humans.

I think they were very tormented. What aspect of that contributed to who they are and what ideas they developed? I mean I think so much. I don't I don't want to promote the kind of trit trope of the mad genius, you know, if you're brilliant, you are insane. I don't think that.

I don't think if you're insane you're brilliant.

Um but I do think if somebody who's very brilliant who also chooses not to go for regular gratification in life Mhm. they don't go for money.

They don't necessarily value creature comforts.

They're they're not leveraging for fame. I mean they're really after something different.

I think that can lead to a kind of runaway instability actually.

Yeah.

sometimes um they're already outside of kind of social norms. They're already outside of normal connections with people.

They've already made that break.

Um and I think that makes them more vulnerable.

So God, you did have a wife and an strong relationship as far as I understand and had a was a successful mathematician and ended up at the Institute for Advanced Study where he walked with Einstein to the institute every day.

Um and they talked about and he proved certain really unusual things in relativity.

You you made reference to these rotating galaxies. We were talking and actually Goodel had a model of a rotating universe that you could travel backwards in time. It was mathematically correct.

Showed Einstein that within relativity you could time travel.

Um just a unbelievably influential and brilliant man.

But um he was probably a paranoid schizophrenic.

Um he did have breaks with reality. Um he uh was I think quite distrustful and feared the government feared his food was being poisoned and you know ultimately literally starved himself to death.

Um and it's such an extreme outcome for such a fil mind you know for for such a brilliant mind. I think it's important to sort of not to glorify or romanticize madness or or um suffering but to me, you can flip that around and just be inspired by the peculiar maladies of a of a human mind, how they can be leveraged and channeled creatively.

Oh yeah. I think a lot of us obviously probably every human has those peculiar qualities.

You know, uh I talk to people sometimes about just my own psychology and I'm extremely self-critical and uh I'm drawn to the beauty in people, but because I make myself vulnerable to the world, I can really be hurt by people and that thing.

Okay, you can lay that out. That's this particular human.

Okay.

And you know, there's a bunch of people that will say, well, you many of those things you don't want to do. Mhm.

Maybe don't be so self-critical.

Maybe don't be so open to the world. Maybe have a little bit more reason about how you interact with the outside world.

It's like, yeah, maybe. Or maybe be that and be that fully and channel that into a productive life into we're all going to die in the time we have on this earth.

Make the best of the particular weirdness that you have. Mhm.

And maybe you'll create something special in this world and in the end it might destroy you. And I think a lot of these stories are that it's not that Oh yeah.

It's not like saying, "Oh, because uh in order to achieve anything great you have to suffer." No.

If you're already suffering Mhm. if you're already weird, if you're already somehow don't quite fit in your particular environment, your particular part of society, use that somehow. I use the tension of that, the friction of that to create something.

I mean that's what I you know um ner who suffered a lot from even like stupid stuff like stomach issues like oh yeah kind of right migraines is like psychosmatic or psychophysical but and all those that's the real it's like that can somehow be channeled into a productive life.

It's it should be inspiring. A lot of us suffer in different ways. Yeah.

I'm a big believer in the tragic flaw.

Actually, I think the Greeks really had that right.

Um, you're describing it.

What makes us great is ultimately our downfall.

Maybe that's just inevitable.

The choice could be not to be great.

Um, and I guess I I that's sort of what I mean by they had already broken from a traditional path because they decided to pursue something so elusive and um that would isolate them to some extent inevitably and that could fail, right?

And whose rewards were hard to predict even.

Um, and I do think that that all the character traits that went into their accomplishments were the same traits that went into their demise. And um, I think you're right. You could say, well you know, Lex, maybe you should not be so empathetic, hold yourself, cut yourself off a little, but protect yourself right?

But isn't that exactly what you're bringing?

one of the elements that you're bringing that makes something extraordinary in a space that lots of people try um to break through.

Yeah. And but we should mention that for every girl on touring, there's millions of people who have tried and who have destroyed themselves and without without reason.

I would find it impossible to not pursue uh a discovery that I could I could imagine my way through. If I can really see how to get there, I I cannot imagine abandoning it for some other reason.

Uh uh fear that it would be misused, which is a real fear. Mhm. Right. I mean, it's a real concern. Um I don't think in my work since I'm doing extra dimensions in the early universe, but or black holes you know, I feel pretty safe.

But I mean, who knows, right?

Bore couldn't think of a way to use quantum mechanics to kill people. Mhm. Um I cannot imagine pulling back and saying, "Nope, I'm not going to finish this." You know, I'll give you a counter example of an exceptionally brilliant person.

Terrence Tao, brilliant. Brilliant mathematician.

Brilliant. Mhm. He is better than out of all the brilliant people I've ever met in the world. He's better than anybody else at working on a hard problem and then realizing when it's for now a little too hard.

Oh, that I can do.

and stepping stepping away and he's like, "Okay, this is now a weekend problem." Uhhuh.

Cuz he has he has seen too much for him.

Everybody's different, but Gregori Pearlman Mhm.

or Andrew Wilds who who give themselves a great story completely for many years over to a problem. Yes.

And for every every Gigor and they might not have cracked it. Yep. So you choose your life story like I totally agree.

Now I'm not going to say sometimes I take too long to come to that conclusion but I will proudly say as most theoretical physicists should that I kill most my ideas myself. Okay.

So, you walk away. I am absolutely able to say "Ah, that's just not I mean, I'm not going to deny that sometimes I maybe take a while to come to that conclusion longer than I should, but I will I absolutely will.

I will drop it.

" And that is that is any self-respecting physicist should be able to do that.

The problem is with somebody like Andrew Wilds, you were describing who to prove last theorem, it took him seven years.

Was that the number?

Something like that. he went up into his mother's attic or something and did not emerge for seven years is that maybe he did he was on the right track. He wasn't wrong and and but that's so it could have been interminable.

He still might not have gotten there in the end and and so that's the the really difficult space to be in uh where you're not wrong, you are on to something, but it's just asically approaching that solution and you're never actually going to land it.

Um that happens and he had a really I it would break me straight up break me. He had he had a proof. Yes. He announced it and they somebody found a mistake in it.

That would just break me. Yeah.

Because you now everybody gets excited, right?

And now you you you realize that it's a failure and to go back taking a year for people to check it. It's not the kind of thing you look over in an afternoon and then to to have the will to have the confidence and the patience to go back.

unbelievable rigorously go through work through it.

It's a great story.

But then there's another great story, Gregori Pearlman, who uh spent seven years he and turned down the Fields Medal.

He did it all alone. And then after he turned on the Fields Medal and the Millennial Prize, proving the porn conjecture, he just walked away. Yeah. Now that's a very different psychology.

That's wired differently. Doesn't care about money doesn't care about fame, doesn't care about anything else. Yep. In fact, where is he now? Uh in St.

in Petersburg Russia trying to trying to get a conversation with him. It turns out when you walk away and you're a recluse and you enjoy that, you also don't want to take some weird dude in a tie.

So, turns out I'm trying. I'm trying. Well, if you look at someone like Tarring his his eccentricities were were completely different, right? It's not as though there's some mold. And I I really don't like it when it's portrayed that way.

These are really individuals who um who were still lost in their own minds but in very different ways.

And Turring was openly gay really um during this time.

You know, he was working during the war, World War II, so we understand the era and it was illegal um in Britain uh at the time. and he kind of refused to conceal himself.

Um there was a time when the kind of attitude was, well, we're just going to ignore it.

But he had been robbed by somebody that he had picked up somewhere.

I think it was in Manchester.

And it was such a small thing.

I don't know what they took. It took like nothing, you know? It was nothing.

But he he couldn't tolerate. He goes to the police and he tells them and then he's arrested.

He's the criminal because it involved this homosexual act.

Now here you have somebody who made a major contribution to the allies winning the war.

I mean it's just unbelievable.

Not to mention the genius mathematical genius.

I mean he saved the lives of the people that were doing this to him and they essentially chemically castrated him as as a punishment. That was his sentence.

And he became very depressed and suicidal.

And um the story is he was he was obsessed with Snow White, which was recently released. And he used to chant one of the uh little I don't know if you would call them poem songs.

Uh dip the apple in the brew, let the sleeping death seep through was a chant from Snow White. And um the the belief is is that he dipped an apple in cyanide and bit from the poison apple.

Now I don't know if this is apocryphal, but people think that the apple on the Macintosh with the bite out of it is a reference to Turring. Now some people deny this.

That's nice. That's nice.

Um but uh some people say he did that so his mother could believe that maybe it was an accident but yeah, quite a terrible end. Yeah.

but to two of the greatest humans ever.

I think the reason why um I I tie them together, not just because ultimately their work is so connected, but but because there's this sort of impossibility of understanding them there's this sort of impossibility of proving something about their lives that even if you try to write factual biography, there's something that eludes you.

And I felt like that's kind of fundamental to the mathematics.

the incompleteness, the undecidable, the uncomputable.

Yeah. Um, so structurally it was it was about what we can kind of know and what we can believe to be true but can't ever really know. Yeah.

Limitations of formal systems limitations.

Exactly.

Biography limitations of fiction and non-fiction.

Limitations. So you I there's so many layers to you. So one of which there's this romantic notion of just understanding humans exploring humans and there's the exploring science there exploring the very rigorous detailed physics and cosmology of things.

So uh there's art the kind of artistry. So I I I saw that you're the chief science officer of Pioneer Works which is mostly like an artist type of situation.

It's a place in Brooklyn. Can you explain to me what that is and what role does art play in your life? Yeah, I can start with Pioneer Works.

Pioneerics in some sense it was inevitable that I would land at Pioneerics.

It felt like I was marching there for many years and and just it it came together again like at this collision.

Um it was founded by this artist Dustin Yellen. Very utopian idea.

He bought this building this old iron works factory called Pioneer Iron Works in in Brooklyn. was in complete disrepair, but a beautiful old um building uh from the late 1800s.

And he wanted to make this kind of collage.

Dustin's definitely a collage artist.

Works in glass, very big pieces, very imaginative and and wild and narrative and into nature and consciousness and and I think he wanted to do that with people.

He wanted a place of a collage a living example of artists and scientists.

And it was founded by Dustin and and Gabriel Florence was the founding artistic director. Um, it it was started just before Hurricane Sandy.

I don't know if people feel as strongly about Hurricane Sandy as New Yorkers do but it was a real moment around 2012 2013.

Sort of paused the project and you can even see the kind of waterline on the brick of where Sandy was. I came in and collided with these two uh shortly after that and it really was like a collision.

I'm science, you know, their art.

Gabe makes everything, builds everything with his bare hands.

Dustin's a dreamer. They love science.

They really wanted science, but science is hard to access. Um I have always loved the translation of science in literature, in art. Uh, I love fiction writers, like really literary fiction writers who dabble thinking about science.

And I I I I very firmly believe science is part of culture. I just I know it to be true. I don't think of myself as doing outreach or education.

I I don't like those labels. I'm I'm doing culture.

an artist in their uh studio working out problems, understanding materials building a body of work. Nobody says to them when they exhibit, why are you doing outreach or uh or are you doing education?

You know, it's the logical extension.

So I feel that if you've had the privilege of knowing some of these people, of seeing a little bit from the summit, if you've had a little glimpse yourself, that that you bring it back to to to to the world. So we boom exploded.

Pioneerics became science and art.

It's not artists who all do science or scientists who do art.

It's real hardcore scientists talking about science and a lot of live events.

We have a magazine called Broadcast where we feature all of the disciplines rubbing together artists working on all kinds of things. When I first started doing events there, my my first guest um like you, I was talking to people and this was like I know how to talk to people because I know these guys and I've been on the interviewe side so much I know exactly it was like fully formed for me how to do those conversations.

Yeah, you're extremely good at that also.

Yeah, thank you.

I appreciate that. I You learn how to do it too though.

I mean, I don't think the first one I did. I think I've learned, right?

And you acquire, you get better.

It's really interesting. Um, and I love to study.

I think you do, too.

I really look into the material and that and I I love science.

I really do. I want to talk to a crisper biologist because I don't understand it and I want to understand it.

And I saw there's a bunch of cool events and very very fascinating variety of humans. Yes, we have a really fascinating variety of humans.

That's a good way of putting it. Yeah.

So, it made me put in my mental map of like it's a cool place to go and visit when in New York. Yes. You have to come see us.

I think you would love it.

Also, I should mention fashion. I've seen you do a bunch of talks and there's there's a lot of fashion. Yeah.

Oh, appreciation of fashion going on. I am so you're giving me an opportunity to give a shout out um to Andrea Lara who's a designer who makes these amazing jumpsuits that I often wear in a lot of my events.

She has a jumpsuit um design line called Risen Division and she just makes these incredible.

They're fantastic.

We also design patches for all of our events.

So there are these string theory patches and consciousness patches and we should show this as overlays.

Hopefully there'll be nice pictures floating about everywhere.

So, you know, I think all of this is is just I just like to experiment with life. I think making the magazine was a big wild experiment.

You said with life. With life. Nice. Yeah.

Um this kind of idea that we were just describing is I I I find it hard to stop the momentum if I think something can I can make something. Um I have to try to make it.

Um, and to me this is the closest I come to experimentation and collaboration because even though I I collaborate theoretically, I have great collaborators, Brian Green, Masimo Paratti, Dan Kat, these are my really close collaborators.

Um, a lot of theoretical physics is alone and you're in your mind a lot. Um, this is something that really was was was built this triad of Dustin, Gabe, and I and all our amazing people who work there and our amazing board. we really are doing it together. You take one element out and it starts to um it starts to change shape and that's a very interesting experience I think and making things is an interesting experience.

Since you mentioned literature, is there is there books that had an impact on your life, whether it's literature uh fiction non-fiction.

I love fiction, which I think people expect me to read a lot of sort of sci-fi or non-fiction. I mostly read fiction.

I had a syllabus of great fiction writers that had science in it and um, I love that syllabus.

Can you ever make that public or no?

Yeah, I suppose I could, but I can tell you some of them as they come to mind.

Um, Katsu Ishiguru, who won the Nobel Prize, wrote Remains of the Day, probably most famously.

Um, his book Never Let Me Go it's unbelievable, totally devastating stunning.

I see. I really love literature.

So, when when people can do that with these very abstract themes um, it's sort of my favorite space for for literature.

Martin Amos wrote a book that runs backwards, Times Arrow.

I love some of his other books even more, but Times Zero is pretty clever.

So, you like it when uh these non-traditional mechanisms are applied to tell a story that's fundamentally human that there's some Yes.

some beauty of language like I really appreciate that. Even Orwell is amazing.

You know, Hitchens writing on Orwell is amazing. Um there was there were some plays on the syllabus.

I have to think of what else was in there.

But there was one book that I think was kind of surprising that I think is an absolute masterpiece which is the road.

And you might say in what sense is the road to science? Well, first of all Cormick McCarthy absolutely loves scientists and science. And you can feel this very subtle influence in that book is um it's it's an remarkable uh precise, stunning, ethereal, all of these things at once. And there's no who, what, where, when, or how.

Um, you might guess it's a nuclear event that kicks off the book or a lot of people know the road I I think from the movie but really the book is magnificent.

Um and it's very very abstract, but there's a sense to me in which it is science is structuring the and still fundamentally that book is about the human story, the human connection.

Boy, yeah.

So, the science plays a role in creating the world and within it there's still really it's it's a it's a different way to explore human dynamics in a way that's maybe land some clarity and depth that maybe a more direct telling of the story would not Yeah.

Yeah. even surreal worlds that I mean to me I don't know why but um I return to Orwell's Animal Farm a lot and there's these kind of like it's another art form to be able to tell a simple story with some surreal elements.

Mhm. Yeah. Well, just simple language.

Mhm. Oh, animal form is incredible.

And in fact, some of the I've kind of played with you know some animals are more equal than others.

There are there are in good old Turring's work there were some infinities that are bigger than others.

Yeah, there certain books just kind of inject themselves into our culture in a way that just rever reverberates and uh I don't know hasn't creates culture not just like influences. It's just like it's quite incredible how writing and literature can do that. Yeah.

If you could have one definitive answer to one single question.

This is the thing I mentioned to you. So hard. Yeah.

Well there's a there's an oracle and you get to talk to that oracle. You can ask multiple questions, but it has to be on that topic.

So, just clarify.

What What mystery of of the universe would you want that oracle to help you with?

You know, it's funny. I should say the obvious thing and but I feel like I almost feel like it would be greedy.

I I think I have a complicated response to this.

The obvious thing for me to say would be I want to understand quantum gravity or if gravity's emergent.

Um it's not even something I work on daytoday.

You know I I mostly just look with interest at what others are doing and if I think I can jump in I would but I'm not jumping into the fray.

But obviously that's the big that's the big one and and there is a sort of sense that with that will come the answers to all these other things.

My complicated relationship is that well, you know part of the scientific disposition isn't having stuff you don't know the answer to.

I mean, we're not going to have all the answers.

I hope because then sort of then what, right? It's sort of dystopian.

I totally agree with you.

There's some I like the mysteries we have.

Yeah. Uh I kind of had this assumption that there will always be mysteries, so you want to keep solving them.

They will lead to more.

In the same way that relativity led to black holes, black holes led to the information loss paradox or the big bang or what happened before or the multiverse.

It's because we learned so much we were able to escalate to the next level of abstraction. Yeah.

Yeah by the way, we should mention that if you're talking historical and even if you ask the obvious question about quantum gravity, I almost guarantee with 100% probability that even if all your questions are answered, it's impossible to get to the end of your questions because it says um you know Oracle will say no, you can't unify.

But then you say well wait yeah yeah yeah and then you say emergent and then the or you know Oracle say well uh everything you think is fundamental is not it's emergent. It's like okay well this is this is we need to more questions right I mean it's been a hundred years more since relativity and we're still picking it apart. Yeah.

No and there will be there may be new ones.

Mhm. You write that eventually all our history in this universe will be erased.

M how does that make you feel?

Yeah, that's a tough thought.

But again I think there's a way in which we can come to terms with that that that's kind of poetic.

You know, you build something in the sand and then you erase it.

Yeah. So, I think it's just a reminder that we have to be concerned about our immediate experience too, right?

how we are to those around us, how they are to us, what we leave behind in the near term, what we leave behind in the long term, have we contributed and and did we, you know, did we contribute overall net positive?

Um eventually I think it's kind of hard to imagine but yes all of these Nobel prizes all of these mathematical proofs all of these conversations all these ideas all the influence we have on each other even the AI eventually will expire.

Well at the very least we can uh focus on drawing something beautiful in the sand.

Yeah. Before it's washed away.

Well, this was an incredible conversation.

I'm truly grateful for the work you do and me for your work.

Thanks so much for having me. Thank you for talking today.

Yeah, lots of fun.

Thanks for listening to this conversation with Channel 11.

To support this podcast please check out our sponsors in the description.

And now, let me leave you with some words from Albert Einstein on the topic of relativity.

When you're courting a nice girl, an hour seems like a second.

When you sit on a red hot cinder, a second seems like an hour.

That's relativity. Thank you for listening and hope to see you next time.