Transcript
00:00:00 The following is a conversation with Avi Loeb, an astrophysicist, astronomer,
00:00:04 and cosmologist at Harvard. He has authored over 800 papers and written 8 books,
00:00:10 including his latest, called Extraterrestrial, The First Sign of Intelligent Life Beyond Earth.
00:00:16 It’ll be released in a couple of weeks, so go preorder it now to show support for what I think
00:00:21 is truly an important book in that it serves as a strong example of a scientist being both
00:00:27 rigorous and open minded about the question of intelligent alien civilizations in our universe.
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00:01:02 As a side note, let me say a bit more about why Avi’s work is so exciting to me and I think to
00:01:08 a lot of people. In 2017, a strange interstellar object, now named Oumuamua, was detected traveling
00:01:18 through our solar system. Based on the evidence we have, it had strange characteristics which
00:01:22 made it not like any asteroid or comet that we’ve seen before. Avi was one of the only
00:01:28 world class scientists who fearlessly suggested that we should be open minded about whether it
00:01:33 is naturally made or in fact is an artifact of an intelligent alien civilization. In fact,
00:01:40 he suggested that the more likely explanation given the evidence is the latter hypothesis.
00:01:45 But we also talk about a lot of fascinating mysteries in our universe including black holes,
00:01:50 dark matter, the big bang, and close to speed of light space travel. The theme throughout is that
00:01:57 in scientific pursuits, the weird things, the anomalies, the ideas that right now are considered
00:02:03 taboo should not be ignored if we are to have a chance at finding the next big breakthrough,
00:02:08 the next big paradigm shift, and also if we are to inspire the world with the power and beauty
00:02:15 of science. If you enjoy this thing, subscribe on YouTube, review on Apple Podcast, follow on Spotify,
00:02:22 support on Patreon, or connect with me on Twitter at Lex Friedman. And now, here’s my conversation
00:02:28 with Avi Loeb. In the introduction to your new book, Extraterrestrial, you write,
00:02:35 this book confronts one of the universe’s most profound questions, are we alone? Over time,
00:02:41 this question has been framed in different ways. Is life here on Earth the only life in the universe?
00:02:47 Are humans the only sentient intelligence in the vastness of space and time? A better, more precise
00:02:54 framing of this question would be this. Throughout the expanse of space and over the lifetime of the
00:02:59 universe, are there now or have ever been other sentient civilizations that, like ours, explored
00:03:07 the stars and left evidence of their efforts? So let me ask, are we alone? That’s an excellent
00:03:14 question. For me, the answer is sort of clear because I start from the principle of modesty.
00:03:22 You know, if we believe that we are alone and special and unique, that shows arrogance. My
00:03:28 daughters, when they were infants, they tended to think that they are special, unique, and then they
00:03:33 went out to the street and realized that other kids are very much like them. And then they
00:03:39 developed a sense of a better perspective about themselves. And I think the only reason that we
00:03:45 are still thinking that we are special is because we haven’t searched well enough to find others
00:03:51 that might even be better than us. And, you know, I say that because I look at the newspaper every
00:03:57 morning and I see that we do foolish things. We are not necessarily the most intelligent ones.
00:04:02 And if you think about it, if you open a recipe book, you see that out of the same ingredients,
00:04:08 you can make very different cakes, depending on how you put them together and how you heat them
00:04:14 up. And what is the chance that by taking the soup of chemicals that existed on earth and cooking it
00:04:21 one way to get our life, that you got the best cake possible? I mean, we are probably not the
00:04:28 sharpest cookie in the jar. And my question is, I mean, it’s pretty obvious to me that we are
00:04:34 probably not alone because half of all the sun like stars we know now as astronomers, half of
00:04:40 the sun like stars from the Kepler satellite data have a planet the size of the earth, roughly at
00:04:47 the same distance that the earth is from the sun. And that means that they can have liquid water on
00:04:54 their surface and the chemistry of life as we know it. So if you roll the dice billions of times,
00:05:00 just within the Milky Way galaxy, and then you have tens of billions of galaxies like it within
00:05:07 the observable volume of the universe, it would be extremely arrogant to think that we are special.
00:05:11 I would think that we are sort of middle of the road, typical forms of life. And that’s why
00:05:17 nobody pays attention to us. If you go down the street on a sidewalk and you see an ant,
00:05:23 you don’t pay attention or a special respect to that ant, you just continue to walk. And
00:05:28 so I think that we are sort of average, not very interesting, not exciting, so nobody cares about
00:05:33 us. We tend to think that we are special, but that’s a sign of immaturity. And we’re very early
00:05:39 on in our development. Yes, that’s another thing that we have our technology only for 100 years,
00:05:44 and it’s evolving exponentially right now on a three year timescale. So imagine what would happen
00:05:50 in a hundred years, in a thousand years, in a million years or in a billion years. Now, the Sun
00:05:56 is actually relatively late in the star formation history of the universe. Most of the Sun like stars
00:06:02 formed earlier, and some of them already died, you know, became white dwarfs. And so if you imagine
00:06:09 that a civilization like ours existed around a typical Sun like star, by now, if they survived,
00:06:16 they could be a billion years old. And then imagine a billion year technology, it would
00:06:22 look like magic to us, you know, an approximation to God, we wouldn’t be able to understand it.
00:06:28 And so in my view, we should be humble. And by the way, we should probably just listen and not speak,
00:06:36 because there is a risk, right? If you are inferior, there is a risk if you speak too loudly,
00:06:43 something bad may happen to you. You mentioned, we should be humble also in the sense,
00:06:50 with the analogy to ants, that they might be better than us. So there’s a kind of scale that
00:06:58 we’re talking about. And in the question, you mentioned the word sentient. So sentience,
00:07:03 or maybe the more basic formulation is consciousness. Do you think that this
00:07:13 thing within us humans in terms of the typical life form of consciousness is the essential
00:07:20 element that permeates other, if there’s other alien civilizations out there, that they have
00:07:25 something like consciousness as well? Or is this, I guess I’m asking, can you try to untangle the
00:07:31 word sentient? Yeah, so that’s a good question. I think what is most abundant, depending on how
00:07:38 long it survives. So if you look at us, as an example, we are now, we do have consciousness
00:07:46 and we do have technology. But the technologies that we are developing are also means for our
00:07:53 own destruction, as we can tell. You know, we can change the climate if we are not careful enough.
00:07:58 We can go into nuclear wars. So we are developing means for our own destruction through
00:08:05 self inflicted wounds. And it might well be that creatures like us are not long lived, that
00:08:13 crocodiles on other planets live for billions of years. They don’t destroy themselves, they live
00:08:20 naturally. And so if you look around, the most common thing would be dumb animals that live for
00:08:26 long times, you know, not those that have conscious. But in terms of changing the environment, I think
00:08:34 since, I mean, humans develop tools, they develop the ability to construct technologies that would
00:08:44 lift us from this planet that we were born in. And that’s something animals without a
00:08:48 conscious, consciousness cannot really do. And so I, you know, in terms of looking for things
00:08:57 that are new, that went beyond the circumstances they were born into, I would think that even if
00:09:05 they’re short lived, these are the creatures that made the biggest difference to their environment.
00:09:10 And we can search for them, you know, even if they’re short lived, and most of the civilizations
00:09:15 are dead by now. Even if that’s the case. That’s sad to think about, by the way.
00:09:19 Well, but if you look on Earth, that, you know, there are lots of cultures that existed throughout
00:09:24 time, and they’re dead by now. The Mayan culture was very sophisticated, died. But we can find
00:09:30 evidence for it and learn about it just by archaeology, digging into the ground, looking.
00:09:35 And so we can do the same thing in space, look for dead civilizations. And perhaps we can learn a
00:09:41 lesson why they died and behave better so that we will not share the same fate. So I think, you know,
00:09:48 there is a lesson to be learned from the sky. And by the way, I should also say, if we find
00:09:54 a technology that we have not dreamed of, that we can import to Earth, that may be a better
00:10:01 strategy for making a fortune than going to Silicon Valley or going to Wall Street. Because
00:10:07 you make a jump start into something of the future. So that’s one way to do the leap is
00:10:13 actually to find, to literally discover versus come up with the idea in our own limited human
00:10:20 capacity, like a cognitive capacity. It would look like, it would feel like cheating in an exam
00:10:25 where you look over the shoulder of a student next to you. Yeah. But it’s not good on an exam,
00:10:30 but it is good when you’re coming up with technology that could change the fabric of
00:10:35 human civilization. But there is, you know, in my neck of the woods of artificial intelligence,
00:10:42 there’s a lot of trajectories one can imagine of creating very powerful beings,
00:10:50 the technology that’s essentially, you know, you can call super intelligence that could achieve
00:10:57 space exploration, all those kinds of things without consciousness, without something that
00:11:01 to us humans looks like consciousness. And there, you know, there is a sad feeling I have that
00:11:09 consciousness too, in terms of us being humble, is a thing we humans take too seriously. That it’s,
00:11:17 we think it’s special just because we have it. But it could be a thing that’s actually holding
00:11:21 us back in some kind of way. It may well be. It may well be. I should say something about AI,
00:11:26 because I do think it offers a very important step into the future. If you look at the Old
00:11:33 Testament, the Bible, there is this story about Noah’s Ark that you might know about. Noah
00:11:41 knew about a great flood that is about to endanger all life on earth. So he decided to build an ark.
00:11:49 And the Bible actually talks about specifically what the size of this ark was, what the dimensions
00:11:55 were. Turns out it was quite similar to Oumuamua that we will discuss in a few minutes. But at any
00:12:02 event, he built this ark and he put animals on it so that they were saved from the great flood.
00:12:08 Now, you can think about doing the same on earth, because there are risks for future catastrophes.
00:12:16 You know, we could have the self inflicted wounds that we were talking about, like nuclear war,
00:12:20 changing the climate. Or there could be an asteroid impacting us, just like the dinosaurs
00:12:26 died. The dinosaurs didn’t have science, astronomy. They couldn’t have a warning system.
00:12:32 But there was this big stone, big rock that approached them. It must have been a beautiful
00:12:37 sight. Just when it was approaching, it got very big and then smashed them and killed them. So
00:12:44 you could have a catastrophe like that. Or in a billion years, the sun will basically boil off
00:12:48 all the oceans on earth. And currently all our eggs are in one basket, but we can spread them.
00:12:57 It’s sort of like the printing press, if you think about it. The revolution that Gutenberg
00:13:02 brought is there were very few copies of the Bible at the time, and each of them was precious
00:13:07 because it was handwritten. But once the printing press produced multiple copies, you know,
00:13:13 if something bad happened to one of the copies, it wasn’t a catastrophe. You know, it wasn’t
00:13:17 disaster because you had many more copies. And so if we have copies of life here on earth elsewhere,
00:13:25 then we avoid the risk of it being eliminated by a single point breakdown, catastrophe.
00:13:32 So the question is, can we build NOx spaceship that will carry life as we know it? Now,
00:13:39 you might think we have to put elephants and whales and birds on a big spaceship, but that’s
00:13:45 not true because all you need to know is the DNA making, the genetic making of these animals,
00:13:52 put it on a computer system that has AI plus a 3D printer so that this CubeSat, which is rather
00:14:02 small, can go with this information to another planet and use the raw materials there to produce
00:14:09 synthetic life. And that would be a way of producing copies, just like the Gutenberg printing press.
00:14:16 Yeah, and it doesn’t have to be exact copies of the humans, it could just contain some basic
00:14:21 elements of life and then have enough life on board that it could reproduce the process of
00:14:29 evolution on another place. So I mean, that also makes you sad, of course, because you confront
00:14:34 the mortality of your own little precious consciousness and all your own memories and
00:14:38 knowledge and all that stuff. But who cares? I care about mine, right? And you care about yours.
00:14:44 No, no, I actually don’t. If you’re an astronomer, one thing that you learn from the universe
00:14:50 is to be modest because you’re not so significant. I mean, think about it, all these emperors and
00:14:56 kings that conquered a piece of land on Earth and were extremely proud. You see these images
00:15:01 of kings and emperors that usually are alpha males and they stand strong and they’re very
00:15:10 proud of themselves. But if you think about it, there are 10 to the power 20 planets like the
00:15:15 Earth in the observable volume of the universe. And this view of conquering a piece of land and
00:15:22 even conquering all of Earth is just like an ant hugging a single grain of sand on the landscape
00:15:29 of a huge beach. That’s not very impressive. So you can’t be arrogant. If you see the big picture,
00:15:35 you have to be humble. Also, we are short lived. Within 100 years, that’s it. So what does it teach
00:15:44 you? First to be humble, modest. You never have significant powers relative to the big scheme
00:15:49 of things. And second, you should appreciate every day that you live and learn about the world.
00:15:56 Humble and still grateful. Yes, exactly. Well, let’s talk about probably the most interesting
00:16:07 object I’ve heard about and also the most fun to pronounce. Oumuamua. Can you tell me the story
00:16:13 of this object and why it may be an important event in human history? And is it possibly a piece
00:16:21 of alien technology? Right. So this is the first object that was spotted close to Earth from
00:16:29 outside the solar system. And it was found on October 19th, 2017. And at that time, it was
00:16:38 receding away from us. And at first, astronomers thought it must be a piece of rock, you know,
00:16:44 just like all the asteroids and comets that we have seen from within the solar system.
00:16:49 And it just came from another star. I should say that the actual discovery of this object
00:16:54 was surprising to me because a decade earlier, I wrote the first paper together with Ed Turner
00:16:59 and Amaya Moro Martin that tried to predict whether the same telescope that was surveying
00:17:06 the sky, PanSTARRS from Hawaii, would find anything from interstellar space, given what
00:17:12 we know about the solar system. So if you assume that other planetary systems have similar
00:17:17 abundance of rocks and you just calculate how many should be ejected into interstellar space,
00:17:23 the conclusion is no, we shouldn’t find anything with PanSTARRS. To me, I apologize for probably
00:17:30 revealing my stupidity, but it was surprising to me that so few interstellar objects from outside
00:17:36 this whole system have ever been detected. No, nothing. None has been. You do maybe talk about
00:17:44 it that there has been one or two rocks since then. Well, since then, there was one called
00:17:50 the Borisov. It was discovered by an amateur Russian astronomer, Gennady Borisov. And that one
00:17:58 looked like a comet. And just like a comet from within the solar system. But this is a really
00:18:05 important point. Sorry to interrupt it. You showed that it’s unlikely that a rock from another solar
00:18:10 system would arrive to ours. Right. And so the actual detection of this one was surprising by
00:18:16 itself to me. Yes. But then, so at first they thought maybe it’s a comet or an asteroid,
00:18:24 but then it didn’t look like anything we’ve seen before. Borisov did look like a comet. So people
00:18:31 asked me afterwards and said, you know, doesn’t it convince you if Borisov looks like a comet,
00:18:38 doesn’t it convince you that Oumuamua is also natural? And I said, you know, when I went on the
00:18:44 first date with my wife, she looked special to me. And since then I met many women. That didn’t
00:18:50 change my opinion of my wife. So, you know, that’s not an argument. Anyway, so why did the Oumuamua
00:18:59 look weird? Let me explain. So first of all, astronomers monitored the amount of light,
00:19:05 sunlight that it reflects. And it was tumbling, spinning every eight hours. And as it was spinning,
00:19:13 the brightness that we saw from that direction, we couldn’t resolve it because it’s tiny. It’s
00:19:18 about a hundred meters, a few hundred feet, size of a football field. And we cannot, from Earth,
00:19:24 with existing telescopes, we cannot resolve it. The only way to actually get a photograph of it
00:19:29 is to send a camera close to it. And that was not possible at the time that Oumuamua was discovered
00:19:38 because it was already moving away from us faster than any rocket we can send. It’s sort of like a
00:19:43 guest that appeared for dinner. And then by the time we realized that it’s weird, the guest is
00:19:49 already out the front door into the dark street. What we would like to find is an object like it
00:19:56 approaching us, because then you can send the camera irrespective of how fast it moves. And
00:20:01 if we were to find it in July 2017, that would have been possible because it was approaching us
00:20:07 at that time. Actually, I was visiting Mount Haleakala in Maui, Hawaii with my family for
00:20:14 vacation at that time in July 2017, but nobody knew at the observatory that the Oumuamua is
00:20:23 very close. That’s sad to think about that we had the opportunity at that time to send up a camera.
00:20:28 But don’t worry. I mean, there will be more. There will be more because I operate by the Copernican
00:20:35 principle, which says we don’t live at a special place and we don’t live at a special time. And
00:20:42 that means if we surveyed the sky for a few years and we had sensitivity to this region between us
00:20:48 and the sun, and we found this object with PanStars, there should be many more that we
00:20:55 will find in the future with surveys that might be even better. And actually, in three years
00:21:01 timescale, there would be the so called LSST. That’s a survey of the Vera Rubin Observatory
00:21:08 that would be much more sensitive and could potentially find an Oumuamua like object
00:21:14 every month. OK, so I’m just waiting for that. And the main reason for me to alert everyone
00:21:22 to the unusual properties of Oumuamua is with the hope that next time around, when we see
00:21:27 something as unusual, we would take a photograph or we would get as much evidence as possible
00:21:32 because science is based on evidence, not on prejudice. And we will get back to that theme.
00:21:37 So anyway, let me let me point out some of the properties, actually, the elongated nature,
00:21:42 all those kinds of things. So the light curve, the amount of light, sunlight that was reflected
00:21:48 from it was changing over eight hours by a factor of 10, meaning that the area of this
00:21:55 object, even though we can’t resolve it, the area on the sky that reflects sunlight was
00:22:02 bigger by a factor of 10 in some phases as it was tumbling around than in other phases.
00:22:09 So even if you take a piece of paper that is razor thin, you know, there is a very small
00:22:14 likelihood that it’s exactly edge on and getting a factor of 10 change in the area that you see
00:22:20 on the sky is huge. It’s much more than any. It means that the object has an unusual geometry.
00:22:27 It’s at least a factor of a few more than any of the comets or asteroids that we have seen before.
00:22:32 You mentioned reflectivity. So it’s not just the geometry, but
00:22:35 the properties of the surface of that thing. Well, if you assume the reflectivity is the same,
00:22:42 then it’s just geometry. If you assume the reflectivity may change, then it could be
00:22:47 a combination of the area that you see and the reflectivity because different directions may
00:22:52 reflect differently. But the point is that it’s very extreme. And actually the best fit
00:23:00 to the light curve that we saw was of a flat object. Unlike all the cartoons that you have seen
00:23:06 of a cigar shape, a flat object at the 90% confidence gives a better model for the way
00:23:13 that the light varied. So like flat meaning like a pancake.
00:23:17 Like a pancake. Exactly. And so that’s, you know, the very first unusual property. But to me,
00:23:25 it was not unusual enough to think that it might be artificial. It was not significant enough.
00:23:32 Then there was no cometary tail, you know, no dust, no gas around this object. And the
00:23:38 Spitzer Space Telescope really searched very deeply for carbon based molecules. There was nothing.
00:23:45 So it’s definitely not a comet the way people expected it to be.
00:23:49 Can you maybe briefly mention what properties a comet that you’re referring to usually has?
00:23:55 Right. So a comet is a rock that has some water ice on the surface. So you can think of it as an
00:24:02 icy rock. Actually comets were discovered a long time ago, but the first model that was developed
00:24:12 for them was by Fred Whipple, who was at Harvard. And I think the legend goes that he got the idea
00:24:19 from walking through Harvard Square and seeing during a winter day and seeing these icy rocks,
00:24:26 you know. So a comet is icy and an asteroid is not.
00:24:30 It’s just a rock. It’s just a rock.
00:24:32 Yeah. So when you have ice on the surface, when the rock gets close to the sun,
00:24:38 the sunlight warms it up and the ice sublimates, evaporates. Because the one thing about ice,
00:24:46 water ice, is it doesn’t become liquid if you warm it up in vacuum, you know, without
00:24:53 an external pressure. It just goes straight into gas. And that’s what you see as the tail of a
00:24:59 comet. The only way to get liquid water is to have an atmosphere like on Earth that has an external
00:25:07 pressure. Only then you get liquid. And that’s why it’s essential to have an atmosphere to a planet
00:25:13 in order to have liquid water and the chemistry of life. So if you look at Mars, Mars lost its
00:25:19 atmosphere and therefore no liquid water on the surface anymore. I mean, there may have been early
00:25:25 and that’s what the Perseverance survey, you know, the Perseverance mission will try to find out
00:25:31 whether it had liquid water, whether there was life perhaps on it at the time, but at some point
00:25:37 it lost its atmosphere and then the liquid water was gone. So the only reason that we can live on
00:25:44 Earth is because of the atmosphere. But a comet is in vacuum pretty much. And then when it gets
00:25:51 warmed up on the surface, the water becomes, the water ice becomes gas and then you see this
00:25:58 cometary tail behind it. In addition to water, there are all kinds of carbon based molecules
00:26:05 or dust that comes off the surface. And those are detectable. Yeah, it’s easy to detect. It’s very
00:26:11 prominent. You see these cometary tails that look very prominent because they reflect sunlight
00:26:16 and you can see them. In fact, it’s sometimes difficult to see the nucleus of the comet
00:26:20 because it’s surrounded and shrouded with, and in this case, there was no trace of anything.
00:26:26 That’s fascinating. Now you might say, okay, it’s not a comet. So that’s what the community said.
00:26:30 Okay, it’s not a, no problem. It’s still a rock, you know, it’s not a comet,
00:26:34 but it’s just a rock, bare rock. You know, okay, no problem. Then, and that’s the thing that
00:26:40 convinced me to write about it. And then in June 2018, you know, significantly later,
00:26:46 there was a report that in fact the object exhibited an excess push in addition to the
00:26:55 force of gravity. So the sun acts on it by gravity, but then there was an extra push
00:27:00 on this object that was figured out from the orbit that you can trace. And the question was,
00:27:06 what is this excess push? So for comets, you get the rocket effect. When you evaporate gas,
00:27:12 you know, just like a jet engine on an airplane, you throw, a jet engine is very simple. You throw
00:27:18 the gas back and it pushes the airplane forward. That’s all. That’s how the jet. So in a case of
00:27:23 a comet, you throw gas in the direction of the sun because it, and then you get a push.
00:27:29 Okay. So in the case of comets, you can get a push, but there was no cometary tail. So then
00:27:34 people say, oh, wait a second. Is it an asteroid? No, but it behaves like a comet, but it doesn’t
00:27:40 look like a comet. So what, well, forget about it. Business as usual. So that’s what they mean
00:27:45 by a non gravitation acceleration. So that’s interesting. So like the primary force acting
00:27:52 on something like just a rock, like an asteroid would be like, you can predict the trajectory
00:27:57 based on the gravity, based on gravity. And so here there’s detected movement that’s not,
00:28:02 cannot be accounted purely by the gravity of the sun. And if it was a comet, you would need about
00:28:07 a 10th of the mass of this comet, the weight of this comet to be evaporated in order to give it.
00:28:14 And there was no sign of that. No sign. 10% of the mass evaporating. It’s huge. Think about it.
00:28:19 A hundred meter size object losing 10% of its mass. You can’t miss that.
00:28:25 So that’s super weird.
00:28:27 It’s super weird.
00:28:28 Is there a good explanation, is there in your mind a possible explanation for this?
00:28:32 So I operated just like Sherlock Holmes in a way. I said, okay, what are the possibilities? And
00:28:37 the only thing I could think, so I ruled out everything else. And I said, it must be the
00:28:42 sunlight reflected off it. Okay. So the sunlight reflects off the surface and gives it a push,
00:28:49 just like you get a push on a sail on a boat, you know, from the wind reflecting off it.
00:28:56 Now, in order for this to be effective, it turns out the object needs to be extremely thin.
00:29:03 It turns out it needs to be less than a millimeter thick. Nature does not produce such things.
00:29:08 But we produce it because it’s called the technology of a light sail. So we are,
00:29:15 for space exploration, we are exploring this technology because it has the benefit of
00:29:21 not needing to carry the fuel with the spacecraft. So you don’t have the fuel, you just have a
00:29:28 sail and it’s being pushed either by sunlight or by a laser beam or whatever. So perhaps this is
00:29:37 the light sail. So this is actually the same technology with the Starshot project. Yes.
00:29:42 So people afterwards say, okay, you work on this project, you imagine. No, that’s a pretty good
00:29:49 explanation, right? Obviously, my imagination is limited by what I know. So I would not deny that
00:29:57 working on light sails expanded my ability to imagine this possibility. But let me offer another
00:30:03 interesting anecdote. In September this year, 2020, there was another object found,
00:30:13 and it was given the name 2020SO by the Minor Planet Center. This is an organization actually
00:30:22 in Cambridge, Massachusetts, that gives names to astronomical objects found in the solar system.
00:30:28 And they gave it that name 2020SO because, you know, it looked like an object in the solar system
00:30:35 and it moved in an orbit that is similar to the orbit of the Earth, but not the same exactly.
00:30:42 And therefore it was bound to the Sun, but it also exhibited a deviation from what you expect
00:30:49 based on gravity. So the astronomers that found it extrapolated back in time and found that
00:30:55 in 1966, it intercepted the Earth. And then they went to the history books and they realized,
00:31:03 oh, there was a mission called Lunar Lander Surveyor 2 that had a rocket booster. It was
00:31:12 a failed mission, but there was a rocket booster that was kicked into space. And presumably this
00:31:18 is the rocket booster that we’re seeing. Now, this rocket booster was sufficiently hollow and thin
00:31:23 for us to recognize that it’s pushed by sunlight. So here is my point. We can tell from the orbit
00:31:30 of an object, obviously this object didn’t have any cometary tail. It was artificially made. We
00:31:36 know that it was made by us and it did deviate from an orbit of a rock. So just by seeing
00:31:44 something that doesn’t have cometary tail and deviates from an orbit shaped by gravity,
00:31:49 we can tell that it’s artificial. In the case of Oumuamua, it couldn’t have been sent by humans
00:31:55 because it just passed near us for a few months. We know exactly what we were doing at that time.
00:32:01 And also it was moving faster than any object that we can launch. And so obviously it came from
00:32:06 outside the solar system. And the question is who produced it? Now, I should say that when I walk
00:32:13 on vacation on the beach, I often see natural objects like seashells that are beautiful and I
00:32:21 look at them. And every now and then I stumble on a plastic bottle that was artificially produced.
00:32:29 And my point is that maybe Oumuamua was a message in a bottle. And this is simply another window
00:32:37 into searching for artifacts from other civilizations. Where do you think it could have
00:32:43 come from? And if it’s so, okay, from a scientific perspective, the narrow minded view, as we’ll
00:32:54 probably talk about throughout, is, you know, you kind of want to stick to the things that,
00:33:00 to naturally originating objects like asteroids and comets. Okay, that’s the space of possible
00:33:06 hypotheses. And then if we expand beyond that, you start to think, okay, these are artificially
00:33:12 constructed. Like you just said, it could be by humans. It could be by whatever that means,
00:33:19 by some kind of extraterrestrial alien civilizations. If it’s the alien civilization
00:33:26 variety, what is this object then? That’s an excellent question. And let me lay out,
00:33:34 I mean, we don’t have enough evidence to tell. If we had a photograph, perhaps we would have
00:33:38 more information. But there is one other peculiar fact about Oumuamua. Well, other than it was very
00:33:47 shiny, that I didn’t mention, you know, we didn’t detect any heat from it. And that implies that
00:33:53 it’s rather small and shiny. But the other peculiar fact is that it came from a very special frame of
00:34:00 reference. So it’s sort of like finding a car in a parking lot, in a public parking lot, that,
00:34:08 you know, you can’t really tell where it came from. So there is this frame of reference where
00:34:13 you average over the motions of all the stars in the neighborhood of the Sun. So you find the
00:34:20 so called local standard of rest of the galaxy. And that’s a frame of reference that is obtained
00:34:28 by averaging the random motions of all the stars. And the Sun is moving relative to that frame at
00:34:34 some speed. But this object was at rest in that frame. And only one in 500 stars is so much at
00:34:41 rest in that frame. And that’s why I was saying it’s like a parking lot. It was parked there,
00:34:46 and we bumped into it. So the relative speed between the solar system and this object is just
00:34:52 because we are moving. It was sitting still. Now you ask yourself, why is it so unusual in that
00:34:59 context? You know why? Because if it was expelled from another planetary system, most likely it will
00:35:06 carry the speed of the host star that it came from. Because it was, you know, the most loosely
00:35:12 bound objects are in the periphery of the planetary system, and they move very slowly relative to the
00:35:19 star. And so they carry the, when they are ripped apart from the planetary system, most of the
00:35:24 objects will have the residual motion of the star roughly relative to the local star. But this one
00:35:30 was at rest in the local star. Now, one thing I can think of, if there is a grid of road posts,
00:35:37 you know, like for navigation system, so that you can find your way in the local frame, then that
00:35:44 would be one possibility. These are like little sensors of, that’s fascinating to think about. So
00:35:48 there could be, I mean, not necessarily literally a grid, but just evenly, in some definition of
00:35:55 evenly spread out set of objects like these that are just out there. A lot of them. Another
00:36:01 possibility is that these are relay stations, you know, for communication. You might think,
00:36:06 in order to communicate, you need a huge beacon, a very powerful beacon. But it’s not true. Because
00:36:12 even on Earth, you know, we have these relay stations. So you have a not so powerful beacon.
00:36:17 So it can be heard only out to a limited distance, but then you relay the message.
00:36:22 And it could be one of those. Now, after it collided with the solar system, of course,
00:36:28 it got a kick. So it’s just like a billiard ball, you know, we gave it a kick by colliding with,
00:36:33 but most of them are not colliding with stars. And so that’s one possibility. Okay. And there
00:36:38 should be numerous, lots of them, if that’s the case. The other possibility is that it’s a probe,
00:36:46 you know, that was sent in the direction of the habitable region around the Sun to find out if
00:36:54 there is life. Now, it takes tens of thousands of years for such a probe to traverse the solar
00:37:00 system from the outer edge of the Oort cloud, all the way to where we are. And, you know,
00:37:06 it’s a long journey. So when it started the journey from the edge of the solar system to
00:37:09 get to us now, you know, we were rather primitive back then, you know, we still didn’t have any
00:37:15 technology, there was no reason to visit, you know, there was grass around and so forth. But,
00:37:20 you know, maybe it is a probe. So you said 10,000 years, that’s faster. So it takes that long.
00:37:25 Tens of thousands, yes. Tens of thousands of years. Yeah. Yeah. And the other thing I should
00:37:30 say is, you know, it could be just an outer layer of something else, like, you know, something that
00:37:38 was ripped apart, like a surface of an instrument. And you can have lots of these pieces, you know,
00:37:45 if something breaks, lots of these pieces spread out, like space junk. And, you know, that…
00:37:51 It could be just space junk from an alien civilization.
00:37:56 Yes. So it’s kind of…
00:37:59 I should tell you about space junk. Let me…
00:38:01 Yes. What do you mean by space junk?
00:38:03 So, I think, you know, you might ask, why aren’t they looking for us? One possibility
00:38:09 is that we are not interesting, like we were talking about ants. Another possibility,
00:38:14 you know, if there are millions or billions of years into their technological development,
00:38:21 they created their own habitat, their own cocoon, where they feel comfortable, they have everything
00:38:28 they need. And it’s risky for them to establish communication with other… So they have their
00:38:36 own cocoon and they close off. They don’t care about anything else. Now, in that case, you might
00:38:41 say, oh, so how can we find about them if they are closed off? The answer is they still have to
00:38:47 deposit trash, right? That is something from the law of thermodynamics. There must be some production
00:38:53 of trash. And, you know, we can still find about them just like investigative journalists going
00:39:00 through the trash cans of celebrities in Hollywood, you know. You can learn about the private lives
00:39:06 of those celebrities by looking at the trash.
00:39:09 It’s fascinating to think, you know, if we are the ants in this picture,
00:39:14 if this thing is a water bottle, or if it’s like a smartphone, like where on the spectrum of
00:39:21 possible objects of space, because there’s a lot of interesting trash. How interesting is this trash?
00:39:28 But imagine a caveman seeing a cell phone. The caveman would think, since the caveman played
00:39:34 with rocks all of his life, he would say, it’s a rock, just like my fellow astronomers said.
00:39:39 Yes, exactly. That’s brilliantly put. Actually, as a scientist, do you hope it’s a water bottle
00:39:45 or a smartphone?
00:39:46 Because I hope it’s even more than a smartphone. I hope that it’s something that is really
00:39:51 sophisticated.
00:39:52 That’s funny. See, I’m the opposite. I feel like I hope it’s a water bottle because
00:39:57 at least we have a hope with our current set of skills to understand it. A caveman has no way of
00:40:03 understanding the smartphone. It’s like, it will be like, I feel like a caveman has more to learn
00:40:08 from the plastic water bottle than they do from the smartphone.
00:40:11 But suppose we figure it out. If we, for example, come close to it and learn what it’s made of.
00:40:17 And I guess a smartphone is full of like thousands of different technologies that we could
00:40:22 probably pick at. Do you have a sense of where a hypothesis of where is the cocoon that it
00:40:32 might have come from?
00:40:33 No, because, okay, so first of all, you know, the solar system, the outermost edge of the
00:40:40 solar system is called the Oort cloud. It’s a cloud of icy rocks of different sizes that were
00:40:49 left over from the formation of the solar system. And it’s thought to be roughly a ball or a
00:40:57 sphere. And it’s halfway, the extent of it is roughly halfway to the nearest star. Okay, so you
00:41:04 can imagine each planetary system basically touching the Oort clouds of those stars that are
00:41:14 near us are touching each other. Space is full of these billiard balls that are very densely
00:41:22 packed. And what that means is any object that you see, irrespective of whether it came from
00:41:28 the local standard. So we said that this object is special because it came from a local standard
00:41:32 of rest. But even if it didn’t, you would never be able to trace where it came from because all
00:41:38 these Oort clouds overlap. So if you take some direction in the sky, you will cross as many
00:41:46 stars as you have in that direction. Like, there is no way to tell which Oort cloud it came from.
00:41:52 So yes, I didn’t realize how densely packed everything was from the perspective of the Oort
00:41:57 cloud. And that’s really interesting. So yeah, it could be nearby, it could be very far away.
00:42:01 Yeah, we have no clue.
00:42:03 You said cocoon. And you kind of paint, I think in the book, I’ve read a lot of your articles too
00:42:13 on the Scientific American, which are brilliant. So I’m kind of mixing things up in my head a
00:42:16 little bit. But what does that cocoon look like? What does a civilization that’s able to harness
00:42:24 the power of multiple suns, for example, look like? When you imagine possible civilizations that are
00:42:31 a million years more advanced than us, what do you think that actually looks like?
00:42:36 I think it’s very different than we can imagine. By the way, I should start from the point that
00:42:42 even biological life, just without technology getting into the game, could look like something
00:42:50 we have never seen before. Take, for example, the nearest star, which is Proxima Centauri.
00:42:55 It’s four and a quarter light years away. So they will know about the results of the 2016 elections
00:43:03 only next month, in February 2021. It’s very far away. But if you think about it, this star is a
00:43:16 dwarf star, and it’s twice as cold as the sun. And it emits mostly infrared radiation. So if there
00:43:26 are any creatures on the planet close to it that is habitable, which is called Proxima B, there is
00:43:34 a planet in the habitable zone, in the zone just at the right distance where, in principle, liquid
00:43:39 water can be on the surface. If there are any animals there, they have infrared eyes because
00:43:45 our eyes were designed to be sensitive to where most of the sunlight is in the visible range.
00:43:51 But Proxima Centauri emits mostly infrared. So in the nearest star system, these animals would be
00:44:00 quite strange. They would have eyes that are detectors of infrared, very different from ours.
00:44:06 Moreover, this planet, Proxima B, faces the star always with the same side. So it has a permanent
00:44:12 day side and a permanent night side. And obviously the creatures that would evolve on the permanent
00:44:19 day side, which is much warmer, would be quite different than those on the permanent night side.
00:44:24 Between them, there would be a permanent sunset strip. And my daughters said that that’s the best
00:44:31 opportunity for high value real estate because you will see the sunset throughout your life,
00:44:37 right? The sun never sets on this trip. So these worlds are out of our imagination.
00:44:46 Just even the individual creatures, the sensor suite that they’re operating with
00:44:50 might be very different. Very different. So I think when we see something like that,
00:44:53 we would be shocked not to speak about seeing technology. So I don’t even dare to imagine.
00:45:01 And I think obviously we can bury our head in the sand and say, it’s never aliens,
00:45:07 like many of my colleagues say. And it’s a self fulfilling prophecy. If you never look,
00:45:13 you will never find. If you’re not ready to find wonderful things, you will never discover them.
00:45:19 And the other thing I would like to say is reality doesn’t care whether you ignore it or not.
00:45:25 You can ignore reality, but it’s still there. So we can all agree, based on Twitter,
00:45:32 that aliens don’t exist. That Umuamua was a rock. We can all agree. And you will get a lot of likes,
00:45:39 we will have a big crowd of supporters, and everyone will be happy and give each other
00:45:44 awards and honors and so forth. But Umuamua might still be an alien artifact. Who cares
00:45:51 what humans agree on? There is a reality out there. And we have to be modest enough to recognize
00:45:59 that we should make our statements based on evidence. Science is not about ourselves. It’s
00:46:06 not about glorifying our image. It’s not about getting honors, prizes. A lot of the academic
00:46:14 activity is geared towards creating your echo chamber where you have students, postdocs,
00:46:19 repeating your mantras so that your voice is heard loudly so that you can get more honors,
00:46:25 prizes, recognition. That’s not the purpose of science. The purpose is to figure out what nature
00:46:31 is. And in the process of doing that, it’s a learning experience. You make mistakes. Einstein
00:46:37 made three mistakes at the end of his career. He argued that in the 1930s, he argued that black
00:46:44 holes don’t exist, gravitational waves don’t exist, and quantum mechanics doesn’t have spooky action
00:46:52 at a distance. And all three turned out to be wrong. So the point is that if you work at the
00:46:58 frontier, then you make mistakes. It’s inevitable because you can’t tell what is true or not.
00:47:04 And avoiding making mistakes in order to preserve your image makes you extremely boring. You will
00:47:10 get a prize, but you will be a boring scientist because you will keep repeating things we already
00:47:16 know. If you want to make progress, if you want to innovate, you have to take risks and you have
00:47:22 to look at the evidence. It’s a dialogue with nature. You don’t know the truth in advance. You
00:47:28 let nature tell you, educate you, and then you realize that what you thought before is incorrect.
00:47:35 And a lot of my colleagues prefer to be in a state where they have a monologue. You know,
00:47:40 if you look at these people that work on string theory, they have a monologue. They know what,
00:47:46 and in fact, their monologue is centered on anti de Sitter space, which we don’t live in now.
00:47:53 To me, it’s just like the Olympics. You define a hundred meters and you say,
00:47:57 whoever runs these hundred meters is the best athlete, the fastest. And it’s completely
00:48:03 arbitrary. You could have decided it would be 50 meters or 20 meters. Who cares? You just measure
00:48:09 the ability of people this way. So you define anti de Sitter space as a space where you do your
00:48:14 mathematical gymnastics, and then you find who can do it the best. And you give jobs based on that.
00:48:19 You give prizes. But as we said before, you know, nature doesn’t care about, you know,
00:48:25 the prizes that you give to each other. It cares, you know, it has its own reality and we should
00:48:32 figure it out. And it’s not about us. The scientific activity is about figuring out nature. And
00:48:37 sometimes we may be wrong. Our image will not be preserved. But that’s the fun, you know. Kids
00:48:46 explore the world out of curiosity. And I always want to maintain my childhood curiosity. And I
00:48:52 don’t care about the labels that I have. In fact, having tenure is exactly the opportunity to behave
00:48:59 like a child because you can make mistakes. And I was asked by the Harvard Gazette, you know,
00:49:05 the Pravda of Harvard, what is the one thing that you would like to change about the world?
00:49:14 And I said, I would like my colleagues to behave more like kids. That’s the one thing I would like
00:49:21 them to do. Because something bad happens to these kids when they become tenured professors.
00:49:27 They start to worry about their ego and about themselves more than about the purpose of science,
00:49:33 which is, you know, curiosity driven, figuring out from evidence. Evidence is the key. So when
00:49:38 an object shows anomalies like Oumuamua, what’s the problem discussing, you know, whether it’s
00:49:44 artificial or not? You know, so there was, I should tell you, there was a mainstream
00:49:49 paper in Nature published saying it must be natural. That’s it. It’s unusual, but it must
00:49:56 be natural, period. And then at the same time, some other mainstream scientists tried to explain
00:50:04 the properties. And they came up with interpretations like it’s a dust bunny,
00:50:09 you know, the kind that you find in a household, a collection of dust particles pushed by sunlight,
00:50:16 something we have never seen before. Or it’s a hydrogen iceberg. It actually evaporates like
00:50:21 a comet, but hydrogen is transparent. You don’t see it. And that’s why we don’t see the cometary
00:50:26 tail. Again, we have never seen something like that. In both cases, the objects would not
00:50:31 survive the long journey. We discussed it in a paper that I wrote afterwards. But my point is,
00:50:37 those that tried to explain the unusual properties went into great length at discussing things that
00:50:44 we have never seen before. Okay? So even when you think about a natural origin, you have to come up
00:50:50 with scenarios of things that were never seen before. And by the way, they look less plausible
00:50:57 to me personally. But my point is, if we discuss things that were never seen before,
00:51:03 why not discuss, why not contemplate an artificial origin? What’s the problem?
00:51:07 Why do people have this pushback? You know, I worked on dark matter, and we don’t know what
00:51:16 most of the matter in the universe is. It’s called dark matter. It’s just an acronym because we have
00:51:22 no clue. We simply don’t know. So it could be all kinds of particles. And over the years, people
00:51:26 suggested weakly interacting massive particles, axions, all kinds of particles. And experiments
00:51:32 were made. They cost hundreds of millions of dollars. They put upper limits, constraints
00:51:38 that ruled out many of the possibilities that were proposed as natural initially. The mainstream
00:51:44 community regarded it as a mainstream activity to search the nature of the dark matter.
00:51:50 And nobody complained that it’s speculative to consider weakly interacting massive particles.
00:51:56 Now, I ask you, why is it speculative to consider extraterrestrial technologies? We have a proof
00:52:04 that it exists here on Earth. We also know that the conditions of Earth are reproduced
00:52:10 in billions of systems throughout the Milky Way galaxy. So what’s more conservative than to say,
00:52:16 if you arrange for similar conditions, you get the same outcome. How can you imagine this to be
00:52:22 speculative? It’s not speculative at all. And nevertheless, it’s regarded the periphery. And
00:52:26 at the same time, you have physicists, theoretical physicists, working on extra dimensions, super
00:52:32 symmetry, super string theory, the multiverse. Maybe we live in a simulation. All of these ideas
00:52:39 that have no grounding in reality, some of which sound to me like, you know, just like what someone
00:52:47 would say. Science fiction, basically. Because you have no way to test it, you know, through
00:52:54 experiments. And experiments really are key. It’s not just the nuance. You say, okay, forget about
00:52:59 experiments. As some philosophers try to say, you know, if there is a consensus, what’s the problem?
00:53:04 The point is, it’s key. Then that’s what Galileo found. It’s key to have feedback from reality.
00:53:10 You know, you can think that you have a billion dollars or that you are more rich than, you know,
00:53:16 Elon Musk. That’s fine. You can feel very happy about it. You can talk about it with your friends
00:53:22 and all of you will be happy and think about what you can do with the money. Then you go to
00:53:26 an ATM machine and you make an experiment. You check how much money you have in your checking
00:53:31 account. And if it turns out that, you know, you don’t have much, you can’t materialize your dreams.
00:53:39 Okay. So you realize, you have a reality check. And my point is, without experiments giving you
00:53:44 a reality check, without the ATM machine showing you whether your ideas are bankrupt or not,
00:53:49 without putting skin in the game. And by skin in the game, I mean, don’t just talk about
00:53:55 theoretical ideas. Make them testable. If you don’t make them testable, they’re worthless.
00:54:01 They’re just like theology that is not testable. By the way, theology has some tests. Let me give you
00:54:09 three examples. It turns out that my book already inspired a PhD student at Harvard in the English
00:54:17 department to pursue a PhD in that direction. And she invited me to the PhD exam a couple of months
00:54:25 ago. And in the exam, one of the examiners, a professor, asked her, do you know why Giordano
00:54:34 Bruno was burnt at the stake? And she said, no, I think it’s because he was an obnoxious
00:54:42 guy and irritated a lot of people, which is true. But the professor said, no,
00:54:50 it’s because Giordano Bruno said that other stars are just like the sun,
00:54:56 and they could have a planet like the Earth around them that could host life. And that
00:55:03 was offensive to the church. Why was it offensive? Because there is the possibility that this life
00:55:09 sinned. And if that life sinned on planets around other stars, it should have been saved by Christ.
00:55:18 And then you need multiple copies of Christ. And that’s unacceptable. How can you have duplicates
00:55:25 of Christ? And so they burned the guy. I’m just like loading this all in because that’s kind of
00:55:34 brilliant. So he was actually already, it’s not just about the stars, it’s anticipating that there
00:55:39 could be other life forms. Like why, if this star, if there’s other stars, why would it be special?
00:55:46 Why would our star be special? He was making the right argument. And he would just follow that
00:55:51 all along to say like, there should be other Earth like places, there should be other life forms.
00:55:56 And then there needs to be copies of Christ. Yeah, so that was offensive. So I said to that
00:56:02 professor, I said, great, I wanted to introduce some scientific tone to the discussion. And I said,
00:56:08 this is great because now you basically laid the foundation for an experimental test of this
00:56:13 theology. What is the test? We now know that other stars are like the sun and we know they have
00:56:20 planets like the Earth around them. So suppose we find life there and we figure out that they sinned,
00:56:26 then we ask them, did you witness Christ? And if they say no, it means that this theology
00:56:33 is ruled out. So there is an experimental test. So this is experimental test number one.
00:56:38 Another experimental test, in the Bible, in the Old Testament, Abraham
00:56:46 was heard the voice, the voice of God to sacrifice his son, right? Only son. And that’s what the
00:56:56 story says. Now, suppose Abraham, my name, by the way, had a voice memo up on his cell phone. He
00:57:04 could have pressed this up and recorded the voice of God. And that would have been experimental
00:57:10 evidence that God exists, right? Fortunately, he didn’t, but it’s an experimental test, right?
00:57:18 There is a third example I should tell, and that is Elie Wiesel attributed this story to Martin
00:57:24 Buber, but it’s not clear whether it’s true or not. At any event, the story goes that Martin
00:57:30 Buber, you know, he was a philosopher and he said, you know, the Christians, you know,
00:57:36 the Messiah arrived already and will come back again in the future. The Jews argue the Messiah
00:57:44 never came and will arrive in the future. So he said, why argue? Both sides agree that the Messiah
00:57:54 will arrive in the future. When the Messiah arrives, we can ask whether he or she will arrive
00:58:01 in the future. When the Messiah arrives, we can ask whether he or she came before, you know, like
00:58:09 visited us and then figure it out. And one side. So again, experimental test of a theology. So even
00:58:16 theology, if it puts a skin in the game, you know, if it makes a prediction, could be tested, right?
00:58:22 So why can’t string theories test themselves? Or why can’t, you know, even cosmic inflation? That’s
00:58:28 a model that, you know, one of the inventors from MIT, Alan Guth, argues that it’s not falsifiable.
00:58:35 My point is a theory that cannot be falsified is not helpful because it means that you can’t
00:58:41 make progress. You cannot improve your understanding of nature. The only way for us to
00:58:46 learn about nature is by making hypotheses that are testable, doing the experiments and learning
00:58:53 whether we are correct or not. So B, and coupled that with a curiosity and open mindedness that
00:58:59 allows us to explore all kinds of possible hypotheses, but always the pursuit of those,
00:59:06 the scientific rigor around those hypotheses is ultimately get evidence. Knowledge of what nature
00:59:15 is should be a dialogue with nature. Yes. Rather than a monologue. Monologue, beautifully put.
00:59:20 Can we talk a little bit about the Drake equation? Another framework from which to have this kind of
00:59:25 discussion about possible civilizations out there. So let me ask, within the context of the Drake
00:59:31 equation or maybe bigger, how many alien civilizations do you think are out there?
00:59:37 Well, it’s hard to tell because the Drake equation is again quantifying our ignorance. It’s just a set
00:59:42 of factors. The only one that we know, or actually two that we know quite well is the rate of star
00:59:50 formation in the Milky Way galaxy, which we measured by now, and the frequency of planets
00:59:56 like the Earth around stars and at the right distance to have life. But other than that,
01:00:03 there are lots of implicit assumptions about all the other factors that will enable us to detect
01:00:08 the signal. Now, I should say the Drake equation has a very limited validity just for signals from
01:00:15 civilizations that are transmitting at the time that you’re observing them. However, we can do
01:00:22 much better than that. We can look for artifacts that they left behind. Even if they are dead,
01:00:29 you can look for industrial pollution in the atmosphere of planets. Why do I bring this up?
01:00:35 Why do I bring this up? Again, to show you the conservatism of the mainstream in astronomy.
01:00:40 And by the way, I have leadership positions. I was chair of the astronomy department for nine
01:00:45 years, the longest serving chair at Harvard. And I’m the chair of the board on physics and astronomy
01:00:51 of the National Academies. It’s a primary board. And I’m director of two centers at Harvard and so
01:00:59 forth. So I do represent the community in various ways. But at the same time, I’m a little bit
01:01:06 disappointed by the conservatism that people have. And so let me give you an illustration of that.
01:01:11 So the astronomy community actually is going right now through the process of defining its goals for
01:01:18 the next decade. And there are proposals for telescopes that would cost billions of dollars
01:01:25 and whose goal is to find evidence for oxygen in the atmosphere of planets around other stars,
01:01:33 with the idea that this would be a marker, a signature of life. Now, the problem with that
01:01:40 is Earth didn’t have much oxygen in its atmosphere for the first two billion years. Roughly half of
01:01:47 its life, it didn’t have much oxygen. But it had life. It had microbial life. It’s not
01:01:53 it’s not clear yet as of yet what the origin is for the rise in the oxygen level after two
01:02:01 billion years, about 2.4 billion years ago. But we know that a planet can have life without oxygen
01:02:10 in the atmosphere because Earth did it. The second problem with this approach is that you can have
01:02:16 oxygen from natural processes. You can break water molecules and make oxygen. So even if you find it,
01:02:23 it will never tell you that for sure life exists there. And so even with these billions of dollars,
01:02:30 the mainstream community will never be confident whether there is life. Now, how can it be
01:02:37 confident? There is actually a way. If instead of looking with the same instruments, if you look for
01:02:42 molecules that indicate industrial pollution, for example, CFCs that are produced by refrigerating
01:02:50 systems or industries here on Earth, that they do the ozone layer, you can search for that. And
01:02:55 I wrote a paper five years ago suggesting that. Now, what’s the problem? You can just tell NASA,
01:03:01 I want to build this telescope to search for oxygen, but also for industrial pollution.
01:03:08 Nobody would say that because it sounds like on the periphery of the field. And I ask you,
01:03:16 why would? Hilarious. Because that’s exactly, I mean, that would be saying is quite brilliant. I
01:03:22 mean, because it’s a really strong signal. And if life, if there’s alien civilizations out there,
01:03:29 then they’re probably going to be many of them. And they’re probably going to be more advanced
01:03:34 than us. And they’re probably going to have something like industrial pollution, which would
01:03:37 be a much stronger signal than some basic gas, which could have a lot of different explanations.
01:03:44 So like something like oxygen or, I mean, we could talk about signs of life on Venus and so on.
01:03:52 But if you want a strong signal, it would be pollution. I love how garbage is.
01:03:58 No, but the pollution, you have to understand, we think of pollution as a problem,
01:04:02 but on a planet that was too cold, for example, to have a comfortable life on it, you can imagine
01:04:09 terraforming it and putting a blanket of polluting gases such that it will be warmer. And that would
01:04:16 be a positive change. So if an industrial or a technological civilization wants to terraform a
01:04:25 planet that otherwise is too cold for them, they will do it. So what’s the problem of defining it
01:04:31 as a search goal using the same technologies? The problem is that there is a taboo. We’re not
01:04:39 supposed to discuss extraterrestrial intelligence. There is no funding for this subject, not much,
01:04:45 very little. And young people, because of the bullying on Twitter, you know, all the social
01:04:51 media and elsewhere, young people with talent that are curious about these questions do not enter
01:04:58 this field of study. And obviously, if you step on the grass, it will never grow, right? So if you
01:05:05 don’t give funding, obviously, you know, the mainstream community says, look, nothing was
01:05:10 discovered so far. Obviously, nothing would be discovered. If talented people go to other
01:05:15 districts, you never search for it well enough, you will never find anything. I mean, look at
01:05:21 gravitational wave astrophysics. It’s a completely new window into the universe, pioneered by Ray
01:05:26 Weiss at MIT. And at first, it was ridiculed. And thanks to some administrators at the National
01:05:34 Science Foundation, it received funding, despite the fact that the mainstream of the astronomy
01:05:39 community was very resistant to it. And now it’s considered a frontier. So all these people that
01:05:47 I remember as a young postdoc, these people that bashed this field and said bad things about
01:05:51 people, you know, said nothing will come out of it. Now they say, oh, yeah, of course, you know,
01:05:57 the Nobel Prize was given to the LIGO collaboration. Of course, now they are supportive
01:06:06 of it. But my point is, if you suppress innovation early on, there are lots of missed opportunities.
01:06:15 The discovery of exoplanets is one example. You know, in 1952, there was an astronomer called
01:06:21 the name Otto Struve. And he wrote a paper saying, why don’t we search for Jupiter like planets
01:06:31 close to their host star? Because if they’re close enough, they would move the star back and forth,
01:06:36 and we can detect the signal. And so astronomers on time allocation committees of telescopes
01:06:44 for 40 years argued, this is not possible because we know why Jupiter resides so far from the Sun.
01:06:53 You cannot have Jupiter so close because there is this region where ice forms far from the Sun.
01:06:59 And beyond that region is where Jupiter like planets can form. There was a theory behind
01:07:03 it which ended up being wrong by today’s standards. But anyway, they did not give time
01:07:09 on telescopes to search for such systems until the first system was discovered
01:07:14 four decades after Otto Struve’s paper. And the Nobel Prize was awarded to that
01:07:20 just a couple of years ago. And then you ask yourself, okay, so science still made progress.
01:07:26 What’s the problem? The problem is that this baby came out barely, and there was a delay of
01:07:33 four decades. So the progress was delayed. And I wonder how many babies were not born because of
01:07:39 this resistance. So there must be ideas that are as good as this one that were suppressed because
01:07:44 they were bullied, because people ridiculed them, that were actually good ideas. And these are missed
01:07:51 opportunities, babies that were never born. And I’m willing to push this frontier of the search
01:07:58 for technologies or technological signatures of other civilizations. Because when I was young,
01:08:04 I was in the military in Israel. It’s obligatory to serve. And there was this saying that one of
01:08:10 the soldiers sometimes has to put his body on the barbed wire so that others can go through.
01:08:18 And I’m willing to suffer the pain so that younger people in the future will be able to speak freely
01:08:25 about the possibility that some of the anomalies we find in the sky are due to technological
01:08:30 signatures. And it’s quite obvious. This is why I like the folks in artificial intelligence space,
01:08:35 Elon Musk and a few others speak about this. And they look at the long arc. They say like,
01:08:41 what, you know, this kind of, you know, you can call it like first principles thinking,
01:08:46 or you can call it anything really is like, if we just zoom out from our current bickering and our
01:08:53 current, like discussions in the what science is doing, look at the long arc of the trajectory
01:08:59 we’re headed at. Which questions are obviously fundamental to science? And it should be asked,
01:09:07 and which is the space of hypothesis we should be exploring? And like exoplanets is a really
01:09:12 good example of one that was like an obvious one. I recently talked to Sarah Seager, and it was very
01:09:18 taboo when she was starting out to work on an exoplanet. And that was even in the 90s. And like
01:09:24 it’s obvious should not be a taboo subject. And to me, I mean, I’m probably ignorant, but to me,
01:09:30 exoplanets seems like it’s ridiculous that that would ever be a taboo subject to not fund,
01:09:36 to not explore. That’s very, but even for her, it’s now taboo to say, like what, you know, to look for
01:09:46 industrial pollution, right? Right. And I find that ridiculous. I’ll tell you why. She can’t take
01:09:51 the next step. It’s ridiculous for another reason. Not because of just the scientific benefits that
01:09:56 we might have by exploring it, but because the public cares about these questions. And the public
01:10:03 funds science. So how dare the scientists shy away from addressing these questions,
01:10:09 if they have the technology to do it. It’s like saying, I don’t want to look through
01:10:14 Galileo’s telescope. It’s exactly the same. You have the technology to explore this question,
01:10:19 to find the evidence and you shy away from it. You might ask, why do people shy away from it?
01:10:25 And perhaps it’s because of the fact that there is science fiction. I’m not a fan of science fiction,
01:10:30 because it has an element to it that violates the laws of physics in many of the books and the
01:10:36 films. And I cannot enjoy these things when I see the laws of physics violated. But who cares that
01:10:43 the, you know, the fact that there is science fiction. I mean, if you have the scientific
01:10:47 methodology to address the same subject, I don’t care that other people, you know, spoke nonsense
01:10:53 about this subject or said things that make no sense. Who cares? You do your scientific work,
01:10:59 just like you explore the dark matter. You explore the possibility that umuamua is an
01:11:05 artifact. You just look for evidence and try to deduce what it means. And I have no problem with
01:11:13 doing that. To me, it sounds like any other scientific question that we have. And given
01:11:18 the public’s interest, we have an obligation to do that. By the way, science to me is not
01:11:24 an occupation of the elite. It doesn’t allow me to feel superior to other humans that are unable to
01:11:29 understand the math. To me, it’s a way of life. You know, if there is a problem in the faucet or
01:11:35 in the pipe at home, I try to figure out what the problem is. And with a plumber, we figure it out
01:11:41 and we look at the clues. And the same thing in science. You look at the evidence, you try to
01:11:47 figure out what it means. It’s common sense in a way. And it shouldn’t be regarded as something
01:11:54 removed from the public. It should be a reflection of the public’s interest. And I think it’s
01:11:59 actually a crime to resist the public. If the public says, I care about this, and you say,
01:12:05 no, no, no, that’s not sophisticated enough for me. I want to do intellectual gymnastics on
01:12:09 anti the sitter space. To me, that’s a crime. Yes, I 100% agree. So it’s hilarious that the very,
01:12:18 not hilarious, it’s sad, that people who are trained in the scientific community to have the
01:12:26 tools to explore this world, to be children, to be the most effective at being children,
01:12:31 are the ones that resist being children the most. But there is a large number of people
01:12:37 that embrace the childlike wonder about the world and may not necessarily have the tools to do it.
01:12:44 That’s the more general public. And so, I wonder if I could ask you and talk to you a little bit
01:12:51 about UFO sightings. That there’s people, quote unquote believers, there’s hundreds of thousands
01:13:00 of UFO sightings. And I’ve consumed some of the things that people have said about it. And one
01:13:12 thing I really like about it is how excited they are by the possibility. It’s almost like this
01:13:21 childlike wonder about the world out there. It’s not a fear, it’s an excitement. Do you think,
01:13:28 because we’re talking about this possibly extraterrestrial object that visited, that flew
01:13:35 by Earth, do you think it’s possible that out of those hundreds of thousands of UFO sightings,
01:13:43 one is an actual, one or some number is an actual sighting of a nonhuman, some alien technology.
01:13:52 And that we’re not, we did not, we’re too close minded to look and to see.
01:14:04 I think to answer this question, we need better evidence. My starting point, as I said,
01:14:11 out of modesty is that we are not particularly interesting. And therefore I would be hard pressed
01:14:17 to imagine that someone wants to really spy on us. So I would think, as a starting point,
01:14:25 that we don’t deserve attention and we shouldn’t expect someone, but who knows.
01:14:30 Now, the problem that I have with UFO sighting reports is that 50 years ago, there were some
01:14:37 reports of fuzzy images, saucer like things. By now, our technologies are much better. Our cameras
01:14:45 are much more sensitive. These fuzzy images should have turned into crisp, clear images
01:14:52 of things that we are confident about. And they haven’t turned that way. It’s always on the border
01:14:58 line of believability. And because of that, I believe that it might be most likely artifacts
01:15:04 of our instruments or some natural phenomena that we are unable to understand. Now, of course,
01:15:09 the reason you must examine those, if, for example, pilots report about them or
01:15:17 the military finds evidence for them, is because it may pose a national security threat. If another
01:15:23 country has technologies that we don’t know about and they’re spying on us, we need to know about
01:15:28 it. And therefore we should examine everything that looks unusual. But to associate it with an
01:15:33 alien life is a little too far for me until we have evidence that stands up to the level of
01:15:43 scientific credence, that we are 100% sure that from multiple detectors and through a scientific
01:15:53 process. Now, again, if the scientific community shies away from these reports, we will never have
01:15:58 that. It’s like saying, I don’t want to take photographs of something because I know what it is,
01:16:04 then you will never know what it is. But I think if some scientist, if grants, let’s put it this
01:16:10 way, if funding will be given to scientists to follow on some of these reports and use scientific
01:16:17 instruments that are capable of detecting those sightings with much better resolution, with much
01:16:24 better information, that would be great because it will clarify the matter. These are not,
01:16:29 as you said, hundreds of thousands, these are not once in a lifetime events. So it’s possible to
01:16:35 take scientific instrumentation and explore, go to the ocean where someone reported that there are
01:16:42 frequent events that are unusual and check it out, do a scientific experiment. Why only do experiments
01:16:50 deep into the ocean and look at the oceanography or do other things. We can do scientific
01:16:57 investigation of these sightings and figure out what they mean. I’m very much in favor of that,
01:17:04 but until we have the evidence, I would be doubtful as to what they actually mean.
01:17:09 Yeah, we’ll have to be humble and acknowledge that we’re not that interesting. It’s kind of,
01:17:14 you’re making me realize that because it’s so taboo, that the people that have the equipment,
01:17:19 uh, meaning, and we’re not just talking, everybody has cameras now, but to have a large scale,
01:17:25 like a sensor network that collects data that regularly collects, just like we look at the
01:17:32 weather, we’re collecting information and then we can then access that information when there is
01:17:36 reports and like have it not be a taboo thing where there’s like millions or billions of dollars
01:17:42 or billions of dollars funding this effort that by the way, inspires millions of people.
01:17:49 This is exactly what you’re talking about. It’s like the scientific community is afraid of a
01:17:55 topic that inspires millions of people. It’s absurd. But if you put blinders on your eyes,
01:18:01 you don’t see it. Right. I should say that we do have meteors that we see. These are rocks
01:18:08 that by chance happen to collide with the earth and they, if they’re small, they burn up in the
01:18:14 atmosphere. But if they’re big enough, tens of meters or more, hundreds of meters, the outer
01:18:21 layer burns up, but then the core of the object makes it through. And this is our chance of putting
01:18:29 our hands around an object if this meteor came from interstellar space. So one path of discovery
01:18:37 is to search for interstellar meteors. And with a student of mine, we actually looked through the
01:18:43 record and we thought that we found one example of a meteor that was reported that might have come
01:18:50 from interstellar space. And then another approach is, for example, to look at the moon. The moon is
01:18:57 different from the earth in the sense that it doesn’t have an atmosphere. So objects do not
01:19:02 burn up on their way to it. It’s sort of like a museum. It collects everything. Of rocks from out
01:19:07 there in deep space. Yeah. And there is no geological activity on the moon. So on earth,
01:19:12 every hundred million years, you know, we could have had computer terminals on earth that could
01:19:17 have been a civilization like ours with electronic equipment. Yes. More than a hundred million years
01:19:23 ago. And it’s completely lost. You cannot excavate and find it, evidence for it, because in
01:19:29 archaeological digs, because the earth is being mixed on these timescales. And everything that
01:19:35 was on the surface more than a hundred million years ago is buried deep inside the earth right
01:19:39 now because of geological activity. Fascinating to think about, by the way. Yeah. But on the moon,
01:19:44 this doesn’t happen. The only thing that happens on the moon is you have objects impacting the moon
01:19:49 and they go 10 meters deep. So they produce some dust, but the moon keeps everything. It’s like a
01:19:55 museum. It keeps everything on the surface. So if we go to the moon, I would highly recommend
01:20:01 regarding it as an archaeological site. Yes. And looking for objects that are strange. Maybe it
01:20:07 collected some trash, you know, from interstellar space. If we could just linger on the Drake
01:20:13 equation for a little bit. We kind of talked about there’s a lot of uncertainty in the parameters
01:20:18 and the Drake equation itself is very limited. But I think the parameters are interesting in
01:20:26 themselves, even if it’s limited, because I think each one is within the reach of science,
01:20:31 right? Did you get the evidence for it? I mean, a few I find really interesting,
01:20:36 could be interesting to get your comment on. So the one with the most variance, I would say,
01:20:43 from my perspective, is the length that civilizations last. However you define it. In the Drake
01:20:48 equation, it’s the length of how long you’re communicating. Yeah, transmitting.
01:20:52 Transmitting. Just like you said, that’s a wrong way to think about it, because we can be detecting
01:20:59 some other outputs of the civilizations, etc. But if we just define broadly how long those
01:21:04 civilizations last, do you have a sense of how long they might last? Like what are the great
01:21:12 filters that might destroy civilizations that we should be thinking about? And how can
01:21:19 science give us more hints on this topic? So I, as I mentioned before, operate by the
01:21:25 Copernican principle, meaning that we are not special. We don’t live in a special place
01:21:31 and not in a special time. And by the way, it’s just modesty encapsulated in scientific terms,
01:21:38 right? You’re saying, I’m not special, you know, I find conditions here, they exist
01:21:43 everywhere. So if you adopt the Copernican principle, you basically say, our civilization
01:21:50 transmitted radio signals for a hundred years, roughly, so probably it would last another
01:21:57 hundred or a few hundred and that’s it. Because we don’t live at a special time.
01:22:02 So that’s, you know, well, of course, if we get our act together and we somehow start
01:22:10 to cooperate rather than fighting each other, killing each other, you know, wasting a lot
01:22:15 of resources on things that would destroy our planet, maybe we can lengthen that period
01:22:23 if we get smarter. But the most natural assumption is to say that we will live into the future as
01:22:31 much as we lived from the time that we start to develop the means for our own destruction,
01:22:35 the technologies we have, which is quite pessimistic, I must say. So several centuries,
01:22:40 that’s what I would give, unless we get our act, unless we become more intelligent
01:22:45 than the newspapers report every day. Okay. Point number one. Second, and by the way,
01:22:51 this is relevant, I should say, because there was a report about perhaps a radio signal detected
01:22:58 from Proxima Centauri. What do you make of that signal? Oh, I think it’s some Australian guy with
01:23:03 a cell phone next to the observatory or something like that, because it was the Parkes Telescope in
01:23:09 Australia. Okay. So it’s human created noise. Yeah. Which is always the worry because actually
01:23:17 the same observatory, the Parkes Observatory, detected a couple of years ago some signal
01:23:22 and then they realized that it comes back at lunchtime. Yes. And they said, okay, what could
01:23:29 it be? And then they figured out that it must be the microwave oven in the observatory because
01:23:34 someone was opening it before it finished and it was creating this radio signal that they detected
01:23:40 with a telescope every lunchtime. So just a cautionary remark. But the reason I think it’s
01:23:47 human made, without getting to the technical details, is because of this very short window
01:23:54 by which we were transmitting radio signals out of the lifetime of the Earth. As I said,
01:23:58 100 years out of four and a half billion years that the Earth existed. So what’s the chance
01:24:04 that another civilization, a twin civilization of ours, is transmitting radio signals exactly
01:24:10 at the time that we are looking with our radio telescopes? 10 to the minus 7. And the other
01:24:19 argument I have is that they detected it in a very narrow band of frequencies and that makes it
01:24:28 cannot be through natural processes, very narrow band, just like some radio transmissions that we
01:24:34 produce. But if it were to come from the habitable zone, from a transmitter on the surface of Proxima
01:24:42 b, this is the planet that orbits Proxima Centauri, then I calculated that the frequency
01:24:48 would drift through the Doppler effect. Just like when you hear a siren on the street, when the car
01:24:56 approaches you, it has a different pitch than when it recedes away from you, that’s the Doppler
01:25:02 effect. And when the planet orbits the star, Proxima Centauri, you would see or detect a
01:25:10 different frequency when the planet approaches us as compared to when it recedes. So there should
01:25:14 be a frequency drift just because of the motion of the planet. And I calculated that it must be
01:25:22 much bigger than observed. So it cannot just be a transmitter sitting on the planet and sending in
01:25:29 our direction a radio signal unless they want to cancel the Doppler effect. But then they need to
01:25:36 know about us because in a different direction, it will not be cancelled. Only in our direction,
01:25:40 they can cancel it perfectly. So there is this direction of Proxima Centauri, but I have a
01:25:48 problem imagining a transmitter on the surface of a planet in the habitable zone emitting it.
01:25:53 But my main issue is really with the likelihood, given what we know about ourselves.
01:26:01 Right. In terms of the duration of the civilization.
01:26:03 The Copernican principle. Yeah.
01:26:06 So nevertheless, this particular signal is likely to be a human interference, perhaps. But
01:26:12 do you find Proxima be interesting? Or the more general question is, do you think we humans
01:26:19 will venture out into outside our solar system and potentially colonize other habitable planets?
01:26:30 Actually, I am involved in a project whose goal is to develop the technology that would allow us
01:26:35 to leave the solar system and visit the nearest stars. And that is called the Star Shot. In 2015,
01:26:43 May 2015, an entrepreneur from Silicon Valley, Yuri Milner, came to my office at Harvard and said,
01:26:51 would you be interested in leading a project that would do that in our lifetime? Because as we
01:26:58 discussed before, to traverse those distances with existing rockets would take tens of thousands of
01:27:05 years. And that’s too long. For example, to get to Proxima Centauri with the kind of
01:27:13 spacecrafts that we already sent, like New Horizons or Voyager 1, Voyager 2, you needed to
01:27:22 send them when the first humans left Africa, so that they would arrive there now. And that’s a
01:27:29 long time to wait. So Yuri wanted to do it within a lifetime, 10, 20 years, meaning it has to move
01:27:36 at a fraction of the speed of light. So can we send a spacecraft that would be moving at the
01:27:42 fraction of the speed of light? And I said, let me look into that for six months. And with my
01:27:47 students and postdocs, we arrived to the conclusion that the only technology that can do that is the
01:27:52 light sail technology, where you basically produce a very powerful laser beam on Earth. So you can
01:28:01 collect sunlight with photovoltaic cells or whatever and then convert it into stored energy
01:28:13 and then produce a very powerful laser beam that is 100 gigawatts and focus it on a sail in space
01:28:22 that is roughly the size of a person, a couple of meters or a few meters, that weighs only a gram
01:28:30 or a few grams, very thin. And through the math, you can show that you can propel such a sail,
01:28:39 if you shine on it for a few minutes, it will traverse the distance that is five times the
01:28:43 distance to the moon, and it will get to a fifth of the speed of light. Sounds crazy. But I’ve
01:28:49 talked to a bunch of people and they’re like, I know it sounds crazy, but it’s actually,
01:28:54 it will work. This is one of those, it’s beautiful. I mean, this is science.
01:28:59 And the point is, people didn’t get excited about space since the Apollo era. And it’s about time,
01:29:08 you know, for us to go into space. A couple of months ago, I was asked to participate in a debate
01:29:15 organized by IBM and Bloomberg News. And the discussion centered on the question,
01:29:22 is the space race between the US and China good for humanity? Oh, interesting. And all the other
01:29:28 debaters were worried about the military threats. And I just couldn’t understand what they’re
01:29:35 talking about, because military threats come from hovering above the surface of the Earth, right?
01:29:41 And we live on a two dimensional surface, we live on the surface of the Earth. But space is
01:29:47 all about the third dimension, getting far from Earth. So if you go to Mars, or you go to a star,
01:29:52 another star, there is no military threat. What are we talking about? Space is all about,
01:29:58 you know, feeling that, you know, we are one civilization, in fact, not fighting each other,
01:30:04 just going far, and having aspirations for something that goes beyond military threats.
01:30:10 So why would we be worried that the space race will lead?
01:30:14 That’s actually brilliant. I didn’t, you know, there’s something in our discourse about it,
01:30:18 the space race is sometimes made synonymous with like the Cold War or something like that.
01:30:23 Right.
01:30:24 Or with wars. But really, yeah, there was a lot of ego tied up in that. I remember,
01:30:28 I mean, it’s still to this day, there’s a lot of pride that Russians,
01:30:32 Soviet Union was the first to space. And there’s a lot of pride in the American side that was the
01:30:36 first on the moon. But yeah, you’re exactly right. Like, there’s no aggression, there’s no wars.
01:30:42 And beyond that, if you think about the global economy, right now, there is a commercial
01:30:47 interest. That’s why Jeff Bezos and Elon Musk are interested about, you know, Mars and so on.
01:30:52 There is a commercial interest, which is international. It’s driven by money,
01:30:57 not by pride. And, you know, nations can sign treaties. First of all, there are lots of treaties
01:31:04 that were signed even before the First World War and the Second World War and the World War took
01:31:08 place. So who cares, you know, like humans, treaties do not safeguard anything, you know.
01:31:15 But beyond that, even if nations sign treaties about space exploration, you might still find
01:31:21 commercial entities that will find a way to get their launches. And, you know, so I think we
01:31:27 should rethink space. It has nothing to do with national pride. Once again, nothing to do with
01:31:33 our egos. It’s about exploration. And the biggest problem, I think, in human history is that humans
01:31:42 tend to think about egos and about their own personal image rather than, look at the big
01:31:53 picture, you know. We will not be around for long. We are just occupying a small space right now.
01:31:58 Now, let’s move out of this, you know, the way that Oscar Wilde said, I think is the best. He said,
01:32:06 all of us are in the gutters, but some of us are looking at the stars.
01:32:11 Yeah, and the more of us are looking at the stars, the likelier we are to, for this thing,
01:32:18 this little experiment we have going on to last a while as opposed to end too quickly. I mean,
01:32:25 it’s not just about science of being humble. It’s about the survival of the human species
01:32:29 as being humble. To me, it’s incredibly inspiring, the Starshot project of,
01:32:36 I mean, there’s something magical about being able to go to another habitable planet and take
01:32:41 a picture even. I mean, within our lifetime, I mean, that, with crazy technology too, which is…
01:32:49 I should tell you how it was conceived. So, I was at the time, so after six months passed,
01:32:56 after the visit of Yuri Miller, I was, usually I go in December during the winter break,
01:33:02 I go to Israel. I used to go to see my family and I get a phone call just before the weekend
01:33:11 started. I get a phone call, Yuri would like you to present your concept in two weeks at his home.
01:33:19 And I said, well, thank you for letting me know because I’m actually out of the door of the hotel
01:33:25 to go to a goat farm in the Negev, in the southern part of Israel, because my wife wanted to have
01:33:34 to go to a place that is removed from civilization, so to speak.
01:33:39 So, we went to that goat farm and I need to make the presentation and there was no internet
01:33:47 connectivity except in the office of the goat farm. So, the following morning at 6am, I sit
01:33:53 with my back to the office of that goat farm, looking at goats that were newly born and typing
01:34:00 into my laptop, the presentation, the PowerPoint presentation about our ambitions for visiting the
01:34:06 nearest star. And that was very surreal to me. Like our origins in many ways,
01:34:16 this very primitive origins and our dreams of looking out that is brilliant. So that is
01:34:23 incredibly inspiring to me, but it’s also inspiring of putting humans onto other
01:34:32 moons or planets. I still find going to the moon really exciting. I don’t know, maybe I’m just a
01:34:38 sucker for it, but it’s really exciting. And Mars, which is a new place, a new planet, another planet
01:34:44 that might have life. I mean, there’s something magical to that or some traces of previous life.
01:34:49 You might think that humans cannot really survive and there are risks by going there. But my point
01:34:55 is, we started from Africa and we got to apartment buildings in Manhattan, right? It’s a very
01:35:03 different environment from the jungles to live in an apartment building in a small cubicle.
01:35:09 Yes. And it took tens of thousands of years,
01:35:13 but humans adapted, right? So why couldn’t humans also make the leap and adapt to a habitat in
01:35:20 space? Now you can build a platform that would look like an apartment building in the Bronx
01:35:26 or somewhere, but have inside of it everything that humans need. And just like the space station,
01:35:34 but bigger. And it will be a platform in space. And the advantage of that is if something bad
01:35:40 happens on Earth, you have that complex where humans live. And you can also move it back and
01:35:47 forth depending on how bright the sun gets. Because within a billion years, the sun would be
01:35:56 too hot and it will boil off all the oceans on Earth. So we cannot stay here for more than a
01:36:01 billion years. That’s for sure. Yes. So that’s a billion years from now. I prefer shorter term
01:36:07 deadlines. And so there’s a lot of threats that we’re facing currently. Do you find it exciting
01:36:13 the possibility of landing on Mars and starting little like building a Manhattan style apartment
01:36:22 building on Mars and humans occupying it? Do you think from a scientific or an engineering
01:36:27 perspective, that’s a worthy pursuit? I think it’s worthy. But the real issue that is often
01:36:35 underplayed is the risk to the human body from cosmic rays. These are energetic particles
01:36:43 and we are protected from them by the magnetic field around the Earth that blocks them. But if
01:36:51 you go to Mars, where there is no such magnetic field to block them, then, you know, a significant
01:36:57 fraction of the brain cells in your head will be damaged within a year. And the consequences of
01:37:04 that are not clear. I mean, it’s quite possible that humans cannot really survive on the surface.
01:37:12 Now, it may mean that we need to dig tunnels, go underground or create some protection.
01:37:19 This is something that can be engineered. Yes. And, you know, we can start from the
01:37:23 Moon and then move to Mars. That would be a natural progression. But it’s a big issue
01:37:29 that needs to be dealt with. I don’t think, you know, it’s a showstopper. I think we can overcome
01:37:35 it. But, you know, just like anything in science and technology, you have to work on it for a while,
01:37:40 figure out solutions. But it’s not as rosy as Elon Musk talks about. I mean, Elon Musk can
01:37:47 obviously be optimistic. I think eventually it will boil down to figuring out how to cope with
01:37:53 this risk, the health risk. Yeah, I mean, in defense of optimism, I find that there’s at
01:37:59 least a correlation, if not their best friends, is optimism and open mindedness. It’s a necessary
01:38:10 precondition to try crazy things. And in that sense, the sense I have about going to Mars,
01:38:18 if we use today’s logic of what kind of benefits we’ll get from that, we’re never going to go.
01:38:28 And like most decisions we make in life, most decisions we’ve made as a human species
01:38:34 are irrational if you look at just today. But if you look at the long arc and the
01:38:41 possibilities that it might bring, just like humans, Europe and destroyed everybody.
01:38:51 But it was a commercial interest that drove that for trade. And, you know, it might happen again,
01:38:58 in this context, you have people like Jeff Bezos and Elon Musk that are commercially driven to go
01:39:02 to space. But it doesn’t mean that what we will ultimately find is not new worlds that have
01:39:10 nothing, you know, have much more to offer than just commercial interest. And as a side effect,
01:39:16 almost. Yeah, yeah. And then that’s why I think, you know, we should be open minded and explore.
01:39:22 And, however, at the same time, because of the reasons you pointed out, I’m not optimistic that
01:39:28 we will survive more than a few centuries into the future, because people do not think long term.
01:39:34 And that means that we will only survive for the short term. I don’t know if you have thoughts
01:39:39 about this, but what are the things that worry you the most about, from the great perspective
01:39:45 of the universe, which is the great filters that destroys intelligent civilizations,
01:39:49 but for our own species here? Like, what are the things that worry you the most?
01:39:55 Yeah, the thing that worries me the most is that people pay attention to how many likes they have
01:39:59 on Twitter. And rather than, you know, basketball coaches tell the team players, keep your eyes on
01:40:10 the ball, not on the audience. The problem is we keep our eyes on the audience most of the time.
01:40:17 Let’s keep our eyes on the ball. And what does that mean? First of all, in the context of science,
01:40:21 it means pay attention to the evidence. When the evidence looks strange,
01:40:26 then we should figure it out. You know, I went to a seminar about Umuamua at Harvard,
01:40:32 and a colleague of mine that is mainstream, conservative, would never say anything that would
01:40:40 deviate from what everyone else is thinking, said to me after the seminar, I wish this object never
01:40:48 existed. Now, to me, I mean, I just couldn’t hear that. What do you mean, nature is whatever it is,
01:40:56 you have to pay attention to it. You cannot say, you know, you cannot bury your head in this. I
01:41:01 mean, you should bless nature for giving you clues about things that you haven’t expected.
01:41:05 Yes.
01:41:06 And I think that’s the biggest fault that we are looking for confirmations of things we already
01:41:12 know, so that we can maintain our pride that we already knew it, and maintain our image,
01:41:20 not make mistakes, because we already knew it, therefore we expected the right thing.
01:41:25 Yes.
01:41:25 But science is a learning experience, and sometimes you’re wrong. And let’s learn from
01:41:30 those mistakes. And what’s the problem about that? Why do we have to get, you know, prizes,
01:41:36 and why do we get to be honored and maintain our image, when the actual objective of science is
01:41:42 learning about nature?
01:41:43 And like you’ve talked about, anomalies in this case are actually are not things that
01:41:49 are unfortunate and to be ignored are, in fact, gifts and should be the focus of science.
01:41:54 Exactly, because that’s the way for us to improve our understanding. If you look at quantum
01:41:59 mechanics, nobody dreamed about it. And it was revolutionary, and we still don’t fully understand
01:42:05 it. It’s a pain for us to figure out.
01:42:07 So I understand from the perspective that’s holding our science back, why do you have
01:42:13 a sense that that’s also something that might be a problem for us in terms of the survival
01:42:20 of human civilization?
01:42:22 Because when you look at society, it operates by the same principles. People look for affirmation
01:42:31 by groups, and they, you know, people segregate into herds that think like them, especially
01:42:39 these days when social media is so strong, you can find your support group. And if you
01:42:44 don’t look for evidence for what you’re saying, you can say crazy things as long as there
01:42:49 are enough people supporting what you say. You can even have your newspapers, you can
01:42:54 have everything to support your view, and then, you know, bad things will happen to
01:42:59 society. Because we’re detaching ourselves from reality. And if we detach ourselves
01:43:04 from reality, all the destructive things that naturally can occur in the real world, whether
01:43:09 from nuclear weapons, all the kinds of threats that we’re facing, even we’re living through
01:43:13 a pandemic, the supposed, you know, a much, much worse pandemic could happen. And then
01:43:19 we could sadly, like we did this one, politicize it in some kind of way and have bickering
01:43:25 in the space of Twitter and politics, as opposed to there’s an actual thing that can destroy
01:43:31 the human species.
01:43:32 Exactly. So the only way for us to maintain, to stay modest and learn about what really
01:43:37 happens is by looking for evidence. Again, I’m saying, it’s not about ourself, you know,
01:43:44 it’s about figuring out what’s around us. And if you close yourself by surrounding yourself
01:43:49 with people that are like minded, that refuse to look at the evidence, you can do bad things.
01:43:57 And throughout human history, that’s the origin of all the bad things that happen.
01:44:02 Yes.
01:44:03 And I think it’s a key. It’s a key to be modest and to look at evidence. And it’s
01:44:07 not a nuance. Now, you might say, Oh, okay, the uneducated person might operate. No,
01:44:15 it’s the scientific community operates this way. My problem is not with people that don’t
01:44:21 have an academic pedigree. It’s included everywhere in society.
01:44:24 On the topic of the discovery of evidence of alien civilizations, which is something
01:44:30 you touch on in your book, what that idea would do to societies, to the human psyche
01:44:38 and in general, do you think, and you talk about the, I still have trouble pronouncing,
01:44:46 but a Muamua wager, right? What do you think is, can you explain it? And what do you think
01:44:54 in general is the effect that such knowledge might have on human civilization?
01:44:58 Right. So Pascal had this wager about God. And by the way, there are interesting connections
01:45:04 between theology and the search for extraterrestrial life. It’s possible that we were planted on
01:45:11 this planet by another civilization. We attribute to God powers that belong really to the technological
01:45:19 civilization. But putting that aside, Pascal basically said, there are two possibilities,
01:45:26 there are two possibilities, either God exists or not. And if God exists, the consequences
01:45:34 are quite significant. And therefore, we should consider that possibility differently than
01:45:42 equal weight to both possibilities. And I suggest that we do the same with Muamua or
01:45:50 other technological signatures, that we keep in mind the consequences and therefore pay
01:45:58 more attention to that possibility. Now, some people say extraordinary claims require extraordinary
01:46:05 evidence. My point is that the term extraordinary is really subjective. For one person, a black hole
01:46:14 is extraordinary. For another, it’s just a consequence of Einstein’s theory of gravity. It’s
01:46:20 nothing extraordinary. The same about the type of dark matter, anything. So we should leave the
01:46:27 extraordinary part of that sentence. Just keep evidence, okay? So let’s be guided by evidence.
01:46:35 And even if we have extraordinary claims, let’s not dismiss them because the evidence is not
01:46:42 extraordinary enough. Because if we have an image of something and it looks really strange and we
01:46:47 say, oh, the image is not sufficiently sharp, therefore, we should not even pay attention to
01:46:51 this image or not even consider. I think that’s a mistake. What we should do is say, look, there is
01:46:57 some evidence for something unusual. Let’s try and build instruments that will give us a better
01:47:02 image. And if you just dismiss extraordinary claims, because you consider them extraordinary,
01:47:09 you avoid discovering things that you haven’t expected. And so I believe that along the history
01:47:17 of astronomy, there are many missed opportunities. And I speak about astronomy, but I’m sure in other
01:47:21 fields, it’s also true. I mean, this is my expertise. For example, you know, the Astrophysical
01:47:27 Journal, which is the main primary publication in astrophysics. If you go before the 1980s,
01:47:35 there are images that were posted in the Astrophysical Journal of giant arcs, you know, arcs
01:47:41 of light surrounding clusters of galaxies. And, you know, you can find it in printed versions of
01:47:49 the Astrophysical Journal. People just ignore it. They put the image, they see the arc, they say,
01:47:54 who knows what it is and just ignore it. And then in the 1980s, the subject of gravitational
01:48:00 lensing became popular. And the idea is that you can deflect light by the force of gravity. And
01:48:11 then you can put a source behind the cluster of galaxies, and then you will get these arcs. And
01:48:16 actually, Einstein predicted it in 1940. And, you know, so these things were expected, but
01:48:23 people just had them in the images, didn’t pay attention. So I’m sure there are lost opportunities
01:48:28 sometimes. Even in existing data, you have things that are unusual and exceptional and are not being
01:48:36 addressed. Yeah, you actually, I think you have an article, the data is not enough from quite a few
01:48:42 years ago, where you talk, you know, we can go back to the 70s and 80s, but we can go also to the
01:48:48 Mayan civilization. Right, the Mayan civilization basically believed in astrology that you can
01:48:53 forecast the outcome of a war based on the position of the planets. And they had, you know,
01:49:00 astronomers in their culture had the highest social status. They were priests, they were elevated.
01:49:08 And the reason was that they helped politicians decide when to go to war, because they would tell
01:49:14 the politicians, you know, the planets would be in this configuration, it’s a better chance for you
01:49:18 to win the war, go to war. And in retrospect, they collected wonderful data, but misinterpreted it,
01:49:27 because we now know that the position of Venus or Jupiter or whatever has nothing to do with the
01:49:33 outcome of World War I, World War II, you know, has nothing to do. And so we can have a prejudice
01:49:40 and collect data without actually doing the right thing with it. That’s such a Pisces thing to say.
01:49:47 I looked up what your astrological sign is.
01:49:52 Well, so you mentioned Einstein predicted that black holes don’t exist, or just didn’t, or thought.
01:49:58 Don’t exist in nature.
01:49:59 Don’t exist in nature.
01:50:00 When Einstein came up with his theory of gravity in 1915, November 1915, a few months later,
01:50:07 another physicist, Karl Schwarzschild, he was the director of the Potsdam Observatory,
01:50:13 but he was a patriot, a German patriot. So he went into the First World War fighting for Germany.
01:50:18 But while he was at the front, he sent a postcard to Einstein saying, you know,
01:50:23 a few months after the theory was developed, saying, actually, I found a solution to your
01:50:27 equations. And that was a black hole solution. And then he died a few months later. And Einstein
01:50:34 was a pacifist, and he survived. So the lesson from this story is that if you want to work out
01:50:40 the consequences of a theory, you better be a pacifist. But the point is that this solution
01:50:47 was known shortly after Einstein came up with his theory. But in 1939, Einstein wrote a paper
01:50:55 in the Annals of Mathematics saying, even though the solution exists,
01:51:00 I don’t think it’s realized in nature. And his argument was, if you imagine a star collapsing,
01:51:05 stars often spin, and the spin will prevent them from making a black hole, collapsing to a point.
01:51:11 So, I mean, can you maybe, one of the many things you have worked on, you’re an expert in,
01:51:20 is black holes. Can you first say, what are black holes? And second, how do we know that they exist?
01:51:26 Right. So black holes are the ultimate prison. You know, you can check in, but you can never check out.
01:51:32 It’s romantic.
01:51:33 You can never check out. Even light cannot escape from them. So there are extreme structures of
01:51:40 space and time. And there is this so called Schwarzschild radius or the event horizon of
01:51:48 a black hole. Once you enter into it with a spaceship, you would never be able to tweet
01:51:54 back to your friends and tell them, by the way, I asked the students in my class, freshman seminar
01:51:59 at Harvard, I said, let me give you two possible journeys that you can take. I said, suppose aliens
01:52:06 come to Earth and suggest that you would board their spaceship, would you do it? And the second
01:52:15 is, suppose you could board a spaceship that will take you into a black hole, would you do it?
01:52:20 So all of them said to the first question, yes, under one condition, that I’ll be able to maintain
01:52:28 my social media contacts and report back, share the experience with them. Personally, I have no
01:52:34 footprint on social media.
01:52:36 Yeah, which is as a matter of principle.
01:52:39 Yeah, my wife asked me when we got married, and I honor that.
01:52:44 And I told you offline, I need to get married to such a woman. She truly is a special agent.
01:52:49 Well, she was wise enough to recognize the risk. But it saves me time. And it also keeps me away
01:52:56 from crowds. I don’t have the notion of what a lot of other people think, so I can think
01:53:03 independently.
01:53:04 Crowd think, exactly.
01:53:04 Yeah, exactly. So I was surprised to hear that for students, it’s extremely important to share
01:53:11 experiences. Even if they go on a spaceship with aliens, they still want to brag about it rather
01:53:17 than look around and see what’s going on.
01:53:19 This is not an option when you go to the black hole, is exactly the point.
01:53:22 So for the black hole, they said no, because obviously you can find your death after you get
01:53:29 into it, you crash into singularity. There is this singularity in the center. So inside the event
01:53:35 horizon, we know that all the matter collects at a point. Now, we can’t really predict what happens
01:53:44 at the singularity because Einstein’s theory breaks down. And we know why it breaks down,
01:53:49 because it doesn’t have quantum mechanics that talks about small distances. We don’t have a
01:53:55 theory that unifies quantum mechanics and gravity so that it will predict what happens near a
01:54:02 singularity. And in fact, a couple of years ago, I had a flood in my basement. And I invited a
01:54:12 plumber to come over and figure out and we found that the sewer was clogged because of
01:54:20 tree roots that got into it. And we solved the problem. But then I thought to myself,
01:54:28 well, isn’t that what happens at the singularity of a black hole? Because the question is,
01:54:33 where does the matter go? In the case of a home, I never thought about it, but the water,
01:54:39 all the water that we use, goes in through the sewer to some reservoir somewhere. And the question
01:54:46 is, what happens inside a black hole? And one possibility is that there is an object in the
01:54:51 middle, just like a star, and everything collects there. And the object has the maximum density that
01:54:56 we can imagine, like Planck density. It’s the ultimate density that you can have, where gravity
01:55:03 is as strong as all the other forces. So you can imagine this object, very dense object at the
01:55:11 center that collects all the matter. Another possibility is that there is some tunnel just
01:55:15 like the sewer. It takes the matter into another place. And we don’t know the answer. But I wrote
01:55:22 a Scientific American essay about it, admitting our ignorance. It’s a fascinating question. What
01:55:28 happens to the matter that goes into a black hole? I actually recommend it to some of my colleagues
01:55:32 that work on string theory. At the closing of a conference, I’m the founding director of the Black
01:55:38 Hole Initiative at Harvard, which brings together astronomers, physicists, philosophers, and
01:55:42 mathematicians. And we have a conference once a year. And at the end of one of them, since I’m the
01:55:49 director, I had to summarize. And I said that I wish we could go on a field trip to a black hole
01:55:56 nearby. And I highly recommend to my colleagues that work on string theory to enter into that
01:56:03 black hole, because then they can test their theory when they get inside. But one of the
01:56:08 string theorists in the audience, Nimar Khani Hamad, immediately raised his voice and said,
01:56:14 you have an ulterior motive for sending us into a black hole, which I didn’t deny, but at any event.
01:56:21 Yeah, that’s true. That’s true. Can you say why we know that black holes exist?
01:56:32 Right. So it’s an interesting question because black holes were considered a theoretical
01:56:38 construct. And Einstein even denied their existence in 1939. But then in the mid 1960s, quasars were
01:56:51 discovered. These are very bright sources of light, 100 times brighter than their host galaxy,
01:56:59 which are point like at the center of galaxies. And it was immediately suggested
01:57:06 by Ed Salpeter in the West and by Yakov Zeldovich in the East, that these are black holes that
01:57:16 accrete gas, collect gas from their host galaxy that are being fed with gas. And they shine very
01:57:23 brightly because as the gas falls towards the black holes, just like water running down the sink,
01:57:32 the gas swirls and then rubs against itself and heats up and shines very brightly because it’s
01:57:41 very hot close to the black hole. By viscosity, it heats up. And in the case of black holes,
01:57:49 it’s the turbulence, the turbulent viscosity that causes it to heat up. So we get these very bright
01:57:56 sources of light just from black holes that are supposed to be dark, nothing but black holes.
01:58:01 You know, nothing escapes from them, but they create a violent environment where gas moves
01:58:07 close to the speed of light and therefore shines very brightly, much more than any other source
01:58:12 in the sky. And we can see these quasars all the way to the edge of the universe.
01:58:17 So we have evidence now that when the universe was, you know, about 7% of its present age,
01:58:24 you know, infant, already back then you had black holes of a billion times the mass of the sun,
01:58:30 which is quite remarkable. It’s like finding giant babies in a nursery, you know, like how can these
01:58:38 black holes grow so fast? You know, less than a billion years after the Big Bang, you already have
01:58:43 a billion times the mass of the sun in these black holes. And the answer is presumably there are very
01:58:48 quick processes that build them up. They build quickly. Very quickly. And so we see those black
01:58:58 holes, and that was found in the mid 1960s. But in 2015, exactly 100 years after Einstein came up
01:59:08 with his theory of gravity, the LIGO observatory detected gravitational waves. And these are just
01:59:16 ripples in space and time. So according to Einstein’s theory, the innovation, the ingenuity
01:59:21 of Einstein’s theory of gravity that was formulated in November 1915 was to say that space and time
01:59:30 are not rigid. You know, they respond to matter. So, for example, if you have two black holes and
01:59:40 they collide, it’s just like a stone being thrown on the surface of a pond. They generate waves,
01:59:48 disturbances in space and time that propagate out at the speed of light. These are gravitational
01:59:53 waves. They create a space time storm around them, and then the waves go all the way through
01:59:59 the universe and reach us. And if you have a sensitive enough detector like LIGO, you can
02:00:05 detect these waves. And so it was not just the message that we received for the first time,
02:00:11 gravitational waves, but it was the messenger. So there are two aspects to it. One is the messenger
02:00:16 which is gravitational wave for the first time were detected directly. And the second was the
02:00:21 message, which was a collision of two black holes, because we could see the pattern of the ripples
02:00:27 in space and time. And it was fully consistent with the prediction that Schwarzschild made for
02:00:33 how the space time around the black hole is, because when two black holes collide, you can sort
02:00:39 of map from the message that you get, you can reconstruct what really happened and it’s fully
02:00:49 consistent. And in 2017 and 2020, there’s two Nobel prizes. That’s right. That had to do with the
02:01:00 black holes. Can you maybe describe in the same masterful way that you’ve already been doing what
02:01:07 the 2017 was given for the LIGO collaboration for discovering gravitation waves from collisions
02:01:13 of black holes? And the 2020 Nobel prize in physics was given for two things. One was
02:01:24 theoretical work that was done by Roger Penrose in the 1960s, demonstrating that black holes are
02:01:32 inevitable when stars collapse. And it was mostly mathematical work. And actually, Stephen Hawking
02:01:41 also contributed significantly to that frontier. And unfortunately, he is not alive, so he could
02:01:48 not be honored. So Penrose received it on his own. And then two other astronomers received it as well,
02:01:56 Andrea Ghez and Reinhard Genzel, and they provided conclusive evidence that there is a black hole at
02:02:03 the center of the Milky Way galaxy that weighs about 4 million times the mass of the sun. And
02:02:10 they found the evidence from the motion of stars very close to the black hole. Just like we see the
02:02:15 planets moving around the sun, there are stars close to the center of the galaxy and they are
02:02:21 orbiting at very high speeds of other thousands of kilometers per second or thousands of miles per
02:02:27 second per second. Think about it. Which can only be induced at those distances if there is a 4
02:02:37 million solar mass object that is extremely compact. And the only thing that is compatible
02:02:46 with the constraints is a black hole. And they actually made a movie of the motion of these
02:02:54 stars around the center. One of them moves around the center over a decade, over timescales that we
02:03:00 can monitor. And it was a breakthrough in a way. So combining LIGO with the detection of a black
02:03:11 hole at the center of the Milky Way and in many other galaxies like quasars, now I would say
02:03:20 black hole research is vogue. It’s very much in fashion. We saw it back in 2016 when we established
02:03:28 the black hole initiative. You kind of saw that there’s this excitement about in breakthroughs
02:03:37 and discoveries around black holes which are probably one of the most fascinating objects
02:03:42 in the universe. It’s up there. They’re both terrifying and beautiful and they capture the
02:03:49 entirety of the physics that we know about this universe. I should say the question is where is
02:03:53 the nearest black hole? Can we visit it? And I wrote a paper with my undergraduate student,
02:04:01 Amir Siraj, suggesting that perhaps if there is one in the solar system, we can detect it.
02:04:09 I don’t know if you heard, but there is a claim that maybe there is a
02:04:14 planet nine in the solar system because we see some anomalies at the outer parts of the solar
02:04:20 system. So some people suggested maybe there is a planet out there that was not yet detected. So
02:04:26 people searched for it, didn’t find it. It weighs roughly five times the mass of the earth. And we
02:04:32 said, okay, maybe you can’t find it because it’s a black hole that was formed early in the universe.
02:04:39 Where do you stand on that?
02:04:40 It could be that the dark matter is made of black holes of this mass. We don’t know what
02:04:44 the dark matter is made of. It could be the black holes. So we said, but there is an experimental
02:04:50 way to test it. And the way to do it is because there is the Oort cloud of icy rocks in the outer
02:04:59 solar system. And if you imagine a black hole there, every now and then a rock will pass close
02:05:06 enough to the black hole to be disrupted by the very strong gravity close to the black hole. And
02:05:12 that would produce a flare that you can observe. And we calculated how frequently these flares
02:05:17 should occur. And with LSST on the Vera Rubin Observatory, we found that you can actually
02:05:23 test this hypothesis. And if you don’t see flares, then you can put limits on the existence of a
02:05:29 black hole in the solar system. It would be extremely exciting if there was a black hole,
02:05:33 if planet nine was a black hole, because we could visit it and we can examine it. And it will not
02:05:41 be a matter of an object that is very removed from us. Another thing I should say is it’s
02:05:47 possible that the black hole affected life on Earth. The black hole at the center of the Milky
02:05:53 Way. How? That black hole right now is dormant. It’s very faint. But we know that it flares.
02:06:04 When a star like the sun comes close to it, the star will be spaghettified, basically become a
02:06:10 stream of gas, like a spaghetti. And then the gas would fall into the black hole and there would be
02:06:16 a flare. And this process happens once every 10,000 years or so. So we expect that these flares to
02:06:22 occur every 10,000 years. But we also see evidence for the possibility that gas clouds were disrupted
02:06:31 by the black hole, because the stars that are close to the black hole are residing in a single
02:06:36 or two planes. And the only way you can get that is if they formed out of a disk of gas,
02:06:42 just like the planets in the solar system formed. So there is evidence that gas fell into the black
02:06:48 hole and powered possibly a flare. And these flares produce x rays and ultraviolet radiation
02:06:56 that could damage life if the Earth was close enough to the center of the galaxy.
02:07:02 Where we are right now, it’s not very risky for us. But there is a theoretical argument that says
02:07:10 the solar system, the sun, was closer to the galactic center early on, and then it migrated
02:07:17 outwards. So maybe in the early stage of the solar system, the conditions were affected,
02:07:27 shaped by these flares of the black hole at the center of the galaxy. And that’s why
02:07:31 for the first two billion years, there wasn’t any oxygen in the atmosphere, who knows. But
02:07:37 it’s just interesting to think that from a theoretical concept that Einstein resisted in 1939,
02:07:44 it may well be that black holes have influence on our life. And that it’s just like discovering that
02:07:51 some stranger affected your family and in a way your life. And if that happens to be the case,
02:08:04 a second Nobel Prize should be given, not for just the discovery of this black hole at the
02:08:10 center of the galaxy, but perhaps for the Nobel Prize in chemistry, for the effect that it had.
02:08:15 For the effect for the interplay that resulted in some kind of, yeah, the chemical effect,
02:08:23 biology, I mean, all those kinds of things in terms of the emergence of life and the creation
02:08:30 of a habitable environment. That’s so fascinating. And of course, like you said, dark matter, like
02:08:35 black holes have some… They could be the dark matter in principle, yes. We don’t know what the
02:08:41 dark matter is at the moment. Does it make you sad? So you’ve had an interaction and perhaps
02:08:46 a bit of a friendship with Stephen Hawking. Does it make you sad that he didn’t win the Nobel?
02:08:52 Well, all together, I don’t assign great importance to prizes because, you know,
02:08:58 Jean Paul Sartre, who I admired as a teenager, because I was interested in philosophy. When I
02:09:04 grew up on a farm in Israel, I used to collect eggs every afternoon and I would drive the tractor to
02:09:11 the hills of our village and just think about philosophy, read philosophy books. And Jean Paul
02:09:16 Sartre was one of my favorites. And he was honored with a Nobel Prize in literature. He was a
02:09:22 philosopher primarily, existentialist. And he said, the hell with it. Why should I give
02:09:27 special attention to this committee of people that get their self importance from awarding me
02:09:36 the prize? Why does that merit my attention? So he gave up on the Nobel Prize. And
02:09:44 you know, there are two benefits to that. One, that you’re not working your entire life in the
02:09:52 direction that would satisfy the will of other people. You work independently, you’re not
02:09:57 after these honors. Just for the same reason that if you’re not living your life for making a profit
02:10:04 or money, you can live a more fulfilling life because you’re not being swayed by the wind,
02:10:10 you know, of how to make money and so forth. The second aspect of it is, you know, that
02:10:17 very often, you know, these prizes, they distort the way we do science because instead of people
02:10:29 willing to take risks, and instead of having announcements only after a group of people
02:10:36 converges with a definite result, you know, the natural progression of science is based on trial
02:10:44 and error, you know, reporting some results, and perhaps they’re wrong, but then other people find
02:10:50 perhaps better evidence, and then you figure out what’s going on. And that’s the natural way that
02:10:54 science is, you know, it’s a learning experience. So if you give the public an image by which
02:11:00 scientists are always right, you know, and you know, some of my colleagues say we must do that,
02:11:06 because otherwise the public will never believe us that global warming is really taking place.
02:11:10 But that’s not true, because the public would really believe you if you show the evidence. So
02:11:15 the point is, you should be sincere. When the evidence is not absolutely clear, or where there
02:11:19 are disputes about the interpretation of the evidence, we should show ourselves. You know,
02:11:23 the king is naked, okay? There is no point in pretending that the king is dressed,
02:11:30 saying that scientists are always right. Scientists are wrong, frequently. And the only way to make
02:11:36 progress is by evidence, giving us the support that we need to make airtight arguments. So when
02:11:43 you say global warming is taking place, if the evidence is fully supportive, there are no holes
02:11:49 in the argument, then people will be convinced, because you’re not trying to fool them. When the
02:11:55 evidence was not complete, you also show them that the evidence is not complete.
02:11:58 And when there’s holes, you show that there’s holes, and here’s the methodology we’re using
02:12:02 to try to close those holes. Exactly. Let’s be sincere. Why pretend? So if there were no,
02:12:06 in a world where there were no prizes, no honours, we would act like kids, as I said before.
02:12:13 We would really be focusing on the ball and not on the audience. Yeah, the prizes get in the way,
02:12:19 and it’s so powerful. Do you think, in some sense, the few people that have turned down the prize
02:12:26 made a much more powerful statement? I don’t know if you’re familiar in the space of mathematics
02:12:31 with the Fields Medal and Google Perlman turned down the prize. One of the reasons I started
02:12:40 this podcast is I’m going to definitely talk to Putin, I’m definitely talking to Perlman,
02:12:46 and people keep telling me it’s impossible. I love hearing that, because I’ll talk to both.
02:12:52 Anyway, but do you have a sense of why he turned down the prize,
02:13:00 and is that a powerful statement to you? Well, what I read is that he was disappointed by the
02:13:10 response of the community, the mainstream community, the mathematicians, to his earlier work,
02:13:17 where they dismissed it, they didn’t attend to the details, and didn’t treat him with proper
02:13:24 respect, because he was not considered one of them. And I think that speaks volumes about the
02:13:32 current scientific culture, which is based on groupthink and on social interaction, rather
02:13:42 than on the merit of the argument, and on the evidence in the context of physics. So in mathematics
02:13:47 there is no empirical basis, you’re exploring ideas that are logically consistent, but nevertheless
02:13:54 there is this groupthink. And I think he was so frustrated with his past experience that he didn’t
02:14:02 even bother to publish his papers, he just posted them on the archive, and in a way saying, you know,
02:14:09 I know what the answer is, go look at it. And then again, in the long arc of history,
02:14:17 his work on archive will be remembered, and all the prizes, most of the prizes will be forgotten,
02:14:23 that’s what people don’t kind of think about. When you look at Roger Penrose, for example,
02:14:29 is another fascinating figure, you know, it’s possible, and forgive me if this, I’m sure,
02:14:35 my ignorance, but he’s also did some work on consciousness. He’s been one of the only people
02:14:40 who spoke about consciousness, which for the longest time, and is still arguably outside
02:14:47 the realm of the sciences. It’s still seen as a taboo subject, and he was brave enough to explore
02:14:55 it from a physics perspective, from just a philosophical perspective, but like with the rigor,
02:15:01 like proposing different kind of hypotheses of how consciousness might be able to emerge in the brain,
02:15:07 and it’s possible that that is the thing he’s remembered for if you look 100 years from now,
02:15:11 right? As opposed to the work in the black holes, which fits into what the current scientific
02:15:22 community allows to be the space of what is and isn’t science. Yeah, it’s really interesting to
02:15:30 look at people that are innovators, where in some phases of their career, their ideas fit into the
02:15:37 social structure that is around them, but in other phases, it doesn’t. And when you look at them,
02:15:44 they just operated the same way throughout, and it says more about their environment than about them.
02:15:51 Well, yeah, and I don’t know if you know who Max Tegmark is, I just recently talked to him.
02:15:55 He’s a friend of mine.
02:15:56 I just recently talked to him again, and he, I mean, he was a little bit more explicit about
02:16:01 saying, you know, being aware, which is something I also recommend, is like being aware where the
02:16:06 scientific community stands, and doing enough to get, like move along into your career, in your
02:16:11 career. And it’s the necessary evil, I suppose, if you are one of those out of the box thinkers that
02:16:17 just naturally have this childlike curiosity, which Max definitely is one of them, is sometimes
02:16:23 you have to do some stuff that fits in, you publish and you get tenure and all those kinds of things.
02:16:27 But the tenure is a great privilege because it allows you to, in principle, explore things that
02:16:32 are not accepted by others. And unfortunately, it’s not being taken advantage of by most people,
02:16:40 and it’s a waste of a very precious resource.
02:16:43 Yeah, absolutely. The space that you kind of touched on that’s full of theories and is perhaps
02:16:52 detached from appreciation of empirical evidence, or longing for empirical evidence, or grounding
02:17:00 in empirical evidence, is the theoretical physics community and the interest in unifying the laws
02:17:07 of physics and with the theory of everything. I’m not sure from which direction to approach this
02:17:15 question, but how far away are we from arriving at a theory of everything, do you think? And how
02:17:25 would we, how important is it to try to arrive at it, at this kind of goal of this beautiful simple
02:17:33 theory that unlocks the very, you know, fundamental basis of our nature as we know it? And, you know,
02:17:45 and how, what are the kinds of approaches we need to take to get there?
02:17:50 Yeah, so in physics, the biggest challenge is to unify quantum mechanics with gravity.
02:17:56 And I believe that once we have experimental evidence for how this happens in nature,
02:18:04 in systems that have quantum mechanical effects, but also gravity is important,
02:18:09 then the theory will fall into our lap, okay? But the mistake that is made by the community
02:18:17 right now is to come up with the right theory from scratch. And, you know, Einstein gave the
02:18:25 illusion that you can just sit in your office and understand nature, you know, when he came up with
02:18:30 his general theory of relativity. But, you know, first of all, perhaps he was lucky, but it’s not
02:18:38 a rule. The rule is that you need evidence to guide you, especially when dealing with quantum
02:18:42 mechanics, which is really not intuitive. And so there are two places where the two theories meet.
02:18:52 One is black holes, and there is a puzzle there. It’s called the information paradox.
02:18:58 In principle, you can throw the Encyclopedia Britannica into a black hole. It’s a lot of
02:19:02 information. And then it will be gone because a black hole carries only three properties or
02:19:12 qualities, the mass, the charge, and the spin, according to Einstein. But then when Hawking
02:19:19 tried to bring in quantum mechanics to the game, he realized that black holes have a temperature
02:19:26 and they radiate. This is called Hawking radiation. It was sort of anticipated by
02:19:35 Jacob Bekenstein before him, and Hawking wanted to prove Bekenstein wrong and then figure this out.
02:19:42 And so what it means is black holes eventually evaporate. And they evaporate into radiation that
02:19:48 doesn’t carry this information, according to Hawking’s calculation. And then the question is,
02:19:53 according to quantum mechanics, information must be preserved. So where did the information go
02:20:00 if a black hole is gone? And where is the information that was encoded in the Encyclopedia
02:20:06 when it went into the black hole? And to that question, we don’t have an answer yet. It’s one
02:20:12 of those puzzles about black holes. And it touches on the interplay between quantum mechanics and
02:20:17 gravity. Another important question is what happened at the beginning of the universe?
02:20:24 What happened before the Big Bang? And by the way, on that, I should say, you know, there are some
02:20:31 conjectures. In principle, if we figure it out, if we have a theory of quantum gravity,
02:20:37 it’s possible to imagine that we will figure out how to create a universe in the laboratory.
02:20:43 And by irritating the vacuum, you might create a baby universe. And if we do that,
02:20:50 it will offer a solution to what happened before the Big Bang. Perhaps the Big Bang emerged from
02:20:55 the laboratory of another civilization. So it’s like baby universes are being born out of
02:21:01 laboratories. And inside the baby universe, you have a civilization that brings to existence a
02:21:07 new baby universe. So just like humans, right? We have babies and they make babies. So in principle,
02:21:13 that would solve the problem of why there was a Big Bang and also what happened before the Big
02:21:19 Bang. So we came, our umbilical cord is connected to a laboratory of a civilization that produced
02:21:26 our universe once it figured out quantum gravity, you know. It’s baby Big Bangs all the way down.
02:21:36 So if we collect data about how the universe started, we could potentially test
02:21:40 theories of, or it can educate us about how to unify quantum mechanics and gravity.
02:21:45 If we get any information about what happens near the singularity of a black hole,
02:21:50 you know, if we get a sense of, you know, somehow we learn what happens at the same,
02:21:56 that would educate. So there are places where we can search for evidence, but it’s very challenging,
02:22:03 I should say. And my point is, you know, the string theorists, they decided that they know
02:22:08 how to approach the problem, that they don’t have a single theory. There is a multitude of theories
02:22:15 and it’s not tightly constrained and they cannot make predictions about black holes or about the
02:22:21 beginning of the universe. So at the moment I say we’re at a loss. And the way I feel about this
02:22:27 concept of the theory of everything, we should wait until we get enough evidence to guide us.
02:22:32 And until then, you know, there are many important problems that we can address,
02:22:36 you know. Why bang our head against the wall on a problem for which we have no guidance?
02:22:43 Right. We don’t have a good dance partner in terms of evidence. There’s not.
02:22:46 Exactly.
02:22:47 I mean, it’d be interesting, just like you said, I mean, the lab is one place to create
02:22:53 universes or black holes, but it’d be fascinating if there is indeed a black hole in our solar
02:22:58 system that you can interact with. So the problem with the origin of the universe
02:23:03 is all you can do is collect data about it, right? You can’t interact with it.
02:23:07 Well, you can, for example, detect gravitational waves that emerged from that. And, you know,
02:23:13 there is an effort to do that and that could potentially tell us something. But yeah,
02:23:18 it’s a challenge and that’s why we’re stuck. So I should say, despite what physicists portray,
02:23:25 that, you know, we live through an exceptional growth in our understanding of the universe,
02:23:31 we’re actually pretty much stuck, I would say, because we don’t know the nature of the dark
02:23:36 matter. Most of the matter in the universe, we don’t know what it is. And we don’t know how
02:23:40 the universe started. We don’t know what happens in the interior of a black hole.
02:23:45 Because you’ve thought quite a bit about dark matter as well. Do you have any kind of hypothesis,
02:23:50 interesting hypothesis? We already mentioned a few about what is dark matter and what are the
02:23:55 possible paths that we could take to unlock the mystery of dark? What is dark matter?
02:24:01 Yeah. So what we need is some anomalies that would hint what the nature of the dark matter is,
02:24:07 or to detect it in the laboratory. There are lots of laboratory experiments searching,
02:24:11 but it’s like searching for a needle in a haystack, because there are so many possibilities
02:24:15 for the type of particle that it may be. But maybe at some point, you know, we’ll find either
02:24:21 a particle or black holes as the dark matter, or something else. But at the moment…
02:24:26 Can you also maybe, sorry to interrupt, comment about what is dark matter?
02:24:30 Like what, it’s just a name we assign to what?
02:24:33 So most of the community believes that it’s a particle that we haven’t yet detected. It doesn’t
02:24:40 interact with light, so it’s dark. But the question is, what does it interact with,
02:24:46 and how can we find it? And for many years, physicists were guided by the idea that
02:24:52 it’s some extension of the standard model of particle physics. But then they said,
02:24:57 oh, we will find some clues from the Large Hadron Collider about its nature. Or maybe
02:25:03 it’s related to supersymmetry, which is a new symmetry that we haven’t found any evidence for.
02:25:07 In both cases, the Large Hadron Collider did not give us any clues. And other people search for
02:25:13 specific types of particles in the laboratory and didn’t find any. A couple of years ago,
02:25:19 actually, around the time that I worked on Oumuamua, I also worked on the possibility that
02:25:25 the dark matter particles may have a small electric charge, which is a speculation, but
02:25:32 nobody complained about it. And, you know, it was published and I regarded it more as
02:25:38 of a speculation than the artificial origin of Oumuamua. And to me, I apply, you know,
02:25:44 as far as I’m concerned, I apply the same scientific tools in both cases. There is an
02:25:48 anomaly that led me to that discussion, which has to do with hydrogen being cold in the early
02:25:55 universe more than we expected. So we suggested maybe the dark matter particles have some small
02:25:59 charge. But then you deal with anomalies by exploring possibilities. That’s the only way to
02:26:05 do it, and then collecting more data to check those. And searching for technological signatures
02:26:14 is the same as any other part of our scientific endeavor. We make hypotheses and we collect data,
02:26:23 and I don’t see any reason for having a taboo on this subject.
02:26:27 In your childlike, open minded excitement and approach to science, you’re, I think,
02:26:33 to anyone listening to this, truly inspiring. I mean, the question I think is useful to ask
02:26:38 is by way of advice for young people. A lot of young people listen to this, whether from all
02:26:45 over the world, and teenagers, undergraduate students, even graduate students, even young
02:26:53 faculty, even older faculty, they’re all young at heart. Like there’s many of them young at heart.
02:26:58 Do you have advice for, but let’s focus on the traditionally defined sort of young folks that
02:27:04 kind of graduate. Do you have advice to give to young people like that today about life,
02:27:10 maybe in general, maybe a life of curiosity in the sciences?
02:27:14 Definitely. Well, first, I should confess that I enjoy working with young people much more than
02:27:20 with senior people. And the reason is they don’t carry a baggage of prejudice. They’re not so
02:27:26 self centered. They’re open to exploration. My advice, I mean, one of the lessons that
02:27:34 took me a while to learn, and I should say I lost important opportunities as a result of that. So
02:27:40 I would regard it as a mistake on my behalf, was to believe experts. So, quote unquote. So on a
02:27:50 on a number of occasions, I would come up with an original idea and then suggest it to an expert,
02:27:57 someone that works in the same field for a while. And the expert would dismiss it most of the time
02:28:04 because it’s new and was not explored, not because of the merit. And then what happened to me several
02:28:11 times is that someone else would listen to the conversation or would hear me suggesting it.
02:28:17 And I would give up because the expert said no. And then that someone else would develop it so
02:28:25 that it becomes the hottest thing in this field. And once it happened to me multiple times,
02:28:31 I then realized the hell with the experts. They don’t know what they’re doing. They’re
02:28:36 just repeating them. They don’t think creatively. They are being threatened by innovation. And it’s
02:28:45 the natural reaction of someone that cares about their ego more than about the matter
02:28:52 that we are discussing. And so I said, I don’t care how many likes I have on Twitter. I don’t
02:28:57 care whether the experts say one thing or another. I will basically exercise my judgment and do the
02:29:03 best I can. Turns out that I’m wrong. I made a mistake. That’s part of the scientific endeavor.
02:29:10 And it took me a while to recognize that. And it was a lot of wasted opportunities. So to the
02:29:16 young people, I would recommend don’t listen to experts. Carve your own path. Now, of course,
02:29:24 you will be wrong. You should learn from experience, just like kids do. But do it yourself.
02:29:30 Your father died in 2017. Your mother died in 2019. Do you miss them?
02:29:40 Very much so.
02:29:42 Is there a memory, that fond memory that stands out? Or maybe what have you learned from them?
02:29:50 From my mother, I mean, she was very much my inspiration for pursuing intellectual work,
02:30:00 because she studied at the university. And then because of the Second World War,
02:30:08 after the Second World War, she was born in Bulgaria. They immigrated to Israel. And she
02:30:15 and she left university to work on a farm. And later in life, when all the kids left home,
02:30:24 she went back to the university and finished the PhD. But she planted in me the intellectual
02:30:30 curiosity and valuing learning or acquiring knowledge as a very important element in life.
02:30:41 And my love with philosophy came from attending classes that she took at the university.
02:30:50 When I was a teenager, I was fortunate to go to some of these and they inspired me later on. And
02:30:58 I’m very different than my colleagues, as you can tell, because my upbringing was quite different.
02:31:03 And the only reason I’m doing physics or astrophysics is because of circumstances.
02:31:08 At age 18, I was asked to serve in the military. And the only way for me to pursue intellectual
02:31:17 work was to work on physics, because that was the closest to philosophy. And I was good at physics.
02:31:25 So they admitted me to an elite program called LPO that allowed me to finish my PhD
02:31:30 at age 24 and to actually propose the first international project that was funded by the
02:31:38 Star Wars initiative of Ronald Reagan. And that brought me to the US to visit Washington, DC,
02:31:45 where we were funded from. And then on one of the visits, I went to the Institute for Advanced
02:31:51 Study at Princeton and met John Bacall that later offered me a five year fellowship there. Under the
02:31:59 under the condition that I’ll switch to astrophysics. At which point, you know, I said,
02:32:03 OK, I cannot give up on this opportunity. I’ll do it. Switch to astrophysics. It felt like a forced
02:32:10 marriage, kind of arranged marriage. And then I was offered the position at Harvard because
02:32:15 nobody wanted that. They first selected someone else. And that someone said, I don’t want to
02:32:22 become a junior faculty at the Harvard Astronomy Department because the chance for being promoted
02:32:27 are very small. So he took another job. And then I was second in line. They gave it to me. I didn’t
02:32:33 care much because I could go back to the farm any day, you know. And after three years, I was
02:32:39 tenured. And eventually, a decade later, became the chair of this department and served for nine years
02:32:46 as the chair of the astronomy department at Harvard. But at that point, it became clear
02:32:51 to me that I’m actually married to the love of my life, even though it was an arranged marriage.
02:32:56 There are many philosophical questions in astrophysics that we can address. But I’m still
02:33:01 very different than my colleagues, you know, that were focusing on technical skills in getting to
02:33:07 this job. So my mother was really extremely instrumental in planting the seeds of thinking
02:33:17 about the big picture in me. Then my father, he was, you know, he was working in the farm.
02:33:24 And we didn’t speak much because we sort of understood each other without speaking.
02:33:30 But what he gave me is a sense of, you know, that it’s more important to do things than to
02:33:39 talk about them. I love the, I mean, my apologies, but MIT mind and hand. I love that there’s
02:33:47 that the root of philosophy that you gain from your mom and the hand, that action is all that
02:33:54 ultimately in the end matters from your dad. That’s really powerful. If we could take a small
02:34:00 detour into philosophy, is there by chance any books, authors, whether philosophical or not,
02:34:10 you mentioned Sartre, that stand out to you that were formative in some small or big way,
02:34:15 that perhaps you would recommend to others, maybe when you were very young or maybe later on in life?
02:34:20 Well, actually, yeah, I, you know, I read the number of existentialists that
02:34:27 appealed to me because they were authentic. You know, Sartre, you know, he declined the Nobel
02:34:32 Prize, as we discussed, but he also was mocking people that pretend to be something better than
02:34:39 they are. You know, he was living an authentic life that is sincere. And that’s what appealed to me.
02:34:45 And Albert Camus was another French philosopher that advocated existentialism. You know, that
02:34:53 really appealed to me. That’s probably my favorite existentialist, Camus. Yeah. Yeah. And he died at
02:34:58 a young age in an accident, unfortunately. And then, you know, people like Nietzsche that, you
02:35:07 know, broke conventions. And I noticed that Nietzsche is still extremely popular. You know,
02:35:16 that’s quite surprising. He appeals to the young people of today. It’s the childlike wonder
02:35:25 about the world. And he was unapologetic. You know, it’s like most philosophers have a very
02:35:30 strict adherence to terminology and to the practices, academic philosophers. And Nietzsche was full of
02:35:36 contradictions. And he just, I mean, he was just this big kid with opinions and thought deeply
02:35:44 about this world. And people are really attracted to that. And surprisingly, there’s not enough
02:35:49 people like that throughout history of philosophy. And that’s why I think he’s still drawn to them.
02:35:55 Yeah. To me, what stands out is his statement that the best way to corrupt the mind of young people
02:36:03 is to tell them that they should agree with the common view, you know. And, you know, it goes back
02:36:11 to the thread that went throughout discussion. Yes. You’ve kind of suggested that we ought to
02:36:18 be humble about our very own existence and that our existence lasts only a short time. We talked
02:36:25 about you losing your father and your mother. Do you think about your own mortality? Are you afraid
02:36:34 of death? I’m not afraid. You know what, Epicurus, actually Epicurus was a very wise person.
02:36:41 According to Lucretius, Epicurus didn’t leave anything in writing. But he said that he’s never
02:36:48 afraid of death because as long as he’s around, death is not around. And when death will be around,
02:36:56 he will not be around. So he will never meet death. So why should you be worried about something
02:37:01 you will never meet? You know, and it’s an interesting philosophy of life. You know,
02:37:06 you shouldn’t be afraid of something that you will never encounter, right?
02:37:09 But there’s a finiteness to this experience. We live every day.
02:37:13 I mean, I think if we’re being honest, we live every day as if it’s going to last forever.
02:37:20 We often kind of don’t contemplate the fact that it ends. You kind of have plans and goals and you
02:37:26 have these possibilities. You have a kind of lingering thought, especially as you get older
02:37:31 and older and older, that this is, especially when you lose friends, then you start to realize,
02:37:38 you know, it does end. But I don’t know if you really are cognizant of that. I mean,
02:37:43 because… But you have to be careful not to be depressed by it, because otherwise you lose the
02:37:48 vitality, right? So I think the most important thing to draw from knowing that you are short lived
02:37:56 is a sense of appreciation that you’re alive. That’s the first thing. But more importantly,
02:38:02 a sense of modesty, because how can anyone be arrogant if they kept at the same time this
02:38:09 notion that they are short lived? I mean, you cannot be arrogant, because anything that you
02:38:14 advocate for, you know, you will not be around to do that in a hundred years. So people will
02:38:19 just forget and move on, you know. And if you keep that in mind, you know, the Caesars in ancient
02:38:26 Rome, they had a person next to them telling them, don’t forget that you are mortal. You know,
02:38:32 there was a person with that duty because the Caesars thought that they are all powerful,
02:38:37 you know. And they had, for a good reason, someone they hired to whisper in their ear,
02:38:47 don’t forget that you are mortal. Yeah. Well, you’re somebody, one of the most respected,
02:38:55 famous scientists in the world, sitting on a farm, gazing up at the stars. So you seem like
02:39:00 an appropriate person to ask the completely inappropriate question of, what do you think
02:39:05 is the meaning of it all? What’s the meaning of life? That’s an excellent question. And if we ever
02:39:11 find an alien that we can converse with, I would like to answer this. I would like to ask for an
02:39:16 answer to this question because… Would they have a different opinion, you think? Well, they might be
02:39:21 wiser because they lived around for a while, but I’m afraid they will be silent. I’m afraid they
02:39:27 will not have a good answer. And I think it’s the process that you should get satisfied by,
02:39:38 the process of learning you should enjoy. Okay, so it’s not so much that there is a meaning.
02:39:45 In fact, there is, as far as I can tell, things just exist, you know. And I think it’s inappropriate
02:39:55 for us to assign a meaning for our existence because, as a civilization, we will eventually
02:40:01 perish and nothing will be… Just another planet on which life died. And if you look at the big
02:40:10 scheme of things, who cares? Who cares? And how can we assign significance to what we are doing?
02:40:17 So if you said the meaning of life is this, well, it will not be around in a billion years. So
02:40:23 it cannot be the meaning of life because nothing will be around. So I think we should just enjoy
02:40:31 the process. And it’s like many other things in life, you enjoy good food, okay? And you can enjoy
02:40:39 learning. Why? Because it makes you appreciate better the environment that you live in.
02:40:47 And sometimes people think religion, for example, is in conflict with science, spirituality.
02:40:55 That’s not true. If you see a watch and you look at it from the outside, you might say,
02:41:04 oh, that’s interesting. But then if you start to open it up and learn about how it works,
02:41:08 you appreciate it more. So science is the way to learn about how the world works. And
02:41:14 it’s not in conflict to the meaning that you assign to all of this, but it helps you appreciate the
02:41:21 world better. So in fact, I would think that a religious person should promote science because
02:41:27 it gives you a better appreciation of what’s around you. It’s like if you buy in a grocery,
02:41:34 buy something, a bunch of fruits that are packed together, and you can’t see from the outside
02:41:42 exactly what kind of fruits are inside. But if you open it up and study, you appreciate better
02:41:47 the merchandise that you get, right? So you pay the same amount of money, but at least you know
02:41:51 what’s inside. So why don’t we figure out what the world is about, what the universe contains,
02:41:56 what is the dark matter? It will help us appreciate the bigger picture. And then you can assign
02:42:02 your own flavor to what it means. Ali, I think I’m truly grateful that a person like you,
02:42:11 exists at the center of the scientific community, gives me faith and hope about this big journey
02:42:19 that we call science. So thank you for writing the book you wrote recently. You have many other books
02:42:26 and articles that I think people should definitely read. And thank you for wasting all this time with
02:42:32 me. It’s truly an honor. Thank you so much. It was not a waste at all. And thank you for having me.
02:42:36 I learned a lot from your questions and your remarks. Thank you. Thank you. Thanks for listening to this
02:42:43 conversation with Avi Loeb. And thank you to our sponsors, Zero Fasting App for intermittent
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02:43:14 this podcast. And now let me leave you some words from Albert Einstein. The important thing is not
02:43:20 to stop questioning. Curiosity has its own reason for existence. One cannot help but be in awe when
02:43:27 he contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough
02:43:34 if one tries merely to comprehend a little of this mystery every day. Thank you for listening
02:43:40 and hope to see you next time.