#213 – Barry Barish: Gravitational Waves and the Most Precise Device Ever Built

[0] The following is a conversation with Barry Barish, a theoretical physicist at Caltech and the winner of the Nobel Prize in Physics for his contributions to the LIGO detector and the observation of gravitational waves.

[1] Ligo, or the laser interferometer gravitational wave observatory, is probably the most precise measurement device ever built by humans.

[2] It consists of two detectors with four -kilometer -long vacuum chambers situated 3 ,000 kilometers apart, operating in unison to measure a motion that is 10 ,000 times smaller than the width of a proton.

[3] It is the smallest measurement ever attempted by science, a measurement of gravitational waves caused by the most violent and cataclysmic events in the universe, occurring over tens of millions of light years away.

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[75] This is the Lex Friedman podcast, and here is my conversation with Barry Parrish.

[76] You've mentioned that you were always curious about the physical, world and that an early question you remember stood out where you asked your dad why does ice float on water and he couldn't answer and this was very surprising to you so you went on to learn why maybe you can speak to what are some early questions in math and physics that really sparked your curiosity yeah that that memory is kind of something i used to illustrate something i think that's common in science, that people that do science somehow have maintained, maintain something that kids always have.

[77] A small kid, eight years old or so, asked you so many questions usually, typically that you consider them pests, you know, tell them to stop asking so many questions.

[78] And somehow our system manages to kill that in most people.

[79] So in school, in school, we make people to study and do their things, but not to pester them by asking too many questions.

[80] And I think not just myself, but I think it's typical of scientists like myself that have somehow escaped that.

[81] Maybe we're still children, or maybe we somehow didn't get it beaten out of us.

[82] But I think it's, I teach it in college level, and it's, to me, one of the biggest deficits this is the lack of curiosity, if you want, that we've beaten out of them, because I think it's an innate human quality.

[83] Is there some advice or insights you can give to how to keep that flame of curiosity going?

[84] I think it's a problem of both parents, and the parents should realize that's a great quality we have.

[85] You're curious, and that's good.

[86] Instead, we have expressions like curiosity killed the cat.

[87] And more.

[88] Basically, it's not thought to be a good thing.

[89] Curiosity, kill the cat.

[90] It means if you're too curious, you get in trouble.

[91] I don't like cats anyway, so maybe it's a good thing.

[92] Yeah.

[93] That, to me, needs to be solved, really, in education and in homes.

[94] It's a realization that there's certain human qualities that we should try to build on and not destroy one of them as curiosity.

[95] Anyway, back to me in curiosity, I was a pest and asked a lot of questions.

[96] my father generally could answer them at that age and the first one I remember that he couldn't answer was not a very original question but basically that ice is made out of water and so why does it float on water and he couldn't answer it and it may not have been the first question it's the first one that I remember and that was the first time that I realized that to learn and answer your own curiosity or questions, there's various mechanisms.

[97] In this case, it was going to a library and or asking people who know more and so forth.

[98] But eventually you do it by what we call research.

[99] But it's driven by, hopefully, you ask good questions.

[100] If you ask good questions and you have the mechanisms to solve them, then you do what I do in life, basically.

[101] Not necessarily physics, but, and it's a great quality in humans, and we should nurture it.

[102] Do you remember any other kind of in high school, maybe early college, more basic physics ideas that sparked your curiosity or mathematics or science in general?

[103] I wasn't really into science until I got to college, to be honest with you.

[104] But just staying with water for a minute.

[105] I remember that I was curious why, what happens to water?

[106] You know, it rains and there's water in a wet pavement, and then the pavement dries out.

[107] What happened to this water that came down?

[108] And I, you know, I didn't know that much.

[109] And then eventually I learned in chemistry or something, water's made out of hydrogen and oxygen.

[110] Those are both gases.

[111] So how the heck does it make this substance?

[112] It's liquid.

[113] Yeah, so that has to do with states of matter.

[114] I know perhaps LIGO and the thing for which you've gotten the Nobel Prize and the things much of your life work perhaps was a happy accident in some sense in the early days.

[115] But is there a moment where you looked up to the stars and also the same way you wandered about water, wandered about some of the things that are out there in the universe?

[116] oh yeah i think everybody's looks and is in awe and is curious about what what it is out there and you know and as i learned more i learned of course that we don't know very much about what's there and the more we learn the more we know we don't know i mean we don't know what the majority of anything is out there it's all what we call dark matter dark energy and that's one of the big questions 20 years when I was a student those weren't questions so we even know less in a sense the more we the more we look so of course I think that's one of the areas that um almost it's universal people see the sky they see the stars and they're beautiful and and see it looks different on different nights and it's a curiosity that we all have what are some questions about the universe that in the same way that you felt about the ice that today you mentioned to me offline you're teaching a course on the frontiers of science frontiers of physics yeah what are some questions outside the ones we'll probably talk about that kind of yeah fill you with uh get your flame of curiosity up and uh firing up yeah you know fill you with all well first i'm a physicist, not an astronomer.

[117] So I'm interested in the physical phenomenon, really.

[118] So the question of dark matter and dark energy, which we probably won't talk about, are recent, their last 20, 30 years, or certainly dark energy.

[119] Dark energy is a complete puzzle.

[120] It goes against what you will ask me about, which is general relativity, and Einstein's general relativity.

[121] It basically takes something that thought was what he called a constant, which isn't, and if that's even the right theory, and it represents most of the universe.

[122] And then we have something called dark matter, and there's good reason to believe it might be an exotic form of particles.

[123] And that is something I've always worked on particle accelerators and so forth.

[124] And it's a big puzzle, what it is.

[125] It's a bit of a cottage industry and that there's lots and lots of searches.

[126] But it may be a little bit like, you know, looking for a treasure under rocks or something.

[127] You don't, it's hard to, we don't have really good guidance except that we have very, very good information that it's pervasive and it's there.

[128] And that it's probably particles, small, that the evidence is all of those things.

[129] but then the most logical solution doesn't seem to work, something called supersymmetry.

[130] And do you think the answer could be something very complicated?

[131] You know, I like to hope that think that most things that appear complicated are actually simple if you really understand them.

[132] I think we just don't know at the present time, and it isn't something that affects us.

[133] It does affect, it affects how the stars go around each other and so forth, because we detect that there's missing gravity, but it doesn't affect everyday life at all.

[134] I tend to think and expect maybe, and that the answers will be simple, and we just haven't found it yet.

[135] Do you think those answers might change the way we see other sources of gravity, black holes, the way we see the parts of the universe that we do study?

[136] It's conceivable.

[137] The black holes that we found in our experiment, and we're trying now to understand the origin of those.

[138] It's conceivable, but it doesn't seem the most likely, that they were primordial.

[139] That is, they were made at the beginning.

[140] And in that sense, they could represent at least part of the dark matter.

[141] So there can be connections, and stark black holes are how many there are, how much of the mass they encompass is still pretty primitive, we don't know.

[142] So before I talk to you more about black holes, let me take a step back to, I actually went to high school in Chicago and we'll go to take classes at Fermilab, watch the Buffalo and so on.

[143] Yeah.

[144] So let me ask about, you mentioned that Enrico for me, was somebody who was inspiring to you in a certain kind of way, Why is that?

[145] Can you speak to that?

[146] Sure.

[147] He was amazing, actually.

[148] He's the last, this is not the, I'll come to the reason in a minute, but he had a big influence on me at a young age.

[149] But he was the last physicist of note that was both an experimental physicist and a theorist at the same time.

[150] And he did two amazing things within months.

[151] In 1933, it was, we didn't really know what the nucleus was, what radioactive decay was, what beta decay was when electrons come out of a nucleus.

[152] And near the end of 1933, the neutron had just been discovered.

[153] And that meant that we knew a little bit more about what the nucleus is, that it's made out of neutrons and protons.

[154] The neutron wasn't discovered till 1932.

[155] And once we discovered that there was a neutron and proton and they made the nucleus and then their electrons that go around, the basic ingredients were there.

[156] And he wrote down not only just the theory, a theory, but a theory that lasted decades and has only been improved on of beta decay, that is the radiation.

[157] He did this, came out of nowhere, and it was a fantastic theory.

[158] He submitted it to Nature magazine, which was the primary best place to publish even then.

[159] And it got rejected as being too speculative.

[160] And so he went back to his drawing board in Rome, where he was, added some to it, made it even longer, because it's really a classic article.

[161] And then published, it in the local Italian journal for physics and the German one.

[162] At the same time, in January of 1932, Giulio and Curie for the first time saw artificial radioactivity.

[163] This was an important discovery because radioactivity had been discovered much earlier.

[164] They had x -rays and you shouldn't be using them, but there was radioactivity.

[165] people knew it was useful for medicine, but radioactive materials are hard to find, and so it wasn't prevalent.

[166] But if you could make them, then they had great use.

[167] And Giulio and Curie were able to bombard aluminum or something with alpha particles and find that they excited something that decayed and gave, decayed and had some half -life and so forth, meaning it was artificial version.

[168] are, let's call it a not a natural version, an induced version of radioactive materials.

[169] And Fermi somehow had the insight, and I still can't see where he got it, that the right way to follow that up was not using charged particles like alphas and so forth, but use these newly discovered neutrons as the bombarding particle.

[170] It seemed impossible.

[171] They barely had been seen.

[172] It was hard to get very many of them.

[173] But it had the advantage that they're not charged, so they go right into the nucleus.

[174] And that turned out to be the experimental work that he did that won him the Nobel Prize.

[175] And it was the first step in fission.

[176] discovery of fission.

[177] And he did this two completely different things, an experiment that was a great idea and a tremendous implementation, because how do you get enough neutrons?

[178] And then he learned quickly that not only do you want neutrons, but you want really slow ones.

[179] He learned that experimentally, and he learned how to make slow ones, and then they were able to go through the periodic table and make lots of particles.

[180] He missed on fission at the moment, but he had the basic information, and then fission follows soon after that.

[181] Forgive me for not knowing, but is the birth of the idea of bombarding with neutrons, is that an experimental idea?

[182] Was it born out of an experiment?

[183] He just observed something, or is this an Einstein -style idea where you come up from I think it took a combination because he realized that neutrons had a characteristic that would allow them to go all the way into the nucleus when we didn't really understand what the, you know, what the structure was of all this.

[184] So that took an understanding or recognition of the physics itself of how a neutron interacts compared to, say, an alpha particle that Julio and Curie had used.

[185] and then he had to invent a way to have enough neutrons and he had a team of associates and he pulled it off quite quickly so it was pretty astounding and probably maybe you can speak to it his ability to put together the engineering aspects of great experiments and doing the theory they probably fed each other I wonder can you speak to why we don't see more of that Is that just really difficult to do?

[186] It's difficult to do.

[187] Yeah, I think in both theory and experiment in physics anyway, was it was conceivable if you had the right person to do it, and no one's been able to do it since.

[188] So I had the dream that that was what I was going to be like Fermi.

[189] So you love both sides of it, the theory.

[190] Yeah, yeah.

[191] I never liked the idea that you did experiments without really understanding the theory or the theory should be related very closely to experiments.

[192] And so I've always done experimental work that was closely related to the theoretical ideas.

[193] I think I told you I'm Russian, so I'm going to ask some romantic questions.

[194] But is it tragic to you that he's seen as the architect of the nuclear age, that some of his creations led to potentially some of his work has led to potentially still the destruction of the human species.

[195] Some of the most destructive weapons.

[196] Yeah.

[197] I think even more general than him, I gave you all the virtues of curiosity a few minutes ago.

[198] There's an interesting book called The Ratchet of Curiosity.

[199] You know, a ratchet is something that goes in one direction.

[200] And that is written by a guy who's probably a sociologist or philosopher or something.

[201] And he he picks on this particular problem but other ones, and that is the danger of knowledge, basically.

[202] You're curious, you learn something.

[203] So it's a little bit like curiosity killed the cat.

[204] You have to be worried about whether you can handle new information that you get.

[205] So in this case, the new information had to do with really understanding nuclear physics.

[206] And that information, maybe we didn't have the sophistication to know how to keep it under control.

[207] Yeah, and Fermi himself was a very apolitical person, so he wasn't very driven by, or at least he appears in all of his writing, the writing of his wife, the interactions that others had with him as either he avoided it all, or he was pretty apolitical.

[208] I mean, he just saw the world through kind of lens of a scientist.

[209] But you asked if it's tragic.

[210] The bomb was tragic, certainly on Japan.

[211] and he had a role in that.

[212] So I wouldn't want it as my legacy, for example.

[213] I mean, but brought it to the human species that it's the ratchet of curiosity that we do stuff just to see what happens, that curiosity, that in sort of my area of artificial intelligence, that's been a concern.

[214] They're on a small scale, on a silly scale, perhaps currently.

[215] there's constantly unintended consequences that you create a system and you put it out there and you have intuitions about how it will work, you have hopes how it will work, but you put it out there just to see what happens.

[216] And in most cases, because artificial intelligence is currently not super powerful, it doesn't create large -scale negative effects, but that same curiosity as it progresses might lead to something that destroys is a human species and the same may be true for bioengineering.

[217] There's people that engineer viruses to protect us from viruses to see, you know, how close is this to mutating so it can jump to humans or going, you know, or engineering defenses against those.

[218] And it seems exciting and the application, the positive applications are really exciting at this time, but we don't think about.

[219] how that runs away in decades to come.

[220] Yeah, and I think it's the same idea as this little book, The Ratchet of Science, the Ratchet of Curiosity.

[221] I mean, whether you pursue, take curiosity and let artificial intelligence or machine learning run away with having its solutions to whatever you want or we do it, it's, I think, a similar consequence.

[222] I think from what I've read about Enrico, for me, he became a little bit cynical about the human species towards the end of his life, about having observed what he observed.

[223] Well, he didn't write much.

[224] I mean, he died young.

[225] He died soon after the World War.

[226] There was already, you know, the work by Teller to develop the hydrogen bomb, and I think he was a little cynical of that, you know, pushing it even further and rising tensions between the Soviet Union and the U .S. and it looked like an endless thing.

[227] But he didn't say very much, but a little bit, as you said.

[228] Yeah, there's a few clips to sort of maybe picked on a bad mood, but in a sense that almost like a sadness and melancholy sadness to a hope that waned a little bit about that perhaps we can do like this science, this curious, species can find the way out.

[229] Well, especially, I think people who worked like he did at Los Alamos and spent years of their life somehow had to convince themselves that dropping these bombs would bring lasting peace.

[230] And it didn't.

[231] And that it didn't, yeah.

[232] As a small, interesting aside, it would be interesting to hear if you have opinions on this.

[233] His name is also attached to the Fermi Paradox, which asks if there is, you know, with, it's a very interesting question, which is if it does seem if you sort of reason, basically, that there should be a lot of alien civilizations out there.

[234] If the human species, if Earth is not that unique, by basic, no matter the values you pick, it's likely that there's a lot of alien civilizations out there.

[235] And if that's the case, why have they not at least obviously visited us or sent us loud signals that everybody can hear?

[236] Fermi's quoted as saying, sitting down at lunch, I think it was with Teller and Herb York, who was kind of one of the fathers of the atomic bomb.

[237] And he sat down and he says something like, where are they?

[238] Yeah.

[239] Which meant where are these other?

[240] And then he did some numerology where he calculated, you know, what they knew about, how many galaxies there are and how many stars and how many planets then are like the Earth and blah, blah, blah.

[241] That's been done much better by somebody named Drake.

[242] And so people usually refer to the, I don't know whether it's called the Drake formula or something, but it has the same conclusion.

[243] The conclusion is it would be a miracle if there weren't other, you know, the statistics are so high that how can we be singular and separate?

[244] That's, So probably there is almost certainly life somewhere.

[245] Maybe there was even life on Mars a while back, but intelligent life, probably white.

[246] So, you know, the statistics say that.

[247] Communicating with us, I think that it's harder than people think.

[248] We might not know the right way to expect the communication.

[249] but all the communication that we know about travels at the speed of light and we don't think anything can go faster in the speed of light that limits the problem quite a bit and it makes it difficult to have any back -and -forth communication you can send signals like we try to or look for but to have any communication it's pretty hard when you it has to be close enough that the speed of light would mean we could communicate with each other.

[250] And I think, and we didn't even understand that.

[251] I mean, we're an advanced civilization, but we didn't even understand that a little more than 100 years ago.

[252] So are we just not advanced enough, maybe, to know something about that's the speed of light?

[253] Maybe there's some other way to communicate that isn't based on electromagnetism?

[254] I don't know.

[255] Gravity seems to be also have the same speed.

[256] That was a principle that Einstein had and something we've measured actually.

[257] So is it possible?

[258] I mean, so we'll talk about gravitational waves and in some sense there's a brainstorming going on which is like how do we detect the signal?

[259] Like what would a signal look like and how would we detect?

[260] And that's true for gravitational waves.

[261] That's true for basically any physics phenomenon.

[262] I'm going to, you have to predict that that signal should exist.

[263] You have to have some kind of theory and model why that signal should exist.

[264] I mean, is it possible that aliens are communicating with us via gravity?

[265] Like, why not?

[266] Well, yeah, it's true.

[267] Why not?

[268] For us, it's very hard to detect these gravitational effects.

[269] They have to come from something pretty that has a lot of gravity, like black holes.

[270] but we're pretty primitive at this stage.

[271] There's a very reputable physicists that look for a fifth force, one that we haven't found yet.

[272] Maybe it's the key.

[273] So, you know, it's...

[274] What would that look like?

[275] What would a fifth force of physics look like exactly?

[276] Well, usually they think it's probably a longer range force than we have now.

[277] but they're reputable colleagues of mine that spend their life looking for a fifth force so longer range than gravity is it like super long it doesn't fall off like one over r squared but maybe separately gravity Newton taught us goes like inversely one over the square if the distance apart you are so it falls pretty fast that's okay so now we have a theory of what consciousness is It's just the fifth force of physics.

[278] There we go.

[279] That's a good hypothesis.

[280] Speaking of gravity, what are gravitational waves?

[281] This may be started from the basics.

[282] We learned gravity from Newton, right?

[283] You and you were young, you were told that if you jumped up, the earth pulled you down.

[284] And when the apple falls out of the tree, the earth pulls it down and maybe you even asked your teacher why but most of us accepted that that was Newton's picture the apple falling out of the tree but Newton's theory never told you why the apple was attracted to the earth that was a missing in Newton's theory Newton's theory also Newton recognized at least one of the two problems I'll tell you one of them is there's more than those but one is why does the earth what's a mechanism by which the earth pulls the apple or holds the moon when it goes around whatever it is uh that's not explained by newton even though he has the most successful theory of physics ever went 200 and some years with nobody ever seeing a violation but he accurately describes the movement of an object falling down to earth but he's not answering why that what's yeah because it's a distance he gives a formula which it's a product of the Earth's mass, the apple's mass, inversely proportional to the square, the distance between, and then the strength he called capital G, the strength he couldn't determine, but it was determined 100 years later.

[285] But no one ever saw a violation of this until a possible violation which Einstein fixed, which was very small that has to do with mercury going around the sun, the orbit being slightly wrong.

[286] if you calculate it by Newton's theory.

[287] But so, like most theories then in physics, you can have a wonderful one like Newton's theory.

[288] It isn't wrong, but you have to have an improvement on it to answer things that it can't answer.

[289] And in this case, Einstein's theory is the next step.

[290] We don't know if it's anything like a final theory or even the only way to formulate it.

[291] either.

[292] But he formulated this theory which he released in 1915.

[293] He took 10 years to develop, but even though in 1905 he solved three or four of the most important problems in physics in a matter of months.

[294] And then he spent 10 years on this problem before he let it out.

[295] And this is called general relativity.

[296] It's a new theory of gravity.

[297] 1915.

[298] In 1916, Einstein wrote a little page paper where he did not do some fancy derivation.

[299] Instead, he did, what I would call it, he used his intuition, which he was very good at too.

[300] And that is he noticed that if he wrote the formulas for general relativity in a particular way, they looked a lot like the formulas for electricity and magnetism.

[301] Being Einstein, he then took the leap.

[302] that electricity and magnetism, we discovered only 20 years before that in the 1880s, have waves.

[303] Of course, that's light and electromagnetic rays, radio waves, everything else.

[304] So he said if the formulas look similar, then gravity probably has waves too.

[305] That's such a big leap, by the way.

[306] I mean, maybe you can correct me, but that just seems like a heck of a leap.

[307] Yeah, and so that, and it was considered to be a heck of a leap.

[308] So first, that paper was, except for this intuition, was poorly written, had a serious mistake.

[309] It had a factor of two wrong in the strength of gravity, which meant if we used those formulas, we would.

[310] And two years later, he wrote a second paper.

[311] And in that paper, it turns out to be important for us, because in that paper, he not only fixed his factor of two, which he never admitted.

[312] He just wrote it, fixed it like he always did.

[313] And then he told us how you make gravitational waves.

[314] What makes gravitational waves?

[315] And you might recall an electromagnetism, we make electromagnetic waves in a simple way.

[316] You take a plus charge and minus charge.

[317] You oscillate like this, and that makes an electromagnetic waves.

[318] And a physicist named Hertz made a receiver that could detect the waves and put it in the next room.

[319] He saw them and moved forward and backward and saw that it was wave -like.

[320] So Einstein said it won't be a dipole like that.

[321] It'll be a four -pole thing, and that's what it's called a quadruple moment that gives the gravitational wave.

[322] So he saw that, again, by insight, not by derivation.

[323] That set the table for which it needed to do, to do it.

[324] At the same time, in the same year, Schwarzschild, not Einstein, said there were things like called black holes so it's interesting that that came the same so what year was that 15 it was in parallel with did i should probably know this but did i understand not have an intuition that there should be such things as black holes that came from schwartz child oh interesting yeah so schwartz child who was a a german theoretical physicist he got killed in the war i think in the First World War a year, two years later or so.

[325] He's the one that proposed black holes, that there were black holes.

[326] It feels like a natural conclusion of general relativity, no?

[327] Or is that, uh, well, it may seem like it, but I don't know about a natural conclusion.

[328] It is a, it's a result of curved space time, though.

[329] Right.

[330] And it's, but it's such a weird result that you might have to, it's a special.

[331] Yeah, it's a special case.

[332] Yeah.

[333] So, I don't know.

[334] Anyway, Einstein then, an interesting part of the story, is that Einstein then left the problem.

[335] Most physicists, because it really wasn't derived, he just made this, didn't pick up on it, or general relativity much, because quantum mechanics became the thing in physics.

[336] And Einstein only picked up this problem again after he immigrated to the U .S. So he came to the U .S. in 1932, and I think in 1934 or five, he was working with another physicist called Rosen, who he did several important works with, and they revisited the question.

[337] And they had a problem that most of us as students always had that study general relativity.

[338] General relativity is really hard because it's four -dimensional instead of three -dimensional, and if you don't set it up right, you get infinities.

[339] which don't belong there.

[340] We call them coordinate singularities as a name.

[341] But if you get these infinities, you don't get the answers you want.

[342] And he was trying to derive now general relativity from general relativity gravitational waves.

[343] And in doing it, he kept getting these infinities.

[344] And so he wrote a paper with Rosen that he submitted to our most important journal, physical review letters and that when it was submitted to physical review letters it was entitled do gravitational waves exist a very funny title to write 20 years after he proposed they exist but it's because he had found these singularities these infinities and so the editor at that time And part of it that I don't know is peer review.

[345] We live and die by peer review as scientists, send our stuff out.

[346] We don't know when peer review actually started or what peer review Einstein ever experienced before this time.

[347] But the editor of physical review sent this out for review.

[348] He had a choice.

[349] He could take any article and just accept it.

[350] He can reject it or he could send it for review.

[351] I believe the editors used to have.

[352] much more power.

[353] Yeah, yeah.

[354] And he was a young man. His name was Tate.

[355] And he ended up being editor for years.

[356] So he sent this for review to a theoretical physicist named Robertson, who was also in this field of general relativity, who happened to be on sabbatical at that moment at Caltech.

[357] Otherwise, his institution was Princeton, where Einstein was.

[358] And he saw that the way they set up the problem.

[359] The infinities were like I make it as a student, because if you don't set it up right in general relativity, you get these infinities.

[360] And so he reviewed the article and told, gave an illustration that if they set it up on what are called cylindrical coordinates, these infinities went away.

[361] He's the editor of physical review was obviously intimidated by Einstein.

[362] He wrote this really not a letter back like I would get saying, you know, you're, screwed up in your paper instead that it was kind of uh what do you think of the comments of our referee Einstein wrote back and it's a well documented letter wrote back a letter to physical review saying i didn't send you the paper to send it to one of your so -called experts i sent it to you to publish i now i withdraw the paper wow and he never published again in the in that journal that It was 1936.

[363] Instead, he rewrote it with the fixes that were made, changed the title, and published it in what was called the Franklin Review, which is the Franklin Institute in Philadelphia, which is Benjamin Franklin Institute, which doesn't have a journal now, but did it at that time.

[364] So the article is published.

[365] It's the last time he ever wrote about it.

[366] It remained controversial.

[367] seal.

[368] So it wasn't until close to 1960, 1958, where there was a conference that brought together the experts in general relativity to try to sort out whether there was, whether it was true that there were gravitational waves or not.

[369] And there was a very nice derivation by a British theorist from the heart of the theory that gets gravitational waves.

[370] And that was number one.

[371] The second thing that happened at that meeting is Richard Feynman was there.

[372] And Feynman said, well, if there's typical Feynman, if there's gravitational waves, they need to be able to do something.

[373] Otherwise, they don't exist.

[374] So they have to be able to transfer energy.

[375] So he made an idea of a Godankan experiment that is just a, a bar with a couple of rings on it, and then if a gravitational wave goes through, it distorts the bar, and that creates friction on these little rings, and that's heat, and that's energy.

[376] So that meant...

[377] Is that a good idea?

[378] It sounds like a good idea.

[379] Yeah, it means that he showed that with the distortion of space time, you could transfer energy just by this little idea, and it was shown theoretically.

[380] So at that point, it was belief theoretically then by people that gravitational waves should exist.

[381] No, we should be able to detect them.

[382] We should be able to detect them, except that they're very, very small.

[383] And so what kind of, there's a bunch of questions here, but what kind of events would generate gravitational waves?

[384] You have to have this, what I call quadruple moment.

[385] that comes about if I have, for example, two objects that go around each other like this, like the Earth around the Sun or the Moon around the Earth, or in our case it turns out to be two black holes going around each other like this.

[386] So how's that different than basic oscillation back and forth?

[387] Is it just more common in nature?

[388] Oscillation is a dipole moment.

[389] So it has to be in three -dimensional space, kind of oscillation?

[390] So you have to have something that's three -dimensional that will give what I called a, potter pole moment that's just built into this and luckily in nature you have stuff uh and luckily things exist and it is luckily because the effect is so small that you could say look i can take a barbell and and spin it right and detect the gravitational waves but unfortunately no matter how much i spin it how fast i spin it so i know how to make gravitational waves but they're so weak i can't detect them.

[391] So we have to take something that's stronger than I can make.

[392] Otherwise, we would do what Hertz did for electromagnetic waves.

[393] Go in our lab, take a barbell, put it on something, spin it.

[394] Can I ask a dumb question?

[395] So a single object that's weirdly shaped, does that generate gravitational waves?

[396] So if it's rotating, it's just much weaker signal?

[397] It's weaker.

[398] Well, we didn't know what the strongest signal would be that we would see.

[399] We targeted seeing something called neutron stars, actually, because black holes, we don't know very much about.

[400] It turned out we were a little bit lucky.

[401] There was a stronger source, which was the black holes.

[402] Well, another ridiculous question.

[403] So you say waves.

[404] What does a wave mean?

[405] Like, the most ridiculous version of that question is, what does it feel like to ride a wave as you get closer to?

[406] the source or experience it?

[407] Well, if you experience a wave, imagine that this is what happens to you.

[408] I don't know what you mean about getting close.

[409] It comes to you.

[410] So it's like this light wave or something that comes through you.

[411] So when a light hits you, it makes your eyes detect it.

[412] I flashed it.

[413] What does this do?

[414] It's like going to the amusement park and they have these mirrors.

[415] You look in this mirror and you look, short and fat, and the one next to you makes you tall and thin, okay?

[416] Imagine that you went back and forth between those two mirrors once a second.

[417] That would be a gravitational wave with a period of once a second.

[418] If you did it 60 times a second, go back and forth, and then that's all that happens.

[419] It makes you taller and shorter and fatter back and forth as it goes through you at the frequency of the gravitational wave.

[420] So the frequencies that we detect are higher than one.

[421] a second but that's the idea so but and the amount is small amount is small but when if you're closer to the to the source of the wave is it the same amount yeah it's it doesn't dissipate it doesn't dissipate okay so it's not that fun of an amusement ride well it it does dissipate but it doesn't it doesn't it's it's just it's proportional to the distance right it's not uh it's It's not a big power.

[422] So, but it would be a fun ride if you get a little bit closer or a lot closer.

[423] I mean, like, I wonder what the, this is a ridiculous question, but I have you here.

[424] I mean, like the getting fatter and taller.

[425] I mean, that experience, for some reason, that's mind -blowing to me because it brings the distortion of space time to you.

[426] I mean, space time is being morphed.

[427] right like this is a way that's right that how that's so weird and we're in space so yeah we're in space and how it's moving i don't know what to do with that i mean does it okay um how much do you think about the philosophical implications of general relativity like that we're in space time and it can be bent by gravity like is that just what it is Are we supposed to be okay with this?

[428] Because like Newton, even Newton is a little weird, right?

[429] But that at least makes sense.

[430] That's our physical world.

[431] You know, when an apple falls, it makes sense.

[432] But like the fact that entirety of the space time we're in can bend.

[433] Well.

[434] That's really mind -blowing.

[435] Let me make another analogy.

[436] This is a therapy session for me at this point.

[437] Yeah, right.

[438] Another analogy.

[439] Thank you.

[440] imagine you have a trampoline yes okay what happens if you put a marble on a trampoline doesn't do anything right no just seems a little bit but not much yeah I mean just if I drop it it's not gonna go anywhere now imagine I put a bowling ball at the center of the trampoline now I come up to the trampoline and I put a marble on what happens no roll towards the bowling wall all right so what's happened is the presence of this massive object distorted the space that the trampoline did.

[441] This is the same thing that happens to the presence of the earth, the earth and the apple.

[442] The presence of the earth affects the space around it just like the bowling ball on the trampoline.

[443] Yeah, this doesn't make me feel better.

[444] I'm referring from the perspective of an aunt walking around on that trampoline then some guy just dropped a ball and not only dropped the ball right it's not just dropping a bowling ball it's making the the ball go up and down or doing some kind of oscillation thing where it's like waves and that's so fundamentally different from the experience on being on flatland and walking around and just finding delicious sweet things as aunt does and just it just feels like to me from a human experience perspective completely is humbling it's truly humbling it's something but we see that kind of phenomenon all the time let me give me another example imagine that you walk up to a still pond yes okay now i throw you like to you throw a rock in it what happens the rock goes in sinks to the bottom fine and these little ripples go out yeah and they travel out out that's exactly what happens.

[445] I mean, there's a disturbance, which is these safe, the bowling ball are black holes, and then the ripples, they go out in the water.

[446] They're not, they don't have any, they don't have the rock, any part pieces of the rock.

[447] I see the thing is, I guess what's not disturbing about that is it's a, I mean, it's it, I guess, a flat two -dimensional surface that's being disturbed.

[448] Like for a three -dimensional surface, three -dimensional surface, three -dimensional, space to be disturbed.

[449] It feels weird.

[450] It's even worse.

[451] It's four -dimensional, because it's space and time.

[452] So that's why you need Einstein is to make it four -dimensional.

[453] To make it four -dimensional.

[454] To make it four -dimensional.

[455] Yeah.

[456] To take the same phenomenon and look at it in all of space and time.

[457] Anyway, luckily, for you and I and all of us, the amount of distortion is incredibly small.

[458] So it turns out that if you think of space itself, now this is going to blow your mind too, if you think of space as being like a material like this table, it's very stiff.

[459] You know, we have materials that are very pliable, materials that are very stiff.

[460] So space itself is very stiff.

[461] So when gravitational waves come through it, luckily for us, it doesn't distort it so much that it affects our ordinary life very much.

[462] no i mean that's great that's great i thought there was something bad coming no this is great that's great that's great news so i mean that i mean perhaps we evolved as life on earth to be such that for us this particular set of uh effects of gravitational waves uh is not that significant maybe maybe that's why you probably used this effect today or yesterday do what so it's it's it's Pervasive.

[463] You mean gravity or the way, or external?

[464] Curvature of space.

[465] Curvature of space.

[466] How?

[467] I only care person as a human, right?

[468] The gravity of Earth.

[469] But you use it every day almost.

[470] Oh, it's curving.

[471] No, no, no. It's in this thing.

[472] Every time it tells you where you are.

[473] Yeah.

[474] How does it tell you where you are?

[475] It tells you where you are because we have 24 satellites or some number that are going around.

[476] in space and it asks how long it takes the being to go to the satellite and come back the signal to different ones and then it triangulates and tells you where you are and then if you go down the road it tells you where you are do you know that if you did that with the satellites and you didn't use Einstein's equations oh no you you won't get the right answer that's right and in fact if you take a road let's say 10 meters wide i've done these numbers and you ask how long you'd stay on the road if you didn't make the correction for general relativity, this thing you're poo -pooing because you're using every day, you'd go off the road about a minute.

[477] Well, actually, that might...

[478] So you use it, so don't poo -poo it.

[479] Well, I think I'm using an Andro is, and the GPS doesn't work that well, so maybe I'm using mutin's physics, so I need to upgrade to general relativity.

[480] So, Gravitation waves and Einstein had, wait, Feynman really does have a part in the story?

[481] Was that one of the first kind of experimental proposed detect gravitational waves?

[482] Well, he did what we call a Goddankan experiment.

[483] That's a thought experiment.

[484] Okay, not a real experiment.

[485] But then after that, then people believe gravitational waves must exist.

[486] You can kind of calculate how big they are.

[487] There's tiny.

[488] And so people started searching.

[489] The first idea that was used was Feynman's idea.

[490] And they all very end of it.

[491] And it was to take a great big, huge bar of aluminum, and then put around, and it's made like a cylinder, and then put around it some very, very sensitive detectors so that if a gravitational wave happened to go through it, it would go, and you detect the extra strain that was there.

[492] And that was this method that was used until we came along.

[493] It wasn't a very good method to use.

[494] and what was the so we're talking about a pretty weak signal here yeah that's why that method didn't work so what can you tell the story of figuring out what kind of method would be able to detect this very weak signal of gravitational ways so remembering the remembering what happens when you go to the amusement park that it's going to do something like stretch this way and squash that that way, squash this way, and stretch this way.

[495] We do have an instrument that can detect that kind of thing.

[496] It's called an interferometer.

[497] And what it does is it just basically takes usually light, and the two directions that we're talking about, you send light down one direction and the perpendicular direction.

[498] And if nothing changes, it takes the same, and the arms are the same length, it just goes down, bounces back, and if you invert one compared to the other, they cancel.

[499] So there's nothing happens.

[500] But if it's like the amusement park and one of the arms got, you know, it got shorter and fatter, so it took longer to go horizontally than it did to go vertically, then when they come back, when the light comes back, it comes back somewhat out of time.

[501] And that basically is the scheme.

[502] The only problem is that that's not a very, done very, accurately in general and we had to do it extremely accurately so what uh what's the what's the difficulty of uh doing so accurately okay so the measurement that we have to do is a distortion in time how big is it one it's a distortion that's one part in 10 to the 21 that's 21 zero is and a one okay wow and this so this is like a delay in the thing coming back back?

[503] It's one of them coming back after the other one, but the difference is just one part in 10 to the 21.

[504] So for that reason, we make it big.

[505] Let the arms be long.

[506] Okay, so one part and 10 of the 21.

[507] In our case, it's kilometers long.

[508] So we have an instrument that's kilometers in one direction, kilometers in the other several.

[509] How many kilometers are talking about?

[510] Four kilometers.

[511] Four kilometers in each direction.

[512] If you take then one part in 10 to the 21, we're talking about measuring something to 10 to the minus 18 meters.

[513] Okay.

[514] Now to tell you how small that is, the proton, thing we're made of, this you can't go and grab so easily, is 10 to the minus 15 meters.

[515] So this is one 1 ,000th the size of a proton.

[516] That's the size of the effect.

[517] Einstein himself didn't think this could be measured.

[518] Have we ever seen?

[519] Actually, he said that.

[520] But that's because he didn't anticipate modern lasers and techniques that we developed.

[521] Okay.

[522] So maybe can you tell me a little bit what you're referring to is LIGO, the laser interferometer or gravitational wave observatory.

[523] What is LIGO?

[524] So can you just elaborate kind of the big picture view here before I ask you specific questions about it?

[525] Yeah.

[526] So in the same idea that I just said, we have two long vacuum pipes, 10 to 4 kilometers long.

[527] Okay.

[528] We start with a laser beam, and we divide the beam going down the two arms.

[529] And we have a mirror at the other end, reflex it back.

[530] It's more subtle, but we bring.

[531] it back.

[532] If there's no distortion in space time and the lengths are exactly the same, which we calibrate them to be, then when it comes back, if we just invert one signal compared to the other, they'll just cancel.

[533] So we see nothing.

[534] But if one arm got a little bit longer than the other, then they don't come back at exactly the same time.

[535] They don't exactly cancel.

[536] That's what we measure.

[537] So to give a number to it, we have to do that.

[538] to we have the change of length to be able to do this 10 to the minus 18 meters to one part in 10 to the 12th.

[539] And that was the big experimental challenge that required a lot of innovation to be able to do.

[540] What you gave a lot of credit to I think Caltech and MIT for some of the technical developments like within this project.

[541] Is there some interesting things you can speak to like at the low level of some cool stuff that had to be solved like what do we yeah yeah i'm a software engineer so okay all of this i have so much more respect for everything done here than anything i've ever done so it's just code so so i'll give you an example of doing uh mechanical engineering at a better at a at a basically mechanical engineering and geology and maybe at a level so what are we what's the problem the problem is the following that i've given you this picture of an instrument that by some magic i can make good enough to measure this very short distance but then i put it down here it won't work and the reason it doesn't work is that the earth itself is moving all over the place all the time you don't realize it it seems pretty good to you i get it but it's moving all the time so somehow it's moving so much that we can't deal with it.

[542] We happen to be trying to do the experiment here on Earth, but we can't deal with it.

[543] So we have to make the instrument isolated from the Earth.

[544] Oh, no. At the frequencies we're at, we've got to float it.

[545] That's a mechanical, that's an engineering problem, not a physics problem.

[546] So when you actually, like, we're having a conversation on our podcast right now, there's, and people who record music work with this, you know, how to create an isolated room.

[547] and they usually build a room within a room but that's still not isolated in fact they say it's impossible to truly isolate from sound from noise and stuff like that but that that's like one step of millions that you took as building a room inside a room you basically have to isolate all now this is actually an easier problem it just have to do it really well so making a clean room is really a tough problem because you have to but a room, inside a room.

[548] This is really simple engineering, our physics.

[549] Okay, so what do you have to do?

[550] How do you isolate yourself from the earth?

[551] First, we work at, we're not looking at all frequencies for gravitational ways.

[552] We're looking at particular frequencies that you can deal with here on Earth.

[553] So what are frequencies would those be?

[554] You were just talking about frequencies.

[555] I mean, I don't...

[556] We know by evolution.

[557] Our bodies know.

[558] It's the audio band.

[559] Okay?

[560] The reason our ears work where they work is that's where the earth isn't going, making too much noise.

[561] Okay.

[562] So the reason our ears work the way they work is because it's just where it's quiet.

[563] That's right.

[564] So if you go to, if you go to 1 hertz instead of 10 hertz, it's the earth is really moving around.

[565] So somehow we...

[566] live in a what we call the audio band it's tens of hertz to thousands of hertz that's where we live that's where we live okay if we're going to do an experiment on the earth might as well do it it's the same frequency that's where the earth is the quiet is so we have to work in that frequency so we're not looking at all frequencies okay so the solution for the for the shaking of the earth to get rid of it is pretty mundane if we do the same thing that you do to make your car drive smoothly down the road.

[567] So what happens when your car goes over a bump?

[568] Early cars did that.

[569] They bounced.

[570] Right.

[571] Okay.

[572] But you don't feel that in your car.

[573] So what happened to that energy?

[574] You can't just disappear energy.

[575] So we have these things called shock absorbers in the car.

[576] What they do is they absorb, they take the thing that went like that, and they basically can't get rid of the energy, but they move it to very, very low frequency.

[577] So what you feel isn't, you feel like go smoothly, okay?

[578] All right.

[579] So we also work at this frequency.

[580] So we basically, why don't we have to do anything other than shock absorbers?

[581] So we made the world's fanciest shock absorbers, okay?

[582] Not just like in your car where there's one layer of them.

[583] They're just the right squishiness and so forth.

[584] but they're better than what's in the cars.

[585] And we have four layers of it.

[586] So whatever shakes and gets through the first layer, we treat it in a second, third, a fourth layer.

[587] So it's a mechanical engineering problem.

[588] Yeah, that's what I said.

[589] So it's not, there's no weird tricks to it, like a chemistry type thing.

[590] No, no, just, well, the right squishiness, so you need the right material inside.

[591] And ours look like little springs, but there.

[592] Springs, there's springs.

[593] So, like, legitimately like shock absorbers.

[594] Yeah.

[595] what okay okay and this is now experimental physics at the at its limit okay so you do this and we make the world's fanciest shock absorbers just mechanical engineering just mechanical genius is hilarious but we didn't we weren't good enough to discover gravitational waves so so we did another we added another feature and it's something else that you're aware of probably have one, and that is to get rid of noise.

[596] You've probably noise, which is you don't like.

[597] And that's the same principle that's in these little bows' earphones.

[598] Noise cancelling?

[599] Noise cancelling.

[600] So how do they work?

[601] They basically, you go on an airplane and they sense the ambient noise from the engines and cancel it because it's just the same over and over again.

[602] They cancel it.

[603] and when the stewardess comes and asks you whether you want coffee or a tea or a drink or something, you hear her fine because she's not ambient.

[604] She's the signal.

[605] Are we talking about active canceling?

[606] Like where are the actual?

[607] Active cancelling.

[608] So this is, okay.

[609] So another.

[610] Don't tell me you have active canceling on this besides the shock absorbers.

[611] So we add this, so inside this array of shock absorbers, we, you asked for some interesting.

[612] This is awesome.

[613] So inside this, it's harder than the earphone problem, but it's just engineering.

[614] We have to see measure not just that the engines still made noise, but the earth is shaking.

[615] It's moving in some direction.

[616] So we have to actually tell not only that there's noise and cancel it, but what direction it's from.

[617] So we put this array of seismometers inside this array of shock absorbers and measure the residual motion and its direction and we put little actuators that push back against it and cancel it.

[618] That's awesome.

[619] So you have the actuators and you have the thing that is sensing the vibrations and then you have the actual actuators that adjust for that and do so in perfect synchrony.

[620] Yeah.

[621] What?

[622] If it all works right.

[623] And so how much do we reduce the shaking of the earth?

[624] I mean...

[625] One part in 10 to the 12th.

[626] One part in 10.

[627] So what gets through us is one part in 10 to the 12th.

[628] That's a pretty big reduction.

[629] You don't need that in your car, but that's what we do.

[630] And so that's how isolated we are from the earth.

[631] And that was the biggest, I'd say, technical problem outside of the physics instrument, the interferometer.

[632] Can I see a weird question here?

[633] You make it very poetically and humorously.

[634] You're just saying it's just a mechanical engineering problem.

[635] but is this one of the biggest precision mechanical engineering efforts ever i mean this seems exceptionally difficult it is and so it took a long time and i think nobody seems to challenge the statement that this is the most precision precise instrument it's ever been built ligo i wonder what like listening to lads eplin sounds on this thing because it's so isolated i mean this is like, I don't know.

[636] No background.

[637] No, but no back.

[638] It's, wow, wow, wow.

[639] So when you were first conceiving this, I would probably, if I was knowledgeable enough, kind of laugh off the possibility that this is even possible.

[640] I'm sure, like how many people believe that this is possible?

[641] Did you believe this is possible?

[642] Oh, I did.

[643] I didn't know for sure that we needed active when we started.

[644] We did dispassive, but we were doing the tests to develop the active to add as a second stage, which we ended up needing.

[645] But there was a lot of, you know, now there was a lot of skepticism.

[646] A lot of us, especially astronomers, felt that money was being wasted, because we were also expensive.

[647] Doing what I told you was not cheap.

[648] So it was kind of controversy.

[649] It was funded by the National Science Foundation.

[650] Can you just linger on this just for a little longer?

[651] The actuator thing, the act of canceling.

[652] Do you remember, like, literal experiments that were done along the way to prove to the team to themselves that this is even possible?

[653] So from our, because I work with quite a bit of robots, and to me the idea that you could do it this precisely is, humbling and embarrassing frankly because like this is another level of precision that I can't even because robots are a mess and this is basically one of the most precise robots ever right so like is there do you have any like small scale experiments that were done that just be like this is possible yeah and larger scale we made we made test change that also has to be in vacuum too but we made test chambers that had this system in it our first mock of this system so we could test it and optimize it and make it work but it's just a mechanical engineering problem okay humans are just ape descendants i got you i got you uh is there any video of this like um some kind of educational purpose visualizations of this active cancelling?

[654] I don't think so.

[655] I mean, does this live on?

[656] Well, we worked for parts of it, for the active canceling, we worked with, for the instruments, for the sensor and instruments.

[657] We worked with a small company and near where you are because it was our MIT people that got them that were, you know, interested in the problem because they thought they might be able to commercialize it for making stable tables to make microelectronics, for example, which are limited by how stable the table is.

[658] At this point, it's a little expensive.

[659] You never know.

[660] You never know where this leads.

[661] So maybe on the, let me ask you just sticking it a little longer, this silly old mechanical engineering problem.

[662] What was to you kind of the darkest moment of what was the hardest stumbling block to get over on the engineer side?

[663] Like, was there any time where there's a doubt where it's like, I'm not sure we would be able to do this a kind of engineering challenge that was hit?

[664] Do you remember anything like that?

[665] I think the one that my colleague at MIT, Ray Weiss, worked on so hard and was much more of a worry than this.

[666] This is only a question if you're not doing it.

[667] well enough.

[668] You'd have to keep making it better somehow.

[669] But this whole huge instrument has to be in vacuum.

[670] And the vacuum tanks are this big around.

[671] And so it's the world's biggest high vacuum system.

[672] And so how do you make it, first of all?

[673] How do you make this four meter long sealed vacuum system?

[674] It has to be made out of four kilometers long.

[675] Four kilometers long.

[676] would I say something else?

[677] Meters.

[678] Four kilometers long.

[679] Big difference.

[680] Yeah.

[681] And so, but to make it, yeah, we started with a roll of stainless steel, and then we spiral it out like a spiral, so there's a spiral weld on it.

[682] Yeah.

[683] Okay.

[684] So the engineering was fine.

[685] We did that.

[686] We worked through very good companies and so forth to build it.

[687] But the big worry, it was.

[688] what if you develop a leak?

[689] This is a high vacuum, not just vacuum system.

[690] Typically, in a laboratory, if there's a leak, you put helium around the thing you have, and then you detect where the helium is coming in.

[691] But if you have something as big as this, you can't surround it with helium.

[692] So you might not actually even know that there's a leak and it will be affecting it.

[693] Well, we can measure how good the vacuum.

[694] vacuum is so we can know that but there are leak and develop and then we don't how do we fix it or how do we find it and so that was you asked about a worry that was always a really big worry what's the difference in a high vacuum and a vacuum what is high vacuum that's like some delta of close to vacuum is like some threshold well there's a unit high vacuum is when the vacuum and the units that are used which are TORs, there's 10 to the minus 9.

[695] And there's high vacuum is usually used in small places.

[696] The biggest vacuum system period is at CERN in this big particle accelerator, but the high vacuum where they need really good vacuum so particles don't scatter in it is smaller than ours.

[697] So ours is a really large high vacuum system.

[698] I don't know, this is so cool.

[699] I mean, this is basically by far, the greatest listening device ever built by human.

[700] The fact that, like, descendants of apes could do this.

[701] That evolution started with single -celled organisms.

[702] I mean, is there any more...

[703] I'm a huge...

[704] Theory is like, yeah, yeah.

[705] But, like, bridges, when I look at bridges from a civil engineering perspective, is one of the most beautiful creations by human beings.

[706] It's physics.

[707] You're using physics to construct objects that can support huge amount of mass. and it's like structural but it's also beautiful and that humans can collaborate to create that throughout history and then you take this on another level this is this is like exciting to me beyond measure that humans can create something so precise but another concept lost in this you just said you started talking about single cell yeah okay if they realize this discovery that we made that everybody's bought off on happened 1 .3 billion years ago somewhere and then the signal came to us.

[708] 1 .3 billion years ago we were just converting on the earth from single cell to multi -cell life so when this actually happened this collision of two black holes yeah we weren't here we weren't even close to being here we're both developing slowly yeah we were going from single cell to multi -cell life at that point all to meet up at this at this point yeah Wow, that's like, uh, that's almost romantic, uh, that's almost romantic, uh, okay.

[709] So on the human side of things, it's kind of fascinating because you're talking about over a thousand people team for LIGO.

[710] Yeah.

[711] Uh, they started out with, uh, you know, around a hundred.

[712] What, and you've, uh, for parts of the time at least led this team, what does it take to lead a team like this of incredibly brilliant theoreticians and engineers and just a lot of different parties involved a lot of egos a lot of ideas you had this funny example i forget where where in publishing a paper you have to all agree on like uh you know the phrasing of a certain sentence or the title of the paper and so on that's a very interesting I'd love you to speak to that, but just in general, how, what does it take to lead this kind of team?

[713] Okay.

[714] I think the general idea is one we all know.

[715] You want to, you want to get where the sum of something is more than the individual parts is what we say, right?

[716] Yeah.

[717] So that's what you're trying to achieve.

[718] Okay.

[719] How do you do that actually?

[720] Mostly if we take multiple objects or people.

[721] I mean, you put them together, the sum is less.

[722] Why?

[723] Why?

[724] Because they overlap.

[725] So you don't have individual things that, you know, this person does that, this person does that, then you get exactly the sum.

[726] But what you want is to develop where you get more than what the individual contributions are.

[727] We know that's very common.

[728] People use that expression everywhere.

[729] And it's the expression that has to be kind of build into how people feel it's working because if you're part of a team and you realize that somehow the team is able to do more than the individuals could do themselves than they buy on kind of in terms of the process so that's the that's the goal that you have to have is to achieve that and that means that you have to have to achieve that and that means realize parts of what you're trying to do that require, that one person couldn't do it, it requires the combined talents to be able to do something, that neither of them could do themselves.

[730] And we have a lot of that kind of thing.

[731] And I think, I mean, build into some of the examples that I gave you.

[732] And so how do you then, so the key almost in anything you do is the people themselves, right?

[733] So in our case, the first and most important was to attract, to spend years of their life on this, the best possible people in the world to do it.

[734] So the only way to convince them is that somehow it's better and more interesting for them than what they could do themselves.

[735] And so that's part of this idea.

[736] I got you.

[737] Yeah, that's powerful.

[738] But Nevertheless, there's best people in the world, there's egos.

[739] Is there something to be said about managing egos?

[740] Well, the human problem is always the hardest.

[741] And so that's an art, not a science, I think.

[742] I think the fact here that combined, there was a romantic goal that we had to do something that people hadn't done before, which was important scientifically and a huge challenge.

[743] Enabled us to say take and get, I mean, just to take an example, we used the light to go and this thing comes from lasers.

[744] We need a certain kind of laser.

[745] So the kind of laser that we used, there were three different institutions in the world that had the experts that do this, maybe in competition with each other.

[746] So we got all three to join together and work with us to work on this as an example.

[747] And they had the thing that they were working together on a kind of object that they wouldn't have otherwise and were part of a bigger team where they could discover something that isn't even engineers.

[748] These are engineers that do lasers.

[749] And they're part of our laser physics.

[750] So could you describe the moment or the period of time when finally this incredible creation of human beings led to a detection of gravitational waves?

[751] It's a long story.

[752] Unfortunately, this is a part that we started.

[753] Lots of failures along the way kind of thing or what?

[754] All failures.

[755] That's all.

[756] It's built into it.

[757] Okay.

[758] If you're not, if you're not.

[759] Mechanical engineering.

[760] you build on your failures that's expected so we're trying things that no one's done before so it's technically not just gravitational waves and so it's built on failures but anyway we we did before me even the people did uh r and d on the concepts but starting in 1994 we got money from the national science foundation to build this thing um it took about five years to build it.

[761] So by 1999, we had built the basic unit.

[762] It did not have active seismic isolation at that stage, didn't have some other things that we have now.

[763] What we did at the beginning was stick to technologies that we had at least enough knowledge that we could make work or had tested in our own laboratories.

[764] And so then we put together the instrument.

[765] We made it work.

[766] It didn't work very well, but it worked.

[767] And we didn't see any gravitational waves.

[768] Then we figured out what limited us, and we went through this every year for almost 10 years, never seeing gravitational waves.

[769] We would run it, looking for gravitational waves for months, learn what limited us, fix it for months, and then run it again.

[770] Eventually, we knew we had to take another big step, and that's when we made several changes, including adding these active seismic isolation, which turned out to be a key.

[771] And we fortunately got the National Slands Foundation to give us another couple hundred million dollars, or a hundred million more.

[772] And we rebuilt it, our fixed, or improved it.

[773] And then in 2015, we turned it on.

[774] And we almost instantly saw this first collision of two black holes.

[775] And then we went through a process of do we believe what we've seen.

[776] Yeah, I think you're one of the people that went through that process.

[777] It sounds like some people immediately believed it.

[778] Yeah.

[779] And then you're like...

[780] So as human beings, we all have different reactions to almost anything.

[781] And so quite a few of my colleagues had a eureka moment immediately.

[782] I mean, it's...

[783] It's amazing.

[784] The figure that we put in our paper first is just data.

[785] We didn't have to go through, you know, fancy computer programs to do anything.

[786] And we showed next to it the calculations of Einstein's equations.

[787] It looks just like what we detected.

[788] Wow.

[789] And we did it in two different detectors halfway across the U .S. So it was pretty convincing, but you don't want to, you don't want to fool yourself.

[790] So being a scientist, we had to, for me, we had to go through and try to understand that the instrument itself, which was new, I said we had rebuild it, couldn't somehow generate things that look like this.

[791] That took some tests.

[792] And then the second, you'll appreciate more.

[793] We had to somehow convince ourselves we weren't hacked in some clever way.

[794] It's a cybersecurity question.

[795] Yeah.

[796] Even though we're not on the internet, but.

[797] Yeah.

[798] No, it can be physical access to.

[799] Yeah.

[800] That's fascinating.

[801] It's fascinating that you would think about that.

[802] I mean, not enough.

[803] I mean, because it's, it matches prediction.

[804] So the chances of it actually being manipulated is very, very low.

[805] But nevertheless.

[806] We still could have disgruntled old graduate students who had worked with us earlier.

[807] Who want you to, I don't know how that's supposed to embarrass you.

[808] I suppose, yeah, I suppose I see.

[809] But about what I think you said within a month, you kind of convinced yourself officially.

[810] Within a month, we convinced ourselves.

[811] We kept 1 ,000 collaborators quiet during that time.

[812] Then we spent another month or so trying to understand what we'd seen so that we could do the science with it instead of just putting it out to the world and let somebody else understand that it was two black holes and what it was.

[813] The fact that 1 ,000 collaborators were quiet is a really strong indication that this is a really close -knit team.

[814] Yeah, and they're around the world.

[815] Or either strong, either strong knit or tight knit or had a strong dictatorship or something.

[816] Yeah, either fear or love.

[817] You can rule by fear or love.

[818] Yeah, right.

[819] You can go back to Mackey Valley.

[820] All right.

[821] Well, this, I mean, this is really exciting that that was, that's a success story because it didn't have to be a success story.

[822] Right.

[823] I mean, eventually, perhaps you could say it would be an event, but he could have taken it over, century to get oh yeah yeah it's uh and um and it's only downhill now kind of it's what do you mean it's only you mean with gravitational waves well we're yeah we've we've now we now uh well now we're off because of the pandemic but when we turned off we were seeing some sort of gravitational wave event each week and now we're fixing we're fixing we're fixing We're adding features where it'll probably be, when we turn back on next year, it'll probably be one every couple days.

[824] And they're not all the same.

[825] So it's learning about what's out there in gravity instead of just optics.

[826] So it's all great.

[827] We're only limited by the fantastic thing other than that this is a great field and, you know, it's all new and so forth, is that experimentally, the great thing is that.

[828] that were limited by technology and technical limitations, not by science.

[829] So another, a really important discovery that was made before ours was what's called the Higgs boson, made on the big accelerator at CERN.

[830] You know, at this huge accelerator, they discovered a really important thing.

[831] It's, you know, we have Einstein's equation, E equals MC squared.

[832] So energy makes mass, or mass can make energy, and that's the bomb.

[833] But the mechanism by which that happens, not vision, but how do you create mass from energy, was never understood until there was a theory of it about 70 years ago now.

[834] And so they discovered it's named after a man named Higgs.

[835] It's called the Higgs boson.

[836] And so it was discovered.

[837] But since that time, and I worked on those experiments, since that time, they haven't been able to progress very much further, a little bit, but not a lot further.

[838] And the difference is that we're really lucky in what we're doing, in that there you see this Higgs boson, but there's tremendous amount of other.

[839] physics that goes on and you have to pick out the needle and the haystack kind of of physics.

[840] You can't make the physics go away.

[841] It's there.

[842] In our case, we have a very weak signal, but once we get good enough to see it, it's weak compared to where we've reduced the background, but the background is not physics.

[843] It's just technology.

[844] You know, it's getting ourselves better isolated from the earth or getting a more powerful laser.

[845] And so, each time, each, since 2015, when we saw the first one, we continually can make improvements that are enabling us to turn this into a real science to do astronomy, a new kind of astronomy.

[846] It's a little like astronomy.

[847] I mean, Galileo started the field.

[848] I mean, he basically took lenses that were made for classes, and he didn't invent the first telescope, but made a telescope, looked at Neptune and saw that it had four moons.

[849] That was the birth of not just using your eyes to understand what's out there.

[850] And since that time, we've made better and better telescopes, obviously, and astronomy thrives.

[851] And in a similar way, we're starting to be able to crawl, but we're starting to be able to do that with gravitational waves.

[852] And it's going to be more and more that we can.

[853] can do as we can make better and better instruments.

[854] Because as I say, it's not limited by picking it out of others.

[855] Yeah, it's not limited by the physics.

[856] So you have an optimism about engineering.

[857] That event, you know, as we, as human progress marches on, engineering will always find a way to build a large enough device, accurate enough device to detect the system.

[858] As long as it's not limited by physics, yeah, they'll do it so you two other folks and the entire team won the Nobel Prize for this yeah big effort there's a million questions I can ask for but looking back where does the Nobel Prize fit into all of this you know if you think hundreds of years from now I venture to say that people will not remember the winners of a prize, but they'll remember creations like these.

[859] Maybe I'm romanticizing engineering.

[860] But I guess I want to ask how important is the Nobel Prize in all of this?

[861] Well, that's a complicated question.

[862] As a physicist, it's something, if you're trying to win a Nobel Prize, forget it, because they give, you know, one a year.

[863] So there's been 200 physicists who have won the Nobel Prize since 1900.

[864] And so that's, you know, things just have to fall right.

[865] So your goal cannot be to win a Nobel Prize.

[866] It wasn't my dream.

[867] It's tremendous for science.

[868] I mean, why the Nobel Prize for a guy that made dynamite and stuff is, you know, what it is.

[869] It's a long story.

[870] but it's the one day a year where actually the science that people have done is all over the world and so forth.

[871] Forget about the people again.

[872] You know, it is really good for science.

[873] Celebrating science.

[874] It celebrates science for, you know, several days, different fields, you know, chemistry, medicine, and so forth.

[875] And everybody doesn't understand everything about these.

[876] They're generally fairly abstract, but then, you know, it's, you know, it's all.

[877] on the front page of newspapers around the world.

[878] So it's really good for science.

[879] It's not easy to get science on the front page of the New York Times.

[880] It's not there.

[881] It should be, but it's not.

[882] And so the Nobel Prize is important in that way.

[883] Otherwise, you know, I have a certain celebrity that I didn't have before.

[884] And now you get to be a celebrity that advertises science.

[885] It's a mechanism to remind us how incredible, how much credit science deserves and everything we have.

[886] Well, it has a little bit more.

[887] One thing I didn't expect, which is good, is that, you know, we have a government.

[888] I'm not picking on ours necessarily, but it's true of all governments are not run by scientists.

[889] In our case, it's run by lawyers and businessmen.

[890] Yep.

[891] Okay.

[892] And at best they may have an aid or something that knows a little science.

[893] So our country is, and all countries are hardly take into account science in making decisions.

[894] Yes.

[895] And having a Nobel Prize, the people in those positions actually listen.

[896] So you have more influence.

[897] I don't care whether it's about global warming or what the issue is.

[898] There's some influence which is lacking otherwise.

[899] And people pay attention to what I say.

[900] If I talk about global warming, they wouldn't have before I had the Nobel Prize.

[901] Yeah, this is very true.

[902] You're like the celebrities who talk.

[903] Celebrity has power.

[904] Celebrity has power.

[905] And that's a good thing.

[906] That's a good thing, yeah.

[907] Singling out people, I mean, on the other side of it, singling out people has all kinds of, you know, whether it's for Academy Awards or for this, have unfairness and arbitrariness and so forth and so on.

[908] So, you know, that's the other side of the coin.

[909] Just like you said, especially with the huge experimental projects like this, you know, it's a large team, and it does, the nature of the Nobel Prize, it singles out a few individuals to represent the team.

[910] Yeah.

[911] Nevertheless, it's a beautiful thing.

[912] What are ways to improve LIGO in the future, increase the sensitivity?

[913] I've seen a few ideas that are kind of fascinating.

[914] Are you interested in them?

[915] I'm not speaking about five years.

[916] Perhaps you can speak to the next five years, but also the next 100 years.

[917] Yeah.

[918] So let me talk to both the instrument and the science.

[919] Sure.

[920] They go hand in hand.

[921] I mean, the thing that I said is if we make it better, we see more kinds of weaker objects, and we do astronomy, okay?

[922] We're very motivated to make a new instrument, which will be a big step, the next step, like making a new kind of telescope or something.

[923] And the ideas of what that instrument should be haven't converged yet.

[924] There's different ideas in Europe.

[925] they've done more work to kind of develop ideas, but they're different from ours, and we have ideas.

[926] But I think over the next few years, we'll develop those.

[927] The idea is to make an instrument that's at least 10 times better than what we can do with this instrument, 10 times better than that.

[928] 10 times better means you can look 10 times further out, 10 times further out is a thousand times more volume so you're seeing much much more of the universe the big change is that if you can see far out you see further back in history yeah you're traveling back in time yeah and so we can start to do what we call cosmology instead of astronomy or astrophysics cosmology is really the study of the evolution of the...

[929] Oh, interesting.

[930] Yeah, yeah.

[931] And so then you can start to hope to get to the important problems having to do with how the universe began, how it evolved, and so forth, which we really only study now with optical instruments or electromagnetic waves.

[932] And early in the universe, those were blocked.

[933] Because basically it wasn't transparent, so the photons couldn't get out when everything was too dense.

[934] What do you think, sorry on this tangent, what do you think an understanding of gravitational waves from earlier in the universe can help us understand about the Big Bang and all that kind of stuff?

[935] Yeah, that's so.

[936] But it's a non, it's another perspective on the thing.

[937] Is there some insights you think it could be revealed just to help a layman understand?

[938] Sure.

[939] First, we don't understand.

[940] We use the word big bang.

[941] We don't understand the physics of what the Big Bang itself was.

[942] So I think my, and in the early stage there were particles and there was a huge amount of gravity and mass being made.

[943] And so the big, so I'll say two things.

[944] One is how did it all start?

[945] How did it happen?

[946] And I'll give you at least one example that we don't understand what we should understand.

[947] We don't know why we're here.

[948] Yes.

[949] No, we do not.

[950] I don't mean it philosophically.

[951] I mean it in terms of physics.

[952] Okay?

[953] Now, what do I mean by that?

[954] If I go into my laboratory at CERN or somewhere and I collide particles together or put energy together, I make as much antimatter as matter.

[955] Right.

[956] anti -matter then annihilates matter and makes energy so in the early universe there you made somehow somehow a lot of matter and antimatter but there was an asymmetry somehow there was more matter and antimatter that matter and antimatter annihilated each other at least that's what we think and there was matter only matter left over and we live in a universe that we see this all matter we don't have any idea we have an ideas but we don't have any we don't have any way to understand that at the present time with the physics that we know can ask a dumb question does antimatter have anything like a gravitational field to send signals so how how does this asymmetry of matter antimatter could be investigated or further understood by observing gravitational fields or weirdnesses in gravitational fields?

[957] I think that in principle, if there were, you know, anti -neutron stars instead of just neutron stars, we would see different kind of signals.

[958] But it didn't get to that.

[959] We live in a universe that we've done enough looking because we don't see matter, antiprotons anywhere, no matter what we look at, that it's all made out of matter.

[960] There is no antimatter except when you go in our laboratory.

[961] laboratories.

[962] So, but when we go in our laboratories, we make as much antimatter as matter.

[963] So there's something about the early universe that made this asymmetry.

[964] So we can't even explain why we're here.

[965] That's what I meant.

[966] Yeah.

[967] Physics -wise, not, you know, not in terms of how we evolved and all that kind of stuff.

[968] So there might be inklings of, that gravitational...

[969] So gravitational waves don't get obstructed like light.

[970] So I said light only goes to 300 ,000 years.

[971] So it goes back to the beginning.

[972] So if you could study the early universe with gravitational waves, we can't do that yet.

[973] Then it took 400 years to be able to do that with optical.

[974] But then you can really understand the very...

[975] Maybe understand the very early universe.

[976] So in terms of questions like why we're here or what the Big Bang was we should be we can in principle study that with gravitational waves so to keep moving in this direction it's a unique kind of way to understand our universe so you think there's more Nobel Prize level ideas to be discovered in relation to I'd be shocked if there gravitational waves if there isn't not even going to that which is a very long range problem but I think that we only see with electromagnetic waves 4 % of what's out there there there must be we looked for things that we knew should be there there should be I would be shocked if there wasn't physics, objects, and with gravity that doesn't show up in everything we do with telescopes so I think we're just limited by not having powerful enough instruments yet to do this.

[977] Do you have a preference?

[978] I keep seeing this E -Lisa idea.

[979] Yeah.

[980] Is it, do you have a preference for earthbound or space -faring mechanisms for?

[981] They're complementary.

[982] It's a little bit like, it's completely analogous to what's been done in astronomy.

[983] Right.

[984] So astronomy from the time of Galileo was done with visible light.

[985] Yeah.

[986] The big advances in astronomy in the last 50 years are because we have instruments that look at the infrared, microwave, ultraviolet, and so forth.

[987] So looking at different wavelengths has been important.

[988] Basically, going into space means that we'll look at instead of the audio band, which we look at, as we said on the Earth's surface, we'll look at.

[989] lower frequencies.

[990] So it's completely complementary.

[991] And it starts to be looking at different frequencies, just like we do with astronomy.

[992] Isn't it a little, it seems almost incredible to me engineering -wise, just like on Earth, to send something that's kilometers across into space.

[993] Is that harder to engineer?

[994] It actually is a little different.

[995] It's three satellites separated by hundreds of thousands of kilometers and they send a laser beam from one to the other and if they the distance, if the triangle changes shape a little bit they detect that from a passage.

[996] Sorry, did you say hundreds of thousands of kilometers?

[997] Yeah.

[998] Sending lasers to each other.

[999] Okay.

[1000] It's just engineering.

[1001] is possible though yes yes okay that's just incredible because they have to maintain I mean the precision here is probably there might be some more what is it maybe noise is a smaller problem I guess there's no vibration to worry about like seismic stuff so getting away from Earth maybe you get away from yeah those parts are easier they don't have to measure it as accurately at low frequencies but they have a lot of tough engineering problems.

[1002] In order to detect that the gravitational waves affect things, the sensors have to be what we call free masses, just like ours, are isolated from the Earth.

[1003] They have to isolate it from the satellite.

[1004] And that's a hard problem.

[1005] They have to do that pretty, not as well as we have to do it, but very well.

[1006] and they've done a test mission and the engineering seems to be at least in principle in hand.

[1007] This will be in the 2030s.

[1008] 2030s?

[1009] This is incredible.

[1010] This is incredible.

[1011] Let me ask about black holes.

[1012] So what we're talking about is observing orbiting black holes.

[1013] I saw it.

[1014] terminology of like binary black hole systems?

[1015] Binary black holes.

[1016] That's when they're dancing.

[1017] We're going around each other, just like the earth around the sun.

[1018] Okay.

[1019] Is that weird that there's black holes going around each other?

[1020] So finding binary systems of stars is similar to finding binary systems of black holes.

[1021] Well, they were once stars.

[1022] So we haven't said what a black hole is physically yet.

[1023] Yeah.

[1024] What's a black hole?

[1025] So, black hole is, first it's a mathematical concept or a physical concept, and that is a region of space.

[1026] So it's simply a region of space where the curvature of space time, meaning the gravitational field, is so strong that nothing can get out, including light.

[1027] And there's light gets bent in gravitational, if the gravitation, if the space time is warped enough.

[1028] and so even light gets bent around and stays in it.

[1029] So that's the concept of a black hole.

[1030] So it's not a, and maybe you can make, maybe it's a, so that's a concept that didn't say how they come about.

[1031] And there could be different ways they come about.

[1032] The ones that we are seeing, there's a, we're not sure.

[1033] That's what we're trying to learn now is what they, but the general expectation is, is that they come these black holes happen when a star dies so what does that mean that a star dies what happens a star like our sun basically makes heat and light by fusion it's made up and as it burns it burns up the hydrogen and then the helium and slowly works its way up to the heavier and heavier elements that are in the star and when it gets up to iron, the fusion process doesn't work anymore.

[1034] And so the stars die, and that happens to stars, and then they do what's called a supernova.

[1035] What happens then is that a star is a delicate balance between an outward pressure from fusion and light and burning and an inward pressure of gravity trying to pull the masses together.

[1036] Once it burns itself out, it goes, and it collapses, and that's a supernova.

[1037] When it collapses, all the mass that was there is in a very much smaller space.

[1038] And if a star, if you do the calculations, if a star is big enough, that can create a strong enough gravitational field to make a black hole.

[1039] Our sun won't.

[1040] It's too small.

[1041] Too small.

[1042] And we don't know exactly what it, but it's usually thought that a star, as to be at least three times as big as our sun to make a black hole.

[1043] But that's the physical way there.

[1044] You can make black holes.

[1045] That's the first explanation that one would give for what we see.

[1046] But it's not necessarily true.

[1047] We're not sure yet.

[1048] What we see in terms of for the origins of black holes?

[1049] No, the black holes that we see in gravitational waves.

[1050] But you're also looking for the ones who are binary solar systems.

[1051] So they're binary systems, but they could have been made from binary stars, so there's binary stars around.

[1052] So that's...

[1053] So the first explanation is that that's what they are.

[1054] Gotcha.

[1055] Other explanation, but what we see has some puzzles.

[1056] This is kind of the way science works, I guess.

[1057] We see heavier ones than up to...

[1058] we've seen one system that was 140 times the mass of our own son.

[1059] That's not believed to be possible with the parent being a big star, because big stars can only be so big or they are unstable.

[1060] It's just the fact that they live in an environment that makes them unstable.

[1061] So the fact that we see bigger ones, they maybe come from something else.

[1062] It's possible that they were made in a different way by little ones eating each other up, or maybe they were made, or maybe they came with a big bang, what we call primordial, which means they're really different.

[1063] They came from that.

[1064] We don't know at this point.

[1065] If they came with a big bang, then maybe they account for what we call dark matter or some of it.

[1066] Like there was a lot of them if they came with a because there's a lot of dark matter.

[1067] Yeah.

[1068] But gravitational waves give you any kind of intuition about the origin of these oscillating?

[1069] We think that if we see the distributions enough of them, the distributions of their masses, the distributions of how they're spinning.

[1070] So we can actually measure when they're going around each other, whether they're spinning you know, like this The direction of the spin?

[1071] Or no, the orientation.

[1072] Whether the whole system has any wobbles.

[1073] What?

[1074] So this is now, okay.

[1075] We're doing that.

[1076] And then you're constantly kind of crawling back and back in time.

[1077] And we're crawling back in time and seeing how many there are as we go back.

[1078] And so do they point back?

[1079] So you're like, what is that discipline called, cartography or something?

[1080] You're like mapping the early universe via the, lens of gravitational waves.

[1081] Not yet the early universe, but at least back and earlier, right.

[1082] So black holes are this mathematical phenomenon, but they come about in different ways.

[1083] We have a huge black hole at the center of our galaxy and other galaxies.

[1084] Those probably were made some other way.

[1085] We don't know when the galaxies themselves had to do with the formation of the galaxies.

[1086] We don't really know.

[1087] So the fact that we use the word black hole the origin of black holes might be quite different depending on how they happen they just have to in the end have a gravitational field that will bend everything in how do you feel about black holes as a human being there's a there's this thing that's nearly infinitely dense can doesn't let light escape isn't that kind of terrifying feels like the stuff of nightmares I think it's it's an opportunity to do what exactly.

[1088] So, like the early universe is an opportunity.

[1089] If we can study the early universe, we can learn things like I told you.

[1090] And here again, we have an embarrassing situation in physics.

[1091] We have two wonderful theories of physics, one based on quantum mechanics, quantum field theory, and we can go to a big accelerator like at CERN and smash particles together and almost explain anything that happens beautifully using quantum field theory and quantum mechanics.

[1092] Then we have another theory of physics called general relativity, which is what we've been talking about most of the time, which is fantastic at describing things at high velocities, long distances, you know, and so forth.

[1093] So that's not the way it's supposed to be.

[1094] we're trying to create a theory of physics, not two theories of physics.

[1095] So we have an embarrassment that we have two different theories of physics.

[1096] People have tried to make a unified theory, what they call a unified theory.

[1097] You've heard those words for decades.

[1098] They still haven't.

[1099] That's been primarily done theoretically or tried.

[1100] People actively do that.

[1101] my personal belief is that like much of physics we need some clues so we need some experimental evidence so where is there a place if we go to CERN and do those experiments gravitational waves or general relativity don't matter if we go to study our black holes elementary particle physics doesn't matter we're studying these huge objects so where might we have a place where both phenomenon have to be satisfied.

[1102] An example is black holes.

[1103] Inside black holes.

[1104] Yeah.

[1105] So we can't do that today, but when I think of black hole, it's a potential treasure chest of understanding the fundamental problems of physics and maybe can give us clues to how we bring the embarrassment of having two theories of physics together.

[1106] That's my own romantic.

[1107] What's the worst that could happen?

[1108] It's so enticing.

[1109] Just go in and look.

[1110] Do you think how far are we away from figuring out the unified theory of physics, a theory of everything?

[1111] What's your sense?

[1112] Who will solve it?

[1113] Like, what discipline will solve it?

[1114] Yeah.

[1115] I think so little progress has been made without more experimental clues, as I said, that we're just not able to say that we're close without some clues.

[1116] The best, the closest, the most popular theory these days that might lead to that is called string theory.

[1117] Yeah.

[1118] And the problem with string theory is it works, it solves a lot of beautiful mathematical problems we have in physics.

[1119] and it's very satisfying theoretically, but it has almost no predictive, maybe no predictive ability, because it is a theory that works in 11 dimensions.

[1120] We live in a physical world of three space and one -time dimension in order to make predictions in our world with string theory you have to somehow get rid of these other seven dimensions that's done mathematically by saying they curl up on each other on scales that are too small to affect anything here but how you do that and that's okay that's an okay argument but how you do that is not unique so that means if I start with that theory and I go to our world here I can't uniquely go to it.

[1121] And if I can't, it's not predictive.

[1122] And that's actually...

[1123] And that's a killer.

[1124] That's a killer.

[1125] And string theory is, it seems like from my outsider's perspective, has lost favor over the years, perhaps because of this very idea.

[1126] Yeah, it's a lack of predictive power.

[1127] I mean, that science has to connect to something where you make predictions as beautiful as it might be.

[1128] So I don't think we're close.

[1129] I think we need some experimental clues.

[1130] may be that information on something we don't understand presently at all, like dark energy or probably not dark matter, but dark energy or something might give us some ideas.

[1131] But I don't think we're, I can't envision right now in the short term, meaning, you know, the horizon that we can see how we're going to bring these two theories together.

[1132] a kind of two -part question maybe just asking the same thing in two different ways one question is do you have hope that humans will colonize the galaxy so expand out become a multi -planetary species another way of asking that from a gravitational and a propulsion perspective do you think we'll come up with ways to travel closer to the speed of light or maybe faster than the speed of light which would get a whole heck of a lot easier to expand out into the universe yeah uh well i i think um you know we're not that's a very futuristic i think we're not that far from being able to make a one -way trip to mars that's a that's then a question of uh whether people are willing to send somebody on a one -way trip but oh i think they are There's a lot of, the explorers burn bright within their hearts.

[1133] There's a lot of people willing to die for the opportunity to explore a new territory.

[1134] Yeah.

[1135] So, you know, this recent landing on Mars is pretty impressive.

[1136] They have a little helicopter that can fly around.

[1137] You can imagine, you can imagine in the not too distant future that you could have, I don't think civilizations colonizing, I can envision, but I can envision something more like the South Pole.

[1138] We haven't colonized Antarctica because it's all ice and cold and so forth.

[1139] But we have stations.

[1140] So we have a station that's self -sustaining at the South Pole.

[1141] I've been there.

[1142] It has...

[1143] Wow, really?

[1144] Yeah.

[1145] What's that like?

[1146] Because there's parallels there to go to Mars.

[1147] It's fantastic.

[1148] what's the journey like the journey involves going the South Pole station is run in the U .S. by the National Science Foundation I went because I was on the National Science Board that runs the National Science Foundation and so you get a VIP trip if you're healthy enough to the South Pole to see it which I took you fly from the U .S. to Australia to to Christ Church in Australia, southern Australia.

[1149] And from there, you fly to McMurdo Station, which is on the coast, and it's the station with about 1 ,000 people right on the coast of Antarctica.

[1150] It's about a seven or eight hour flight, and they can't predict the weather.

[1151] So when I flew from Christ's Church to McMurdo Station, they tell you in advance.

[1152] You do it in a military aircraft.

[1153] They tell you in advance that they can't predict whether they can land because they have to land on ice.

[1154] That's reassuring.

[1155] Yeah.

[1156] And so about halfway the pilot got on and said, sorry, this is a, they call it a boomerang flight.

[1157] You know, a boomerang goes out and goes back.

[1158] So we had to stay a little while in Christchurch, but then we eventually went to McMurdo Station and then flew to the, South Pole.

[1159] The South Pole itself is, when I was there, it was minus 51 degrees.

[1160] That was summer.

[1161] Zero humidity.

[1162] And it's about 11 ,000 feet altitude because it's never warm enough for anything to melt, so it doesn't snow very much, but it's about 11 ,000 feet altitude.

[1163] feet of snowpack so you land in a place that's high altitude um cold as could be and uh dry and incredibly dry which means you have a physical adjustment uh the place itself is uh it's fantastic they have this great station there they do astronomy at the south pole nature wise is it beautiful what's the experience like or is it like visiting any town no it's very small there's only less than 100 people there even when I was there you know there there were about 50 or 60 there and in the winter there's less half of that their winter it gets real cold it gets really cold yeah and but it's but it's it's a station and I think and that's I mean, we haven't gone beyond that.

[1164] On the coast of Antarctica, they have greenhouses and they're self -sustaining in McMurdo Station, but we haven't really settled more than that kind of thing in Antarctica, which is a big country or, you know, big plot, a big piece of land.

[1165] So I don't, I can't envision kind of colonizing at people who, living so much, as much as I can see the equivalent of the South Pole station.

[1166] Well, in the computing world, there's an idea of backing up your data, and then you want to do off -site backup, you know, to make sure that if the whole thing, if your whole house burns down, that you can have a backup off -site of the data.

[1167] I think the difference in Antarctica and Mars is Mars is an off -site backup, that if we have nuclear war, whatever the heck might happen here on Earth, it'd be nice to have a backup elsewhere.

[1168] And it'd be nice to have a large enough colony where we sent a variety of people except like a few silly astronauts in suits, you know, have an actual vibrant, get a few musicians and artists up there, get a few maybe like one or two computer scientists, those are essential, maybe even a physicist, but I'm not sure.

[1169] Yeah, maybe not.

[1170] So that comes back to something you talked about earlier, which is Fermi's paradox, Fermi's paradox, because you talked about having to escape.

[1171] And so the missing, one number you don't know how to use in Fermi's calculation or Drake, who's done it better, is how long do civilizations last?

[1172] Yeah.

[1173] Before they, are we, you know, we've barely gotten to where we can communicate with electricity and magnetism and maybe we'll wipe ourselves.

[1174] out pretty soon.

[1175] Are you hopeful in general?

[1176] Like, you think we've got another couple hundred years at least?

[1177] Or are you worried?

[1178] Well, no, I'm hopeful, but I don't know if I'm hopeful in the long term.

[1179] You know, if you say, you know, are we able to go for another couple thousand years?

[1180] I'm that we can do things that don't allow us to kind of keep going, or there can be, whether it, you know, ends up being a virus that we create or it ends up being the equivalent of nuclear war or something else.

[1181] It's not clear that we can control things well enough.

[1182] So speaking of really cold conditions and not being hopeful and eventual suffering and destruction of the human species, let me ask you about Russian literature.

[1183] you mentioned how's that for transition I'm doing my best here you mentioned that you used to love literature when you were younger and you were even were hoping to be a writer yourself that was the motivation and some of the books I've seen that you listed that were inspiring to you was from Russian literature like I think Tolstoy Dostoevsky Solzhen yeah right maybe in general you can speak to your fascination with Russian literature or in general what you picked up from those.

[1184] I'm not surprised you picked up on the Russian literature.

[1185] I'm sorry.

[1186] With your background, but that's okay.

[1187] You should be surprised that didn't make the entire conversation about this.

[1188] That's the real surprise.

[1189] When I didn't really become a physicist or want to go in science until I started college.

[1190] So when I was younger, I was good at math and that kind of stuff, but I didn't really.

[1191] I came from a family.

[1192] I didn't know what he went to college, and I didn't have any mentors.

[1193] But I'd like to read when I was really young.

[1194] And so when I was very young, I read it.

[1195] I always carried around a pocketbook and read it.

[1196] And my mother read these mystery stories, and I got bored by those eventually.

[1197] And then I discovered real literature.

[1198] I don't know at what age, but about 12 or 13.

[1199] And so then I started reading good literature.

[1200] And there's nothing better than Russian literature, of course, in reading good literature.

[1201] So I read quite a bit of Russian literature at that time.

[1202] And so you asked me about, well, I don't know, I'll say a few words, said Dostafsky.

[1203] So what about Dostafsky?

[1204] For me, Dostafsky was important in two, I mean, I've read a lot of literature because it's kind of the other thing I do with my life.

[1205] And he made two incredible, in addition to his own literature, he influenced literature tremendously by having, I don't know how to pronounce polyphony.

[1206] So he's the first real serious author that had multiple narrators and that's a that he absolutely is the first and he also was the first he began existential literature so the most important book that I've read in the last year when I've been forced to be isolated was existential literature it was I decided to reread Camus the Plague.

[1207] Oh, yeah, that's a great book.

[1208] It's a great book, and it's right now to read it.

[1209] I think that book is about love, actually.

[1210] Love for humanity.

[1211] It is, but it has all the...

[1212] It has all the...

[1213] You should, if you haven't read it in recent years, I had read it before, of course, but to read it during this, because it's about a plague, so it's really fantastic to read down.

[1214] But that reminds me of, you know, he was a great existentialist, but the beginning of existential literature was Dostoevsky.

[1215] So in addition to his own great novels, he had a tremendous impact on literature.

[1216] And there is also, for Dostoevsky, unlike most of their existentialists, he was, at least in part, religious.

[1217] I mean, religiosity would permeated his idea.

[1218] I mean, one of my favorite books of his is The Idiot, which is a Christ -like figure in there.

[1219] Well, there's Prince Miskin, is that a name?

[1220] Prince Mishkin, yeah.

[1221] Yeah, Michigan.

[1222] Yeah, that's one thing about, so you read it in English, I presume.

[1223] Yeah, yeah, yeah.

[1224] Yeah, so that's the names, that's what gets a lot of people.

[1225] There's so many names, so hard to pronounce, you have to remember all of them.

[1226] It's like, you have the same problem.

[1227] But he was a great character, so that, yeah.

[1228] I kind of, I have a connection with him, because I often, the title of the book, you do the idiot is I kind of I often call myself an idiot because that's how I feel I feel so naive about this world and I'm not sure I'm not sure why that is maybe it's genetic or so on but I I have a connection the spiritual connection to that character to Michigan to Michigan yeah that you're just but he was far from an idiot no in some sense in some sense but in another sense maybe not of this in another sense he was yeah I mean but he was a bumbler yeah but you also mentioned Solzhen yeah very interesting did and and he always confused me of course he was really really important and writing about the Stalin and first getting in trouble and then he later he is he wrote about Stalin in a way I forget what the book was in a way that was very critical of Lenin.

[1229] Yeah, he's evolved through the years and he actually showed support for Putin eventually.

[1230] It was a very interesting transition he took, no, journey he took through thinking about Russia and the Soviet Union.

[1231] But I think what I get from him is basic um it's like uh victor frankel has a man search for meaning i have a similar kind of sense of um of the cruelty of human nature yeah cruelty of indifference but also the ability to find happiness and the small joys of life that that's something there's nothing like a prison camp that makes you realize you could still be happy with a very very little well yeah he was his description of kind of how to make how to go through a day and actually enjoy it in a prison camp is pretty amazing yeah oh and some prison camp i mean it's the worst of the worst the worst of the worst and also just uh i you know you do think about the role of authoritarian states and um in you know like hopeful idealistic systems somehow leading to the suffering of millions.

[1232] And I, you know, this might be arguable, but I think a lot of people believe that Stalin, I think genuinely believed that he's doing good for the world.

[1233] And he wasn't.

[1234] It's a very valuable lesson that even evil people think they're doing good.

[1235] Otherwise, it's too difficult to do the evil.

[1236] The best way to do evil is to believe framing in a way like you're doing good.

[1237] And then this is a very clear picture of that, which is the Gullogs.

[1238] Solzhenitsyn is one of the best people to reveal that.

[1239] The most recent thing I read, it isn't actually fiction, was the woman, I can't remember her name, who got the Nobel Prize about within the last five years.

[1240] I don't know whether she's Ukrainian or Russian, but their interviews, have you read that?

[1241] interview of Ukrainian survivors of?

[1242] Well, I think she may be originally Ukrainian.

[1243] The book's written in Russian and then translated in English, and many of the interviews are in Moscow and places.

[1244] But she won the Nobel Prize within the last five years or so.

[1245] But what's interesting is that these are people of all different ages, all different occupations and so forth, and they're reflecting on their reaction to basically the present Soviet system, the system they lived with before.

[1246] There's a lot of looking back by a lot of them with, well, it being much better before.

[1247] Yeah.

[1248] I don't know what.

[1249] In America, we think we know the right answer, what it means to be to build a better world.

[1250] I'm not so sure.

[1251] I think we're all just trying to figure it out.

[1252] Yeah, there's doing our best.

[1253] I think you're right.

[1254] Is there advice you can give to young people today, besides reading Russian literature at a young age, about how to find their way in life, how to find success in career or just life in general?

[1255] I just, my own belief, It may not be very deep, but I believe it.

[1256] I think you should follow your dreams.

[1257] And you should have dreams and follow your dreams if you can to the extent that you can.

[1258] And we spend a lot of our time doing something with ourselves.

[1259] In my case, physics, in your case, I don't know, whatever it is, machine learning and this.

[1260] We should, yeah, should have fun.

[1261] What was, wait, wait, wait, wait, follow your dreams.

[1262] What dream did you have?

[1263] Well, originally I was...

[1264] Because you didn't follow your dream.

[1265] Well, I changed along the way.

[1266] I was going to be.

[1267] But I changed.

[1268] What happened?

[1269] What happened?

[1270] Oh, I read...

[1271] I decided to take the most serious literature course in my high school, which was a mistake.

[1272] I'd probably be a second -rate writer now.

[1273] Could be a Nobel Prize winning writer.

[1274] And the book that we read, even though I had read Russian novels, I was 15, I think, cured me from being a novelist.

[1275] Destroyed your dream?

[1276] Yes.

[1277] Cured you.

[1278] Okay.

[1279] What was the book?

[1280] Moby Dick.

[1281] Okay.

[1282] So why Moby Dick?

[1283] Yeah, why?

[1284] So I've read it since, and it's a great novel.

[1285] maybe it's as good as the Russian now I've never made it through I lost it was too boring too long okay your words are going to mesh with what I say excellent and you may have the same problem at older age that's where I'm not a writer it may be so the problem is Moby Dick is what I remember was there was a chapter that was maybe a hundred pages long all describing us why there was Ahab and the white whale and it was the battle between Ahab with his wooden peg leg and the white whale.

[1286] And there was a chapter that was 100 pages long in my memory.

[1287] I don't know how long it really was.

[1288] That described in detail the great white whale and what he was doing and what his fins were like and this and that.

[1289] And it was so incredibly boring, the word you used, that I thought, if this is great literature, screw it.

[1290] Fascinating.

[1291] Okay.

[1292] Now, why did I have a problem?

[1293] I know now in reflection, because I still read a lot, and I read that novel, you know, after I was 30 or 40 years old, and the problem was simple.

[1294] I diagnosed what the problem was.

[1295] I, that novel, in contrast to the Russian novels, which are very realistic and, you know, point of view, is one huge metaphor.

[1296] oh yeah at 15 years old i probably didn't know the word and i certainly didn't know the meaning of a metaphor yeah like why do i care about a fish why are you telling me all about this fish exactly it's one big metaphor so reading it later as a metaphor i could really enjoy it but the teacher gave me the wrong book or maybe it was the right book because i went into physics and so uh but it was it was truly i think i may oversimplify but it was really that i was too young to read that book because But not too young to read the Russian novels, interestingly, but too young to read that.

[1297] Because I probably didn't even know the word, and I certainly didn't understand it as a metaphor.

[1298] Well, in terms of fish, I recommend people read Old Man in the Sea, much shorter, much better.

[1299] It's still a metaphor, though, so.

[1300] But you can read it just as a story about a guy catching a fish, and it's still fun to read.

[1301] I had the same experience as you, not with Moby Dick, but later in.

[1302] college I took a course on James Joyce don't ask me why I was major in computer science I took a course on James Joyce and I was kept being told that he is widely considered by many considered to be the greatest literary writer of the 20th century and I kept reading like I think so his short stories the dead I think it's called it was very good well not very good but pretty good and then you'll see it's actually very good it is very good only the dead the final story it still rings with me today but then ulysses was i i got through ulysses with the help of some cliff notes and so on but uh and so i did ulysses and then finnigan's wake the moment i started finnigan's wake i said this this is stupid this is that's when i went full into like um i don't know that's where i went full kofka bakowski like people who just talk about the darkness of the human condition in the fewest words possible and without any of the music of language so it was a turning point as well i i wonder i wonder when is the right time to do the to appreciate the beauty of language like even shakespeare i was very much off put by shakespeare in high school and only later started to appreciate it's its value in the same way let me ask you a ridiculous question I mean, because you've read Russia literature, let me ask this one last question.

[1303] I might be lying.

[1304] There might be a couple more.

[1305] But what do you think is the meaning of this whole thing?

[1306] You got a Nobel Prize for looking out into the trying to reach back into the beginning of the universe, listening to the gravitational waves.

[1307] But that still doesn't answer the why.

[1308] Why are we here?

[1309] Beyond just the matter and antimatter, the philosophical question.

[1310] The philosophical question about the meaning of life I'm probably not really good at.

[1311] I think that the individual meaning, I would say it rather simplistically, is whether you've made a difference, positive difference, I'd say, for anything besides.

[1312] yourself, meaning you could have been important to other people, or you could have discovered gravitational waves that matters to other people or something, but something beyond just existing on the earth as an individual.

[1313] So your life has meaning if you have affected either knowledge or people or something beyond yourself.

[1314] that's a simplistic statement but it's about as good as I can I have that may in all of its simplicity it may be very true do you think about does it make you sad that this ride ends do you think about your mortality yeah are you afraid of it I'm not exactly afraid of it but saddened by it And, you know, I'm old enough to know that I've lived most of my life.

[1315] And I enjoy being alive.

[1316] I can imagine being sick and not wanting to be alive, but I'm not.

[1317] And so I'm not...

[1318] It's been a good ride.

[1319] Yeah, and I'm not happy to see it come from then.

[1320] I'd like to see it prolong.

[1321] long.

[1322] But I don't fear the dying itself or that kind of thing.

[1323] It's more.

[1324] I'd like to prolong what is, I think, a good life that I'm living and still living.

[1325] It's kind of, it's sad to think that the finiteness of it is the thing that makes it special.

[1326] and it and also sad to um you know to me at least it's kind of i don't think i'm using too strong of a word but it's kind of terrifying the uncertainty of it the mystery of it you know the mystery of death the mystery of it yeah of death when we're talking about the mystery of black holes that's somehow distant that's somehow out there and the mystery of our own but but but but even life the mystery of consciousness i find uh so hard to deal with to I mean, it's not as painful.

[1327] I mean, we're conscious, but the whole magic of life we can understand about consciousness where we can actually think and so forth.

[1328] It's pretty...

[1329] It seems like such a beautiful gift that it really sucks that we get to let go of it.

[1330] We have to let go of it.

[1331] What do you hope your legacy is, as I'm sure they will?

[1332] Aliens, when they visit, humans have destroyed all of human civilization.

[1333] aliens read about you in an encyclopedia that will leave behind what do you hope it says well i would i would hope they if to the extent that they evaluated me uh felt that i helped move science forward as a tangible contribution and that uh i served as a good role model for how humans should live their lives and we're part of creating one of the the most incredible things humans have ever created.

[1334] So, yes, there's the science.

[1335] That's the Fermi thing, right?

[1336] And the instrument, I guess.

[1337] And the instrument.

[1338] The instrument is a magical creation, not just by a human, by a collection of humans.

[1339] The collaboration is, that's humanity at his best.

[1340] I do hope we last, quite a bit longer, but if we don't, this is a good thing to remember humans by.

[1341] At least they built that thing.

[1342] That's pretty impressive.

[1343] Barry, this is an amazing conversation.

[1344] Thank you so much for wasting your time and explaining so many things so well.

[1345] I appreciate your time today.

[1346] Thank you.

[1347] Thanks for listening to this conversation with Barry Barish.

[1348] To support this podcast, please check out our sponsors in the description.

[1349] And now, let me leave you with some words.

[1350] from Werner Heisenberg, a theoretical physicist and one of the key pioneers of quantum mechanics.

[1351] Not only is the universe stranger that we think, it is stranger that we can think.

[1352] Thank you for listening and hope to see you next time.