2018 Reines Lecture: Exploring the Universe with Gravitational Waves by Kip Thorne

[Music] welcome to the fourth Frederick - lecture my name is Ken janda and I'm lucky to serve as the Dean of physical sciences here at the University of California Irvine and tonight we're really honored to have Kip Thorne 2017 Nobel laureate to teach us about gravity waves Thank You Kip for making a trip down it's great to see so many of our alums and supporters students and students especially from local high schools and middle schools we'll learn a little about physics Frederick Frederick rinette's was you see eyes founding dean and was the recipient of the 1995 Nobel Prize for the observation of the neutrino Fred's words of wisdom that's become our school model were never stop asking why since his founding the UC Irvine school of physical science embodies the spirit we ask the really hard questions and through visionary interdisciplinary research we deliver the answers we catalyze breakthrough solutions and insights to some of our times most existential challenges human disease climate change and advancing humanity through a deeper understanding of the world around us faculty and students in the department of physics and astronomy continue to be at the forefront of their fields and to share the department's rich history I'd like to introduce chair of the department James Bullock James is a theoretical cosmologist who studies galaxy formation he attended the Ohio State University in the University of California Santa Cruz where he was awarded the PhD degree after a postdoctoral stint at Harvard he joined the UCI faculty in 2004 among his many honors and awards are the he's a fellow of the American Association for the Advancement of science and a UCI Chancellor's fellow his research has featured on BBC News LA Times science magazine Discovery Channel National Geographic the Science Channel and how the universe works another primont prominent shows James thanks so much Ken it's really a great pleasure to be here and welcome you all to the fourth annual Fred Ryan s lecture Fred - as we just heard was the founding dean of the school of physical sciences and before introducing tonight's speaker Professor Kip Thorne I'd like to give you a little background on Fred - and then tell you a little bit more about what we're doing here within the department of physics and astronomy right now is dean john de mentioned fred - is famous for discovering a brand new elementary particle of nature the neutrino and for this he win the Nobel Prize in Physics in 1995 now the idea of the neutrino had actually been around since 1930 when Wolfgang Pauli proposed its existence to explain a puzzle the puzzle had to do with radioactivity and when nuclei decay they spit out radiation and this radiation was missing energy and what Pauli suggested was that this energy wasn't really missing him is being carried away by this new particle this neutrino that was just incredibly hard to detect now this neutrino was so it had to be so weak weakly interacting then in fact it could pass all the way through the earth without being without being stopped by anything it was a ghost and Hans bethe calculated and sorry Hans bethe famously proclaimed that it was impossible to detect this thing Pauli himself bet a case of champagne that no one would ever detect it enter Fred - together with his colleague Clyde Cowan they set out to do the impossible and they built an experiment that did just that it detected neutrinos coming from a nuclear reactor this was the man who founded our school he was creative enough a little bit stubborn enough and hardworking enough to do this thing that other people said could not be done and let me tell you that that spirit is alive and well within our school and within the department of physics and astronomy today physicists within our department are continuing to try to unlock new cosmological mysteries one of them for example has to do with dark matter dark matter is another theoretical particle dark matter in fact is so weakly interacting it makes in the neutrino look like an extrovert within our department astronomers are working together with particle physicists to scan the skies and smash atoms to try to figure out just what this dark matter is still others within our department condensed matter physicists are working to bring about the next technological revolution by developing quantum computers and build molecular scale electronics and others are working on ways to diiie sahlan eyes seawater and to stop harmful bacteria from infecting cells one more tip that you may not know this but the world's largest and most advanced private fusion energy company in the world was founded on ideas developed right here at UC Irvine by Norman Ross docker who was a contemporary of Fred - fusion of course is what powers the Sun and ideas on how to make it work here on earth developed here at UC Irvine are now being utilized to attempt to produce carbon free uninterrupted power generation that could one day power the world so now on tonight's to tonight's speaker Kip Thorne no professor Thorne perfectly honors this legacy of Fred - in 2017 he was awarded the Nobel Prize in Physics along with Rainer Weiss and Barry barish for his contributions to the development of the LIGO detector in its observation of gravitational waves but not only has he done fundamental prize-winning research in astrophysics in physics throughout his entire career but he is also among the most successful and important teachers of scientific ideas alive today most professional physicists myself included learned general relativity from his famous textbook gravitation more recently he co-authored a new textbook on modern classical physics that I suspect his motivating departments across the globe to rethink how they're teaching the subject as you'll soon see professor Thorne is also a gifted popular communicator of science he was an executive producer of the 2014 film interstellar now if you don't remember this movie officially had to start it starred Anne Hathaway and Matthew McConaughey but the real star was a wormhole if you want to learn more about wormholes and the science of interstellar I strongly suggest you check out check out professor Thorne's book about the science of interstellar now as we're about to hear one of professor Thorne's many contributions to basic science was developing the ideas that led to the detection of gravitational waves now one of the reasons why this was really important is that by detecting gravitational waves from distant astronomical objects this opened up a brand new window into the field of astronomy historically astronomers have always relied on basically light so even the first astronomers who looked up at the sky we're studying stars with the light coming from them today we study all kinds of light electromagnetic radiation x-rays gamma rays microwaves but ultimately it's always been electromagnetic radiation thanks to LIGO there's a brand-new thing gravitational waves we're entering a new era of multi messenger astronomy that allows us to hear or see or possibly you might say here the universe an entirely different way now Fred rhinos would have loved this development one of the last experiments he led here at UCI actually detected neutrinos coming from a distant supernova that blew up in 1987 today researchers within our department are working to construct a new neutrino telescope called arianna on the surface of the cold transparent ice in Antarctica the hope is that one day we'll be able to study the same explosive events from deep space using neutrinos light waves and yes gravitational waves but of course this will be in the future before then I invite you to sit back and enjoy the fascinating story of gravitational waves from the Big Bang to black holes by our 2018 Fred - lecturer professor Kip Thorne [Applause] it's a great honor to be here and give this lecture I came to Caltech on the faculty before almost any of you were born 1965 or 66 and one year earlier in 65 I believe was when Fred started to build the physical sciences division here at UCI I had a collaborator here who was on the faculty in 1966-67 and so I came down to Irvine quite a bit to work with him on research working on the theory of pulsations of relativistic stars neutron stars and so forth and I watched the early period of the building of this great institution in the physical sciences and admired Fred's work on that and then cherished him as a colleague through the subsequent decades as you see I grew stronger and stronger and I had then further collaborations and interactions with people here such as Joe Weber and Virginia Trimble who were not only their colleagues but dear friends so it's really as wonderful to be here to give this lecture and I would like to begin with a little story that 1.3 billion years ago if we can turn the lights off when Mulla celled life was just forming on earth but in a galaxy far far away two black holes orbited around and around each other creating ripples in the fabric of space and time called gravitational waves this is what they would have looked like if you had been up there looking with your own eyes they create spiral the spiraling pattern in the Stars behind them through a phenomenon called gravitational lensing the bending of this star light is it goes around and around the black holes black holes collided as you just saw merged and in that merger they created a gigantic burst of gravitational waves that went traveling out of the galaxies in which those two black holes lived into intergalactic space across the great reaches of intergalactic space and reached the outer fringes of our galaxy the Milky Way galaxy 50,000 years ago when our ancestor was sharing the earth with the Neanderthals just think of that moved onward through our galaxy for 50,000 years and on 14 September 2015 they arrived at Earth they arrived actually initially at the tip of the Antarctic Peninsula these waves traveled up through the earth just like neutrinos to penetrate through the earth unscathed gravitational waves do as well and emerged at the LIGO that is laser interferometer gravitational wave detector in Livingston Louisiana and one point and Oh point so and seven milliseconds later seven one thousand a second later they arrived at anniversary earth at the detector in Hanford Washington the LIGO team of a thousand people analyzed the data for a period of several months trying to be absolutely sure that they what we saw and coming out of our detector was a signal it really was due to gravitational waves these are a few of the 1,000 members of the likeö collaboration that worked on this plus several hundred people from the vertical collaboration in Europe and finally on I guess it was February 12 of 2016 the discovery of the gravitational waves was announced and it made headlines in all of the major newspapers around the world for example the New York Times here with a photograph of the vacuum tube in which the laser beams go back and forth as part of the LIGO experiment and a headline with a faint chirp scientists prove Einstein correct they've discovered gravitational waves almost immediately this discovery seeped into popular culture for example Ray Weiss my collaborator was on a subway two days later in New Yor city and saw this and this is an actual photograph that his son-in-law who was with him took of two people on the subway typical New Yorkers and this says scientists found gravitational waves in outer space if only were that easy to find an apartment in New York City with a walk-in closet and the day after the discovery was announced in The New Yorker that came out on that day a cartoon two birds sitting on a branch the sound of the gravitational wave if you were to put it on a speaker is that of a chirp and he says was that you I heard just now or was it two black holes colliding so how did we get here and I'm going to change batteries my battery is already going out and fortunately I did bring some more how did we get here I'm going to tell you the story in brief from my own personal perspective just give me a moment I thought I had fresh batteries in there but I didn't my story begins with Albert Einstein a little over 100 years ago Albert Einstein predicted the existence of gravitational waves he had just formulated his theory of gravity called general relativity and he used the equations of his theory to make this prediction and he told us that there should be these waves that travel across the universe and that their physical manifestation is that they stretch and squeeze space what that means when two are Technol times is if you have two inertial reference frames one here and one there as the gravitational waves goes by the nurse'll reference frames move back and forth respect to each other that means that if you have two particles that are sitting one here and one there as the waves pass the particles always try to remain inertial so they're pushed back and forth with respect to each other but there's a they put a stretching along the horizontal direction if the waves are propagating into the screen while there's the squeezing vertically and then when there's a stretching vertically there's a squeezing horizontally and so that's what the pattern would look like if the waves went through a set of particles now Einstein wrote a technical paper describing these gravitational waves in 1916 just 100 years before we announced the discovery of the waves and he said in that paper these waves for any phenomenon that occurs in the universe he said in effect it wasn't quite in these words these waves will be so weak that humans are unlikely ever to detect them however Joseph Weber at the University of Maryland beginning about in 1958 or 59 but well most of his work done in the 1960s built a gravitational wave detector he was the first person to have the courage to do this and to figure out a way to do it that might have a possibility to succeed and why did he have the hutzpah to do this why not Einstein said it was impossible basically because there was new knowledge I don't think he really well I don't think it mattered to him but it did matter to me that there were now sources of gravitational waves that you could believe might be detectable black holes and neutron stars which were unknown in Einstein's period but for Joe the important thing was that there had been a major developments in technology such as lasers and computers new technology that enabled him to have new tools that ice I never dreamed of to do the experiment now I spent a two months in laser in the French Alps in 1963 and Joe lectured there at laser sh about gravitational waves I was a student and I listened to his lectures and then I went walking with Joe in the French Alps talking about gravitational waves and the experiment that he was developing and I basically became a convert that this was really exciting gravitation ways would be wonderful if they can be detected and so largely inspired by Joe on the experimental side and then on the theoretic side-by my PhD advisor John wheeler and a few other theorists I decided that I wanted to pursue gravitational waves as one of the fields in which I worked when I moved to Caltech on the faculty in 1966 and yes that's me the hair moved off of my head and under my chin so I built a theory group beginning in 1966 where we worked on black holes neutron stars and gravitational waves and we began to develop a vision for the science that might be done with gravitational waves if they could be detected and the key thing that underlay this vision is the vast contrast between the electromagnetic waves with which astronomers normally study the universe light being the primary version in gravitational waves electromagnetic waves or oscillations of the electromagnetic field that propagates through space time while gravitational waves or oscillations in the fabric or shape of space-time itself as I have described electromagnetic waves in astronomy are almost always incoherent superpositions of emission from individual particles or atoms or molecules whereas gravitational waves are coherently emitted by the boat motion of matter or more precisely of mass and energy electromagnetic waves are all too easily absorbed and scattered as they travel across the universe by matter and they gravitational waves are never significantly absorbed or scattered not even if they are created in the birth of the universe near what we call the planck era and there is these extreme differences have some important implications first of all many gravitational wave sources won't be seen electromagnetically because the emission process are so different the propagation the penetration is so different and so forth and second enormous surprises are we felt would be likely if gravitational waves could ever be detected and so it was clear to me by 1972 that this was really the most exciting thing that I could work on if the experimenters could really pull it off successfully now Joe Weber published a result 1969 announcing evidence for he didn't say he discovered gravitational waves but evidence for gravitational waves it turned out that he was not seeing gravitational waves in the end but nevertheless he got everybody else in this field going as an inspiration for us and he also developed much technology and some data analysis techniques that underpin what we do today so we regard him as the pioneer of our field Ray Weiss was another pioneering figure ray in 1972 April 15 1972 he published in an internal MIT technical report the idea for an analysis of the kinds of gravitational wave detectors that we would ultimately use in illegal for detected detection of gravitational waves he had mirrors that hung from overhead supports you're looking down on this diagram and laser beam that would go in get split in half and go down and bouncing fat back and forth many times between these mirrors the same thing between those laser beam would come back recombine and by and when these mirrors moved apart and those moved together there would be a change in the different distance that the light in this arm traveled compared to that arm and as a result through the interference of the two light beams the intensity of the light going down here to a 42 detector would increase and decrease and just precisely the pattern that gave you this shape of the wave that is passing so this was his idea the remarkable thing was that ray then identified all the major noise sources the first generation of our lie of gravitational wave detectors would face described ways to deal with each and every one of them an estimated then what kind of sensitivity could be achieved with such a detector and concluded by comparing with the strength of the waves that I and my other theorist colleagues were predicting concluded that if you made such a detector that was a few kilometers long you might have a serious chance of success now I heard about this I had not yet studied a Ray's paper well first wasn't published in the regular literature because ray being Ray had the attitude that you don't publish something like this until after you've built the instrument and detected gravitational waves and so but he did disseminate it to his colleagues but at that same time and before I saw a copy of this or had had any serious discussions with him we were finalizing the text of our book gravitation the textbook that I co-authored on relativity theory and so I looked at the basic idea I looked at some numbers and was obvious to me that Ray was crazy or stupid or something and so I used very gentle words in this text book I wrote a sentence which said this idea is not promising and I wound up eating crow I spent about 60% of the energy of my whole career trying to help ray and the other experimenters pull it off afterwards but why did I regard this as crazy at the time well just look at some numbers you're trying to measure the motion of two mirrors using light and I'm going to tell you how big the motion of these mirrors is that you have to measure let's begin with one centimeter which is just a little smaller than an inch of course you divide by a hundred you get the thickness of a human hair divided by a hundred again you at the wavelength of the light that is being used to try to measure the motions of the mirrors divided by 10,000 you get the diameter of an atom divided by a hundred thousand year the diameter of the nucleus of an atom divided by a thousand again you get the magnitude of the mirror motions that you would that we thought you might have to be able to measure in order to pull this off and I look through those numbers I said ray is crazy all right this is one trillions ten to the minus twelve one one trillionth the wavelength of the light that ray is going to use to make this measurement the in technical terms are going to split a fringe by a part in 10 to the 12 I mean this is this is obviously not possible and then I study his paper in detail I did some more serious calculations I had extended discussions with Vladimir Brzezinski a dear friend physicists in Moscow Russia and with Ray and I became convinced that it could succeed being convinced I decided that I as a theorist would do everything I could to help ray and his experimental colleagues pull this off successfully but about this time a few years later I guess it was probably two years or so later than the beginning of this story with ray Ron griever and musk in Glasgow Scotland had a brilliant idea for an alternative way to bounce the light back and forth in the arms he I think ray recognized before this that could you could do it this this way but it was only Ron who really identified that it was possible to pull it off technically and that would have some very very big advantages over Ray's way that is to bounce the light back and forth fold it onto itself by making this these mirrors be the mirrors in a resonant cavity so the light resonates back and forth upon itself building up coherently a very intense beam in here and that kind of a technique then turns turned out to have great versatility and great power although it was harder technically to pull it off it is fundamentally simpler and more powerful in the end in the modern era 1976 to 1978 I talked to my colleagues in Caltech and said we really ought to get into this game we should build an experimental group to work alongside or a wisest group at MIT because this is really a very exciting field and my colleagues in the Caltech administration jumped in with with both feet with great enthusiasm and we brought Ron dreamer then to Caltech to lead the effort we also brought Stan Whitcomb a who began as an infrared astronomer he was a young guy he was just got had just recently received his PhD we brought him in to work with Ron and leading this and to be the person the hands-on leader in building a 40 either prototype detector of the sort that Ray had invented and then Ron had modified by changing what goes on in the arms of the malai pouncing back and forth in parallel with building the forty hour building the 40 metre prototype at Caltech ray weiss and his group at MIT completed the construction of a smaller prototype gravity wave detector and they also carried out a feasibility study four kilometer scale interferometers costing of them technical issues you had faced in enlarging the eastern kilometer scale and on the basis of that of that of their feasibility study the prototype work they did the prototype work done at Caltech and prototype work done in Ron's dreamers group in Glasgow Scotland and a group in Garching Germany we went to NSF and were encouraged by Richard Isaacson a superb program director at NSF to move forward in creating the LIGO collaboration from 84 to 87 and our collaboration of Caltech and MIT in planning to build these gravitational wave detectors with kilometer scale sizes it was led by Ray and Iran and me this was the most dysfunctional leadership you can imagine it was almost like a cartoon and it was a fundamental issue that although Ron driver was highly creative he had difficulty functioning in a collaboration where he didn't have full control over everything he was doing and there were big disagreements between ray and Ron about how you would go about things and I was the mediator and by 19 at the end of 1986 early 1987 it was just clear that this was a disaster waiting to happen and so we brought in Robby volt to be a single director with the authority to bash heads together and get Caltech and MIT working together jointly and delete us in writing a proposal for the construction of LIGO so under Robby's leadership we wrote and sent to NSF and I think it was November of 1989 a proposal to construct facilities in which we would place the interferometers and we would then build two generations of interferometers an initial set of interferometers that would be simple enough that we knew how to do it then and that we really were confident we could pull them off but would not be sensitive enough to have a high probability of detecting gravitational waves if we were lucky we would see ways but we would have to be awfully lucky nature would have to be awfully kind to us but then with the experience we got with the initial interferometers we would build a second generation called the advanced interferometers which should have a high probability of seeing gravitational wave so that was our strategy in our 1989 proposal we struggled from 1990 to 1992 to get this funded and did ultimately succeed in 1992 NSF and Congress bought into this in 1992 and they never turned away from us we had complete backing from the National Science Foundation and from a Congress regardless of which political party was in power from then until we ultimately discovered gravitational waves I have to hand it to Congress as well as Danis F that I am impressed by how they stuck with us but part of that is frankly that we told them we would have to build two generations in order to succeed and so they were prepared for our not seeing anything with the first interferometers when it came time to move forward with the construction and to develop the detailed plans for construction we brought on Barry barish who had been leading when the construction of one of the large particle detectors in the superconducting supercollider which was cancelled by Congress and I think 94 and so we grabbed Barry and brought him in to lead us through construction and the organization of construction and on through the early interferometers and Barry was just superb I think by my judgement and I think many many people agree with me in physics he's the most skilled leader of large experimental projects that the world has ever seen and experienced Peres mental physic projects he led us in constructing the facilities he organized like Oh in part expanding it to other institutions by setting up something called the LIGO scientific collaboration that collaboration now has 1,200 scientists and engineers in about 80 institutions in 18 nations around the world so because we just did not have by any means enough and enough scientists and engineers to pull this off successfully at Caltech and MIT alone because these instruments are so complex there are so many things that go wrong with it that you have to pre be prepared for and you have to build into the instruments ways of dealing with everything if you go wrong and that just required a very large team he led us through the construction of the initial interferometers and their first searches and then we he left us to go back to high-energy physics to lead the design study for the next generation of large particle colliders and we brought then on Jay marks and now David writes he'd lead our project the initial interferometers were installed and operated between 2000 and 2010 the advanced interferometers were installed between 2010 and 2015 and now I'm going to lose pause because I don't want to tell you the gravity is already ejected yet because I wanted to go back and pull in a couple of other ideas in the meantime on the theory front there was a very deep issue that Vladimir Brzezinski the Russian that I mentioned to you I pointed out to us already in 1968 he said that basically no matter what kind of a gravity wave detector you try to build you're going to wind up trying to measure the motions of very big masses human sized masses that are where the motion is so small that you will see those masses behaving according to the laws of quantum physics not classical physics let me explain a bit more in the context of LIGO you have two mirrors separated by four kilometers the light beams bouncing back and forth between them they're trying to measure in the advanced detectors the motions of 40 kilogram mirrors then the precision of 10 to the minus 17 centimeter switches approximately in technical terms the half width of the Schrodinger wave function or the center-of-mass degree of freedom of the mirror what that means is that the mirror physically this is center of mass the thing you actually measure with your laser beam it's bouncing back and forth fluctuating and where it is in a manner that is unstoppable and unpredictable these are quantum mechanical fluctuations and those fluctuations are at the level that they begin to be detectable by the advanced LIGO detectors at their design sensitivity and who if you go beyond that you have to deal with that you have to be able to measure the motion of a mirror that is caused by a passing gravitational wave where the motion is smaller than these quantum mechanical fluctuations and how the heck do you do that Brzezinski said well look first of all you're going to see human sized objects behave quantum mechanically he said it has to be possible to build quantum non demolition technology to deal with this and so in fact much of the work in my own theory research group in collaboration with Berg in skis experimental research group from about 1980 up until the present has been devoted to conceiving the ideas for and developing the technology for this quantum non demolition so this just gives you a sense of the challenges here and as we go into the future this is a huge piece of the experimental effort this so-called qnd technology on the theory front there was another issue we expected I expected the first thing we would see would callate be collisions of heavy black holes and that is what we did see but we could not predict what the signal would look like we could predict while they were spiraling around each other but not when they were colliding and the collision waves would be the strongest waves and so we had to have computer simulations we had to use computers to solve Einstein's equations during the collision to figure out what the shapes of the waves would be and then when you saw the waves you would have to be able to go back to the computer simulations and compare with the computer simulations to deduce the details of the black holes that were colliding so we had to have simulations simulations were not going well because of a variety of very technical problems and so in 2001 I myself left day-to-day involvement with a LIGO project and devoted my energy then for the next few years to building at Caltech a group doing computer simulations of colliding black holes in collaboration with a group at Cornell it was already going and that I judged was the best group elsewhere in the world and we built what is called the sxs project I should emphasize that just as I did not build LIGO similarly I didn't write the computer code for sxs all I did was provided some scientific vision for where we were going and judgment as to what kinds of accuracies need to be achieved and things of this sort so it was really the younger scientists who pulled everything off technically on both the experiment and these simulations okay back to September 14 2015 the advanced LIGO detectors just gone into operation they were being prepared for their first search the first search was supposed to begin about three days later they were just being tuned and brought into the final state they're very complicated as I say and there's a lot of tuning to do bring them in a final state to begin the search when suddenly the first signal came in so the experimental team froze the state of the detectors they said this is the final state our search has now begun and they searched then that first search continued onward for several months the first signal that it came in this is the raw signal with bandpass filtered so you throw away everything at frequencies below 30 Hertz and above about 300 Hertz because the detector isn't noisy at those frequencies you just keep the raw signal in between this is the signal and the raw signal no fancy signal processing in Livingston Louisiana essentially the same signal in Hanford Washington by then cleaning the signals up and comparing them with the sxs numerical relativity simulations the simulations are in red the cleaned-up incoming signal is in gray it could be doo dee doo then through those comparisons that what had been seen was two black holes one weighing 29 times what the Sun weighs the other 36 times the sun's weight that's a total of 65 solar masses they collided and they merged the final black hole only weighed 62 solar masses three solar masses of energy three solar masses of energy had been thrown off as gravitational waves it's as though you had taken three suns and annihilated them completely and turned that all into pure energy and putting them all into gravitational waves and that is what happened in this first cob servation the first source all right and the distance we inferred then by comparing what the simulations was 1.3 billion light years so you're off and running as of now we have seen six pairs of colliding black holes these are the signals we saw from each of them the lower the mass of the black holes the longer the signal lasts in the LIGO frequency band and so we have signals of various lengths at 36 and 29 solar mass black holes at 1.3 billion light years 29 and 13 at 3 billion and so forth and so on etc the sixth one doesn't appear here because by that time detection was getting sufficiently routine that we didn't the LIGO team didn't bother to put the sixth one on there but it is playing a significant role in starting to do statistics in order to figure out details with a population of colliding black holes in the universe I it was very important to be able to determine where the source was on the sky so we could look and see if there was any electromagnetic emission for the first five signals there the signal on the sky was very uncertain the location of the sky was very uncertain these are Arab boxes as to where the signals were for each of these but the signal that came in on August 14 of last year we identified its location with an amazingly small arrow box real small a little a few times bigger than the moon but that's still that small compared to what what we were doing the reason was we now had a third gravity wave detector in our system it was in Europe it's called the Virgo gravity wave detector it was built by a scientist in nineteen laboratories in France Italy of Netherlands Poland Hungary to a roughly 250 scientists and with then these 3d textures we could triangulate we determined where the sources on the sky by the delay in arrival time of pieces of the signal at different locations and that helps us see where the source was I told you that the first signal came from the south and it arrived at Hanford wha at Livingston Louisiana before I arrived at Hanford Washington and so that told us the signal was down in the south we were able to pinpoint it as hitting the earth near the Antarctic Peninsula and so if you had three detectors you can do triangulation a lot better and pin down where it was on the sky and this turned out to be very important three days later when we saw collision not of two black holes but of two neutron stars these are stars that are basically made of pure nuclear matter that have sizes of diameters saved about 20-25 kilometers but yet weigh something like one and a half times as much as the Sun amazing kinds of stars the signal this is a signal in where we plot frequency upward as a function of time is called a time frequency plot the single a lot in Hanford Washington the little dots in here are noise but you see the signal sweeping up this is just a way to visualize the signal you get much better accuracy on the signal by other data analysis methods but this enables me to see it visually in Livingston Louisiana and very very faint in Virgo in Italy but with those data it was all possible to pinpoint where this was on the sky it was somewhere in this little error box on the sky 1.7 seconds after those two black holes collided or after the signal arrived from the collision I'm sorry the two neutron stars they deploy at one point seven seconds after the two neutron stars touched and began to smash each other there was a burst of gamma rays arrived on earth seen by the Fermi gamma satellite and also by an integral a gamma-ray satellite called integral and the air box on where that was was here this big air box it overlapped with the direction to the gravitational waves and then looking with x-rays ultraviolet infrared and radio a signal was seen within a day suddenly turned on in a galaxy at that location and so we are convinced from these coincidences if when this happened and where it was on the sky that all of these different forms of telescopes were seeing the same thing they were seeing electromagnetic waves or gravitational waves from two colliding black holes this is the beginning of Mulder messenger astronomy each messenger is a different kind of radiation what we had seen was something that had been called by theorists Aquila Nova from collide to colliding neutron stars and the theory said that in Killa Nova you should make through the atomic nuclei smashing against each other you should make you should make very heavy elements like gold and platinum the pressure medics precious metals a large fraction of them in the universe should be made through colliding neutron stars by looking at the details of the electromagnetic a mission that was seen from this it's very strong evidence that in fact that is what happened that there was the formation of these very heavy precious metals in this pair of colliding neutron stars and also it was possible with this observation by comparing the gravitational waves in the electromagnetic waves to measure the expansion rate of the universe with a remarkably good accuracy not as good as electromagnetic astronomers do by themselves working very very hard about trying to pile together lots and lots of data with one observation doing almost as good as had been done by electromagnetic astronomers over the years I went by very much more complicated methods so the combination of electromagnetic and gravitational waves is be to show its power for astronomy now let me show you a few pictures of the advanced LIGO detectors this is what the detector at Hanford Washington looks like as seen from the air the light beams bounce back and forth inside vacuum pipes that are under concrete cap covers here to prevent protect the to protect the light beams from the elements and protect protective protect the vacuum pipes from being buffeted by wind and rain and bullets in the United States they don't worry about that in Italy and and here is the include vacuum enclosures in which the beamsplitter sits in here the corner mirrors sit in there and this is the size of a human being and very bearish our brilliant director chose to put a baseball player there this is one of the mirrors that tank is hanging by a fused quartz fiber a few silica fiber and the light beam bounces off of the face of that mirror it looks colored because of the interaction of light with a mold with multiply electric coatings that provide the high reflectivity of the mirrors but I show this just in order to lead up to the statement that these are complex instruments they have a hundred-thousand dated shout and channels coming out of them telling the experimenters what's going on in the interior of these instruments and in the environment so that you really know whether the instruments are operating properly but a hundred thousand data channels just think about that that is really a complicated instrument and that means that these instruments although they were built to a particular design there are always some things they're not quite right and they wind up having a personality of their own the experimenters must understand after they've built them and so that is what is going on today advanced LIGO was shut down at the end of August last August will not start again until about the first of next year so it's shut down for about a year and four months while the experimenters poke and prod the instrument to write try to learn it's in personality and try to coax it toward the design sensitivity hoping to get there by 2020 and hoping to make some major progress this year before we start observing again next year once we reach design sensitivity we will be able to see three times farther then we have been seeing roughly three times that means you see a volume of the universe three cubed or 27 times bigger that means instead of seeing roughly one pair of black holes collide per month when the instruments are up and operating properly you see 30 times that which is about one per day or a few per week so that's where we expect to be in roughly 2020 at design sensitivity looking to the future at design sensitivity we expect to see not just colliding black holes also we see spinning neutron stars that have some deviation from axial symmetry such as a small mountain on the surface of the neutron star black holes that tear apart neutron stars where the two are going or being around each other neutron star spirals in gets too close to the black hole gets torn apart by the black hole two neutron stars colliding well we have seen that now I put we prepared this slide when we first announced the discovery discovery of gravitational waves and we had not yet seen this one and now we've seen it if we're lucky we will see gravitational waves from the core of what is called a supernova explosion or we don't understand very well what goes on in the core but a combination of gravitational waves and electromagnetic waves and neutrinos are really going to pin down what goes on in supernova when we ultimately see gravitational waves from those but that's a much harder target because they're much weaker gravitational waves than the others and there are bound to be enormous surprises so that's where we are going beyond advanced LIGO beyond 2020 there are concrete plans now for a modest upgrade called LIGO advanced LIGO plus or a plus plus a new third LIGO detector will be operating in India which will enable us to get much better all sky coverage and better localization of where the signal is on the sky so we can tell the electromagnetic strana verse where to go look and by that point we should be seeing 1.6 times farther than in 2020 and black hole collisions rates a few per day late 2020s if we're limited only by the technical issues and not getting money and not political issues which is a big if then we'll have a third generation operating in the late 2020s seeing two times farther than light than a plus black hole collisions perhaps once an hour and then sometime in the 2030s who are fairly confident we will manage to build a fourth generation of gravity wave detectors that will be able to see so far that you pick up every black hole collision in the entire universe where the black holes are less heavy than a thousand solar masses so this is just the beginning of what has happened thus far and there are other gravitational wave windows that is other frequency bands in which we can see gravitational waves in fact I expect that by the mid 2030s we will be looking at gravitational waves in four different frequency bands that is through four different gravitational windows if you think of x-ray astronomy is one being one kind of a window ray radio astronomy another optical astronomy and other gamma ray astronomy another but where I'm saying is that by the mid 2030s we will have done the equivalent of turning on optical radio x-ray and gamma-ray astronomy all over a period of twenty years and these are all in the works first we do have gravitational wave detection with waves that have periods of milliseconds with LIGO and now with like as partner virgo in europe by about the early 2030s we will have we expect something called Lisa where you have three satellites in orbit around the Sun that are tracking each other with laser beams and looking for gravitational waves with periods of minutes to hours the difference between milliseconds for Lionel and the space-based instruments minutes to hours that's 10,000 times longer wavelengths and that is the same as the ratio of the wavelength of radio waves to light so if you think of Lionel and Virgo today as being like optical Astronomy then this is like radio astronomy with radio telescopes you see radically different things about the universe than with optical Astronomy in the same way we will see radically different things with Lisa in space compared to what we see on the ground pulse are tiny arrays if you have an array of pulsars these are spinning neutron stars that is they they have a a radio beam shining off their surfaces and that rainbow beam sweeps around in the sky as the stars spin the spin the inertia of the stars make them have very regular spin rates which means that as a beam sweeps past you earth time and again you get very very regular pulses and so you can think of these as clocks on the sky sending their ticking rates to earth if a gravitational wave sweeps across the earth in effect it speeds up and slows down all our clocks on earth and so it looks like all of these pulsars are slowing down and speeding up in unison and so this then gives us the possibility to detect gravitational waves with periods of years to decades and then finally a technique that I will say just a bit about at the very end of the talk caused me polarization of Cosmic Microwave Background can look for gravitational waves with periods of well say hundreds of millions into billions of years now that's a little longer than the lifetime of graduate student and so we're not going to watch the way these waves oscillate what you do is you look for a pattern on the sky and spatially instead of looking for a oscillating pattern here on earth and I will return to that as I say at the end of the talk so those are four different frequency bands in which we will be doing gravitational astronomy by the 2030s I want to conclude my talk about talking about some of the things I expected using some of these frequency bands I'm going to focus on two things basically studies of black holes and studies of the birth of the universe so let me begin with black holes a black hole is not made from matter like you and I rather it's made from a warping or curvature of space and time and this diagram depicts that if you take a slice a two-dimensional slice through the equator of a black hole and look at its geometry it's not geometry is not that of a flat sheet of paper it's not that of what we would call a flat Euclidean two-dimensional space rather the geometry is highly distorted and in order to visualize the distortion we can imagine taking that geometry of that sheet and just embed the sheet in a flat surrounding space and this is what the sheet would then look like near the black hole it bends down in a funnel like this the horizon of the black hole is there it looks like a circle because I've removed one spatial dimension it would look like a flattened sphere if I hadn't removed that one spatial dimension all right so space is warped in this manner and then the color coding shows the slowing of time near the black hole for example of where it's yellow time is flowing at ten percent the rate that it is far away and down at the horizon time is slowed to a halt if you're hovering at the horizon and refusing to fall in which is not easy to do the arrows describe the dragging of space into whirling motion or what is called the dragging of inertial frames with an angular velocity that is proportional to the length of the arrow so a spinning black hole creates a whirling motion of space that's very much like the whirling motion of air in a tornado fast near the horizon slower farther away now Lisa with the two three spacecraft for acting each other with laser beams can look at giant black holes with masses of millions of Suns and one of the things that Lisa will do is to map the geometry the shape of space and time around a quiescent black hole with enormous accuracy it's like mapping the surface of Mars down to say an accuracy of a foot or an inch I don't know what the accurate subi mean the analogy but extremely accurate mapping of the geometry of space and time around the black hole and how this is done is when a small black hole goes orbiting around and around the big black hole gradually spiraling in in the last few years before it goes crashing into the horizon of the big black hole it sends off a long long train of gravitational waves that's very rich in its structure and carries the full details of the map and you can understand why that might be true by just looking at the orbit of the small black hole around the big black hole I've now removed the geometry of space I'm pretending the space is flat here just so I can visualize it and this is then Steve Drass Co at Cal Poly San Luis Obispo has made these movies by solving Einstein's equations for the motion of the small black hole around the big black hole as it gradually spirals in and that orbit does not look at all like the elliptical orbits of the planets around the Sun that orbit is grabbed by the whirling of space and whipped around by the whirling of space it behaves differently because gravity is not an inverse-square lies it is according to Newton it's affected by the curvature of space and this small black hole basically explores essentially the entire region of space around the big black hole as it goes around and around sending off its gravitational waves and so you have the information there if you can do the data analysis and so the Lisa team which is preparing for this mission has shown how to do the later data analysis successfully and what if the central body is not a black hole well here is what the orbit would look like if it is what is called a Manco Novikov singularity down in here these are the orbits of a number of smaller black holes going around this central singularity is a region where space and time are infinitely curved this is a naked singularity which means it's not inside a black hole conventional wisdom bet that I have had with Stephen Hawking says that that black holes always in charin side black I'm sorry seeing you Larry's always occur inside black holes where you can't see them there are no naked singularities but we have the possibility to go to search for them by the building a map from the gravitational waves that come off from these objects going around that naked singularity you see the inner object the orbit is actually mathematically chaotic it turns out and the math would be wildly different from the map that you would get if that central object were a black hole we expect to explore the dynamics of the space-time geometry that are created the dynamical behavior of a veritable storm in space-time that is created by the collision of two black holes we do so by building computer simulations and comparing them with gravitational wave observations so we saw the first two black holes collide back on a September in September of 2015 and the sxs team then did the calculations to compare with the observations and determine just which set of masses and spins of the small of the two black holes correspond to what was seen what had produced the gravitational waves and then going back to the simulation you can see then the warpage of space and time during the collision so you have the two black holes each with a sort of funnel going down here the red is where time is flowing slowly the green arrows are the dragging of space into motion and down here is the actual gravitational wave signal being traced you notice now Isis got into slow motion and they're about to collide I'm going to stop at a moment of collision it says like a huge splash of a storm at sea there's the collision now it oscillates and gravitational waves go to fly I'm moving out and three solar masses of gravitational wave energy were carried off by those waves produced by that great splash in the shape of space and time and those three solar masses came off so quickly in about a tenth of a second that the power output during the collision the amount of energy per unit time was 50 times larger than the total power output of all the stars in the universe put together 50 universe luminosities for a tenth of a second just a tenth of a say it was very brief but an enormous power the most powerful explosion that humans have every had any observational evidence of except for the birth of the universe itself now this movie captures only a small portion of the space-time storm that's created by the collision of those two black holes we call this space-time storm the wild vibrations for the shape of space and time geometric sub word coined by John Wheeler I'm going to just give you a little bit of a flavor of what else is going on just to give you some sense that there's a lot more being explored here and to be explored in black hole collisions both observational E and by simulations I told you that when a black hole spins at drag space in the whirling motion I hang my wife up here Carolee above the North Pole of the black hole and if she has a gyroscope tied to her feet and one at her head the gyroscopes that her feet whirls around faster than that in her head due to inertia there and due to the dragging of space into motion and so her head sees her feet going around counterclockwise but her feet look up at her head they see her head going around counterclockwise it's like taking a wet towel you wring water out of the wet towel just think about it if your right hand sees your if your left hand sees your right hand going counterclockwise then your right hand will see your left hand going counterclockwise so their counterclockwise twist in space at the North Pole and a clockwise twist in space at the South Pole and these are what we call vortex lines taking a phrase from fluid mechanics that guide the twist of space and I draw a vortex line for a counterclockwise twist of space red and for a clockwise blue so I this is gives you now some flavor of what we've learned from our sxs simulations and what we will observe observation with LIGO and Lisa and I'm going to give you that flavor by watching two black holes collide this is from a computer simulation this has the red vortex up and that has the blue vortex up otherwise they're identical but they just have opposite polarity and as and I'm going to remove the vortex lines and just color code the surface of the black hole the horizons of black hole by the kind of vortex lines that are sticking out it's clockwise or counterclockwise twist of space and so the two black holes collide and merge and now we have four vortices of twisting space sticking out of this black hole to came from each black if each the original black holes the horizon of the black hole is shaped like a dumbbell this is just a pause momentarily to look at it and it turns out black holes do not like to have four vortices they only like to have two vortices maximum and so these vortices fight with each other in a very interesting way but the key thing is that they robustly retain their individuality and so now let's watch the collision and watch what's going on here's a blue vortex in the upper right collided merged now it's a red vortex in the upper right now it's blue now it's red those vortices fight with each other an exchange vorticity exchange direction of twist or precisely what's going on is once the black holes of whirs the vortex lines have reconnected themselves the red vortex lines counterclockwise go out of this red vortex on the horizon around and back into the red vortex on the backside of the horizon Lewin comes out here the blue this is the blue vortex goes back and to the backside of the horizon this is from the simulations these are just steals from the simulations and then every time this goes green the vortex lines pop off of the black hole they embrace each other and they create a ring around the black hole like a small cream that goes traveling out at the speed of light and so you get smoke ring after snow cream after smoke green as the this ring goes off it kicks back at the black hole and recreates an image of itself but with reverse Bulevar tissa T and then as the second one goes off it kicks back and creates rings with again reverse vorticity and some amazing process to watch on the computer and then as these as these rings go traveling out of intertwined vortex lines of twisting space their motion creates 10 disease these are things that stretch and squeeze these are objects that live in the fabric of space that stretch and squeeze things they are tidal forces it's the same kind of stretch and squeeze caused them by the moon pulling on the Earth's oceans who create the Earth's tides stretching 10 Dex lines going around this ring and squeezing 10 Dex lines going around the circumference of the Ring and this is a gravitational wave and LIGO is designed to measure the tendencies that stretch and squeeze it doesn't see the vortices it doesn't have the technology to see the vortices now this is far more complicated and far more interesting than anything I imagine what's going on when we began doing this these simulations and it's really exciting to see this coming off of the simulations at the same time as we can then go and look at the shapes of the waves that are coming off and see that they agree that LIGO detects and see they agree perfectly to within the accuracy of the data within the noise of the data perfectly with the predicted shapes of the waves that are seen from the black hole collisions this is just one very simple example I want to conclude now with a few words about exploring the birth of the universe with gravitational waves because this is what I believe is going to be the really exciting thing that's going on with gravitational wave astronomy the most exciting thing and within the next twenty years and it's going to actually begin probably within the next ten years first of all we have a hope of watching the birth of the fundamental forces of nature in the early universe and I'll give you one example when the universe was about one trillionth of a second old the electromagnetic force and the weak magnetic force which previously were unified to form what is called the electroweak force they came apart and the electromagnetic force that is the electric force of the magnetic force were created they came to exist and with them it came to exist the Maxwell's equations that govern them previously Maxwell's equations were not relevant to our universe and there were no electric and magnetic fields but they were created together according to theory at age 10 to minus 12 seconds if this happened in what is called a first-order phase transition and there is reason to suspect it may not have been first-order we just don't know but if it was first-order this is a technical phrase for the physicists and chemists in the audience and some engineers if it were a first start of phase transition then the separate forces are born inside bubbles it's rather like the formation of water droplets out of a water vapour and the water droplets the interior the water droplets you have an electric force and a magnetic force outside you don't between water droplets but these water droplets then are predicted to expand very rapidly collide and in their collision they produce a burst of gravitational waves according to the theory and this this is all very strong and well understood theory except the issue of whether or not this was a first order phase transition again a technical phrase these gravitational waves then the wavelength of the waves was very short at that time but it expanded as the universe expanded so that today the prediction is that these gravitational waves are in the frequency range that Lisa will be able to see so one of Lisa's primary goals is to look for gravitational waves from the birth of the electric and magnetic forces and fields lyall could see a similar phase transition a change in the nature of the physical law when the universe was 10 to the minus 22 seconds old but current theory as we now understand it says that that was a desert there was nothing interesting going on then unfortunately but of course we don't know for sure but so LIGO is searching finally there if something had to come off the Big Bang in terms of gravitational waves at an absolute minimum there had to be fluctuations associated with quantum mechanics just Quantic what are called quantum fluctuations of the gravitational field because you can never get rid of those and maybe there was something much more than that created in the Big Bang coming right off the earliest moments of the universe well whatever came off of the earliest moments of the universe the so-called planck era is predicted to have been amplified enormous ly by a process called inflation I'm extremely rapid expansion of the universe in the first roughly ten to the minus thirty-three ten to minus thirty two seconds of the life of the universe and then these gravitational waves even if you've just began with vacuum fluctuations you still get a rich spectrum of gravitational waves they travel on as the universe expands and interacted according to theory with the electrons and protons in the hot plasma of the universe when the universe is a 380,000 years old and electrons and protons were combining onto each other to form neutral hydrogen and they allowing photons electromagnetic waves to propagate freely for the first time in the life of the universe those photons then released suddenly from being trapped in the hot plasma they will be affected in terms of their polarization by the gravitational waves that are stretching and squeezing the plasma as as these photons are being released and there is a prediction then that there should be a certain pattern of polarization put on to these cosmic microwaves the so-called CMB a polarization pattern that could be found today and if it is seen and separated from any other causes of such polarization that will give us evidence of the details of the birth of the universe and the inflationary expansion the universe and so the key point is that the gravitational wave spectrum that would be seen then in the polarization of the Cosmic Microwave Background is if to use a technical phrase a convolution or a combination of whatever came off the Big Bang and the influence of inflation and so I envisioned that in the mid 2020s say when the data have been cleanly separated out the I mean it's polarization pattern has been found by a group called the bicep collaboration but it is mucked up with a polarization that was created in other ways by a mission from dust and what is called synchrotron radiation the challenge is to separate off that foreground noise from the observed polarize from the polarization that comes from gravitational waves I do expect that will be done successfully within years not decades and at that point we will be using these gravitational waves to probe a convolution of inflation and whatever came off the Big Bang and by 2050 there should be a successor mission to Lisa in space that is looking directly at the same gravitational waves but a very different period of oscillation periods of seconds versus hundreds of millions of years for the CMB polarization so by 2050 we may have observations of the gravitational waves from the very birth of the universe involved with inflation in two widely separated frequency bands there is a prediction as to what that spectrum ought to look like and having lived through a number of theorist predictions that were wrong during my career I will hazard a prediction of my own that our predictions today are wrong and the struggle in the 2050s may be as early as the 2020s will be to understand what the heck is going on why is the pattern not what the spectrum not what we expect and hopefully that struggle will help us to understand much better the Big Bang and the laws of physics that govern the Big Bang the so called loss of quantum gravity so let me just conclude by saying it was just 400 years ago approximately that Galileo created modern electromagnetic astronomy by turning it to building a small optical telescope turning on the sky and discovering the four moons of Jupiter discovering the craters on our Moon it was about two and a half years ago the LIGO gravity wave detectors turned on and saw gravitational waves from colliding black holes Galileo opened electromagnetic astronomy Lyell opened gravitational astronomy there are only two kinds of waves that can propagate across the universe bringing us information about what's a very faraway gravitational and electromagnetic waves and that's it according to our current understanding of the laws of nature so LIGO has done what Galileo did and when you just look at the enormous changes in our understanding of the universe that have come from electromagnetic waves since the era of Galileo I let you speculate what will happen over the next 400 years with gravitational waves and electromagnetic waves working together thank you [Applause] [Applause] oh my goodness so for you students out there you can say you were there at the beginning of gravitational wave astronomy and you have the responsibility to carry this forward yeah alright we have time for two questions we're gonna have one so it seems like LIGO was detecting more gravitational wave incidences or black hole mergers and expected so what does that mean for like how we see the universe differently so the number that the rate at which the signal would come in was highly uncertain we didn't know how far away the earliest signals would be because we just don't know how many pairs of black holes there are in the universe and we didn't know by a factor of 10 how far the way there would be that means we didn't know the volume of the universe we would be searching by a factor of a thousand so the signals were near the upper end the range of uncertainty so it was not terribly surprising it was a little surprising that nature was that kind to us but not terribly surprising what was a bigger surprise was that the black holes were as heavy as they were because they and theoretical work simulations and and pencil and paper calculations had suggested to astrophysicists that if you had a very heavy star that had the potential to collapse and form a very heavy black hole there would be winds blowing off the star that would blow away most of the mass of the star before the core collapse and so you would not get really heavy black holes and so the mass of the black holes was a moderately big surprise but do you know astrophysicists are good at explaining surprising result usually not always and so there are two explanations either these black holes formed when the universe is very young and there was almost nothing except hydrogen and helium in them and so they had low opacity because there wasn't much else and so they didn't not have strong winds or else these black holes were created when you made smaller black holes inside clusters of stars called globular clusters the smaller black holes collided and merged and made bigger black holes and the bigger black holes collided and merged made bigger black holes and this is basically in a chain what we've seen is in a chain of those kinds of hierarchical collisions so those are the two approaches to two theories at the present time for the surprising result and that will get sorted out as we get more statistics on these black hole collisions how can you see that I can't yeah I'm ten years older than you are no I know you're a young kid so for one of the slides it was the birth of fundamental forces and it said that the electromagnetic force and weak force came apart gaining their I do their own identities what caused them to come apart the universe was cooling as it expanded whenever you have a gas that's hot and you expanded it it cools because it doesn't work on the molecules do work on each other during the expansion in such a way as to make it cool how do you explain this and so so anyway the universe cools it as it expands and I think it's cooler and cooler the the fundamental laws change because there is as I said a phase transition so at very high energies the electroweak force dominates and at lower energies or lower temperatures the electromagnetic force being separate from the weak force dominates so it's just because of the cooling of the university that as it expands I think at the present time we have not had huge surprises there will be I am sure some very very big surprises well I the thing I hinted at was that whatever came off the Big Bang will not be vacuum fluctuations and that will be because the loss of quantum gravity are doing something else in the planck era that's a moderately wild speculation but I think not extremely a while

Channel: UCI School of Physical Sciences

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Keywords: Reines, Kip Thorne, Kip, Thorne, Interstellar, UCI, School of Physical Sciences, Physical Sciences, Physics, Astronomy, Physics and Astronomy

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Length: 80min 57sec (4857 seconds)

Published: Thu Apr 12 2018