Gravitational Waves: A New Era of Astronomy Begins

English World Science Festival(Gravitational Waves) Applause Thank you. Thank you. Appreciate that thank you, I am Brian Green co-founder with Tracy and I also want to welcome you to day four of the 2016 world science festival. The program tonight on gravitational waves its a timely program I trust you all heard the announcement on February 11 through you read about it The first direct detection of gravitational waves. amazing, amazing discovery. [clapping] [clapping] and we have here tonight a group of very individuals who made this discovery possible And I'm gonna bring amount just a little bit, but just a few words at the outset You know this discovery - to put it in context, it's a kind of achievement that happens maybe a few times a century in fundamental science I mean we were thrilled some years ago for the discovery of the Higgs boson something that was searched for - for very long period of time and finally was definitively discovered at CERN Great discovery. This ranks on par with that kind of experimental observational achievement and the other side of the story that will come out in the conversation here tonight is that we're as for the Higgs boson just about everybody was convinced that the experiments would succeed. mean most people who are following closely the search for the Higgs boson were saying well if it's not found that's the craziness means that is got to work out the theory said that all of the circumstantial evidence suggests that the particle is out there and indeed it was found Now with gravitational waves as we'll see there was never really any doubt after ... I don't know call it 1950-1960 that these ripple and the fabric of space were a real feature of Einstein's general theory of relativity but there definitely was controversy as to whether we would ever have the capacity to catch one of these waves and we'll hear about why in just a moment, but what it means is it takes a certain kind of internal fortitude it takes a certain kind of vision, it takes a certain kind of stubbornness it takes a certain kind of independent spirit to devote your life to this kind of project and our hats are off to individuals - they now number roughly a thousand - who made this discovery possible OK, a little bit of a background before I bring the panels on stage just to set the stage scientifically, right so we're all more or less familiar by this stage of the game that Albert Einstein gave us a new theory of gravity in 1915 the general theory of relativity The Newtonian picture that we all learned in high school simply spoke about objects pulling on each other through space with some sort of force that was described mathematically but whose mechanism of exerting its influence was not articulated Albert Einstein comes along and articulates a way that this force is communicative and just to give a picture of it, we can bring up the first little clip here It goes like this objects within bring like some free will like the sun or the planet They warp the environment of space and time and it is warps encurves the space that are able to cause other objects to move along peculiar trajectory if you weren't aware of this picture the metaphor that we love to use, it's imperfect to be sure but if you think about space and time as sort of like a trampoline you put some heavy objects in the middle of it it warps the surface and then if you roll a marble, a marble goes into orbit much like a planet would much the same way the sun warps the environment and then the planets go into the orbital trajectory that we are familiar with OK, so Einstein give this very beautiful new description of gravity in 1915 and then the question of course is "Is it correct?" and indeed they were very quickly to pieces of evidence that seal the deal The first was an explanation of a puzzle have to do the motion of the planet Mercury according to Newtonian gravity the planet should just trace out the same orbit year after year after year but observation shows the orbit's actually shifting a little bit Nobody could get a good explanation of this Einstein comes along and uses his new approach, the new picture of gravity, uses the equation of general relativity and is able to spot on predict this sort of procession of perihelion of Mercury now that was kind of a post diction explaining a puzzle that was already known observationally But then he was able to go further and make a prediction for something that has not yet been seen and indeed that had to do with the bending of light by the sun so if you have a distant star, it sends like toward the earth going in night trajectory of the sort but then later on if the earth is on the other side of the sun and you now consider that starlike according to Einstein new picture it's going to go in a curve trajectory as it goes to the curve environment surrounding the sun and that has the affect of making the position of the star in the sky shift Einstein was able to use the equation of general relativity to calculate the angle and it was just a few years later that team of astronomers went out and measured the angle between those two positions, taking photographic place during a solar eclipse so you could see the distant star compared with photographic place taken 6 months earlier and indeed the data with a little bit of massaging, little bit of force, a little bit of knowing answer in this particular case seem to show that Einstein ideas were correct. Now since then these experiments have been done over and over. There's no doubt any longer that Einstein's theory is correct. Now, Einstein then went further and as we'll discuss here tonight He wrote a paper in 1916 in which he basically said he didn't use quite this language basically said mathematically that if space is sort of like a trampoline and it can warp and curve well if you start to tap the trampoline, disturb the trampoline you'll send ripple going along the trampoline Those ripples, taking away the metaphor, were the ripples in the fabric of space and that's what gravitational waves are Now the very interesting story that we get into a little bit in just a moment with our panels is Einstein himself he writes his paper 1916 actually made a little mistake and maybe it's kind of weird concept - Einstein making a mistake in doing calculation of relativity. But relativity is hard and Einstein was the first one who's actually working on this calculation so he was making what we now call mistakes of a beginner Novice mistakes. But he was the guy who plays in the trail, so it makes perfect sense that he might have make those kind of errors. Anyway, he corrects the error in 1918 but then he continues to have a really interesting relationship with this idea thinks it's not quite right, writes a later paper that suggests that's not right. Bottom line is others come along develop a very beautiful systematic framework for avoiding the pitfall that Einstein fell into and people absolutely certain that these things are real What would that mean? It means that if you disturb the fabric of space you should get the gravitational waves, the ripples. and typical example might be something like this rapidly orbiting neutron stars or black hole sending out this march of gravitational waves and as we discuss here tonight what would that mean for somebody in the wake of these waves the object would be stretched or squeezed according to the map. I just wanna emphasize one thing This is not true scale [laugh] and that is a big deal because when you actually do this calculation out, you will discover that the stretching and squeezing is so small that it is enormous challenge to detect this gravitational wave and that the Ligo team has done Alright now, lets get into the actual discussion I gonna bring in our panelist on and let us begin with Rai Weiss of MIT is one of the creator of LIGO. He first proposed large scale interferometer back in 1972 and he has been scientific and engineering leader ever since Alright next Barry Barish, many people say that Barry Barish of Caltech saved LIGO at the time it transition into big science and built the two huge detectors in Louisiana Washington state He joined LIGO in 1994 and was director for 1997 to 2005. Welcome Next up, Nergis Mavalvala I got it. I'm so proud of myself of MIT, is an astrophysicist who was called a genius award winner for work on LIGO in 2010 She got a PhD from MIT in 1997, post-doctoral Caltech from 97 to 2002 and then joined the faculty of MIT. Welcome. Next up, Frans Pretorius , who is professor of physics at Princeton University His primary field of research is general relativity specializing in numerical solution through Einstein's equation and now we'll see a vital part of this discovery Finally, David Schoemaker, who is director of the MIT LIGO lab and was the team leader of advanced LIGO He spent many years upgrading the technology of the observatory

Channel: World Science Festival

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Keywords: Gravitational Waves, A New Era of Astronomy Begins, Albert Einstein prediction, LIGO, ripples in spacetime, big science discovery, Revolutionary discovery, Interferometer, Black holes, Neutron stars, colliding black holes, eLISA, Brian Greene, Barry Barish, Nergis Mavalvala, Frans Pretorius, David Shoemaker, Rai Weiss, New York City, NYC, world science festival, full program, World, Science, Festival, 2016, colliding neutron stars, new kind of gravitational wave, nobel prize, nobel

Id: xj6vV3T4ok8

Length: 99min 21sec (5961 seconds)

Published: Wed Jun 22 2016