INR5: Lawrence Krauss: A Journey to the Beginning of Time

I did want to say two things first of all you know unlike Gerry's talk which is about really complicated things I'm going to talk about easy stuff okay so don't have to worry about freewill or any of those things you really have to think about it's just the beginning universe that's that's the good news the bad news I can't help resist I just tweeted it I was very upset because I just got news that the Saudi courts have reaffirmed the thousand lashes and made the final judgment it can't be subject to and the 10-year imprisonment sentence for rape but but that way so I said you although although I agree with Jerry that the supreme court the judges in us in Saudi Arabia don't have free free will they are nevertheless barbarian savages and and we should I don't know how we can boycott Saudi Arabia but we should and and we should certainly protest although they express surprise that anyone was protesting but anyway okay but so that bad news one of the reasons we talked do cosmology talks there's a bunch of things I want to do today that show something about the nature of science as well as confuse you but but one of the reasons is to avoid the crap we we have in them in the current world so cosmology is great because unlike questions of free will which are pressing and urgent the the you know we can worry about the universe and it takes us away from our normal thing so so I think so point it oh it works okay good I can hit this network so it's the best of times and by that I mean that the Large Hadron Collider is turned on okay and and it hasn't it hasn't destroyed the world with a black hole yet oh there's my pointer and of course at the same time it's the worst of times let's see yeah no actually that's not the one um Neil Tyson is a friend I guess I just he amuses me this was this is the next president United States and this is the most surreal one of the most surreal moments I've had in my life when he approached me a meeting that I was at in the World Economic Forum in in Japan China and he thought I was someone important any one of the Selphy so I agreed but it was kind of weird anyway and he's just as stupid in person as he is and this in case you're wondering I'm very friendly very I'll give him that anyway so I want to so but the purpose of going back to universe is just is to get away from worrying about Rick Perry as it doesn't reman to the universe so I want to go back in time and and and I always can't help but show these Hubble this is one of the more recent Hubble pictures it's a multi chromatic image it's many different colors that was just produced a few months ago so it's one of the deepest images that shows by real color where the which galaxies are and every every image in that except for one every dot in that image is a galaxy not a star okay so every these are galaxies that go back to ten almost 10 billion light-years away and and and and every dot there is a galaxy and that's the kind of thing that causes me spiritual on wonder because many of those this the light from those galaxies were emitted ten billion years ago that's and our Sun was only going to last about ten billion years so if you look at it most of many of the stars in that image no longer exist and the civilizations around those stars which had beings that didn't have free will no longer also exist and it amazes me but when we try and look at the universe it makes us think of corsica questions of origins which is of great interest to me and one of the neat things about the universe is that that thinking about those questions ties together the biggest scales on the universe and the smaller scales this is one of an image that's almost in certain it goes back 4,000 years I'm not going to carry this even though I like the idea of walking around with it just to prove I can do that okay here we go almost this is a something called Ouroboros in different cultures as different things it's a snake that eats its own tail this doesn't look like a snake has legs but it's evolved and the but it was Shelly Glashow a physicists friend of mine who first sort of suggested this but the point is because the universe is expanding it was one smaller than it is now and it was smaller still and if we want to understand the conditions that led to the largest structures we see in the universe today like those galaxies we really want to understand the fall in small scale so so as we try and understand physics on different scales from human scale up to the earth planets galaxies and clusters of galaxies and universe ultimately we come back again to that earliest moments of the Big Bang - the really fundamental forces that that govern nature which is the reason why I got interested in this field in the first place that's a particle physicist and that wonderful connection between the very largest and the very smallest tell us that we can learn by looking at large scales something that tells us about our fundamental makeup and and and the laws that govern our existence and so when we do that we want to look back as far as we can see because the further back we look that we're looking at earlier times the universe was smaller and smaller and smaller but when we look out at the universe of the farthest back we can see is there this is the Cosmic Microwave Background the radiation coming at us from the Big Bang and that's as far as we can see because when we look back at the universe before the time when this was created when the universe was three hundred thousand years old the universe was opaque so we can't see past that time look you can't see past these walls and so what we look out we look out as far as we can see we see those galaxies and etc of the earliest galaxies and then we if we look out we can see back to the time in the universe was three hundred thousand years old and then we see this this this fear and this is a sphere this is the sphere in the same sense that that this is a sphere actually it's upside down let me there we go my wife's from Australia and I spent alone time there but it's so we're northern hemisphere accent eccentric but if we when we make projection of the sphere of the earth we do that and that's what we've done here we just made a projection of the of the whole sky and these this is this is your microwaves and these are temperatures so the hot spots and the cold spots are different temperatures very small deviations in temperature the difference between one color and another here is about one one thousandth of a degree the overall background is about three to two point seven four degrees above absolute zero it's the smoothest background you can imagine the universe is incredibly uniform in all directions one of the biggest mysteries actually that we're trying to solve why is the universe the same over there as over there because in fact when the universal swinger thousand years old light could have only traveled about what is now the equivalent of one degree on this surface so no where over here could have known anything over there was it was in existence why are they the same temperature to one part in a thousand or to almost one part sorry in a hundred thousand and at the same time where do these little lumps come from these hot and cold spots that would eventually collapse to form everything we see today to form all the stars and galaxies this is the these are the primordial lumps that will potentially put in at the beginning of time where did they come from also by the way when you look at this this is the stuff in the center is the plane of our galaxy and and you have to get rid of that if you want to go back to the real primordial umsana normally wouldn't show that but the plane of our galaxy will become important in a bit so we but we can do manipulations on this and try and subtract the galaxies and then this is the image the primordial image from the most recent Planck satellite which is a microwave background satellite that's gone and looked at the entire sky and those are the hot spots and cold spots that we want to understand but we're stuck that is a pretty late in the history of the universe 300,000 years is it what is pretty late we want to go back earlier but we can't ever go back earlier if we're using light because we can't see back before that time so if we want to go back earlier we have to use something that can get through the universe from the beginning of time to that moment okay and that means we have to use stuff that interacts less strongly than light okay and what we can use is if fact something--in interacts very weakly in fact its its gravity gravity is the weakest force in nature most of us don't appreciate that when wake up in the morning and try and get out of bed because it's gravity or or climbing the stairs but but that's because the whole earth is attracting every atom in our body gravity is unbelievably weak and Einstein when he developed general relativity and showed that matter and energy curved space also recognized that when you wave your hands like I do a lot we're producing a disturbance in space and that disturbance that space propagates out it's not just a disturbance of space it's observance in space and time and when I do this I create something called gravitational waves just like when I shake an electron in in the in the stuff that this microphone is connected to it jiggles electrons and that creates an electromagnetic wave which goes to the back of the room and gets amplified and then you can hear my voice so electromagnetism is when I shake electrons when I shake any mass when I move any mass around I produce gravitational waves and and and and there in many of them in this room right now going right through you the thing is gravity is so weak we can't detect gravitational waves but if a let me I think Evan I'm going to show you whatever gravitational wave looks like I think I'll run a long thing let's see if I can do this okay so if a gravitational wave was coming out of these screens okay then this is what would be happening literally when a gravitational wave goes through this room it changes lengths the length of the room will get a little smaller in this direction and a little bigger in that direction and it'll oscillate okay back and forth that's what a gravitational wave does and that's happening all the time in this room but they're so weak we can't detect them and in fact we haven't yet been able to detect them directly they're so weak I'll show you the best gravitational wave detector we've ever built but but this is a three-dimensional version if you like it it looks like a snake but the three-dimensional things never are understand but that's what it would look like if it's propagating out and so we would like to write inside predicted them actually 1917 and then by the way I know Jerry was being facetious but Einstein was wrong a hell of a lot of times not just never and and one of the many things he was wrong about was gravitational waves he predicted them and then he thought they didn't exist and he wrote a paper saying they didn't exist and happily the peer review process saved him although he had he was never turned out he discovered he was peer-reviewed and he got so mad he'd never been peer-reviewed in his life before or after not once he was so he objected so much the process that he would through the article and refused to ever submit to that journal again when he found out that they dared to send his work to anyone else to read it's an interesting thing I just wrote an article for Scientific American about Einsteins mistakes and I discovered that it was kind of amazing anyway that's got nothing to do with this but it's amused me to tell you but uh so if we could detect gravitational waves they are so weak that they could actually make it from the beginning of time to here and that's what I want to talk about because this gives us may give us an empirical handle on the beginning of the universe and far more so I said gravitational waves are extremely difficult to detect and these are this is the biggest gravitational wave detector we've detected we've we've built so far it's a the LIGO interferometer gravitational-wave Observatory and there's one of these in Hanford Washington another one in Louisiana and they're designed to detect gravitational waves from so when I move my arms I create gravitational wave but my arms aren't very massive so it's not a very strong wave so we try and look at the most cataclysmic processes we can see in the universe and and hope that they produce gravitational waves and and and two of some of the things that might do that are colliding stars or colliding black holes or colliding neutron stars in our galaxy and so this detector was built to the trying to TechEd events from these cataclysmic things when two massive objects a million times the mass of the earth collide and but they have to be incredibly set and this amazes me because this is the kind of stuff that science fiction would never write about or theologians because so they're there to arms here because that sends you both but all of both arms but their two arms they're three kilometers long at right angles okay and if a gravitational wave came down from above then one of the arms would get a little bit shorter and one of the arms would get bit longer and then it would change right okay so you can calculate how sensitive these have to be in order to try and detect gravitational waves from two stars colliding in our galaxy and it's kind of amazing it's amazing to me that this works because what they can do right now what can be done right now is with with these detectors you can they're designed so you can detect a change in length of this three kilometer arm we send a laser beam down that direction the laser beam down that direction and reflect it and see if they come back at the same time basically and we right now the sensitivity is such that you can detect a change in length of these two arms three kilometers long by an amount 1/100 the size of a proton you should do that it's amazing I mean it amazes me that these that it can be done I just never thought I'd be able to be done it is remarkable we actually use principles of quantum mechanics to try and do this it's the sensitivity here is so amazing that when a truck drives along like 50 miles away it would produce a bigger disturbance so you've got to insulate this from those kind of sonic disturbances it's amazing that you can isolate all those processes and do it but this machine works it hasn't detected any gravitational waves yet though because they're not there apparently it's not sensitive enough so it's actually been improved it's being improved right now and it's going to come online in next years in the improve so it can detect a variation about one one thousandth the size of proton and we're pretty certain at that level we should see lots of events of stars colliding in our galaxy or maybe other galaxies we never swear we've never seen gravitational waves directly in this sense from these things but it turns out that there's another source of gravitational waves which some people thought they had detected and we may undetected you'll see and that is the universe itself because as cataclysmic as colliding stars are that's that's one thing but the Big Bang itself is pretty damn cataclysmic and it turns out the Big Bang in a very specific way produce gravitational waves that I want to talk about and tell you what we can what we can see if we see them this detector claimed to see gravitational waves this is a sector called the bicep detector said the South Pole it's actually a microwave background a Tector it's looking at that cosmic microwave background but what it claimed to see was the imprint in that cosmic microwave background of gravitational waves that had traveled from the beginning of time and left a signal that I'll tell you about it's the kind of an interesting thing to build it the director of the South Pole I would kind of amaze me when I learned the limits after all we can we can go to the moon well that was faked but we can we can we can you know go to the deep oceans we can go all these places but you can't really travel to the South Pole other than during the summer in the South Pole this is a setting up this is another telescope the South Pole telescope next to bicep and we have and this so this is a big cargo plane this is delivering liquid helium to these detectors which you do in the summer because although the South Pole is cold it's not cold enough and look at helium is a few degrees above absolute zero and so this is delivered during the summer because you can't fly down to the South Pole in the winter and it surprised me when I first learned that because it's just the rule when you so that means this is interesting picture I want to show you it's one of my favorites of bicep this is it's a picture of bicep at sunset which if you think about is an amazing picture because sunset happens once in the South Pole every year so the minute the Sun Goes Down it's winter and it's dark and you don't leave so undoubtedly the person who took this picture was a graduate student because those are the people we send down for the winter in the South Pole and then they have to have special tests to make sure they can survive and not another thing that's entirely relevant but I can't miss telling his audience so one of my students that one of our students went down there and and was there and the test they administer he claimed was the same test that they that the Armed Forces used to do to see if you were gay I don't understand that at all but anyway it's that's what they did okay so the bicep detector made an announcement a year ago in March a year ago that was that astounded the world because they claim to see gravitational waves from the Big Bang so let me see so I want to give you a little bit of where these come from doesn't tell you very well but so we have this remember one of the paradoxes I told you about is the fact that why is the universe the same over there as over there to a one part in 100,000 if those regions could never have communicated with one another that's been a paradox we've been living with for over 40 or 50 years why actually over of that but it was really recognized about 50 years ago that that was a real problem with the Big Bang unless God set it up to be that way how could it be that way okay and so we of course got rid of God in that sense by recognizing that there's a physical process that can make that happen not only can it make it happen all of our ideas from particle physics suggested it should happen namely at very early times the universe energy gets stuck in empty space in the universe and I'll talk about how that happens in a second but we're not in a second a few minutes actually but energy get stuck in empty space and that causes the universe to expand very fast for a very short time and this period is called inflation and if it happened the universe expanded by a factor in volume of 10 to the 90th that's one with 90 zeroes in a time period of a millionth of a millionth of a millionth of a millionth of a millionth of a second it sounds like science fiction but it but it when the universe was 10 to the minus 35 seconds old or so for a very short time the universe puffed up by a huge amount and then inflation ended and then the regular Big Bang you know continued now what would that do that would mean that two regions which are now very distant if you work back we're always further away apart the like could have traveled were actually once much closer together before the expansion and that means they could have communicated to one another and the universe could have become you know uniform and then it puffed up and and then went underwent its stuff the other interesting thing is that during this period of puffing up quantum mechanics is very important in causing the universe to expand very fast its its energy and empty space and there are quantum fluctuations about the energy energy space and we can actually predict what they would do and they would produce small variations which look just like the variations in the cosmic microwave background radiation so that suggests that not only isn't inflation happen it suggests it doesn't prove it suggests it happens but it also tells us something really interesting we that we are actually here we're quantum mechanics in action we often talk about quantum mechanics that happening over very small scales but the lumps that eventually being in the galaxies and stars and planets and aliens and people were there because they were began as quantum fluctuation so we are there were direct result of quantum mechanics operating at a macroscopic scale and it is remarkable if it's true it is so remarkable we want to find out but during this period inflation breaks many things and the problem is it's very malleable it's a non interesting idea but it could be compatible even if the lumps we see in the microwave background we're slightly different an inflation model could predict that so if you can predict something that agrees with anything it's not a prediction at all so you know just being consistent is not what science is all about it's being falsifiable and so the question is is there a prediction of inflation that that is sort of unique ubiquitous and and falsifiable and the prediction is gravitational waves during that period of expansion when there are quantum fluctuations if gravity also responds to quantum mechanics there should be quantum fluctuations in the gravitational field and that would produce gravitational waves of a very specific type and that's what we've been looking for and that's what the bicep experiment claimed to have seen sorry in in in in March allows you this complicated image from a scientific American article I wrote a year ago so I I spent endless amounts of time trying to get the artist or not to make mistakes so I thought even though it's incomprehensible I'd show it but but I'll give you a heuristic argument so this is the idea so there's this this is the sort of universe is a quick there's a big bang there's a rapid period of inflation and then the universe expands and then there's the microwave background then today so this is a time history I will look start there and then I'll go here for the for all the rest of you so so we start there and there's a rapid period of expansion and during inflation gravitational waves get produced start oscillating but then they get stretched out during inflation and they stop oscillating because their period is longer than the age of the universe so they just get frozen in then inflation ends and what happens well the smallest wave length highest frequency gravitational waves start to oscillate because their period is now shorter than the age of the universe so they can actually start to oscillate and so what happens is after inflation I'll show you guys here after inflation the shortest gravitational waves start to oscillate but as the universe evolves gravitational waves die off so the shortest wavelength waves gravitational waves die off then there are longer gravitational wave lengths gravitational waves they start to oscillate later in the history of the universe and they start to white die off but there are long enough gravitation wave length gravitational waves that their period is say 300,000 years and they don't start to oscillate until the time in the universe when the universe is 300 thousand years old just the time when the microwave background is being created and those gravitational waves will produce an imprint on the microwave background I'll show you I think I have it oh yeah in this image so so the microwave background is caused because radiation is everywhere and it's interacting with electrons and it gets scattered to us and then the universe becomes neutral and those free electrons get captured and they stop scattering and so that radiation can come to us because the universe becomes transparent so the minute that surface the last moment of that surface is when the last radiation scatters off an electron it comes to us now if if universe is uniform the electron sees uniform radiation coming out in all directions but what is a gravitational wave of very long size the size of the visible universe for that electron comes along what it'll do is it'll shrink the universe in one direction and stretch it another and that means the rate electron will see a university in one direction stretch another well that means that the intensity of radiation will be greater coming from this direction than that direction and that means the electron will scatter radiation preferentially in one direction radiation that's oscillating in one direction rather than other it'll produce what we call polarized radiation polarized radiation is just electromagnetic electromagnetic waves that are just oscillating in one direction rather than another that's why you you get polarized glasses when you're fishing because the sunlight comes up and and it reflects but that reflected light is polarized and if it's oscillating in this direction and your glasses only see radiation I'll say in that direction you won't see the reflected image so you won't see the glare that's why you can see you can fish with polarized lenses okay so the bottom line is that there'll be a signal of polarized radiation if there are gravitation waves and it's a very specific kind of signal it's not easy to see but I'll show it to you for example here is the microwave an image of the microwave background and I put I put random polarizations because if there's no gravitational waves and then the electrons are oscillating in random directions and and and this is what it would look like if there were gravitational waves you can't see a difference okay it's really really hard to do but the people try and do it and the bicep experiment I think that a simulation which I hope I have this is what they thought things would look like the thing about gravitational waves is they produce these snake-like patterns almost like Ouroboros of polarization in the mic in the microwave background so you predict these very particular kind of polarization snake-like ways where things are moving around sort of going around in a circle as you can see that was the prediction March 17th maybe st. Patrick's Day the bicep experiment published this result this is what they saw in the microwave background and this was astounding because if this is true this is in my opinion literally perhaps the most important image that science has ever produced because if it's true this is first of all the first direct detection of gravitational waves and secondly the this is an image of stuff that was created not when the universe was 300 thousand years old but when the universe was a millionth of a billionth of a billionth of a billionth of a second old this is an image directly from the Big Bang and therefore if you think about it it pushes our window of the universe back by a peer abaya factor about 10 to the 49th I mean you when you improve things by an order of magnitude it's pretty good in science but if this is true it pushes our window back to the history of the universe by 49 orders of magnitude in time and therefore it's profoundly important because it allows us to directly test ideas about the beginning of the universe and that's important if you want to turn metaphysics into physics okay so this was profoundly important unfortunately it might not be right and I'll show you why this is I want to show you a graph but it doesn't matter so this is this is um if you look at these things you'll see a little bump here this is the signal that that that that they claimed to see it's it doesn't really matter what this is this is a this is really a strength of polarization as a function of degrees across the sky and and you see the bump these are all these other curves are the noise the expected noise which you have to worry about in science because there's always noise there's always background there's always uncertainty and what's interesting is what is amazing to me and what was amazing to me when I first saw this is not that it's just there but there's a dotted a dotted line there that and that's the prediction from inflation if inflation happened these this should the specific character and it has it and it was just amazing and it was way above the noise this noise comes from a lot of sources lots of things in the universe between then and now to get in the way just like remember you saw the picture that cosmic might pay back when you saw the galaxies in the center we had to subtract it out the galaxy is between us in the microwave background well the galaxy contains a lot of things most importantly it contains dust and thus can get in the way and dust can be polarized by magnetic fields and electric fields and therefore if the radiation scatters off dust and our galaxy it'll get polarized be a background so but they said look we can figure out how much dust there is in our galaxy we think we know how much there is and and it's not enough well the Planck satellite that I that I showed you earlier that showed the Cosmic Microwave Background actually is better able to look at this because it looks at the entire sky this was a small region of the sky as seen from the South Pole but the Planck satellite looked at the microwave background over the whole sky and they said we can kind of estimate how much dust there really is and a couple of months after this result they came up and produced a paper that said well you know what here it sort of this little bump here if you look at it here the first one is that bump there so this is kind of the prediction the prediction of gravitational waves for inflation this is what they saw but what what the Planck satellite said is well all of this shaded region is what dust could do this the galaxies much dustier than we thought and dust could produce within this uncertainty this much much of a signal and up here you see it could Bruce a signal that's comparable to the signal that was seen now the dust would produce a flatline and this signal is up and down which is one of the reasons I found it a little compelling but they said look extraordinary claims require extraordinary evidence as we've heard everyone say wasn't Carl Sagan who said at first but he popularized it and it's true and this is perhaps the most extraordinary claim that science has ever made so you better be absolutely certain it's not something it's not background and and and this is really interesting to me because here's the difference need science than theology or whatever you want to call it religion because the Planck people really wanted the by some people to be wrong because for a number of reasons one is they wanted to make the discovery and you know it's good win Nobel Prize or two okay so they really wanted them to be wrong and the guys really wanted to be right and they want to be them to be wrong so what do they do each of them had their if you want to call it ideologies you might people who claim scientists have ideologies each of them felt that their experiments right and so what do they do they didn't go out and and the bison people didn't go and cut the heads off of the people from from plank and vice versa yeah they may have wanted to it's true but they didn't the difference is what they do said let's get together and do an experiment together and figure out who's right that's the difference because what they cared about was what the answer was not what they wanted the answer to be and that's a profoundly so that even this is yeah you should all applaud because so in February of this year the two experiments actually did combine together and reported a result and I'll read it to you it says the original experiment that was this thing found that the level of oh that's the that's the plank experiment found that the level of dust power in a field centered on the bicep region but somewhat larger than it is the same magnitude as a reported excess but note of that the present uncertainties are large and that a joint analysis was required and so then they wrote in this paper we performed this joint analysis so the two groups got together and what did they do what did they discover well they discovered there's a lot more dust this is a likelihood this is the result this is the likelihood this number are at the bottom which you came to read if it's zero then there's no gravitational waves if it's nonzero there isn't and this is the likelihood that that the combined analysis finds that that of our and you notice it's peaked at nonzero okay but it's fairly close to zero if I put on the same scale and I couldn't I had to expand the original paper so that our 0.1 was the same in close paces this is the original bicep observation and you see it's just much bigger than that okay but again this is the power and importance of understanding of making claims in science so this is what this is what the result is the final result is expressed as a likelihood curve for our i Neil's an upper limit doesn't matter at 95% comfortable it peaks at a non-zero value but disfavor zero by only a factor of 2.5 this is expected by chance in 8% of the universes basically as confirmed by simulations in a dust only model we emphasize that this significance is too low to be interpreted as a detection of primordial gravitational waves so what this means is 92 percent of the time if this result that's right 92 percent of the time that would imply their gravity that their gravitational waves from the Big Bang but in 8% of random universes it would just be an accident and in a lot of fields of of science unfortunately and in a lot of fields in the rest of 92 percent would be enough for you to say it's there I mean 92 percent like belief that I saw ghosts yesterday okay or that God talked to me but in science in this kind of science for this kind of important result 92 percent just doesn't make it so when you actually read this quoted in the popular literature and by scientists you won't read that there's a nonzero result even though the curve peeks at it you'll read that there's no evidence for gravitational waves that the original claim was wrong okay it may not be wrong it could still be right we need to do further experiments and that's what's interesting it may be on the threshold of being detected and I want to talk to you about what would be the case of the implications if it were detectable because they change everything they allow us to explore aspects of the universe and indeed beyond our universe and the beginning of time in a way that makes many things I talked about in my last book that may have seen metaphysical actually testable and I find that fascinating so I want to talk about what the implications of those things are in the last bit okay to do that I have to explain what inflation was in a little in a little bit inflation is like when you um in the winter time which you experience here if you're if on the roads some of the things that may be dangerous is in a day where the temperature is changing very fast okay and there's water on the roads and then and then and then it's goes way below zero and and and it eventually it turns in ice but the wall there's still water on the roads right because it's getting squashed around and stuff so the water is far below freezing but it's still liquid okay that's what's called a metastable state because what can happen is BAM the water can suddenly freeze and when it does that by the way it releases energy the temperature the water even though that even though the the day is cooling the temperature the water remains constant because energy is released as water goes from its disfavored fate this favored phase liquid into ice it would rather be ice and that and as it moves from one to another it releases energy so the temperature the water remains constant that's what we call a phase transition in physics and I'm not a more pointing an example which you become relevant is if you look at a the frost on a window and on a winter morning you'll see all sorts of beautiful icicles pointing in random directions because it each place the water froze in Iran and the icicles get put in a random direction there's no governing it okay they're all random think about that for a moment because it'll be important because while we can see that they're all random if you lived on one of those icicles one direction in your universe would be very special the direction the icicle and as far as you concerned that would be a very special direction but it's random if you can see all the icicles okay so what we turns out we can predict is in the early universe we think that all the forces non-gravitational forces of nature were unified in something called a grand unified theory and the reasons I'll show you to think that that exists and then at some point as universe cools down that becomes a disfavored state when all the forces look the same and some of the forces want to look different it's called a phase transition we know that happened by the way because happened much later in the history of the universe when the universe was only a millionth of a millionth of a second old and at that point electromagnetism and an interaction called the weak interaction which originally looked the same begin to look different and that's a phenomena we're exploring at the Large Hadron Collider right now okay we know that those that really happened they originally were just the same force electromagnetism and the weak force which governs nuclear reactions and the Sun were once the same force and looked the same but they started to look different they start to look different as the universe cooled and the disfavor and the favorite state was for them not to look the same anymore we think that happened in a much earlier time when all three non-gravitational forces came together when the universe was a millionth of a billionth of a billionth of a billionth of a second old for reasons I'll show you in a second and then the universe wouldn't what could happen and what Alan Guth realized could happen is the universe as universe cooled it was cooling fast enough the universe could get stuck in this metastable state where all the forces were looking the same before it relaxed into this new state just like water ice okay but when it gets stuck in that metastable state energy is stored in empty space and we store energy in empty space it's gravitationally repulsive it's not attractive it's what's actually think for a different reason happening today and that means during that time it would cause this incredible expansion of the universe which called inflation but then that expansion would end just like when it went up when ice crystal forms some seed would happen would would happen and there'd be a phase transition in in some region and that phase transition would leave that accelerating phase and all that energy would be released that was stored into particles and radiation causing the Big Bang we see now okay and that's what this picture is is just saying we call it a false vacuum for a while the universe got stored in that it got stuck in that metastable state and then eventually left that metastable state and boom and that's inflation that would happen if all the forces in nature other than gravity were unified at that time scale and we have a reason to think they should be we can measure the strengths of the three forces in nature other than gravity the weak force the electromagnetic force and the strong force and back in 1970s we could measure them relatively poorly this is the scale we measure they but one of the most amazing things we've discovered about nature is that the strength of the forces change with scale electromagnetism as you get closer actually gets stronger not just the one over R squared force but the actual force itself gets stronger one of the great discoveries that surprised everyone in the 1970s was a strong force the strong the force between quarks which is the strongest force we know in nature actually gets weaker as you bring quarks closer together the force between them gets weaker it was a huge surprise something called asymptotic freedom was predicted 1973 in this and it basically discovered and eventually that in 2004 my friends Frank will check on other people won the Nobel Prize for that discovery so the strong force gets weaker and the weak force gets stronger well that's a hint then maybe if we go to ever smaller scales these two forces which seem very different on our scale if we look on very much smaller scales they'll begin to look similar and the weak force does to weak force get stronger as well well that was a great idea and it suggested we could do wild extrapolations from what we could measure in the 1970s and that suggested that if we went to a scale 19 while 16 orders of magnitude smaller in size than the size of a proton maybe all the forces would have the same strength and that was called grand unification was a lot of excitement about it unfortunately it doesn't work it's a good idea but it doesn't work most good ideas don't work okay we don't publicize that but it's true if they did anyone could do physics okay so we can now actually measure these forces we can as you know they don't come together at a single point if all the particles we measure are all the particles that exist but for other reasons which I really won't go into well be happy to in the question period we think that actually there's new stuff that's going to happen at the scale of the Large Hadron Collider that's why we continue to that's why we've turned it on again there's a new symmetry of nature which we think will help us explain some things we don't and it's called supersymmetry it predicts a whole bunch of new particles and those new particles will change the nature with which the forces the rate at which the force has changed as a functional scale and when you plug them in if you assume supersymmetry exists and you plug them in and do the mathematics what do you find all the forces come together at the scale almost 16 orders of magnitude smaller than the size of proton or if you wanted to probe that with energy 16 orders of magnitude and energy higher than the mass of the proton incredible we'll never be able to see that directly with the Large Hadron Collider we can at best explore here 14 orders of magnitude in scale larger than that time so you might think we'd never be able to detect it but what's interesting is if you ask what scale that corresponds to when was the universe that dense when those kind of energies existed when it was a millionth of a billionth of a billionth of a billionth of a second old so if grand unification happened and inflation happened it should happen at a time in the universe is a millionth of a millionth of a millions of billions of billions of billions of a second old and it turns out if you do the calculations it should produce gravitational waves of a scale that might be detectable at bicep so that's one of the reasons that gravitational waves are such an amazingly important tool if that they're really there we are probing physics at a scale 14 orders of magnitude smaller in size 14 mortars of orders of magnitude more in energy than the Large Hadron Collider greater an energy then will ever be able to provoke explore here on earth to do produce an accelerator that of that kind of energy would require radius greater than the earth-moon distance and I don't think that the NSF of the future will ever approve that they won't even approve a day I wouldn't even approve a damn machine in our country we were going to build the Large Hadron Collider was called the superconducting supercollider we were building it in Texas in 1993 but Congress in its immense wisdom and you know it by present standards it does seem wise back then but said we couldn't afford it because it was six billion dollars so we couldn't afford to build this thing that would probe the fundamental structure of nature that's like the air conditioning bill in Iraq in a week okay during the war but we couldn't do it so we didn't do it and it's now being built in Europe but that's okay but that it would be great that's why gravitational waves are so important but if gravitational waves are sort of iffy and there's backgrounds we got to ask where can we is there another place we could explore these things and the answer is there it's not the only place we might get a signal there are other wonderful experiments that we're building sorry it's not this is this that we're building this is one of my favorites this is in Japan in the kameoka mine in Japan this is the super cameo kind of detector this is an amazing device it's fifty thousand tons of water in a mine in a working mine in Japan and this is these are I think these are physicists in little boat floating in the water as it's filling up this is kept in the dark it's kept with the cleanliness of a laboratory cleanroom so there's no radioactivity in it it's surrounded by eleven thousand photo tubes and it's kept in the dark and what was it designed for well it turns out if the forces of nature unify at this incredibly small scale then I am sorry to say and I've noticed a number of people will be depressed about this looking at their hands that diamonds aren't forever okay because it turns out if the forces of nature are unified even protons are unstable the particles that make the fundamental particles that make us up and we calculate the lifetime if it occurred then the lifetime of a proton should be about 10 to the 33 years so you don't have to worry but now you might say well 10 233 years is a long time which is true but advising Woody Allen joke but I'm not gonna tell it um but it and so it's much longer than the current age of the universe which is 10 to the 10th years it's 10 billion years so it's irrelevant to us but the laws of physics are probabilistic as Jerry was pointing out in some sense quantum mechanics anyway so the average proton lives 10 to the 33 years in this prediction but if you were somehow to bring 10 to the 33 protons together in a room then an average one of them would be expected to decay each year ok so where can you get 10 to the 33 protons 50,000 tons of water so this experiment was built in the 1970s and the heyday of grand unification and it was put aside and put in the dark and it's been operating for 20 years and we haven't seen a proton decay now the challenge here this is why I'm a theorist and not an experimentalist the challenge is great because you might expect one proton decay every ten years or five years doesn't like that but if the experiments offline for the minute when that happens you got to wait another 10 years okay so it's a really hard experiment to do the fact that hasn't seen anything well maybe it was offline or it turns out when you put supersymmetry in the mix the scale of grand education goes up a little bit and you'd expect it one-to-one decay every 10 to 30 years and so maybe it's going to happen so the point is that we might this is still operating it might be that we will see a signal when a proton decay improves a flash of light and it and this experiment might be able to actually probe grand unification on another scale the other place of course is is the Large Hadron Collider itself the most complicated machine ever built by humans one of the greatest that it's these are the this is the Gothic cathedral of the 21st century it was created by thousands of just like the coffee cathedrals which are then built for the beauty of God this is to understand the beauty of nature but just like they were built over centuries this was built over decades by thousands of physicists from hundreds of countries speaking dozens of languages dozens of religions but they all work together to build these things to an accuracy machines that require accuracies of a millionth of this is the something called the compact muon solenoid which which I have a better picture because it has me in it but it doesn't show it as much um this it's built in two halves each half has more iron than in the Eiffel Tower and and just to give you a sense of this the magnetic fields that are used here are so great these two halves are sitting on the ground each of them is more than 20,000 tons and the magnetic field is so great that if it were turned on when they are apart it would actually drag them together okay and and the machine itself is 26 kilometers at a temperature of almost absolute zero with liquid helium the largest superconducting magnets in the world with a vacuum that's greater than the vacuum of space there are fewer particles in that tunnel than there are in empty space outside the earth it's amazing and these detectors all designed to try and explore the fundamental structure of matter and it could be for example if we if with these when now that the Large Hadron Collider is turned on many people hope that we'll see these particles due to supersymmetry a whole slew of new particles if that's true in fact most of us thought we'd see them before the Higgs particle most of us would have bet it's a lot easier to see them than the eggs the fact that we haven't seen them is worrisome or interesting depending upon your attitude important it's I'm still hoping they're not there even though I hope they're there because because if they're not there it means all our ideas are wrong and there's something more interesting to discover but but if it turns on it'll tell us supersymmetry exists if it discovers them that'll tell us when give us more evidence for grand unification and again support this idea so it'll tell us the gravity if we detect gravitational waves we'll be able to probe the nature of inflation at a time that we might be able to detect at some sense with these indirectly with these other detectors but it'll allow us to probe the physics of the universe when it was a millionth of a billionth of a billionth of a billionth of a second old directly essentially the beginning of time but more than that it will allow us to probe for the existence of other universes I find that fascinating cuz I've written about the multiverse but and I never always said well that's just religion that scientists having faith in something because they like God and as you probably heard if you heard the meat on the unbelievers it's true I don't like God but but we didn't invent the multiverse because we didn't like God we invent the multiverse because physics suggests that it actually exists that unfortunately and I mean unfortunately because I don't like it the laws of nature in our universe may just be an accident and there may be many universes with different laws of physics and why well inflation predicts that because remember I told you what happened is inflation is this phase transition and in one place uh Dhin Li boom that phase changes but just like icicles on that window I was telling you about before in different regions of the universe the phase transition might not have had even completed so the space between us and those regions is still expanding ever faster but in some other place in what we would have called the universe boom inflation ends but it can end in different ways just like the icicles can do you know point in different directions the phase transition that happens inflation can produce three different forces that are very different in different riu naver's what we call now different universes because they're separated will never be able to detect them because they're farther away and expanding away from us faster than the speed of light but inflation generically predicts that there will be many many universes many regions which leave inflation at different times in different ways and in each such universe the laws of physics could be different and in some universes there a lot of stars and other universes there aren't any another artists image these are both I think for my son took American articles so I but some of them and that some universes have no stars because the laws of nature don't allow stars we would find ourselves living in one with stars and planets and and carbon and nitrogen and oxygen and all the things that are created by stars and therefore the fact that our universes appears to be conducive to life is not evidence that their universe is fine-tuned for life but rather as Darwin discovered as far as biology is concerned life is fine-tuned for the universe in which it lives life evolves on earth to live in the environment in which it finds itself otherwise it doesn't evolve it doesn't reproduce similarly we find ourselves living in a universe that's acceptable for our existence it would be fascinating to find ourselves living in another universe but but we haven't so but the interesting thing is this is just an idea that we have if inflation happened grand unification happened all that stuff but if we detect gravitational waves from the Big Bang from inflation we will be able to test that idea we'll be able to probe the theory itself see if it predicts many universes and even though we'll never be able to detect those otherwise we'll know they exist in the same sense that in the nineteen early 1900's physicists and chemists eventually realized in fact after Einstein that atoms exist - man was really the first person to show that atoms existed by his thesis on Brownian motion but no one ever thought you'd ever see an atom fact there were good arguments you'd never be able to see atoms now we've been able to get around those arguments but everyone no one doubted their existence because the same theory that predicted atoms existed could be tested by a hold of bunch of different observations and and and so if you if it makes a hundred different predictions and they're all right you're willing to believe the one prediction that you can't test similarly if we could test inflation and it explained and we can explain why there are three forces in nature and why grand unification happened why the proton is two thousand times every in the electron and all of those things then the fact that it also predicts all the universe is that we can't see will be at least highly plausible scientifically it won't be metaphysics it's not religion it also for reasons I won't want to describe as I want to leave time for you have some time for questions um it also as as of colleague of mine just showed actually will allow us to test something that also we thought we never be able to test in fact my friend and colleague Freeman Dyson who is this contrarian has argued that there's no test we could ever do to prove that gravity is a quantum theory because if gravity is a quantum theory then the particles that transmit gravity are called gravitons just like the particles that transmit electromagnetism are called photons and we can measure photons but he pointed out brilliantly because he's brilliant that if you wanted to build a detector to detect gravitons here on earth the detector would collapse to form a black hole before you could do the experiment so he said it will never know it turns out as we show the universe as a detector because it turns out that it's quantum processes that proves the gravitational waves that we would see and we can prove it for mathematical reasons I won't tell you so if we detect gravitational waves from the Big Bang then gravity is a quantum theory and we know we need to there's a big problem that we need to solve so I want to conclude by saying oops well that was a picture again on conclude with Virgil these are the tears of things and the stuff are more mortality cuts us to the heart when you think about the universe when we look at that Hubble space it causes us to think about our own existence and I find it remarkable that in less than a human lifetime from the time Hubble first of fact discovered the universe expanding and we could see the fact that there are other galaxies that we have come but using the techniques of science to this threshold of maybe seeing back to the very beginning of time and the beauty of it as I say points out a number of things one the fact that science works the fact that you can bring people together of very different cultures and make it work and to this beauty of the fact that what we really care about is what the right answer is the fact that we haven't seen gravitational waves yet is incredibly disappointing to me as a scientist and it was incredibly disappointing to the people at bicep who felt very embarrassed but what they did was try and find the right answer and that's what we have to keep doing whether we like it or not we want to learn how the universe works and whether this beautiful picture I presented for you holds together or not will depend on observations we make and if it's all wrong great thank you very much okay thank you

Channel: BillJ Castleman

Views: 98,088

Rating: 4.8287797 out of 5

Keywords: Lawrence Krauss, INR5, Imagine No Religion 5, Physics, Athiesm, Humanism, Humanist, Gravity

Id: gvDX9uEWdbk

Length: 57min 30sec (3450 seconds)

Published: Wed Jul 01 2015