Lawrence M. Krauss || A Universe from Nothing || Radcliffe Institute

good afternoon everybody and thank you for joining us today at the Radcliffe Institute I'm Liz Cohen and I'm the Dean of the Institute I'm pleased to see you here for what promises to be an exciting lecture by Professor Lawrence Krauss who is the foundation professor in the school of Earth and space exploration and the physics department and inaugural director of the origins Institute at Arizona State University professor Krauss is lecture today entitled a universe from nothing we'll examine what we know and what it means to inquire about the formation expansion and future of the universe in so doing it fits closely with our mission at Radcliffe to support creative work in the humanities the sciences the social sciences and the arts and to share that work among both scholars and a general audience something professor Krauss has practiced with fine results throughout his career in fact I just this past weekend encountered the ever-present educator Lawrence Krauss I was in New York City on Sunday morning and I happened to turn on WNYC which is the NPR station if you don't know in New York and it was broadcasting Christa Tippit's on being NPR's version of Sunday spirituality she was interviewing a physicist who was saying very intriguing things and so I was running around looking for a piece of paper and a pen to write down some of these things though I might use them in my introduction today and he was saying some things I'll just give you one example he said I liked science fiction until I learned about real science which I found much more interesting and then suddenly Krista Tippett said I'm here talking with Lawrence Krauss and I was amazed that it was our guy as it happens the Radcliffe enjoys a significant historical connection to the subject of Professor Krause's talk in 1892 a young woman named Henrietta Swan Leavitt graduated from the Society of the collegiate instruction of women soon to be renamed Radcliffe she had taken one class in astronomy in which she earned an a-minus and soon after graduating she began working just a few blocks up Garden Street at the Harvard Observatory women were not at the time allowed to use the observatories telescopes so Levitz job was to look intensively at large photographic plates of the sky carefully measuring individual stars she did this full-time until 1896 and then she rejoined the observatory staff in 1902 when she obtained a raise all the way from 25 cents per hour to 30 cents an hour in 1908 Leavitt published a paper in the annals of the astronomical observatory of Harvard College which helped push astronomy forward levert had catechol catalogued 1777 stars known as variables by 1908 by the end of her career I should say her total was closer to 2400 there she noticed that their brightness fluctuated over repeating stretches of time in some cases she noticed there were clear court there was a clear correlation between the relative brightness of a given star and a period of time in which it remained in a phase of brightness moreover astronomers recognized that the brightness of a star also served as a measure of its size that led to Levin's insight suppose two stars had phases of brightness lasting equal periods of time but were not equally bright the implication would be that the stars were the same size but that the dimmer one must be located farther away from us this helped astronomers measure the distances between us and these stars and when linked to other advances it helped us grasp both that there are other galaxies apart from our own and that the universe is expanding today of course the since the concepts and the mathematics of astronomy are far more complicated than they were a hundred years ago rather than photographic plates astronomers are using tools such as the Kepler space telescope to find hundreds of exoplanets while other scientists wrestle with unknowns such as the nature of dark matter and yet while science may be full of mysteries it doesn't have to be mysterious to us citizens can learn in general form what some of the leading questions are in any given area of inquiry in this effort we are greatly aided by the president's presence of interlocutors such as Lawrence Krauss who are willing and able to explain to us both how far we have come while still giving us a sense of how much remains to be known in an area of study that often sparks people's scientific curiosity for the first time and here I'm referring to astronomy he makes the universe explicable even to those of us who did not as Henrietta Leavitt did take an astronomy class in college by taking the public understanding of science seriously and explaining scientists work in just this way by showing how science can advance cumulatively while simultaneously raising new questions Krauss presents us with a true picture of research in action he has also been added a pretty in-depth critic of popular misrepresentations of science in dissecting how the media's dissemination in findings can leave us with a misleading picture of scientific inquiry Krause's willingness to engage with the public and the media has done a great service I am pleased now to introduce my Harvard colleague demitasse a sloth who is professor of astronomy at Harvard and director of the Harvard origins of life initiative some of us here know well professor Salif has also previously served a science advisor to the Radcliffe Institute and he is in fact a co-investigator on the Kepler space telescope team which at last count had confirmed 115 new exoplanets like Henrietta Leavitt SAS sloth has studied pulsating stars and like lawrence krauss he has written lucidly about his field for general audience especially in his recent book the life of super Earths which links astronomy and biology by suggesting how life may evolve given the composition of certain planets so please join me in welcoming professor sass Olaf who will give a fuller introduction to Professor Krauss's work de matar thank you all for coming how do I go about introducing our distinguished speaker today it's really difficult because we have somebody who is a very distinguished original physicist in some of the most exciting fields of physics understanding the fabric of space-time and the origin of the cosmos and yet we also have somebody who has distinguished himself in much more than fundamental science and so maybe the best way to describe him is to say that he hails from New York City lived most of his childhood in Toronto which to me as a former student in Toronto is the New York City of Canada and has left a trail of distinguished career from his PhD at MIT in 82 to being a Harvard fellow in the Society of Harrod Falls here right after that to then on to Yale as a professor in physics to then on being the chair of the physics department at Case Western in Cleveland and participating in some of the concerts of the famous Cleveland town orchestra which I remember back in Bulgaria was very famous I think they had I think Aryan composer don't they yes so that's a very distinguished career in physics with the fundamental contributions to the connection between elementary particles and the cosmos as a whole and so this brings us to what is nothing and the title of his lecture which is also title of his book which makes a lot out of nothing a whole universe for that matter and it helps us for the first time in layman's terms to understand something which I personally remember as the sole reason I became a physicist when I went to college fascinating fact for me then that the vacuum was not empty that there was energy and there was all the time something being created and disappearing in what we call vacuum which then led to the amazing discoveries which still continue today in fact just last year with the discovery of what imparts mass to those particles which is the Higgs boson so that what drove me then as a young fellow who could have ended up as a probably a hotel attendant on the Bulgarian Black Sea coast if not going to college I hope is what would motivate a lot of young people in the future and it is people like Lawrence Krauss who manages to get those young people to school and then to us here in Harvard and other places so his contribution to bringing that understanding of what is at the forefront of physics and science in general is just immeasurable I would say that he's probably the only physicist who has been nominated for a Grammy Award and he's probably going to be a were nominated for an Oscar next year because of his new full full length documentary with Richard Dawkins the unbelievers which I haven't seen yet so I'm free to speak about it as a theorist we like to speculate about things but I understand it will be open at the festival in Toronto just in a week or two and so hopefully we'll be able to since see it soon afterwards this is just to give you a sense of who professor Krauss is and just as a final remark he is the founding professor of the Department of Physics in Arizona State University but more importantly the co-founder and founding director of a program there which embodies what he himself embodies personally which is called the origins project which is an amazingly wide academic endeavor both in scope as well as in talent in trying to combine understanding of the origins of the cosmos to human origins understanding cognition and the origins and evolution of culture with that I think you now understand that you have amazing individual whom our Dean named our man and so let's invite our man to the podium and hear from him I normally like to switch from this but I would this list I was reading this again while I was in the back and it means a lot to me today in particular while I had to I was working out this morning and well this Lawlor medically make me unpopular but I was I was subjected to a lot of interfaith services downtown and I was thinking that this quote would be more appropriate but anyway um I want to begin with another quote which is one of my favorite quotes that began a book but it's the that the initial mystery that attends any journey is how did the traveler reach its starting point in the first place and I think that's perfectly appropriate for the origins program here and the one that I run but really if one thinks about mysteries it's getting to the beginning that's a really important part and the mystery of our universe and getting to the beginning of what is in fact one of the greatest mysteries around right now in science is what I want to get you to today so we'll get there but we will do it by addressing this question that's been around for as long as people have been around why is there something rather than nothing and people have asked that question as as I say as soon as they could ask questions and there are lots of different ways of answering it there you can just sort of you can write in the beginning and then have a whole book that doesn't explain anything about anything and or you can at you can actually turn to the universe and try and figure out the answer and that's what I want to talk about and the fact that we the universe is giving us answers that we as was mentioned in that interview with Krista Tippett that humans would never have come up with our imaginations pale in comparison to the imagination of the universe which is why we have to keep looking this is a Hubble Space Telescope picture the Hubble Deep Field and like all Hubble Space Telescope pictures it's my favorite one but in this particular picture every dot is a galaxy not a star and there are 400 billion galaxies in the observable universe and when I look at pictures like this it does inspire my imagination because many of these galaxies especially the small dark ones there are are maybe up to ten billion light years away and that means the light left them ten billion years ago and well before Earth and and Sun formed and there and therefore most of the stars in that picture are dead now and any civilizations that may have existed around them are dead as well and if they take the picture and look at us ten billion years from now we'll be long gone and forgotten as well and so these kind of things are inspiring and that's what I want to do to inspire the actual understanding of the universe ourselves really if you remember if you read the poem at the beginning it's the universe one of the points I want to make is that the universe doesn't exist so that we can be happy and and we just have to get over it and and and and we should take it for what it is and and and and learn from it so that's what I'll try and do now following Henrietta Leavitt was this guy here who I'm going to praise for a different reason although he used much of her work this is one of my heroes Edwin Hubble and he's one of my heroes because he gives me great hope for Humanity because he began life is a lawyer and then became an astronomer and so there's hope for many of the Harvard students in this audience but so so Hubble did many things but he really was the first one what the thing that is a side to what I want to talk about but I'll mention with the Mount Wilson telescope in 1925 he changed our picture of the universe in a very important way just think about a single human lifetime ago 88 years ago the universe consisted of one galaxy surrounded by an eternal vast empty void and that's a single human lifetime ago now we know there are 400 billion galaxies in the observable universe and the universe is expanding I mean everything has changed so it's not it's it's not surprising that we're surprised we are like the early map neighbors just beginning to understand the universe on larger scales and what we're learning is amazing us but he was actually the first one to demonstrate that there were other galaxies up to that point when you look through telescopes that were then existing you saw these fuzzy things called nebulae which is Latin for fuzzy thing and and and it with it with the telescope he was able to my wilson telescope to see that these were in fact other Island universes other galaxies so until that point one galaxy now 400 billion but then of course he made the discovery that we all remember him for he discovered that the universe is expanding by using this data he made it clear that the universe was expanding so what well let's just serviced eclis see what he saw these are there a lot of biologists here but these are not sperm these are galaxies and and what we sweat is schematically saws as we look out one of the most amazing things is that galaxies on average are moving away from us and objects that are twice as far away or moving twice as fast and three times as far away moving three times as fast and so on and so when you see this immediately you know what it implies it means we are the center of the universe it's obvious when you look at it and it certainly seems that way but as many of my friends remind me on a daily basis that's not true it means the universe is expanding and the problem with with you know I've thought of a lot of different ways to try and show this and and the problem is that we live in our universe well most of us do the Republican Party doesn't but the rest of us the rest of us do and and so we have this myopic picture to really understand that this implies that the universe is expanding we'd have to get outside of our universe not so easy to do but it's easy to do for a universe you can draw and here's a two-dimensional universe I can draw on a screen so these are galaxies I put down at regular intervals and you can see that a time t1 this it this region is smaller than a time t2 so if you're standing outside of it you can see that it's expanding so that's that's clear but what would you see if you lived in that universe well quite simply just pick a galaxy any galaxy to see what you'd see we can superimpose this image on top of this one placing this galaxy on top of itself and and and what we see is exactly what Hubble saw every galaxy is moving away from this galaxy here and those that are twice as far away are moving have moved twice a distance at the same time those that are three times as far away three times the distance and so on and it doesn't matter what galaxy you pick you see the same thing from every galaxy so this means that it depends on how you like to think things either there is no center of the universe or every place as the center of the universe it doesn't really matter what it really means is that the universe is expanding and that changed everything because once the universe was expanding it meant first of all working backwards the universe had a beginning the Big Bang which is we now know is about 13.8 billion except for in Arkansas and Ohio and a few other places since 13.8 billion years ago and of course it also means that the universe is expanding the central question of 20th century cosmology then became will that expansion end well universe end with a bang or a whimper well the expansion go on forever or will it stop and in fact actually as someone who's trained as a particle physicist the reason I got into cosmology was because I wanted to be the first person to know how the universe would end it seemed like a good idea at the time and you'll see my reasons were all wrong but in any case so that not only had profound significance course for science but also obviously for religion theology the beginning of the universe meant well what it may have happened before the beginning and how did it begin etc and we'll try and address those questions now in order to know how the universe would end and the reason as I said I got into part in two cosmology it's quite simple Einstein told us the remarkable fact that space is curved in the presence of matter and energy and that means that space the geometry of space can be interesting and in fact while in three dimensions and in two dimensions there are three possible geometry so-called open closed or flat it's very hard to draw curved 3-dimensional universes because we're three dimensional beings so we couldn't picture them but I can draw two dimensional universes so these are just guides for the eye but but as with three dimensions there are just three types open closed or flat and a closed two-dimensional universe is the surface of a sphere for example and a flat two-dimensional universe is a flat piece of paper well one can't draw them in three dimensions similar things would be true in a closed three-dimensional universe if I look far enough in that direction I would see the back of my head like we go around the universe and a flat three-dimensional universe isn't flat like a piece of paper but instead is it's flat in the sense that it's universe you always thought you lived in and the one where the XY and z axes always point in the same directions and light travels in straight lines and the big question of twentieth-century cosmology was which university we live in because it would determine our future because if you have a universe full of matter and it's closed will expand stop and contract in a Big Crunch service the Big Bang where as an open universe will go on expanding forever and a flat universe is the boundary between those two will slow down but never quite stop so when we determine the geometry we figured we'd know the future so since to determine the geometry requires knowing how much mass and energy there is in the universe all you have to do is weigh the universe it's really quite simple and and that that's taken us many years I wrote a whole book about it in fact but but a single picture in fact nowadays will do the job but before we get there I want to take you back for some historical perspective especially for the young people to 1936 science magazine many of you young people will will will become scientists and you'll submit articles to science and you'll be rejected and and and the point I want to tell you is that what you know it was used to be kind or gentler was just easier back then I want to show you so this is article in 1936 the title is lens like action of a star by the deviation of light in a gravitational field but here's how it begins some time ago our w Mendel paid me a visit and asked me to publish results of a little calculation which I made his request this note complies with his wish okay try that today and see what see what happens okay see if you get in now the author had credentials cuz Albert Einstein's okay maybe that helped but what he published was something he thought was very unimportant is he had shown that light bends in a gravitational field but if there's a large enough mass clearly if you put a large enough mass and have a light source behind it the light rays can bend around it and converge and come back together going to be magnified like my glasses magnified nearby objects or if I had a cut glass goblet here and I looked at all of you I'd see many images of all of you so he realized that space can act like a lens but he thought it would be unobservable and very unimportant so actually here's his notes from 1936 from his notebook and the interesting thing is it was so unimportant that he forgot the 1990 12 if you look at his notebook exactly the same calculation he forgot he done it didn't think was important and my favorite part of this is his letter to the editor after it was published he wrote let me thank you for your cooperation with the little publication which mr. Mandal squeezed out of me it is a little value but it makes the poor guy happy that's how science is done okay well it wasn't a little value because it allows us to weigh the universe and here's a picture of what Einstein said would never be observed this is gravitational lensing this is a cluster of galaxies clusters of galaxies are the largest bound objects in the universe so if you can weigh them you can weigh everything okay so if you weigh these guys you can weigh the universe and they're so larger maybe ten million light years across they contain many many galaxies and this is a picture of a galaxy located 5 billion light-years away again every dot in the picture is a galaxy not a star each containing maybe 100 billion stars but you don't have to be a rocket scientist to see that in this image there are these weird blue things they look different and what they are are multiple images of a single galaxy located 5 billion light-years behind that cluster one that might not even be observable if it are magnified but it's it's magnified and distorted and we have multiple images so this is proof this is evidence of the fact that space is a lens it's curved around matter and it can lens things which is wonderful but of course we understand general relativity and so we can use it we can say well how much matter would there have to be in this system and how is it distributed in order to produce this image it's a complicated mathematical inversion but you can do it and when you do you get a picture like this the spikes are where the galaxies are but you notice that most of the mass in this system is where the galaxies aren't there's a huge mountain of mass almost 40 times as much mass in that image as meets the eye in fact around each galaxy there mountains of mass that don't correspond to visible light most of the mass in these systems and indeed at all such systems doesn't shine and physicists were so creative we call it dark matter it doesn't shine and the interesting thing if you're a particle physicist is that there's enough of it there's so much of it ten at least ten times more of it then can be accounted for by protons and neutrons the stuff that makes us up and everything in this room up we know how many there are for different reasons and there's far more dark matter than can be accounted for by protons and neutrons so we're virtually certain it's a new type of elementary particle which makes it exciting because it means it's not just out there it sits in this room going right through your bodies as you not off during this lecture and that means we can do experiments here to detect it and that's that's of great interest in their experiments around the world some of which actually I proposed many years ago and I was going to go into them but I think I'm not going to in order to save time given the length of the introductions but so it doesn't read it's a fascinating if we detect it we'll learn what the nature of most of the mass in the universe is and most of it isn't us but for this purpose we right here we don't have to care what it is we just have to care how much of it there is and this kind of image adding up matter in these kind of systems and so finally allowed us to answer the question of how much stuff there is there in the universe way in the universe and so I'll do a drumroll okay and the answer is that I see their people in the back fainting I can see in physics whenever whenever one has an important number one gives it a Greek letter to sound scholarly and and Omega here is the ratio of the amount of stuff not a matter in the universe you the actual amount of matter divided by the amount you'd need to make a flat universe in exactly flat universe so if it's less than one universe is open if it's greater than one universe is closed if it's equal to one the universe is flat and you can see with this and many subsequent measurements it's now definitively known that within a fact by a factor three or so there's three times too little matter to make the universe flat so the university fears be open we've answered the holy grail it's all done but there's a problem because we theorist knew the answer we always know the answer we're not often right but we always know the answer and we knew that we lived in a flat universe because it's the only mathematically beautiful universe and the observers were doing what they do so well which is getting it wrong and and and of course the problem is it is a difficult thing to do because it's a very indirect way to measure the geometry of the universe after all because you try and add up the amount of matter in the universe you plug it in Einstein's equations and try and measure the other terms and put it all together and you try and measure the curvature wouldn't it be better to measure the curvature of the universe directly and it is amazing than the last decade or so we can now do that we've been able to measure the curvature of the universe directly and to figure out how to do it let's ask question how could you measure the curvature of the earth if you couldn't go around it or couldn't go into space and see that the earth was round it's really simple you draw a triangle and then you ask a European high school student or a Harvard undergraduate what's that sum of the angles in a triangle and it's 180 degrees okay where you came from they know those things okay but that's because you learned your geometry from Euclid on the surface of a sphere be quite different on the Earth's surface I could do a triangle this way I could go across the equator make a right angle go up 90 degrees to the North Pole then another right angle back down to the equator and now I have a triangle with three right angles three times 90 s 270 so literally if you were able to draw a big enough triangle on the surface of the earth you would be able to show the earth was curved now it is remarkable that exactly the same thing is true for even three dimensional curved spaces if you were to draw a big enough triangle you could measure the curvature of the universe and people have tried tried for hundreds of years to do that but we now have been able to measure a big enough triangle and we use what is perhaps one of the most important observations in in cosmology the cosmic microwave background radiation the afterglow of the Big Bang discovered in New Jersey of all places in 1965 by two people who didn't know what the hell they were doing but they won the Nobel Prize anyway because you really don't have to know what you're doing to Wheldon win the nobel prize for given to at least one Nobel laureate I know on the audience um but could you just have to discover something important and they did they discovered the afterglow of the Big Bang and here's what it is so when we look out at the universe we're looking back in time we're doing cosmic archaeology when we look at galaxies that are billion light-years away a billion years back in time so if the universe is 13.8 billion years old you think if you look out far enough you see the Big Bang and a principal you could accept between us and the Big Bang there's a wall not a physical wall like this but effectively like the one in this room because I can't see past this wall because the walls opaque if I look out at an early time the universe was hot enough before about a hundred thousand years or so it was hot enough that that neutral matter couldn't exist hydrogen was broken apart into its protons and electrons it was a plasma and it's opaque to radiation so you can't see an electromagnetic radiation back before that time but then the universe cooled down matter became neutral and just like this wall which I can see because the air is transparent between me and the wall space became transparent and one of the predictions of Big Bang is that I would see radiation coming at me from all directions from that so-called surface of last scattering and because the universe is cooled since that time it's no longer 3,000 degrees but three degrees and that's what they discovered in New Jersey now this is such an important image that that if you took a picture of this you get a baby picture of the universe another Nobel Prize is to give that picture I'll show you one two versions of it in a minute but from our perspective what's really important is that there's one scale on that baby picture and it's one degree and that's because one degree represents about a hundred thousand light years now Einstein told us no information can travel faster than light and therefore anything that happened over here on their surface can't affect anything over there because light can only travel this far in a hundred thousand years and that means if you're a lump of matter say this big you start to collapse like lumps do and heat up and do all sorts of neat things but if you're a lump of matter that's this big across you don't even know you're a lump because gravity travels at the speed of light so it's like wily coyote you and he goes off the cliff and those cartoons he sort of hangs around for a while before he knows he's supposed to fall lumps at bigger than this size don't collapse so if we can image this this surface and look at the lumps and ask how big are they we could get a sense of in fact the largest lumps that would collapse due to causality but that gives us a triangle you see because it's a it's a it's a it's a ruler of a known length a given distance away and you see in a flat universe where light rays travel in straight lines that hundred thousand light year across ruler will September 9 but in an open universe as you go back in time light rays diverge as you go back in time so the same ruler will look smaller maybe half a degree and in a closed universe light rays converge as you go back in time and so the same ruler will look bigger maybe two degrees so all you have to do is take it that picture and look at the lumps and ask how big are they and just by causality you'll measure the curvature of the universe and so we can do that and this is one of the first experiments that that this is the boomerang experiment it was a balloon and a microwave radiometer is sent up in Antarctica went around the world which is easy to do in Antarctic actually if you're in South Pole you just do this but that it wasn't those of McMurdo so it took two weeks to go around came back to where it began called the boomerang experiment for that reason and it and it imaged a region of the microwave sky and this is superimposing the original picture this is the picture this is a false color image these are the lumps this is a hot spots and cold spots in the microwave background this is an amazing image it is a baby picture these are the lumps input at very near the beginning of time that would later on collapse to form all the stars and galaxies and planets and aliens and everything that's in the universe today it is really remarkable to see this primordial picture but again for our purposes the question is how big are those lumps okay and we want to and we can do that but I should show you at least a more recent picture this is as you've probably seen in the in the press there have been several satellites have gone and looked at the full sky and this is a picture from the from the what's called the Planck satellite that just published results and this is the full sky this is a galaxy get rid of the galaxy and then you can more clearly see these are these primordial lumps that would later on form all the galaxies and structures we see today question is how big are they so to see that we can take this is the boomerang image at different false colors but we can create universes on computers and we can lay down 100,000 light-years on average and ask how big they look so in a closed universe an open universe or flat universe and a closed universe the average hundred thousand light year across lump should look that big but that's bigger than these lumps in an open universe the average hundred thousand light year across lump should be about that big but that's smaller than these lumps but just like Goldilocks in a flat universe it's just right and we now know today to an accuracy of better than one percent almost that the universe is flat we finally know the universe is flat so the first thing we do is this but we don't do that okay because we you know because there's a problem there just a few minutes ago I showed you the universe was open there's only 30 percent of the amount of stuff needed to make a flat universe but the universe is flat so where could the other stuff be well if it isn't where the galaxies are it's got to be where the galaxies aren't but what's where the galaxies aren't nothing and that's the first clue that nothing is interesting because nothing as roomy as just pointed out earlier is actually a very interesting thing in modern physics empty space is is a very fascinating object because it's really a boiling bubbling brew of virtual particles popping in and out of existence in a time scale so short you can't see them now that sounds like religion or kind of counting angels on the head of a pin you know inventing things that you can't see it would be you can't see them directly but do the laws of quantum mechanics and relativity they have to be there and moreover we can see their effects indirectly and that's really important in fact I have a picture here in animation this is an actual animation based on a real calculation of what the space inside of a proton looks like okay in fact it was shown at the Nobel Prize ceremonies by the people who first allowed this calculation to be done and you can see that and if you went to a good high school you learned that that protons are made of three quarks but we lied okay they're made of three quarks but if you add up the mass of those quarks they only add up to about 10% of the mass of proton most of the mass the proton comes from these particles and fields that are popping in and out of existence in a time scale so short we can't see them and that's remarkable so we know they're there and we can actually calculate their contribution of the proton now and and and two elementary particle masses and that's a remarkable success well emboldened by that success we can try and use the same physics and if you can calculate the contribution to the energy inside a proton surely we then try and calculate the contribution to the energy of the universe and so we can cry and calculate the energy of empty space and when we do that we come up with the worst prediction in all of physics okay we come up with the prediction of the energy of empty space is roughly a gazillion times the energy of everything we see and that is the worst prediction because in fact we know it can't be much more than what we see or we wouldn't be here yet we predicted naively that it's about 120 orders of magnitude larger and this problem has been around since I was a graduate student since I was here in Boston and that we never talked about it because it was so important it's called and and but again it wasn't a problem because we theorist knew the sir we always know the answer we knew it was zero knew the energy of empty space had to be zero it's the only sensible value because it wasn't let's say it was comparable to the energy of everything we see then you have to cancel this big number to 120 decimal places leaving some nonzero number in 120 first decimal place but we don't know how to do that in physics no one knows how to do that but it's easy to get zero mathematical symmetries can produce zero equal and opposite things that cancel exactly so all of us theorists knew the answer we knew there was some new symmetry of nature we hadn't yet discovered but we would that would one day explain why all those things canceled and you get exactly zero and we could go home at night and sleep but as I pointed out at the beginning this lecture the universe doesn't care what makes us happy it's not sufficient to say that's the only sensible thing cosmology is a science and therefore you have to go out and look so how can you determine the energy of empty space well remarkably Einstein tells us something wonderful all of the physics students here know that grete know that gravity sucks okay always pulls it never pushes but if you put energy and empty space it blows okay it produces a kind of cosmic antigravity you put energy and empty space in the equations of general relativity tell you it must be gravitationally repulsive so if you were to measure the expansion of the universe as mr. Hubble did based on henrietta Levitz data and measuring the velocity of objects versus time this is a hubble plot nearby then the idea is you can look to see in a sensible universe should be slowing down but if you put energy in empty space it'll speed up so how can you do this what means you have to measure distances and velocities not just nearby but across the whole universe okay and to do that how do you measure distances that are from objects that are so far away well it's very very difficult because you know we don't have tape measures of that long you need something we call a standard candle something whose intrinsic brightness we believe we understand and then you look at it through a telescope you see how bright it looks and therefore you determine the distance objects and it's taken a long time and and on much of the last century to come up with good standard candles but we have come up with a good standard candle here's a picture of one this is a galaxy long long ago far far away actually not that far away it's only 70 million light years away and here's and it's a spiral galaxy much like our own once you've seen one you've seen them all my apologies the astronomers in the center of the galaxy there's about 100 billion stars here the center of the galaxy contains maybe 10 billion stars and here's a star shining with a brightness of 10 billion stars how could that be well there's two possibilities one it could be a star in our galaxy that got in the way the picture which is reasonable to assume but it isn't it's a gala it's a star at the edge of that galaxy shining with the brightness of 10 billion stars why because it's the star that's just exploded a supernova and supernovae are the brightest cosmic fireworks in the universe when they when they explode for a period of a month or so they shine with the brightness of 10 billion stars now fortunately for us stars don't explode too often but fortunately for us they explode fortunately for the projects we're involved in here and at ASU because you wouldn't be here if they didn't explode because all the important elements that make up your body were created in stars that in the Big Bang the only things were created were hydrogen helium and a little bit of lithium but the important stuff well some people here lithium may be important but for the rest of us carbon nitrogen oxygen iron all those things are created only in the nuclear furnaces inside stars and the only way they could get into your body is that the stars were kind enough to explode so you are literally start us it is the most poetic thing I know about the universe I wrote a whole book about it you are star children you are intimately connected to the cosmos in ways that you might never imagined in any case the problem is they don't explode too often they explode about once for a hundred years for Galaxy so if you want to study these objects as standard candles how do you do that once for a hundred years per galaxy well it's quite simple you sign a graduate student teach galaxy okay 100 years about right for the PhD and and as we all know you know graduate students are cheap so they die you just get a new one it's no problem but you don't have to do that because the other amazing thing about the universe is that it's big and it's old and rare events happen all the time so tonight if it's if it's still clear and you hold your hand up and hold a dime-sized hole and look at a region of the sky where there are no stars with one of the largest telescopes on earth we have down in Chile say if you looked at that region of the sky where there no stars dime-sized region you'd see about a hundred thousand galaxies and if you work it out once for a hundred years for galaxies 100,000 galaxies on a given night years are going to see a few stars explode and and observers do that they apply for telescope time they see stars exploding as a result we can measure exploding stars in many cases and follow them over the period of a month while their brightness will really go over again there's the star it's going to explode this brightness we can measure its colors and from its colors we can determine what kind of supernova it is the different types this is called type 1a and it turns out to be a wonderful standard candle so wonderful that you can use it to measure the distance and Gallic distances and galaxies in which these supernovae exist but since they're so bright you can measure them across the universe and in 1998 two groups of astronomers who really didn't know what they were doing we're trying to measure the rate at which the universe was slowing down and they were able to measure though this is a new Hubble curve this is nearby stuff and the big question was does this curve curve upwards or downwards they were looking to see how fast it curved downwards and to see what happens here you just draw a straight line to that dataset bring the whole thing horizontal and what they expected to see was measure was how well the supernovae were falling this curve which is a universe that's slowing down but much to their surprise these supernovae I didn't even lie on the straight line but I'll above the straight line and there's only two ways to explain that one the date is wrong is or to the expansion the universe is actually speeding up and just for fun if you try and fit that data and ask how much energy would you have to add to empty space to fit the data you need exactly what we're missing if you put 70% of the energy of the universe of a flat universe in empty space everything fits together and these people won the Nobel Prize for that discovery so here we have the current picture of the universe that I want to use our starting point for talking about the future and trying to ask where we came from this is a a universe in which 70% of the energy in the universe resides in empty space and 30 percent almost resides in dark matter and 1% or so resides in everything we see so we are just a bit of cosmic pollution in a vast sea of dark matter and dark energy you get rid of us and all the stars and all the galaxies and everything we see in the night sky and the universe would be largely the same so so much for universe that's made for us but the other thing is and there's two lessons I want you to draw from this lecture and the first one now is very important you are far more insignificant than you ever thought you were okay that's the first takeaway lesson you are that's you not me no all of us are are far more insignificant than we ever thought okay but let's now let's summarize in so the dominant energy in their wrists resides an empty space we don't have the slightest idea why it's there and if someone here comes and gives a lecture next year and says they know why they're lying especially if they're a string theorist okay and its existence is probably tied to the beginning of space and more importantly as you'll see it will determine our future okay so in fact when we talk about determining the future I want to go back to say why you know why I got into this why I thought we could determine our future for measuring the the curvature of the universe and I want to take you back to your favorite time high school physics now you may remember and that we teach you how if I take a coin which I don't have oh I do have a foreign coin here somewhere I just came from Norway I have a gold coin I think have a big coin yeah okay Sweden anyway and I throw it off that comes back down if I throw it up faster it comes back down if I throw it up really fast and there's no ceiling it doesn't come back down at all and we teach students how to calculate that by turning that problem into bookkeeping because we say the coin has energy and has two bits of its energy a so-called positive piece the kinetic energy and a negative piece the potential energy positive peace comes from motion negative piece comes from the mass of the Earth and gravitational attraction but what's really neat is that that we then it just becomes bookkeeping if this term beats that term the coin will escape if that term beats that term the coin will fall back down so if the total energies positive escapes if the total energy is negative it comes back down well the really neat thing is in a universe full of matter you can do the same thing let's just take Hubble's picture here and we're at the center and if the universe is the same everywhere then what happens to every galaxy will happen to any galaxy so to help calculate the future of the universe you just have to calculate the future of the motion of any galaxy say this one and then it's just the same as for the coin to determine whether it'll go on expanding forever we just calculate its total energy and the positive peace comes from its motion but mr. Hubble and Henrietta Leavitt told us its motion the negative peace comes from the mass of all the stuff in the region pulling it inside which includes dark matter so we calculate that and weaken it and so if the negative piece beats the positive piece of B over a is bigger than one this regional collapse if B over a is less than one so the positive piece beats the negative piece will go on expanding forever and the really neat thing is it turns out B over a is nothing other than this quantity Omega and I remind you we measure Omega Omega is one we live in a flat universe and of Omega is 1 then B is equal de and if B is equal de than the negative piece equals the positive piece but if the negative piece equals the positive piece then the total gravitational inner energy of every object in the universe is zero now if you want it to make universe from nothing what would you make the total gravity so this begins to suggest that maybe we can create a universe from nothing without any supernatural shenanigans and we and what I want to argue is we absolutely in principle can can we prove our universe came that way no but I want to discuss that now in the last few minutes to talk first of all I've learned that one has to be careful when you talk about nothing because as I said in the book and if your aid some people philosophers and theologians or experts at nothing and and they get upset if you if you don't talk about it in the way they like so I want to talk about the three different versions of nothing the first version just empty space and nothing of the Bible the vast cosmic void well it turns out that nothing is unstable because that nothing I remind you is avert bubbling brewing sea of virtual particles well those aren't real particles if you try and measure the particles in empty space coming from this way you won't see anything there aren't any real particles but if you allow gravity into the mix then there can be a gravitational attraction between the particles and that can produce a negative energy component their total energy the reason virtual particles pop in and out of existence so quickly as they carry energy and if they existed for a long time they violate energy conservation so they have to disappear according to the Heisenberg uncertainty principle but if I put enter gravity in the mix then I can make the total gravitational energy a total energy of these particles zero and if that's the case they can exist with impunity and quantum mechanics says fluctuations will happen all the time so if you allow gravity into the mix and you have empty space you are guaranteed if you wait long enough particles will be spewed out so in fact that kind of empty space is unstable the big question would not be wise or something rather nothing but why is there nothing rather than something but if there were we wouldn't be here to ask the question so okay so that kind of nothing easy to get rid of automatically you can make enough stuff to account for everything you see but you might say that's not nothing because got no particles you got no radiation start with but we got the space where did the space come from well if we have a quantum theory of gravity I remind you general relativity is a theory of space and time and the big question is can you make it a quantum theory we don't know for sure but if it was a quantum theory if it is a qualm theory then space and time become quantum mechanical variables and I remind you in space because of quantum mechanics and relativity particles will pop in and out of existence if space and time are quantum mechanical then spaces and times can pop in and out of existence in a time scale so short we can't see them so once you once you allow once you make gravity a quantum mechanical theory you are guaranteed that whole universes spaces that did not exist can pop into existence and out of existence virtual spaces can pop in and out of existence now if I create a whole space that has zero energy it doesn't have to pop out of existence right ok so now it's sounding like there's a grand synthesis in the air because I told you the gravitational energy of every object in the universe is zero but it's not that simple because the only universe in which we can mathematically show that it has zero total energy is a closed universe not a flat universe and we don't live in a closed universe so what gives well the point is that most closed universes as I as I told you before our closed universe will expand stop and contract if it's full of matter and these microscopic closed universes will expand and contract on a time scale so short it will be microscopic timescales the only way you could have a closed universe that would survive long enough for us to ask the question is if you put energy in space in that closed universe that would cause that closed universe to puff up and not collapse well remarkably that's just what particle theory predicts and Alan Guth is in the audience was the first one to predict it given what we know about particle physics we have every reason to believe that in fact at early times there was a vast energy stored in empty space that caused our universe to expand potentially exponentially in a very short time in fact in a timeframe of a millionth of a billionth of a billionth of a billionth of a second the universe could have expanded by a factor of 10 to the 90th it sounds like science fiction but we don't think it is because it turns out that not only does that in fact explain various general properties of our universe but if you look at that baby picture of the universe that I showed you with those lumps quantum mechanical fluctuations during inflation will produce lumps that look just like the lumps that are seen up there so we have great reason to believe that inflation actually happened but that does just what we need because if you have inflation like blowing up a balloon when it gets very big it looks flat the earth looks flat in Kansas I just flew over it yesterday and so the only closed universe that could survive long enough for life to evolve on this planet is one that looks flat there's inflation so what this tells us is if you wanted to create a universe from nothing in which there was no space now I repeat no particles no radiation no space no time what would the properties that that universe would have it would have the properties just like the properties of the universe we see today now does that tell us it had to happen no it doesn't of course it doesn't but it tells us it's plausible and that to me is an amazing thing there are several eminent biologists in the audience here and they know that it before Darwin life was a miracle every bit of life was specially designed for its environment okay but Darwin showed that it was plausible given genetic variation and natural selection that you could Bruce complete diversity of life on earth without any supernatural shenanigans okay and it was plausible he had Evan some evidence on the basis of what he saw but he didn't know about DNA he didn't know about the details of genetics well we're at that situation now we don't have a quantum theory of gravity but what we know is based on what we know it's plausible you don't need anything supernatural to create everything we see from nothing now some people will say of course that's not nothing because you have no particles no radiation no space no time but where did the laws come from surely for that you need God okay well this is what I just said it turns out the laws of physics we now think may themselves be accidental and to show you that I'm going to show the last slide that requires any thinking okay this is a brief history of the universe brief history of time this is the density of matter in the universe as universe expands it goes down as one over the volume the energy density of empty space remains constant and we live right here when the energy of empty space is about three times the energy density of matter but if you stare at this long enough you go crazy if the particle physicists have in particular because you look at that you say there's something wrong with this picture we live at the only time in the history of the universe when these two numbers are about the same at all earlier times the energy of empty space sorry the energy empty space was much less than the energy of matter at all later times the energy of empty space much greater why do we live 13.8 billion years that Copernicus told us it isn't supposed to be that way there's no no combination of fundamental parameters and physics and particle physics they give 13.8 billion years it shouldn't be special so there's some problem here and physicists have suggested a solution it's quite simple galaxies exist why well let's say the energy of empty space was 50 times bigger then these terms wouldn't cross here they cross there but what time is this this is the time in galaxies first formed but the energy of empty space is gravitationally repulsive if it dominated over the energy of matter before galaxies formed galaxies wouldn't form the repulsive force would beat out the attractive force there'd be no galaxies and the first person to suggest that with Steve Weinberg maybe this is telling us something this has led to what I've called anthropic mania if there are many different universes and let's say the energy empty space is a random quantity it's just no fundamental physical reason that should have any value and it varies and it varies in each one then only those it's not much greater than what we measured a will galaxies form and only then will stars and planets form and only then will astronomers form so the universe is the way it is because they're astronomers here to measure it sounds it sounds very whatever solipsistic to say the least it sounds like a tautology it also sounds religious but it's none of those it's more like natural selection it's like cosmic natural selection we would be amazed to find ourselves living in a universe in which we couldn't live I mean that would be worth writing about okay so it's not too surprising in this case and maybe it's pretty depressing though if it's true because it means this fundamental parameter of the universe is an accident now you see particle physicists have jumped on this because particle physics is way ahead of cosmology because in cosmology there's one number we haven't understood for a long time in particle physics there's many more numbers we haven't understood for much longer we don't know why the gravity is a weak is forced nature we don't know that protons mm I'm sorry and electro and only three generations of elementary particles a lot of things we don't know but particle physicists jumped in the system maybe we don't have to understand anything maybe it's all an accident and then you don't need a theory of everything you just need a theory of anything we have such a theory it's called string theory I'll give you a one-page summary of it one guy says to another just had an awesome idea suppose that all matter energy is made of tiny vibrating strings and the second guy says okay what would that imply the first guy says I don't know so that's that's the history of string theory in the last 40 years the string theory used to be a theory of everything because it we hoped it would give a unique theory of everything but in fact it was realized early on of course that in order to be consistent you need lots of extra dimensions but we don't see those extra dimensions so you have to get rid of them and the standard way is to curl them up and so small you don't see them but each different way of curling up those extra dimensions produces a different three-dimensional universe with different laws of physics which we used to be a problem but every wort in string theory becomes a beauty mark now it's a landscape because now you could imagine maybe 10 to the 500 different universes and they collapse in different ways and the extra dimensions on them for 3 dimension universes some of them form two-dimensional universes but one of them is bound to look like ours and therefore maybe the reason we're in it is because we can be in that one now that is pretty depressing really because it turns physics into environmental science god forbid but in means that there's nothing fundamental and it would be very depressing in fact for people like me who grew up trying to hoping to explain the fundamental laws of physics but it may be true whether we like it or not and if it is you see then when each of these universes comes into being not only do you get space and time and matter and radiation but the laws themselves arise when the universal in every one of these universes there's different laws and all possible laws could reside so now you got no particles no radiation no space no time no laws that's nothing as far as I'm concerned now the final kind of nothing I have to do because my I am wearing this little pin from my late good friend Christopher Hitchens whose birthday was earlier this last was last week and I used to talk to him a lot about physics and he he came up with another argument which I want to present you in last to two or three minutes he point out that nothing is actually heading straight towards us so what does he mean by that well the second thing I want to tell you the first thing is that you are insignificant the second thing is the future is miserable okay those are the two important takeaway lessons here now the reason who is the first person to show the futurism is well well of course was George Orwell long time ago he said to see what is in front of one's nose requires a constant struggle and this is clearly what he meant by it what he meant by it was the fact that in the universe full of energy and empty space it's expanding faster and faster but that means objects bigger than a certain distance away from us are actually moving away from us faster than the speed of light which is allowed in general relativity and because it's accelerating the longer we wait the less we'll see and in fact in a time frame which you can calculate about two trillion years all of the galaxies we can now see except for the ones that bound to us in our local cluster which will collide together all of those other galaxies will disappear and so the rest of the universe is going to disappear not before our very eyes but you can ask yourself what would observers see in the far far future so imagine there'll be stars that main sequence stars can live two trillion years there'll be organic materials water and sunlight and so there the life will evolve and they'll be civilizations that will discover quantum mechanics electromagnetism and general relativity to build telescopes and they'll look out and what will they see with their telescopes the look out and discover the universe we thought we lived in a hundred years ago to look out and see a single galaxy surrounded by an eternal empty space all evidence of the Big Bang will have disappeared all evidence that there was ever a Big Bang will have disappeared but then those stars will die out and the universe will become cold and dark and empty and then as Christopher said the answer to the question why is there something rather nothing is really quite simple just wait there won't be for long and that I think is a really important way to end in a sense because it perfect it demonstrates our cosmic hubris we think we're the pinnacles of evolution that evolution was designed for us in some way but of course it wasn't similarly we think that the universe is the way it is now and it will always be that way in the far future we'll be quite different and so let me conclude science has demonstrated that not only is universe from nothing plausible but I would argue quite likely but more importantly than that what we mean by something and nothing is completely changed from the time the classical philosophers and theologians first raised the issue that's okay changing what we mean by things is called learning it doesn't happen in theology but it happens in scholarship and and that's fine we have learned that that nothing is quite different than we thought and so something and what we've really learned it seems to me is that the real important question is not at why question why questions are meaningless because why questions we don't really mean why when we ask why why questions presume purpose you presume the answer before you ask the question what we really mean is how and everyone knows everyone who says kids knows that you know the infinite number of why questions the only answer is because go to bed okay the really really important question is how because that doesn't presume purpose and the important questions therefore is not why is there something rather nothing but how did the universe evolved and how can we find out and that's what science is continuing it to tell us and I think what I'll show I'll show this brief picture at the end to say to remind you the two lessons I've given you you're insignificant the future is miserable but you should be happy because we are here at this random time in the middle of nowhere and we've been able to discover the history of the universe back to the earliest moments the Big Bang discover four hundred billion galaxies because we have fortunate enough to have evolved within intelligence and so instead of being depressed about a miserable future and being insignificant we should enjoy our brief moment in the Sun thank you very much yep my name is Keith Geddes I'm a college's visiting from UCLA uh-huh um it's not directly on topic but it has to do with the general topic here um Richard talked Dawkins has been advocating for this this coming out movement for atheists uh-huh and myself as a scientist I feel this issue is a bit more difficult as it is our duty to remain unbiased in our research and especially in this country where there is an underlying suspicion by the religious right that atheists and scientists are in some nefarious pact together to conjure up results to support their worldview as a scientist does proclaiming oneself an atheist not undermine our battle for science literacy and education by giving more fuel to the right of an underlying bias or objective of science okay well look I'm sympathetic to some of what you said but if you think about it I think you'll think it's ridicu realize it's ridiculous because if you're a scientist and you came out would you say it's unfair for a scientist to come out as a Catholic for Francis Collins to proclaim his his religious belief for or for a Nobel prize-winning physicist to to proclaim his being proud of being a Christian absolutely not but somehow somehow saying you're an atheist is an offensive thing and in that sense I completely agree with Richard that we should have a society where you you are not penalized for just simply asking the question or saying that the evidence suggests to you you don't see any need for a creator but we don't live in such a society and I was just telling some students today it's rather interesting a study was done by psychologists in Canada in the United States about a year and a half ago if college students and adults asking for trust what groups they trust and atheists were crusted the least actually they're not the least they were right alongside rapists okay so when you live in a society like that what you have to do would have to be people I think who point out that simply asking the question or claiming their their point of view is not evil and unless we're if we're as long as we're afraid to do that because we think it's going to offend people well that will persist it's like being afraid to say during the Suffragette period that women have the right to vote because you know you'll be just the point is we should feel free and as I say in the movie very clearly nothing should be above ridicule ridicule as you've noticed from my lecture is very important satire ridicule or one way of getting people to think and so I think it's very important to point out that nothing is above ridicule if we can ridicule politics and sex we can certainly ridicule religion and we have to you know so I've had this debate with Richard for many years early on and I don't think you have to push in people's faces and in fact when I go on Fox News as I've done when moments when I've been drinking too much ah I point out that and the only thing I could ever get across without being yelled at is you don't have to be an atheist to believe in evolution you certainly don't have to be an atheist of leading the Big Bang because you don't appear cool evidences or a lot of scientists I know we're religious okay but so it's fine to say that I think it's important to point that out because people are being told the opposite people are being told in classrooms all around in churches in particular all around the country that to accept the fact of evolution makes you an atheist so it's really important for us to tell people you don't that's not the case but at the same time it seems to me we have to like you know I my first slide I'm sorry you pushed a button I and this may offend some people in the room but I don't care I was I was disgusted this morning again when I was working out and had to see the preacher in chief had to come and do a inter quote interfaith service here why every time there's a national tragedy do we have to suddenly immediately do that we should come together and mourn and grieve and share our common humanity and try and care for each other but why do we have to do it in prayer it's offensive to me and we should realize it isn't a given and unless some people speak up and say it doesn't have to be a given then it's always going to remain that way okay that's my little speech okay professor Krauss my name is Joni Khan I'm not a scientist and my head is spinning so thank you for that achieve my goal yes but one thought started to form in my mind as you were saying about a trillion years or so from now will no longer have any evidence of what we now know to be true yeah you're gonna throw up now right no no I'm just I'm wondering if if there is however a record a trillion years from now that we knew these things but it's really only hearsay because we no longer can prove it what's the future of the scientific method well look I mean that was my point I think it's subtly what I was trying to suggest is that falsifiable science can lead to false results we are and I've written about this extensively and it's an area of some sense my own research we are we are an embarrassment of riches we are at the point of asking questions in cosmology that that we wouldn't have thought of asking 40 years ago because of the amazing discoveries we made about the universe but it tell it immediately gives the limits of science because we live in one universe again most of us and that means that we're forever limited in the knowledge we have for example if there's a multiverse we may not know about it directly I would argue their inferences you could make that there are many universes without knowing it directly but we are limited by that fact and that means there are limitations to the empirical method because we live in a single universe and it should real should also take away our give us some cosmic humility because if there are things we can't see 102 trillion years from now we should realize that although we have this interesting picture of the universe it all holds together that there may be important observe that we can't see now that are essential that if had we've been smart enough to evolve five billion years earlier may have been observable or maybe a hundred billion years from now may be observable so so we should realize it that we shouldn't assume we know everything and as I say the only thing that the good news is we live in a very special time the only time when we can observational e-verify that we live in a very special time and by that I'm facetious I really mean that we have to realize that there are limitations to empirical science and it could be then in the far future there are some things that are not falsifiable that we say well look you know it walks like a duck and quacks like a duck it's probably a duck but we can't prove it isn't a duck we may just have to accept that fact because we're stuck in one universe yeah thank you professor Krauss Rodrigo Martinez I live in the design world and part of what we try to do is design for serendipity whatever that means and I'm probably thinking about it differently after today's talk something good um so if if I can push you to imagine what whatever version of humans or whatever we are I don't know five thousand ten thousand years from now what do you think are going to be the fields or or areas that influence the thinking of people like you five thousand years from now that that that create this ah this was really unexpected now we know why there was like that where do you think those fields or those areas grain from the great answer to that is I don't know and that's what makes it so neat because I don't know what the what the people are going to be odd about in a year that's why I do science the great thing is that you know what I have to write grant proposals always lie and say what you'll be doing three years in the future but you don't if it's interesting field you don't have the slightest idea and that's what's great nature keeps surprising us and people tell me what's the next big thing I say if I knew I'd be doing it okay so we just have what we need to do is we need to keep on exploring the universe and it will keep on surprising us and my hope is that what people are thinking about in five thousand years is well beyond anything I can imagine and I would be very surprised if that weren't the case but not because of their imagination because the universe if we locked physicists in a room without windows and asked them 10,000 years what the picture of the universe would be you we'd ask a woman physicist and she'd come out and say she'd give a picture and it would be not at all related to the real universe all of us would have been that way we need experiment and observation and if we stop doing that sad ok last question I professor Krauss it's an honor to see you thank you I was I was recently watching that debate where you protested the segregation by sex yeah yeah um yeah you you won yeah you you want to be other people there that many of them didn't think I did but but um you actually the women who were segregated were the maddest of me of anyone that's why that's apparent but um your opponent was arguing that infinity doesn't exist and say you know I said infinity if it know that the other guy said infinity can't exist it's not a physical exactly he was arguing that doesn't exist and you pointed out many situations in which it does and I believe that you said that the sum of an infinite series is negative 1/12 oh yeah yeah yeah now I couldn't find anything about that online so I was wondering email data function what's that it's it is it is a true and ridiculous fact about mathematics like I'd love to give a whole riff on infinity again I wrote about it along the book but this is an amazing fact if you take the series 1 plus 2 Plus 3 plus 4 plus 5 plus 6 to infinity what's the sum well of course it's infinite infinite but math nations can summing an infinite series is very ambiguous so you can divine a set of rules that give that makes self-consistent things that sum that series and and you can do it and there's a whole way of doing it involves anyway and it turns out the self-consistent number assigned to that series is called the Riemann zeta-function of argument of argument minus one I think is that that sum of that series 1 plus 2 Plus 3 plus 4 plus 5 all the way to infinity is minus 1/12 which is an amazing result because no term is negative and every term is bigger than minus 1/12 which shows of course how weird mathematicians are but but the this is not just a matter of academic interest because it turns out to be a central fastest theory it turns out that that's the original string theory had to be in 26 dimensions specifically because you wanted to avoid infinities and you could show that two terms would cancel and give zero if you had this infinite series and it added up to minus 112 so people take these things seriously and it just means that that we need to be able to it just means that we're uncomfortable and being uncomfortable to infinity is a good thing I guess I want to close I think I may have even said it in the Krista Tippett thing I did I remember one of the purposes of science it seems to me is to make us uncomfortable because that requires us to rethink our place in the cosmos that's why science is like art music and literature because it forces us to rethink our place the cosmonaut because it produces technology because it is a tribute to the human intellect and it makes worth being human being human and that's why I'll end thank you very much you

Channel: Harvard University

Views: 126,859

Rating: 4.7754679 out of 5

Keywords: Radcliffe Institute, Harvard University, Lawrence M. Krauss, universe, cosmology, particle physics

Id: vwzbU0bGOdc

Length: 76min 37sec (4597 seconds)

Published: Wed Jul 17 2013

Reddit Comments

[u/markevens]

This is a bit long, but completely mind blowing when he reaches his conclusions. If my auto time-link didn't work, jump to around 12:45 to skip the people talking about stuff that is completely irrelevant.