we need to come with us and so far off message we need to find a way to deal with it and once we've dealt with at publicly it's over. at that point in the book it seems as if it already won the election in their own mind, so i was kind of wondering if those scandals had in a changing numbers. thanks. >> to the question about the state of the campaigns i don't think there is anything that is going to fundamentally change campaigns in the near term. our politics are what we seek. i could throw it back on everybody here who's watching and say >> in the sense we get the kind of campaigns that we ask for. that's not always literally true. but we're a polarized country. we are in a media environment in which anything and everything now somehow seeps in the public domain and often the worst of it or the least important of it becomes as the saying goes catnip for cable. and, you know, and we all obsess on it. it doesn't matter whether it's we in the media or you who are consumers on it. not everybody but a lot of people. it is the nature of the beast right now. and it is not necessarily a very pretty one. but it's going to take -- it's going to take us a lot to move away from that kind of politics and i think that given how polarizing the first 15 months -- or 14 months of the obama administration have been, you know, we're heading into a 2010 cycle that's going to be very tough. as long as political control of house and senate are up for grabs which they seem to be in every election now, politics will take precedence often the ability to come together and cooperate and work together. that's kind of a gloomy answer and i'm sorry. it is what it is right now. it's going to take a lot of effort on the part of a lot of different people and institutions and individuals for that to change. on the issue that you raise about the scandals on the campaign or the difficult moments, let me just talk specifically about the jeremiah wright thing. and i think you make a very good point. in the middle of a campaign, what a campaign -- what a candidate and a campaign worry about is how is this hurting us and if it is, how are we getting out of it? and, you know, larger more important questions about it, you know -- they can answer that later but the first goal is, this is killing us. we got to stop it right away. now, barack obama had the feeling when that happened that he had to deal with it himself. that is not something david pluff or david axlerod could deal with it. the first day it broke, he said i want to go on tv tonight. and they said to him, that's not a good idea. he said yes, it is. the world says sees jeremiah wright tonight, they need to see me as well beginning to answer it. he then said i want to give a speech about race. now, that speech was a very, very good speech. but it was a speech declined with a political problem. now, he was able to elevate the particulars of his relationship with reverend wright into the broader question of race in america. and as a result that speech got a lot of praise. and i think helped pull the -- pull him out of a tailspin. he told us after the election, had i not handled the jeremiah right correctly or well, it could have killed my campaign. and it certainly could have -- even if he had won the nomination it could have been fatal in a general election so he had -- he had to do what he did. but barack obama never wanted to be a racial or a racially based candidate. so much of his appeal was he was a post-racial politician. they had talked about talking about race but there was never a time that he wanted to wade into that subject. he was drawn into it because of jeremiah wright, but it was not something he wanted to dwell on or continue to make part of the campaign. so that was run. let me just say at the end, this festival is terrific. i can't thank all of you enough and the organizers of this. i mean, this is a great weekend for books and book-reading. and i feel honored and privileged to be part of it so thank you very much. [applause] >> thank you. dan will be signing in the maddon media area, 10b. please come by. thank you again for all of you coming out here today. [applause] >> we just saw a panel from book's tv with dan balz's book. booktv continues live coverage of the tucson festival of books sunday at 1:00 pm. >> in his latest book "from eternity to here," researcher sean carroll shares his insight on time and the origins of the universe. the book works in del mar, california, is the host of this book. it lasts about an hour. [applause] >> thanks, lisa. it's great to be here. it's great to be at any independent bookstore in the united states. i'm very, very happy to have these kinds of events. [applause] >> and, you know, i'm also happy but i've stopped being surprised to see a whole bunch of people deciding the best way they can spend their thursday evening is thinking about the beginning of the universe and the origin of time. but i do -- i do need to explain, you know, part of why this particular question is the question we're being asked. at one point, you know, i mentioned to a student that i was thinking about -- as lisa said why time runs forward rather than backwards. and the response was, and after that you will tackle the problem of alphabetical order. [laughter] >> how could it else run? you might have heard of einstein who said time is kind of like space. one of einstein's great intuitions what we think of as space and time which seem completely different to us are, in fact, part of one thing called space time. one four dimensional thing. space is three-dimensional. space where we move and live and he with say it's three-dimensional that there's three different directions. right and left, up and down. to pick a point in space toumd give me three numbers. but if you want to meet somebody -- if you want to meet somebody for coffee or be at a book-reading you need to not only pick out a point in space, you also have to give them the moment in time. so in a very, very trivial, simple way we live in a four dimensional, you know, sles there's three dimensions of space around us and one dimension of time but there is something deeper going on than that because einstein says not only are there four dimensions. not only is time a dimension like space is but the division of four dimensional space time into three dimensions of space and one dimension of time is kind of arbitrary. different people will divide it up different ways. different people will -- moving at different space will decide that space is completely different. that a simultaneous moment many, many light years away is different to one person than another person. what i want to do is not talk about that. what i want to talk about is the fact that nevertheless, despite the fact that einstein made all these great advances and we all think of time and space of two different reflections of the same underlying reality, nobody ever confuses time with space. you might be driving around a neighborhood that you don't understand very well and you might make a left turn where you wanted to take a right turn. no one ever makes a wrong turn into yesterday when they want to go into tomorrow. so time is clearly not exactly the same as space. and so what is it? what is this difference? why do we never have the danger of mixing up time and space in our every day lives? well, there's many different answers depending how deep you want to go. time unlike space has a direction. that if you're floating out in space, really far away from the earth or far away from any other object, you're just floating in your astronaut space suit, you would not be able to tell the difference between up/down, left/right, forwards/backwards. every direction would be equally as good as every other direction. but yesterday and tomorrow would still be different. there's all sorts of ways in which the past is different from the future. space does not have a direction but time has what we call an arrow. there's an arrow pointing from the past to the future. in fact, some people talk about lots of different arrows of time and that's a little bit confusing. there's really one thing going on that gets manifested in many, many different ways. we remember yesterday. we do not remember tomorrow. i hope no one in the room remembers what is going to happen tomorrow. we are born as young people and we grow older. no matter what you might have seen in the curious benjamin button, everyone ages in the same direction. we want to understand this uniformity of experience causes precede effects. we start young and we grow old. we accumulate memory. we have a feeling we pass through time from the past into the future. so we would like to explain that scientifically. there's no arrow of space. there's no direction that points out in space but there is an arrow of time and why is that? well, it all comes down to something that was put together in the early 19th century, over 150 years ago for fundamentally nationalistic reasons. the reason why scientists invented it because the french were annoyed that the british were building better steam industries. the industrial revolution was going on and some of the french scientists were a little bit irked by this. it was asked, how could i possibly build the world's most perfect steam engine? he's very practical. he's not thinking about the origin of the universe or anything like that. he wanted to build an everyone that would give him enough out of fuel. and as you often do in these practical solutions. you start thinking big and the most abstract thing you can do and he figured out exactly how you could have the most efficient engine possible. what he realized is that there's no such thing as a perfectly efficient engine. you can't get all of the energy out of something and put it to useful work. why not? well, he said there's some sort of tendency of things in the universe to wind down. the universe is kind of like a wind-up toy that ticks along and it declines with time and eventually it will stop. so this got codified into a law of nature. the second law of thermodynamic. the first dynamics is the law doesn't change and the third is there's a thing that where it goes up. so that's where the arrow of time comes from is that when you compare the past to the future, the future has more so what is it? the great thing is he was able to invent the concept and tell us it increases without knowing what it meant. it was years later what entropy meant. if you have an office and you neatly stack papers on your desk, they are all organized and they're nice and neat, that is low entropy. that's organized. if you wait around, people come in to your office and they bump into things, you don't try to clean things up, that stack of papers is going to scatter. it's going to become more disorganized. and we say that the entropy has increased. so the entropy is something that measures how messy something is. how disorganized and messy. you know from your every day experience if it's disorderliness is something that goes up left to its own devices. you're not surprised if you start with a nice neat stack of paper or books and they become scattered. you'd be surprised as you spread papers across your desk and this is they come into the room they gently nudge into one neat little pile like that. that is the arrow of time. it's easy to go from stacked and organized to messy. it's hard to go from messy to neatly stacked. so the question is, can we really make this quarterback tatetive? -- quantative and do it scientific. it does done in the late 19th century, in the 1870s. his advantage over his fellow physicists over the today was he believed in atoms. many physicists didn't believe that atoms existed. they said look you're inventing these little things. physics should not talk about unobservable things. and this is a little bit of rhetoric down with the ages. there's this tension between people who want to explain things in the simplest and down if i can't see it i'm not going to believe it's there. but boltsman said if you believe in atoms then they make up everything. atoms are in every single object and we can use the same logic that we use for the pieces of paper neatly stacked and apply them to every object in the universe. we can say that the entropy, the messiness counts the number of ways that we can rearrange the atoms in something. so, for example, if you have a glass of water with an ice cube in it, one manifestation of the arrow of time is that ice cubes melt, right? you start with a warm class of water. you put the ice cube in it and you let it go all by itself. the ice cube will cool off the water around it. 10 minutes later you have a cool glass of water. now, you put a cool glass of water down there, wait 10 minutes it's not going to form an ice cube, okay? all by itself. it never happens. the atoms of time goes this way to melted never backwards. so if this story i'm telling you holds together, entropy increases when the ice cube melts. and boltsman said, look, i had the ice. it's made of atoms, molecules that we have now. he called he them atoms. water is made of atoms but when it's an ice cube, they are different than the water. there's some separation. there's some degree of organization there. whereas, when the ice cube has melted, all of the atoms in that glass of water are more or less created equally. and what that means is there's more ways that i could rearrange the atoms so that you wouldn't notice, okay? the atoms are so small that i can't tell the exact position of every single atom are on the exact temperature of every single atom in the glass of water so i measure some things about it. i measure how cold it is. the temperature at different points in the glass of water and there's more ways to rearrange things when the entropy is high than when the entropy is low. and the brilliant thing is this understanding of entropy extends to every single way in which the past is different from the future. and this is -- this is an astonishing but true fact that is not really controversial, okay? if you sit down and think about all the different ways in which the past is different from the future, it's all due to the fact that in the past, things were organized and as things go forward in time, they become more disorganized. so you might ask well, what about memory? you said that i remembered yesterday and i don't remember tomorrow. what does that have with atoms and organization and entropy and things like that? well, consider walking down the street and you find egg splatterd, okay? a broken egg on the sidewalk just sitting there and you can ask yourself, what can i tell about the future behavior of that egg? what's going to happen to that egg over the next 24 hours? in the real world? well, it might just sit there. it might grow moldy. it might rain and the egg washes away. a dog might come by and lick up the liquid or things like that. it's hard to predict a splatterd egg on the sidewalk. but now you ask yourself, all right, what was the egg doing 24 hours ago? what was it doing in the past? and the answer is, well, if it looks like a freshly broken egg, then 24 hours ago there was an unbroken egg. that's it. that's the only choice. there was not a dog that sort of spat out the egg or anything like that. there's only a very small number of things that could have happened in the past and so that egg went from being low entropy, organized, there's a egg, shell and egg white to medium entropy let's say, broken on the sidewalk and it will increase in entropy toward the future. so the point is that knowing that entropy goes on is what allows us to make inferences about what happened in the past. towards the future, given the egg, lots of things could happen, why? well, because things are going to become messier and messier. there's a lot of ways that can happen. toward the past, that egg was clean. it was organized. it was unbroken. why do we know that? because we assume that from the beginning of time, entropy was very, very low. and here's where the great assumption comes in that even physicists haven't quite internalized. they haven't quite accepted it. but again it's one of those things where it's not really able to be argued with. it's a true statement that not a lot of people have thought about carefully enough to really buy into. the statement is that ideas like boltsman's, the definition of entropy where i can rearrange a constituency of a system so that you won't notice, that is very, very helpful if we want to tell you why the entropy will be higher tomorrow than it is today. given the universe today, there are more ways to be high entropy than low entropy. so there's more ways to be messy. so if we just take the universe, an egg, might mild model a whole egg. it's easy to scramble the egg and make it more organized. doing from what the universe is doing today, it becomes messier. it makes sense the house bowlsman derived equations starting today how the entropy of the universe will change over time. the underlying laws of atoms and physics that is handed down by newton, they don't have an arrow of time. if you don't think about messy things like eggs and water and your memory or anything like that -- if you think about two particles at a time, two billiard balls bouncing into each other, the billiard balls hit each other and go in a different direction and that whole process is absolutely reversible. there's nothing that could tell the difference between the balls that have not scattered and now the balls have scattered. so let me put it this way. if there's two billiard balls on the table we ignore friction and noise and all those things, and i make a movie, balls hit each other, they scatter off, i play you the movie backwards. you would not know. if i think of the moon orbiting around the moon or the earth moving around the sun, if i make a movie on that, i play it for you backwards, you would not know. if i have an egg breaking and turning into scrambled eggs and make a movie of it and play it backwards, yeah, you know, okay. you can tell. so this arrow of time that exists in our microscopic world by playing a movies playing backwards you can tell, it doesn't exist at the microscopic level. it doesn't exist at the level of individual atoms or two or three atoms. it only exists when you have billions and billions of atoms together. so what we need to be able to do is to derive the behavior of entropy, which has an arrow of time, entropy increases from these underlying laws. that's what physicists like to do. they like to start with the basics. they can derive things. if you say the atoms -- the air in this room is made of atoms, with certain properties, i can derive the pressure, the temperature, what would happen if i added more air to the room and so forth. i can derive the fact that starting with ice cube in the glass, forward in time, the ice cube will melt. why. ? well, there's a lot more ways to be melted. what i can't derive given a glass of cold water, 10 minutes ago was there an ice cube in it or not? there's no way starting from the rules of atoms which work equally well backwards and forwards to derive the fact that the entropy was lower yesterday. i can derive the fact of the entropy of the universe will be higher tomorrow. that's the arrow of time. that makes sense but we don't think just that entry will increase starting now into the future. we think it was smaller yesterday. and there's no way to get that out of the fundamental laws of physics. and boltsman kind of knew this. he really tried. he tried to deny it. he tried to prove theorems. he wrote papers saying, no, i can show entropy must increase in the future. and his friends said what do you mean by the future. the rules of physics work equally well. you're cheating. you're putting some ingredient in there if you try to derive an arrow of time from rules that don't have any such arrow. he eventually admitted that this was true and so what is the answer. we know what the answer is. we know that starting today with the entropy we have it will be bigger tomorrow, if that makes sense. the question is why was it smaller yesterday? why was the universe more orderly yesterday than it is today? why is the entropy lower? the answer is that the entropy was even lower the day before yesterday. i hope you find that very satisfying. [laughter] >> some of you might say well, why was the entropy even lower the day before yesterday but i have an answer for that, too. it was even lower the day before the day before yesterday. and the point is that number one this is the best answer we have. i'm not going to be able to tell you, you know, we can do better than that. that was the right answer. why was the entropy lower than the day before that. number two the law of reasoning keeps going throughout the history of the observable universe. so boltsman in the 1870s didn't know about something called the big bang, okay? now we know that we live in a universe where we look outside and we see other galaxies. we live in a galaxy with 100 billion stars in our observable universe there are about 100 billion galaxies and the whole thing is expanding from something called the big bang about 14 billion years ago. so you only need to know one number if you want to think about how big the universe is. the number is $100 billion. 100 billion stars and 100 billion galaxies in the universe. therefore we have a beginning. 14 billion years ago all of the stuff we see in the universe was sitting on top of each other. everything was smooshed together in incredibly high state, hot, densed background packed. so that's where the story begins or ends however you want to say it. boltsman can explain why entropy is increasing but only if you start in a universe that is very, very low entropy. so again every manifestation of the arrow of time, everything that happens towards the future that is different from the past is because entropy is increasing. entropy is a measure of the disorderliness of the universe. it's been increasing because it started low. so this is an amazing, remarkable fact about our universe. that the big bang 14 billion years ago was not messy and chaotic. it was incredibly orderly. the universe started in a very, very, very specific unlikely configuration of atoms and parts of photons and those kinds of things. and cosmologists people who study the stars have a question. why did the early universe start in an orderly arrangement? once that starts we can discover anything. here on earth you might have talked to creationists. if you're in my business you have to talk to creationists sometimes. people who say well, evolution -- we think the earth started in a fairly chaotic state and we have all this complicate stuff, complicated organisms processing information. doesn't that violate the second law of thermodynamics. isn't that increasing order? but the point is that we have a tremendous amount of entropy that we're increasing the whole universe by. it's just that we gain -- we lose entropy here on earth. we make things more organized by increasing the entropy for the rest of the universe. what happens is we get light from the sun. and we radiate light back in the, you know, we radiate some from the sun. we keep a little bit of the energy we get from the sun but for every one photon, for every one particle of light that we get from the sun we radiate 20 photons back in the universe. each photon has 1/20th of the energy so we give the same amount of energy that we get back. but along the way we increase the entropy of that light by a tremendous amount. by a factor of 20. so we're the tiny little decrease in entropy that represents us here on earth is nothing compared to the tremendous increase of entropy that we've created in the universe and it goes back to the big bang so everything i said so far is true and you're not allowed to disagree. but now of we don't know what we're talking about. now we reached questions that we don't know the answer. 14 billion years ago had a low entropy, that's true. why did have it a low entropy. why was it like that. remember the entropy is telling us the number of ways we can arrange things without telling the difference. if the entropy is very, very low that means you're in an order, delicate precisely chosen configuration of stuff. that was our early universe. now, you could say it was just like that. that's absolutely possible. a lot of cosmologists will come around telling you that a lot of the big bang was the beginning of everything. that there's no such things the day before the big bang. that asking before what happened of the big bang what happened north of the north pole and. -- and it's not something that it's on the basis of what we understand. it's just a guess. really what the big bang is, is a place marker where our knowledge gives out. for where we don't know what happened. the big bang is not the beginning of the universe universe necessarily. it's the end of our knowledge. it is possible that the big bang really was the first moment in the history of the universe. there was nothing before that. it's also possible the big bang is a fades. it's like being a teenager. it's something you go through and there was something before that and there's something after. in fact, i would claim that if you want to explain the arrow of time, which means explaining the low entropy of the early universe, explaining how you're universe began our best bet is to imagine that the big bang was not to given. after all we see eggs in the universe, right? eggs tend to break and scramble and get messier but nevertheless when we open the refrigerator we are not surprised to find an egg. why not? because the egg is not all by itself isolated in the universe. it came out of a chicken. the chicken helped create the egg. the egg is not just the entire system. it's not a closed system. it's not isolated. so if you want to ask the same questions about the universe, why did the universe start? why was it found in such a low entropy state, one possible answer is it came out of a universal chicken. [laughter] >> which we call the multiverse. so there's an idea -- here's the following idea. imagine that there was space in time before our universe came into existence. but unlike our universe, like something that started low entropy finely tuned hot dense big bang, this universe was big space. it was quiet. there was nothing going on. the thing is recent discoveries in cosmology convince us even empty space is not completely quiet, okay? that's because we've recently discovered that the universe is not only expanding it's accelerating. you may have heard this. back in 1998 we still call that recently by scientific history terms. what we found if you look at a galaxy, galaxies are moving away. what we guessed back in the '90s when i was a kid learning cosmology that galaxies are moving away but they're pulling hooper all these hundred billion galaxies are exerting a gravitational pull. so even though they're moving apart, we should be moving apart ever so slowly. so there should be a deceleration in the universe. there were two teens that decided to go measure the desell ration. you know, with of them, in fact, named their collaboration the high registertive supernova team measuring the desell ration of the universe. imagine their embarrassment when what they measured was that the universe is accelerating. so if you look at a galaxy it's moving away from you. you measure its velocity and you come back a billion years later. you measure the velocity to the same galaxy it will be moving away from you faster. so the galaxies are not only moving away they're accelerating away from us. this is the most important experimental discovery in cosmology since the 1960s at the very least. we're still trying to make sense of it but we have a favorite idea. and the favorite idea is that empty space itself has energy. einstein says that if you have energy then you curve space in time. and empty space -- if it has energy, the thing is that energy doesn't go away, it's intrinsic and inherent in empty space itself. space itself, every cubic centimeter, you empty it out so there's nothing there. there's no matter. there's no radiation. there's nothing going on. an empty cubic centimeter you can still ask yourself how much energy is in that empty cubic centimeter of space? and according to einstein the answer is not necessarily zero. the answer is some number that we need to measure. some parameter. some part of the laws of physics. and if the answer is not zero,ñ if there's some positive energy in empty space, that imparts a perpetual impulse to the expansion of the universe. so the reason why we see a galaxy accelerating away from us because as it moves away from us there are more and more centimeters between us and that galaxy. and there's more and more push on space itself so we see the galaxy fly away from us. that's great. it helps cosmologists a lot and explanations that we make about the universe. but it might also help explain where our universe came from and provide a bonus explanation for the arrow of time. here's the sketch of this idea. and now this is totally speculation land so i don't want you to completely believe this. but this is the kind of direction in which we need to go to try to explain what the universe should be like. if we didn't have the big bang. if we just had empty space -- we had this preexisting space time, the idea is that even empty space has some energy. and what one of the things that steven hawking figured out is that if empty space has energy, it has a temperature. if you put a thermometer in empty space it would occasionally detect a little bit of radiation. very, very cold. and if you even calculate what it is, it's 10 to the minus 30 times as cold as the universe it is today. the universe today is pretty cold, right? the universe is only 1% of the temperature of us here in the room. if you went out in the middle of the empty space. it's cold out there. no one can hear you scream. if you wait long enough. if you wait for the universe to empty out and nothing is going to on it would be much, much colder but it will not be zero. the universe will never be absolutely quiet. so keep that in mind. and add to that to the idea of quantum mechanics. it says if you have a subatomic particle like an electron, the right question to ask is not where is the electron. there's no such thing as where is the electron. what is there is is -- if i look for the electron, what's the chance i will see it here versus what's the chance i will see it there? there is probabilities. there's no absolute answer to where will the electron be. there are different chances you will see it in different places. you can't pin down an elementary particle to one absolutely precise location in the universe. that's the lesson of quantitiom mechanics. so apply that idea to the universe. you can't pin down the universe to one absolute configuration of space and time itself. there's bubbling. there's sort of fluctuations. things happen. very, very rarely. but you might wait a long time and after all, we're assuming that you're an empty space and nothing is happening. you have infinitely long to wait. space with just a little bit of energy, these quantum fluctuations going on, very rarely but every once in a while one of these fluctuations will make a new universe. you will function a universe that will peer off and you make a baby universe. it's easier to make small baby universes than make big ones. you can imagine small baby universes require less of an unlikely fluctuation than having a billion year light year across. you make this little tiny bubble of space time and guess what? it expands. and the best way to make it expand is if it has this energy in it that doesn't go away. this dark energy stuff that makes it expand more and more and that happens and if you wait long enough, that dark energy decays just like an ice cube melts. an ice cube goes from being solid to liquid. it can go from being dark energy to matter and radiation. and there's a lot of energy there and matter and radiation really, really hot, really, really the same in different places in the universe. so what does this sound like? it sounds like our universe. it sounds like the big bang. sort of in other words, putting it all together we have empty space. fluctuations because of quantum mechanics that we absolutely can't get rid of. it's a prediction of the theory. occasionally these fluctuations make a new universe. this new universe starts hot and dense and smooth and grows up and cools off and becomes empty space itself. and lasts that way forever. but it doesn't just happen once. it happens again and again. so in other words, the universe, which we started off empty space nothing going on can't sit there forever quietly. there is no way to keep the universe well behaved all by itself. it's just an implication of quantum mechanics. it keeps making new universes and the way it makes small universes is small and hot and dense like ours is. the idea is that we are aibaby universe of some quiet unassuming universe that came before. to really put this in perspective, though, that's what happens if you start with this empty space, this protouniverse and let it move forward in time but you can ask well, what happens if you let it move backward in time. where did it come from? the answer is because the underlying laws of physics are completely symmetric they don't know the difference between the past and the future exactly the same story happens toward the past. you make more universes -- more and more universes as you go to t equals minus infinity. the infinitely far past but those new universes have an arrow in time pointing in the opposite direction. so if time runs this way, you start with a nice quiet universe. you bubble off more universes that have an arrow of time pointing that way but you bubble off more universes that have an air of time pointing that way. the whole shebang is completely symmetric. there's no overall direction of time that you put in by hand. it arose naturally out of the laws of physics. that's fun and interesting to think about. how would we ever know and why should we care? these are legitimate questions to ask and i know if you let you ask them you'll think i'm hiding it. i'll tell you why we should care. i don't know how to test an idea like this. what i'm proposing is most of the universe is empty space. nothing going on except these tiny fluctuations. every now and then you make a new baby universe with an arrow of time that expands and cools. but how would we know if there was a preexisting universe. if there were other baby universes that are our siblings in the multiverse. we have no way right now of answering that way. i don't know how to tell you that we would know. but i'll tell you two things. number one, it is possible that without observing other universes directly we will nevertheless put together the laws of physics well enough that we can absolutely with confidence say that they must be there. if we understand the laws of physics well enough based on experiments that we can do, and those laws of physics predict the existence of other universes then we should take that prediction seriously. we're not there yet but we could imagine getting there. and the second thing is, we might be able to make a prediction about our universe based on a scenario like this. we might some day improve the state-of-the-art so much that we can say there's a slight remnant in the sky of this era before that big bang. in fact, there are hints. i don't want to make too much of this. it's probably nothing. but when we look at the real sky, it doesn't look exactly like we think it should. there's sort of vague hints that maybe there's a remnant from an era before the era we think we understand. however, we're not there yet. i don't want to make too much of it. science doesn't know everything yet. otherwise, it would stop, okay? we have work still to do. what amazes me is that putting believe story together starts with an ice cube in a glass of water. we want to understand why ice cubes melt and don't unmelt. we want to understand why you can take eggs and make scrambled eggs. you can't take scrambled eggs and make an egg. and the logic of trying to understand how it works leads us to believe in a multiverse. i'd be very, very happy if we came up with an explanation that was multiuniverse one that's tangible and easy to touch. we're not there yet. this is the best example to have. this is a great lesson that we are part of the eisen verse. that we are not separate from the laws of nature and all the stuff around us. that the features that we enjoy being in this room living our every day lives depend on things that happened 14 billion years ago. once we understand it better, give us two or three years, we'll get it all figured how the [laughter] >> we'll be able to put the entire story together and make more predictions and learn more about the laws of nature. thank you. [applause] >> so i'm going to take few questions and we can't take too long and i'll start signing books. you need to wait for the giant gizmo to come by. >> bear with me, we've got entropy. we've got time, right. you can measure that. >> yes. >> as we know with the experiment with the atomic clock that was put in the plane, that affects time. >> yes. >> does entropy also get affected so that you can either measure the decrease for increase of entropy because of speed or something -- >> no, that's a great question. if i had had five hours to talk instead of 45 minutes, one of the things i would have told you about is time dilation. the idea -- forgetting about the arrow of time. even before we worry about entropy in the arrow of time we measure time. and the way we measure time is using clocks. and the real reason einstein went through all that rigamarole because clocks moving in different ways can end up reading different amounts of an elapsed time, if a clock sits here stationary and i take another clock that is initially synchronized and i send it out close to the speed of light and come back it will experience less time than the clock that stayed behind. so what does that say about entropy? the short answer is nothing. and the reason why is because the second law of thermodynamics, the law that governs the law of entropy says entropy never goes down. okay. the entropy of a closed system, one that is isolated from the rest of the world either goes up or remains constant. but it says absolutely nothing about the rate at which entropy changes. so, unfortunately, entropy is something that can remain very constant and then go up suddenly. there's to simple rule for telling you how fast entropy changes so, therefore, i can't tell you from the rate at which clocks particular. -- tick. yes. >> instead of acceleration there's a big crunch, what happens to entropy at the point where the crutch comes to a single point. >> that's a great question. back in my day, it was very, very common to imagine that the expansion of the universe was just temporary. at some point it might be possible -- people weren't dogmatic about it. they thought the universe would expand, stop and recontract. now you notice in other universe as we observe it today, the universe is getting bigger and the entropy is going up. so you begin to wonder is that a necessary connection? if the universe began to recollapse would entropy go down again? the simple way of thinking about thinking of ways there's no reason for the entropy to start going down again. the universe can continue to become lumpier and smooth out. just because the universe starts contracting means omelets start turning into eggs. however, we might not know everything. after all we do have this weird thing at the big bang the entropy was low. whatever unknown explanation we need for that fact implies that if there was a big crutch it would also have a low entropy. in fact, steven hawking wrote a paper he said if the entropy collapsed it will go down again. he said it was his greatest blunder to be a great blunder. hawking predicted that the entropy would decrease. he realized that was just a mistake. number one we don't think the universe is collapsed but if it did there's no reason to think entropy would go down. >> how urgent -- how much time pressure do you feel to figure out what's going on with this faint glow of the distant past? when will that information be lost to civilizations like ours. >> that's a great question. the universe is changing and not constant and the evidence we have with what's going on in the past in the universe in some sense becomes less accessible to us. personally i'm worried about, you know, nuclear proliferation or global warming more than i am about the microwave background disappearing from our telescopes. but it could happen. so one way to conceptualize it is what will the future of the universe -- what will play out? we live in a galaxy with 100 billion stars. those stars burn fuel. they start low entropy. they increase in entropy by burning their fuel. eventually they'll burn out. we live in the galaxy where it has a black hole a million times the mass of the sun but that's not compared to the whole galaxy but if you wait long enough every star will spiral in and become part of that black hole. and then if you wait long enough, that black hole will evaporate. and there'll be nothing left. so how many years is it between now and nothing left? one google. the good old fashion sense of the google, not the search engine. 100 years from now we're going to be an empty space. that's sort of the point at which it's hard to make much sense of the universe anymore. the universe is only 10 to the 10 years old so don't change your portfolio on the basis of this. yes. >> this is a question about explanatory methodology. >> yeah. >> i was pretty cool with the thermodynamic explanation, the low entropy state get the uniformed distribution and you get this beautiful explanation of all these thermodynamic things but i wonder whether the explanatory edge you want to scratch after that is really, you know, worth the price? you get all this speculative stuff happening and it just curse to me well, look, every theory has its primitives. you know, you can wonder why is the speed of light exactly what it is rather than a slightly different number. all explanations have together stop. i mean, why do you think -- what's moving you in thinking that the -- why the initial state being that state is an itch you got to scratch rather than just saying, hey, it's just the initial condition? >> well, that's another very good question. you guys are well prepped here. in fact, i alluded to the existence of that question. the question says who says i need to come up with an explanation the fact that 14 billion years ago the universe was in a low entropy state. maybe it's a brute fact i need to accept. right now with the current state of our knowledge i cannot say that might not be true. that might absolutely be true. however, there's no -- there's no reason why the universe sort of had to be like that for our existence, for example. i mean, we live in a universe with 100 billion galaxies in it. we don't need 100 billion galaxies in it. we could have said our flax. you could -- gloks. -- galaxy. what i'm saying is yet in other words not only is the universe in early times in a very finely tuned state it's in a much more finely tuned state and there's any reason for it to be. that might be just a fact. or it might be a clue. until we know, we should spend some fraction of our intellectual effort acting as if it is a clue and trying to come up with a better explanation. ultimately if we fail, if we find that we can't learn anything by pursuing that clue, then we'll just say well, that's one of the facts we have to accept about the universe. let's go over here. yes. >> what do you think about people that are psychic? where they're -- where they genuinely have psychic experiences, and i'm one of them who's had them. >> the question is what do i think about genuine psychic experiences. i'm skeptical on that. i'm a hardcore materialist who believes in atoms and the standard model of particle physics and within that paradigm i can sort of show within those rules there can't be psychic experiences. now, logically speaking it's absolutely possible mhat paradigm is incomplete and there are things about the universe that we don't and understand that is true. i don't see on the evidence that i have access to, to make that leap. i think there's a much more -- there's easier ways to understand the things i observe in the universe than that. yes. >> thank you for your wisdom. i wish i had lecturers like you when i was in college. [laughter] >> all right. here's my conundrum. he with measure a lot of things with respect to time. time is on the independent variable. i think of time as the independent variable. in your theory is time an independent variable? >> the question is isn't time just a label in some sense? isn't an independent variable that goes from wherever its starting point to wherever its ending point is versus something that depends on other things. i think that in some sense most physicists are what philosophers call eternalists. they think the whole four dimensional universe including the past and future is just as real. every event in space time is just as actual as every other event. we exist in a succession of moments where we have the passage of time even though i don't know what the future is it's just as real as the past. and i buy into that. that's the traditional thing that most physicists don't believe. i think the simplest way to think of the universe is think of the whole thing as there. i don't have access to it. so both space and time are just labels of different points that are events in the universe. [inaudible] >> it can be thought of as an independent variable is the short answer. i have time for one more question and they're in the back so yes. >> i know you said you didn't want to make a big deal but i haven't heard before and i wasn't sure that i understood. are you saying that we can see in our current sky sort of into this parent universe? is that it? what is it that you're seeing. >> despite my explicit discussion are there hints in what we see in the universe that could be traced to a preexisting phase that the universe was in? the answer is there seemed to be hints. so, you know, the big bang happened 14 billion years ago. everything was on top of everything else. the universe was not only dense it was hot. it was giving off radiation. and it was opaque and you wouldn't be able to see your hand in front of your face but 400,000 years after the big bang it cooled off the universe became transparent. now light can through it and that light travels unimpeded throughout the universe and we see it today. it's microwave, that's the wavelength that it's in. and that's the cosmic background radiation and we look all over the sky and it's there in every direction looking more or less the same in every direction reflecting the fact that the universe is basically uniformed. but it's not perfectly uniformed. there's slight deviations of the temperature of the microwave background from point to point. so what patterns do you see in those deviations of temperature. to a good approximation they're radiation. there's fluctuation here and there. however, there are hints that the fluctuations in temperature from place to place are a little bit bigger in that direction than in that direction. there seems to be an asymmetry in sky in one direction of space than the other direction. the question is is this real? is it a statistical fluctuation? does it represent something that we're trying to explain and i and some of me colleagues said maybe this slope in the universe, this slight gradient from place to place across everything we observed is a remnant of what happened before the annual of the universe that we can actually observe. the amazing thing about that hypothesis is, it's really hard to make it work. you know, you think it's so vague that it must be possible possible to at least write down some equations and make that work. what happens is once you put that little slope in the universe it shows up elsewhere and you can start ruling it out. so right now i don't think that this difference between one side of the sky and the other is telling us something us something concrete before about what happened. we're trying to decide which anomalies are flukes, which are mistakes in the experiment and which are crucial clues that will lead us to something better and hopefully it will sort something out. better experiments, smarter theories, harder working graduate students weilfigure it out. thank you very much. [applause] >> sean carroll is a senior physics research assistant at the california institute of technology. he's the author of "space, time and geometry: an introduction to general relatively." for more information visit preposterousuniverse.com. >> john nickols and robert chesney in urban a champagne says commercial journalism is ending and a new era of journalism that is partisan and subsidized by the government must emerge. the national press club in theor and 50-minute event. >> before john comes up i did want to thank all of our cosponsors for their help in promoting tonight's event so thanks to the "nation" magazine to unity journalists of color and the national associations of black journalists and the national associations of journalists and fire dog lake and i want to give a special thanks to folks at c-span for being here to film tonight for booktv so thanks so much for that. when i first got to know bob and john i was an editor at a small magazine in chicago. i went to journalism school and suddenly i discovered these books that had something to say about independent journalism and about the structure of the media. and i liked it so much that i started getting myself booked on panels around chicago, you know, basically giving the bob mcchesney and john nichols rap which i guess was sort of a harbinger of my future at free press. and i was at an event and there were a bunch of independent journalists there and i started going into the history of the media. and in walked in the back of the room john nichols who kind of came up and whispered saying i think you're giving my speech. this time i'm going to let him give his speech himself and turn over the mic to john. >> thank you. [applause] >> thanks, craig. and the great tragedy of trying to get people talking about issues is that eventually they start to do it and they do it better than you do. so i'm very honored to besd anplatform with greg aaron who is a far better spokesman than i will be on these issues. i want to give a special additional shoutout at folks at unity. for a reason that they know but many of the other people in the room may not. their pressure over the years for an accounting of hiring within newspapers to make sure that there really is not just to talk about diversity but a reality of that has provide