Book festival with my colleague. We want to welcome you all as you come in for this wonderful final panel of the day. This has been a week of events and special programming and all of you are having a literary fest with us and we are glad you are here. This is the 12 annual brooklyn book festival and thank you for coming. The final panel of the day is going titsgoing to be on the mf time, and i wish i could stay. Dont take it badly if i dont. But the really think all of our offers, i want you to show them some love, by their book and enjoy the rest of the festival. Thank you so much for coming. [applause] good afternoon, everyone. I am the moderator and ive been asked to make this clear to you that the books by the authors will be available for purchase in the lobby at the end of the event and immediately following the program they will be signing their books at the signing tables and in the lobby. So my name is oliver and im a columnist at the guardian [inaudible] and im excited about the panel that we have today. We couldnt ask for a more interesting set of people to talk about their topics as the ones we are going to try, completely sold out in all respects for the next 15 minutes. Its interesting to me, probably not anybody else on the planet [inaudible] [applause] its one of those reminders of how science functions ecologically i can be the same person that was born years ago but every part of me psychologically has changed since then. Why is it the last few years seem to have gone by about ten times the speed of these years when i was a teenager. Time is such a precious resource, why do i waste so much on twitter. But the main point of this is [inaudible] its valuable to have people on the stage but we quickly introduce in alphabetical order alan burdick, stockbroker and an author of the new book by tying flies. Hes a historian of science and books include the philosopher, he wrote among other things black hole blues about the gravitational wave and the philosopher jim holt wrote the book why does the world exist among other things. I will kick this off with a few questions. For me one of the things that is fascinating about the topic is the way that tim is such a ubiquitous daily source of stress and we always beat ourselves up for using time wrong. At the same time it is such a huge controversial and scientific mystery. When you ask what time really is, its really hard to answer that question. We think about th of time as ife space, market on a calendar, as if it were money but it is in its own terms just it leaves you a little lightheaded. So we are finally going to solve this mystery today. I wonder if i can talk to you first, janna levin. Im going to ask anyone to interrupt, especially me but at the start by asking you if you could give us just a sense of where physicists are now with the understanding of time, because you read this thing and people have had this notion that somehow it is an illusion or maybe everything is happening at the same time like the Peloponnesian War and the impeachment next year. [laughter] there is an anecdote i guess wrong. Im not sure about the history that there is the same time is what keeps everything from happening at once. And i think john wheeler said it but then i heard from the ambassador so im not sure if he read it on the bathroom wall or if it was after he transcribed. But there are things articulator and the sense that we do know to be true that are measurable and real and scientifically confirmed, like time is relative, it is not an absolute. We used to believe that tim was just like this backdrop, a stage against which all of the universe and the universe occur buoccurbut we know that isnt t. If you are closer to the earth versus further away, you will experience the passage of time differently. You will compare clocks with those of the space station and they will not match. They will be off by your tiny bit but they wont match. Its where you are in the universe if you are near massive objects, traveling relative to other objects very quickly gossip about you believe the time is already very spectacular. Spectacular and true. But then there are other aspects that are still under investigation. Whether or not tying continues to exist in the past after it unfolded and is in the future there as you described and we are just rolling through it like a bowl down a hill. That is controversial. And whether, you know, id like to say its like it rolls up like a carpet behind us and it doesnt exist anymore or in the future. These are things we dont know and we argued about and it might be crucial to understand in a lot of the physics, so they are still under debate. One more question, the relativity of time what you think it is counterintuitive . If we are drifting in space and i feel that i am still yet you are still and we are moving relative to each other and i hear its constantly getting out of sync so why shouldnt the same thing be true now . Its generally true now. It is intuitive if you are posteinstein and he teaches it to you. Heres the spectacular thing we are very confused by all the distractions. There does seem to be a frame of reference like this table or the arrest or whatever. If i imagine an astronaut and i have the foresight to remove everything distracted, then it becomes intuitive. If you are an astronaut floating into space, there is no frame of reference. I see another astronaut in the speed of light he looks like hes aging very slowly relative to the biological norms and the clock is ticking very slowly but from his perspective i am moving by the speed of light and im the one aging slowly and there is zero physical experiment in either of us can perform to dispute or verify which one is actually moving. There is no physical meaning to it. So there is a beautiful aspect of the round elephant being a valuable simplification in physics and in this case the truth of everything else. I hope that wasnt longwinded. [laughter] im not sure that im there with the idea that even the possibility for things that have already happened are still there. Behind me its still there even though im not occupying that space. So, time is peculiar because unlike space, i can go back behind the later today but i cant go back to 3 p. M. We dont know why time is different in that particular way. I cant make an accidental turn into yesterday. I think i stole that from sean carroll. And so, we dont know why its different because in many respects, tim looks just like a spatial dimension mathematically. And so, it is peculiar that it insists. One possibility or at least historically one possibility is that you wrote in many of your books theres always been a strong were some resistance from some waves of philosophy to the thought that this whole frame of looking up time. You write in the book about a very important debate between einstein and the philosopher and i wonder if you can just briefly summarize what that was about . I can try. It is more of the discussion from the question of what is time to who is authorized to speak about what is time so in that sense i think it is going back to the sources and elucidate quite a bit. So the debate between the french philosopher who was more famous than einstein at the time and actually met einstein one day on april 6, 1922. It was a dream defined as a historian for me to find this document, where i knew obviously einstein who he was com, and i w who henry bergson was because i was a historian of the 19th century, and solve them together in this same room on the same day debate about the nature of time. And it was a day that had echoes for the rest of the century and that really came to represent the divide that you talk about between the way of telling time and movies, cinema, literature, poetry in a scientific way of telling time. Its a book where i dont take sides and its about the divided 21st century and about the division between science and the humanities and the rights of the authorities of science. The people, the person embodied in the einstein who can talk about time and tell us what time actually is. I think if we go on with the conversation, i dont want to take everybodys time. [laughter] and then perhaps i can say a little bit more about the specifics. The idea of time flowing is very important and something that has no role at all in the conceptual world. Absolutely. Its generally the psychological time, so bergson as the person that tells why time flows differently if you are doing something boring it seems to go slow. And einstein is generally described as time is with clocks measure but this is a bit simplistic and both men come a bergson used his claws and einstein in his personal correspondence repeatedly talked about how time works for him so we need to go beyond this division between the two men to see how they talk about it. But the gist of it is disputing this idea that time is like space and that there was no privileged frame of reference. So even if bergson agreed that you couldnt have an experimentt that would help you distinguish these references see what to say that it was a privileged frame of reference for the time being and considering that and the same level as the astronaut to fly as close to the speed of light. Its a science fiction. And this was one of the reasons why he seemed to lose the debates against einstein. That is a common interpretation because indeed of the critics, he didnt understand the science of the relativity. It was einstein who didnt understand him. For me, the moment when time goes from something in physics to being something psychological is like in the century he basically says time is strictly in the mind. Before then, theyd all been kind of wrapping themselves up into knots to find out how long is it. Is it like this big or that big and if it has a duration, you should be able to slice it into his mauler durations but then if its a series, whats going on in between, how do you get them and you just sort of forget all that and he just wants to deal and offers a great example of him speaking out loud saying there is a series of syllables that come out one after another. He says i kno know that one syle is longer than the next. But how do i know that and when am i getting that measurement . I cant be measuring two of them at the same time because im only measuring one of them. Okay, well we talk about the the passing of the present and future buthefuture but they aree thing. Theres the persons experience of memory of what we just said, and the present experience of the future of what we are about to say and what we are saying right now. So every moment basically you are stretched between the memory of what you said and the anticipation of what youre going to say. And he says it is just amazing. Time is nothing other than tension. He means the tension between stretched out and i wouldnt be surprised if its not the catching of consciousness. Hes basically a quaking time and the experience of now which for a lot of us i this is what e mean by consciousness. I just wonder in these psychological definitions if you think the universe requires us to exist to have a sense in the package of time. Here a few hundred thousand years ago would be very unlikely and unlikely we will be in a few hundred thousand years. So does the universe continue to move in time or a psychological definition based on consciousness which probably emerged from a process in a certain way . Psychologists are sort of kicking the can down the road saying we are not even mike talking about the time, all we are talking about is our perception of time. And the perception of time as a whole series of perceptions if you are understanding how long the duration is in the sense of before and after so with all thosits allthose things that ko into this. One of the things that we do in our own experience to sort of see what happens when you take away the sort of rhythm of life are we talking about two completely Different Things like this is a panel of safety and the history of australian cookery. [laughter] they are just unrelated things. Sure, to a certain degree. I think where id begin to think of it and again, psychologists are talking about perception. So the experience all of these bindings of time and time is sort of expanding and contracting depending on the situation but a psychologist would say its not like there is some kind of strictly accurate representation of time in your brain against which you have this subjective experience. There is time as we know it on a clock which is basically einsteins definition, but its not like you have an accurate clock in your brain and then youve got this kind of function thats constantly screwing up. Its just the two are the same. Its constantly subjective. Theres nothing else. But everybody asks me does that mean time doesnt exist . I begi began to think it does et very much almost like a language. It is in the same way as the language does or math does. It serves a purpose of stitching together the use of experiences that we have, these things we have in what we call moments. Going back i think this is a great reference that you bring up and also if nobody asks what the time is, nobody knows perfectly well and its a bit of this original moment in the year 397, 398. I would like to become a medievalist just because of that but when you see the divided way of thinking about time what is rational if i think about it i no longer know becaus but if i i know perfectly well. So i would like to see this not as a result of the conflict but as the way that its always been. Weve always had these contradictory is with ways to resolve it. Bergson would say why do we construct clocks, why do we use these clocks and if we go back to the time, the language is a practice is 33 rounds in a lot of important philosophers and the century have taken it upon themselves finding a way to stop the fight between the science and the humanities and find another way of explaining it that elucidates both areas. To continue the fight its been important. Can i ask you it seems like we are going around what is real. Theres sort of an nx capable reality that we are here now rather than a very long time a ago. I know you are suggesting we speak about what it means to be here now and we are living a moment in the 21st century you might ask the question why arent we living in the age of george 3 or back in the age of the astronauts. Its an interesting question. Or maybe it sounds like a foolish question. You might ask how can we think about this. While, think about all of us in another sign. Here we are in the most populous city of new york third most populous country in the world so in that sense we are very nonspecial. We are not living in some kind of remote unpopulated corner. All the rest of the people are. So nothing should be surprising there. Now also consider where we are living in time. We are looking at a particular moment when as it happens about 27 of all the people that existed, all the human beings that ever existed exist now. Succumb in that sense its rather than existing say several millennia ago when the entire population of the world was only maybe a couple hundred thousand. So thats kind of interesting. You might think what does this tell us about the rest of the humanities and our future. Just imagine this as time proceeds the markers are drawn ouout of here and here we are. Weve been drawn out about 200,000 years into the existence of the human species and you might ask how long is this process going to go on. And if you think about this, you think we are nonspecial. And about 40 Million People already existed but we are on to existence he would only expect there would be maybe another 40 billion people until the humanity is extinguished somehow. That wouldve put us right about in the middle of the process and make us very ordinary and most observers are nonspecial. If you think about 40 billion people, that is another three or four centuries of for the population of the year stabilizes about 10 billion. So, that is a sort of indication that we should be a little bit concerned about the future of the humanities. If we are not very special, if we are in the middle of the whole metaphorical drawing of human life, we shouldnt expect humanity to go on much longer. It suggests that there is some sort of extinction process and a doomsday scenario because if humanity goes on for millions and millions of years and if we televise the galaxy and televise other galaxies, theres trillions of people in the future, why should we be among the very first ones kind of like adam and eve sitting on the home planet in the beginning of the process that would make us very special so this is just kind of a liberating way of thinking. [laughter] also, to continue on. You said we dont feel that we have enough time. We all live less than 100 years pretty much. If you put that in seconds, that is about 3 billion seconds. When you put it in those terms comin,it isnt so bad. If you want a really basic clock, ticking off the clock is going to be a prime on which is [inaudible] so enough leisure time, we live almost as long as the universe. The universe has existed [inaudible] [laughter] so i worked it out. If the universe of 60 units award come each of us lives about 52. 5 units. So almost as long. [laughter] im coming back to the same question of these completely different divergence. That doesnt make it uninteresting to compare them. There is the sense that we all show up at 5 p. M. In the race to get here and walk into the room none of us were quibbling about whether they would say there was a reality. Maybe we should be asking that. We might be asking, but here we are. I think that there are interesting dimensions to the psychological aspect and they are not totally unrelated because i think you have an interesting point we dont have these clocks around they are just taking perfectly at the speed of light. We have axon axons and they hava certain firing time schedule and its, you know what sort of gives a looseygoosey sense. Some of us fired faster or slower. These are our internal clocks and they are not great, but we do know that there is a not subjective external measure and well try to make our flight. But its actually weirder than you would think. So in this day and age, all of our cell phones basically tell the same time. And why is that . It is because upstream there is a National Laboratory that has a fancy clock that, you know, takes out its time and sends out to all of us. And the way it does because its basically has a measurement of a second base baserunning measures made in the 1960s an into use as an atomic clock to basically measure the most accurate second and ends at 86,400 of them and if it gives you a 24 hour day. And the clock can check in at any moment to figure out what time it is. So, that works for us and keeps us on the same time, but the problem is there are National Labs and atomic clocks all over the world and they also have to figure out what time it is right now. So you would think that up above them. Some even bigger clock thats fancier and i actually went looking for it and it is totally counterintuitive. What it is is an agency in paris that is a group of scientists and of the way they work as they have all these National Labs and the clocks tick out the most accurate second, the most accurate representation of the second. They do it all at the same time to figure out how complicate cod this page with all of the all at the same time independent the people at the bureau compared with display 004 were just a little slow and then they give you feedback and say if you could just slow your clock down a little bit and speed yours up, then the time would be a lot more accurate. It takes them several days to do this. So once a month, they send out a newsletter it used to be paper but now its email that basically tells everybody how to direct their time. And so the most accurate clock in the world is this. It tells you how slow or fast so that it can be faster or slower. So we are looking moment to moment on this average that we basically decided a month ago. You would like to have had a frame of reference. On the same footing sorry, go ahead. [inaudible] [laughter] must be that all measures are ambiguous with an uncertainty and we try to reconcile to the best of our ability, and space is no different than time in this regard that we have to see what we mean by a foot or inch or meter, and they are off. In addition to determining the standards for the question, reading the standards and practices that teach you to read a clock so it is a question if we can take psychology completely out of science. I mean, science is made by humans and used by humans, so its not clear if we talk about the timing it isnt completely clear that we could extract the psychological from the objective because they were made by humans athat a certain historical perid and now they are used for humans to go to the event. I would be curious just as someone deals with physics at times, how do you square the physics and psychology of this on a daytoday basis . I live in a blissful denial as most of trying to reconcile the things. [laughter] the notion of time but im interested in is very much the physics notion and there is no room for this measure because most of what i do im interested iand interestedin what happenedn years ago before there were human beings and before there was psychology. Does this say nothing about the fact that all of m my memors lie in the future of that event . I mean the direction of time, we remember the past without the future. It is a phenomena of physics that has to do with the fact that the universe began and entropy is increasing enough time and what is the implication of that is that our memories accumulate only in one direction and this is what gives the sense of being pushed into the future just to be one of the most compelling psychological aspects of time and thats something that they start to shed light on. It doesnt tell you why time seems to flow with brigh but bye is different from the past and why we can affect the future and the causal changes, why do we remember the past without the future. When we discuss physics in the human center and this it could be an interesting way of the described. And we are observers of this with every observation that we make in that we dont remember the future exactly as you said and we only remember the past and that is whatever reason we cant sit still with time. Jim just said an interesting thing about entropy is not a complete solution. We know that the universe began and the reason we know that a movie is Going Forward in a glass breaks and goes into a state of disorder and if we see a glass go from a state of shards into a reassembled gauntlet than we know its running backwards. Thats how time works at increasing entropy and not decreasing. And that is an observation of the universe that we make as human beings that is psychologically very impactful. Getting psychology to understand the laws of physics is the other way around. But of course its interesting to connect these things. But we still dont understand. Sometimes entropy doesnt increase. It is called the law of the entropy which is a principal and a tendency. Its absolutely possible sometimes it happens spontaneously and decreases the. The. We just dont understand these things yet. It is possible that all the particles choose to spontaneously organize into the left corner. Its typically unlikely but it is a small and physics and is just unlikely so we live with this tendency but it feels much more forceful than that. [inaudible] [laughter] the brooklyn book festival [inaudible] [laughter] i dont want to shift away from this completely. Its part of the same question but i wonder if we can speak briefly. I am touched by this idea that, and this is a sort of historical angle. The centurys past experience in a way that is fundamentally different there are certain ways weve learned to offer our experience. I think it was radically different and its an exercise that still needs to be done to go back without the preconceived notions of time to try to figure it out and i think we would be quite surprised this part of time telling is connected to literacy and the order of the words and the auditory but you have to ask how this is experienced in other cultures on one thing that strikes me is basically once they print the example of the film in reverse and that makes me think the introduction in cinema and the First Experience of actually playing in reverse and the reversing film made us think that tim went differently and was connected to the historical period when it was discovered so i think there is a lot that can be gained by going back to the practices and instruments. Another comment about the book for the second, its a history book that starts around 1850 thats the first time that people notice there was a reaction time it takes about a tenth of a second to step on the brakes. That was a crazy idea. We thought that it was more in sync with the world because we didnt have the experience of all of these other things that came with the instruments of modernity. They came with wheels and brakes and paragraph keys but then made us realize that we were delayed by about a tenth of a second and you wont find scientific articles that express the reaction time and speed of thought. You would essentially go to the observatory and youve got astronomers sitting there waiting for the stars to cross. The way he would do it if he would look at a clock and would tie in it as it crosses the line and they would mark down when that happens so it turns out that because of this, that estimate is always going to be wrong and a astronomers realized that they have what they call the personal equation. It was ultimately physiological and the way they dealt with it is they watched where it hit and let the machine. Its much more consistent than looking at a clock and trying to remember what the clock is doing. The related question to that, the intellectual journey of your book has this changed your daytoday experience and does this change how you live in the . I spent a lot of time in the accurate timepiece to coordinate with each other as kind of a master clock in the brain that things can get out of sync. Going into this project with the idea that tying is a terrible thing and then i realized that this very much out of me not just biologically but also psychologically. William james is just kind of beautiful at this point when he talks about lying awake in the middle of the night and these things popping out of him now. Hes thinking what is now and he realizes there is no such thing. There are experiments to figure out what part can detect the empty moment and theres no such thing. All there is psychologically theres a moment in time in which something changes. And at the least thing that can happen that can change in the middle of the night is you have a thought or two or the lights flicker on in the back of your eyelid and that is enough to signify a moment is happening in the changing. So what is going down is up to you. And again its kind of an augustinian thing that essentially take takes a momenf time with consciousness. Im afraid to go too far now. This kind of comforting as a way to feel like whatever the time is in a strictly physics sense is strangely something that emanates from me. Its not something that comes out. It comes out of me and out of all of us and we all share and we all need in order to spend time together and to be here at 5 00. I would like to recognize if any of you have questions for the panel. I suppose i should ask you to keep them brief. If you can keep them relatively brief that would be wonderful. Can you talk to us about these bubbles and if there are parts in the universe that are shaped so entirely differently this time is a different concept . It is once you start thinking of time as a dimension and imagine the universe was created three spatial dimensions and one time dimension user to ask why. And they are very soon after einstein first started talking about spacetime. Why three. Some people started talking about the possibility that it had multiple dimensions that we are not aware of. You talk about the psychological aspect of the observations and there are three spatial dimensions. We mentioned at the time and up north, south and east and west and up and down into the covert threats we need to specify to be here together. Where are these others and why arent you lost in some transfers to mention because we didnt specify. In the theory one of the suggestions is they are small. I literally cant stick my hand in them they are too small and wrapped up and have a particular shape so this is stuff we work on all the time. Every possibility for that happens we just live and learn and there are other universes where they are large and you cant stick your hand and demand to find each other at a conversation we need to specify the ten dimensions. There are reasons to think you could live in a world with more or fewer than three dimensions. You cant have a scan imposing an interior in less than three. You cant have an orifice that cuts your body in half and still be an entity in less than three. So getting high year it just means the universe might be sparse like it might be hard for me to find you. You couldnt have chemistry. If you assume that we are then you dont just have the particles that you have a higher dimension. These are interesting questions and this is why i have a job. [laughter] pointing back five rows i think. I just want to post something and get your reaction. If it is one of the systems we live in or the duration as he called it in that it is a dimension and that we have our own philosophies along that time dimension and the degree as individuals we are prisoners of time which we are not in space. Given that, that means that if tim means the dimension that means it exists outside of us we have our own velocity but if we start describing time as something that is personal to us and interpretation, we start getting into areas like a did divisive than 4 billion years ago or 400,000 years ago. We are opening the door to a lessening of truth, and acceptance of truth. As we define a second which is defined by astronomical criteria that is not fake news. What is the question though. [laughter] the question is if we start thinking outside of the idea of time in terms of physics, are we not leaving ourselves down a dangerous road in which nothing is definable . Let me jump in. Weve been talking about time and we havent really defined the terms. I found when i talked to psychologists it was like how to use the time and they would all say to me what do you mean by time and in a psychological sense, its a whole bunch of things. Again its our experience of duration and what time i it is right now and our experience of before and after which turns out to be an incredibly plastic experience that is quite malleable. These are all distinct experiences and im not sure have we really said what it is in the physical sense so like change. The it was very much part of the debate between einstein and bergson and one of the recent reasons why there was such a decline in the continental philosophy. It got us intthey got us into ts and during the meeting, einstein was talking about time and said the timsetthe time of the philos doesnt exist and that was the detonator to this whole debate but the reason hes lost words isnt in this binary. There are specifics but rather a seeing how it also uses stories and is a practice that is situated with the hope of getting to the sturdy concept of time which acknowledges how it is made and our relation to the instruments of measuring things like that so i dont think it is a sort of fake news or physics option. You in the front. When you said states exist and we passed through it but it may or may not be tolerant, i was thinking if im other words the time has passed and no longer exists in our presence what if you had some kind of a wormhole Thing Holding up space where that connects us to the past or that create a paradox or become impossible if time in the past no longer existed . In einsteins formulation is kind of implied that the past and future just to sort of lay it out there. Time isnt treated differently in space other than its a different curvature on the manifold. It is possible to go back in time to. But they are very special states and ones that are not easy to realize but nonetheless that should give you pause and it did give pause. He was one of the first to discover a universe that rotated and allowed you to go back. You have to preserve the famous paradox. I go back in time and kill my grandfather before my parents were born how could i be going to go back because a certain kind of free will but i can choose to do something inconsistent there was an interesting story where he said imaginhes adimension i go backt my grandfather and then theress this with a degree of possibilities. One is that i only injure him which is why my father is more kind of bad and im a rotten kid and then i come back and shoot my grandfather. [laughter] another question. Right there in the center. I am a former paleontologist and what has been talked about is as we know in the Geological Sciences we are looking at the history of the earth 4. 5 billion years ago and i dont think that this is true in physics and a strong sense of time if anyone is interested i can mention the writings extensively about time. You in the second row from the front. I was wondering is there a discussion about how time is watched and time is passing and we understand that its changed but its something that is financed some entity and i think you spoke about the consciousness and i dont know if you can expand on that. But it seems that when you mentioned the quote when you asked me i cant think about it is this because there is some conflict with thoughts and your mind cant conceive of time but you know Something Else knows what it is so if you are not the witness of time, then time is the witness of you. This is probably an area that one has to define terms very carefully like what do we mean by time does it mean something is changing. They are saying the most fundamental change you can experience is the change in your own thoughts and its the smallest amount of time in which something changes since all of its circular but in that formulation the kind of time hes talking about it doesnt really exist without a. That they deal with time all the time they just are not aware of what they are doing. [laughter] [inaudible] [applause] they are signing their books and signing tablinto signing table e library in the back of. In audible conversations [inaudible conversations] that wraps up booktv live coverage of the brooklyn festival in new york. If you missed the program is everything will be on again tonight beginning at 1 a. M. Eastern time, 10 p. M. On the pacific coast. The. To hear from michael, andrea ritchie, robin spencer, devon allen and other authors. Thats a look at some of the events book tv will be covering this week. Many of the events are open to the public. Look for them to air in the near future on book tv on cspan2. Now, we want to introduce you to mark sosa, an entrepreneur and author, economist and