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 th