Transcripts For CSPAN2 Sean Carroll Something Deeply Hidden 20240713

Interact directly with them and be informed at the same time, energized by scientific ideas and at bell house in brooklyn. Back here tonight, the kickoff of the fifth many season of secret science club north and we are happy to kick off symphony spaces this season behind the new republic. And joanna thompson, rebecca wise and mary mead, the most helpful. A very special thanks, they created the libation of the night. The quantum cocktail, exhibit a. And a smoky ginger ale topped with lemon. We get it at the bar. If you are bored by me. A heads up part of the many season, by december 3rd with astronaut kathy sullivan, former nasa astronaut, the First American woman to walk in space and a former director of noaa. You might have read some of her thoughts yesterday in the paper. You can visit our website at we are so high tech we have a blog spot. You can sign up for our mailing list. Our wonderful secret tonight, sean carroll has a new book out. It came out today. And it is a book party. The lovely folks at books on call nyc are booksellers tonight, and we will be signing copies after his talk and the q and a with you. Our wonderful audience. We are excited to have sean carroll with us tonight and a special guest to introduce sean carroll. Brian greene is a professor at Columbia University and director of the center for theoretical physics and also a playwright, sometimes an actor and bestselling author of several Popular Science books including the elegant universe and the fabric of the cosmos. And the pbs nova miniseries based on his book, he is the founder of the good old world science festival. Brian greene. [applause] thank you. Thank you very much. The quantum cocktail. I was shocked Dorian Devins did not follow it up by saying you get it at the h bar. I will leave now. You have been a great audience, thank you very much. Tonights focus with sean carroll is on Quantum Mechanics. As many of you know, we have a wonderful, quite straightforward understanding of the universe. Classical physics. We you tell me how things are today and i use the equations of newton or maxwell or einstein to figure out what they will be like tomorrow and then it all changed. In the early decades of the 20th century beginning with the work of einstein himself the paradigm changed and the new way of thinking about the world is tell me how things are now in the best we can do is probability of what they will be like tomorrow. That was not an easy transition in the era to take on board. It was an emotional upheaval to make this transition but heres the thing. As sean no doubt will describe in more detail, the laws of Quantum Mechanics even though they are probabilistic, make predictions that agree with observations with fantastic accuracy. Decimal point digit digit digit onward to 9 or 10 decimal places and that agreement between theory and experiment is so potent, so powerful that people began to stop thinking about what the theory means, what it tells us about the nature of reality and began to use it as a wonderful structure to make predictions about the world, to control the microworld to yield all the wonderful technological gadgets that we walk around with all the time. And the meaning of Quantum Mechanics, what it was really telling us about how the world works. They were looked on as somebody who lost their way, it wasnt something we were supposed to do. Few people are trying to figure out in particular how we transition from this probabilistic description of the world to the definite reality that we all experience and many ideas we put forward, wild ideas. Sean carroll will talk about the most wild of those ideas, the possibility that we are part of a multiverse, many worlds, parallel universe. A very strange idea but i will tell you this. Ever since the events at least i have found in talking about those ideas, the events of november 8, 2016, people have a much easier time understanding the concept of parallel universes. [laughter] with that, gives me great pleasure to introduce tonights speaker. You all know him from his many bestselling books on the nature of time, the higgs particle, the nature of reality, a physicist we all know and love, one of the great leaders, pioneers in understanding cosmology and quantum physics, tonight you have a great treat to hear from one of the profound thinkers who are willing to push into the meaning of quantum physics to try to figure out what it tells us about the nature of reality. Give a warm welcome to my friend and colleague, sean carroll. [applause] thank you. Who do i need to thank . Thank you secret science club, thank you for figuring out the secrets that you can come here. I dont know how that happens but im happy it does. When you become a physics professor, you teach other people even if it is an abstract physics concept it is best to do demonstrations and bring it back to earth. I will start by doing a demonstration, push a button which will send a signal over the internet to a laboratory in switzerland which will send a photon of particle of light down the tube and a beam splitter, it will go left or right with 50 50 probability and depending whether it goes left or right it will come back here and tell me whether i should hop to the left or the right. Ready . Here we go. The device is ready, photon is emitted, quantum event, the universe just split, hop left. Ready . That is the demonstration. Why is this demonstration worth anything at all . Physical comedy, yes. In my favorite version of Quantum Mechanics, the many worlds version of Quantum Mechanics, it predicts, i believe it is true, there is another reality where i hop over there and him standing right there. There is a different version of me that did something different. Like i said, i believe this is true. What you should be saying is what kind of crazy person would believe this is true . That is what we are here to figure out. Let me see if i can do this, technology is a good thing. The reason we talk about these things is Quantum Mechanics is enormously successful, we needed to understand lasers and transistors, particle physics like sunshine and even why chairs and tables dont collapse, why matter is stable itself but as my illustrious predecessor said i think i can safely say no one understands Quantum Mechanics. I usually dont like to appeal to authority by bringing up other physicists but the claim i am making is that nobody understands something, the person who understood things the best is a good authority, that nobody else understands it anyway. How in the world can it be possible that even though we use Quantum Mechanics to make these protections to enormous accuracy Richard Friedman can say we dont understand it . It is because we can make predictions but if us professional physicists what is going on, what is the reality that meets that prediction . They will say i dont know. They will say i dont want to know. Who cares about reality . Im a physicist, i want to make predictions. Isnt that a terrible attitude . My fellow physicists should be embarrassed with themselves. It wasnt always like this. No one would have said this 100 years ago. Only since Quantum Mechanics came on the scene that people attended to think the only reason we do physics is to make predictions, not to understand how nature works. Given that we dont understand Quantum Mechanics, you would imagine Quantum Mechanics is so important, the path to understanding Quantum Mechanics would be the most important thing in all of physics. The people who specialize this are superstars of physics. In the room tonight will, we have several of the worlds leaders in understanding the foundations of Quantum Mechanics, these people should be millionaires living in penthouse apartments. They are not. They are great people and they are underpaid and undervalued. It is not only that we dont understand Quantum Mechanics, it is that we havent even tried. It is a complicated set of reasons why but that is a holder can talk. Maybe you will get that some other time but i want to highlight the degree of embarrassment physicists should have. It reminds me of the fable of the fox and the grapes, fox sees some grapes and hops over and over trying to get the grapes that they are too high and the fox cant get them so the foxes i didnt want those grapes anyway, they are probably sour. In case the parable is not perfectly clear the fox represents physicists, the grapes represent understanding Quantum Mechanics. We use to try, we couldnt do it so we said we never really wanted to understand Quantum Mechanics anyway. Until tonight. Starting tonight everyone is going to understand Quantum Mechanics. Im going to do oral wind tour of why we came up with Quantum Mechanics in the first place and why it led us to these crazy suppositions i will try to entertain, not a historically accurate tour but history is messy and we dont have time for that so i will tell you a story that gets us there in a relatively brief period of time. 100 years ago or a little more scientists put together a picture of the atom. Everyone has seen those pictures was the cartoon picture of an atom. There is a nucleus at the center. Today we know the nucleus is made of protons and neutrons, they didnt know that. Orbiting around sorry. Orbiting around the nucleus like planets orbit the sun are these little particles called electrons. This is very successful for various reasons. It also cannot possibly be right. The reason why, before Quantum Mechanics came along we had extremely successful theory called classical mechanics, the theory given to us by isaac newton and his followers. Classical mechanics makes predictions. When you take an electron, a charged particle and send it zooming in circles or jiggling up and down it emits light. Radio or infrared or visible electromagnetic waves. All the light you are seeing in this room you are seeing comes from an electron jiggling up and down so here you have electrons zooming around being accelerated. They should radiate, they should lose energy and what they should do according to classical mechanics is spiral into the center and collapse into the nucleus. The timescale for this to happen, maybe it takes a long time, less then a picosecond, a short period of time. You, the chair you are sitting on, everything you see in the world should just collapsed. Matter should have 0 extent. It should collapse into a black hole but it apparently doesnt. Scientists had a good theory, it was conceptually completely inadequate meaning we can do better. It was hard to do better. There is a long set of steps i am missing but eventually they came up with the following radical idea. Maybe the electron is not a particle. Maybe the way to think about electrons is as waves, not particles. There was previously a long debate about whether weight is life particles or waves, maybe it is wavelike in certain ways. Calls for ways to represent the electron, the wave function, one of the least romantic names for one of the most import concept in physics but that is what we call it. There is a wave function that spreads out around the nucleus, it fades away and you can do the math problems saying what are the different ways that an electron wave could settle down into an atom . Even though the wave is all energetic and so forth, waving back and forth, there are certain discrete specific shapes the wave can have where it has specific energy, it can sit there and not change. The electron settle into this. This is data, the only time in the talk im showing you any data. This is a picture of science involved in getting there. Pictures of the electron around the helium atom, it is not in some elliptical orbit. It is spread out along the wave function so thats why electrons dont dk. They are not moving. It is not a little point going in a circle. There is this cloud, this wave and it is unchanging. That is why it doesnt radiate. That is pretty good, that is progress. More progress a couple years later from erwin schrodinger who gave us any equation. I need to show you details of the equation because of a quiz we are going to have at the end, youre going to have to solve these boundary conditions. I hope everyone is happy with that but conceptually it is not that hard. The greek letters i represents the wave function of the electron and on the left you have the question that is asked of the wave function, how much energy is in you. On the right you have an answer which says how fast are you moving . Typical wave function will have various different parts that have different energies and schrodingers equation says highEnergy Particles change reveille, low Energy Particles change slowly and that is the whole story. What matters is there is any equation. Scientist love equations, physicists love equations. Any equation is cool employment for scientists and students solving the equation. The equation says now that i know about a particular circumstance i can figure out what the wave function will do in any circumstance so schrodingers equation, gave scientists the ability to say how wave functions evolve with time. Everything was looking good except one obvious dramatic flaw, when you look at electrons, if youre not hightech, this is a recent picture, a reconstruction based on delicate stuff. Usually when you look at electrons they dont look like waves. They look like particles. This is actually a little chunk of uranium that is radioactive so it is emitting particles and this is in a Cloud Chamber which means when a charged particle dips through it, it leaves a string of bubbles behind and every one of those lines you see being created as a result of a charged particle being emitted by the radioactive uranium. I showed you most of it is cool. What i want you to learn from this picture is the prediction of the schrodinger equation is when the uranium atom emits some radioactivity it is emitted in a spherical shell. It goes in all directions equally. That is not what you see when you look at it. What you see is a particle like thing moving. That is why we call them particles in the first place. Schrodinger had the hope that when he started equation what he would find was the wave bunches up and looks like a particle. Then people did actually solve the equation, thats not what happens. It spreads all over the place. There is a dramatic mismatch between the formalism that says the wave function spreads out and the observation which says it localizes and looks particle like. So the following terrible no good idea is wave functions can be spread out but when you look at them they collapse. They are shy. I am you think im kidding you. This is what we teach our students. This is what i got taught. There is the wave function all by itself which has a particularly nice form and on the right it says when you measure, where is the electron, want to take a picture of it with my electron camera, you dont see zack cloud. You see it located in some particular location. Why is that . The word went out that there is something called the measurement process. The measurement process involves collapse of wave function. This was figured out, what people told themselves in 2628. This came to be codified in the copenhagen interpretation of Quantum Mechanics and this is what we teach our students today. If you open a textbook in Quantum Mechanics you will find that if you ask what do wave functions do . There are two sets of rules. Wave functions do one kind of thing when you are not looking at them, they obey the schrodinger equation. They do another kind of thing when someone looks at them. They collapse into a particular value and the probability of getting any particular outcome is what the wave function was squared. When you have something spread out like that on the left it means the probability of measuring the electron is relatively large and the probability out there is relatively small. This is why people tells because no one in the right mind thinks that this is the ultimate way of reality, okay . Highlight two of the problems with this cookbook we are given. One is what we might call the oncology problem. Philosophers use that were to talk about what is real, the study of being. What is the world, not just what you observe but what does it mean when youre not observing it. We noticed we split around on the question when we are being introduced to the copenhagen interpretation. There is a wave function but is it what reality is . Is the one to one representation, the complete story of reality . Or only part of reality, maybe a wave function of the things, particles as well as ways. Maybe it has nothing to do with reality, maybe its just a black box that we can use to make predictions about experiment outcomes. There are people believe all these things. We do not agree about what reality is. Slightly more publicized is what we call the measurement problem which is more obvious. What do you mean, look at . Looking at things changes in, like what does it mean . Do i have to look at it . Could a cat look at it . What about something nonliving like a photograph or video camera . What if i just glanced at it . Does it imply somehow my agency and consciousness, my disembodied mind has something to do with the fundamental recipe of reality . Again there are people who believe all of these things. I dont want to discount them but at least we dont agree on the answer so that is a problem. What are we going to do . I have ideas. The talk is not over yet. There is a very wellestablished tradition and Quantum Mechanics popularization of highlighting how mysterious and weird and spooky thing is and never telling you how to get right. Im going to take at least my papers to get it right. Hugh everett who is a graduate student in 1957 basically acted as a quantum therapist. What he said was look, you have been working too hard. Chill out a little bit, okay . You had some goodlooking rules of what is going on. There are wave functions clearly, they obey the equation a lot of the time, clearly. The simplest dumbest most reporting is to say the wave function is everything. What it does is obey the equation all the time. Theres nothing else. That was his prescription. Naturally he left academia right away. He published his thesis. He tried to convince others what he said was interesting and they said no, its not. Here is the everett interpretation of Quantum Mechanics. Theres one set of rules that applies all the time the matter whats happening, and its exactly parallel to every other theory of physics and every other theory, there are states, position and fields or the coverage of spacetime at those dates evolved according to the equation. All the stuff about measurements and nonsense, just erase it can get rid of it. You dont need it. Okay, it sounds like it would be good if it worked, but that stuff about measurements was invented for a good reason. We saw the picture with the particles go out. We dont seem to see wave function so how could this simple pure vision of Quantum Mechanics possibly fit the data to match our experience . The secret is a a little featue of quantum mcculloch skulled entanglement which you may have heard of. Let me sex ed appear by putting it in modern terms of talk about the higgs those boson which woa book about. I would not be hurt if you took out your phone right now in order that book. You could do that, thats okay. But the higgs boson is the particle, the only particle we have detected that is a fundamental particle that has zero spin. Spin is a quality that elementary particles can have, very much similar in spirit, the ordinary spin of the spinning top or the earth but it comes in discrete amounts. For Something Like the higgs boson the spin is zero. Its not spinning at all. The higgs boson indicate inverse ways. When what is a good decay into to make electrons, and electron and a positron, but we will call them to make electrons. Electrons you have spin. Electrons we say spin one half for historical reasons, but a stimulus particle decays into two articles with spin, angular momentum of which spin is one example is concerned. So it must be the case that the spin of the electrons cancel out from each other because it has to add to zero to give you the same spin the higgs boson had before decayed. They electrons we talked about, spin up or spin down, the choices, and electron one could be spin up or spin down. Electron two could be spin up or spin down but there must be opposite. Thats what we know. The way that happens in Quantum Mechanics is the higgs boson decays into what we call a superposition. There are two possibilities, either electron one is spin up and two is spin down, or electron one is spin down and two is spin up but its not that we dont know. Its just like when electron with its wave function was spread out, thats what the way function is, taking the what if you the wave function is everything now. What this means is the higgs boson decays into a quantum wave function that is both possibilities at once. We say the two electrons are entangled with each other. We dont know if we measure the spending electron one, we dont know where that will be spin up or spend them. If we measure the spin of electron two we dont know whether it will be spin up or spin down but if we measure the one, we know electron two will be opposite because have to cancel each other out. They are related some way. These systems are not separate from each other and the lesson here is that in Quantum Mechanics, there are not separate states for individual parts of nature. There are not separate wave functions for each particle. There is only one way to function, the universal way function. These days we call it the way function of the universe, and it describes the probability of measuring everything in the world all at once. You might think if youre trained on classical physics that theres a state for particle one, which is a plus down, and estate for particle two which is a plus down. But thats not right to Quantum Mechanics says theres only one state, the wave function of universe and its the combination of both. Thats entanglement. The possible and you can get for one particle is related to the other one. What does this have to do with measurement . To get there we will bring up the thought experiment stylings of to put a cat in the box. Youve heard of this one. Imagine a box that is you and cat inside and some radioactive source like the uranium we saw before. Theres a Geiger Counter and the Geiger Counter can detect when radioactive source hits the particle. Theres some quantum mechanical probability that the Geiger Counter clicks, and when it does it will open the box, castle, outofthebox and in schrodinger original telling it is poison gas, sinai and cat dies. As schrodingers daughter once that i think my father just didnt like cats. [laughing] thats really too. I could make that went up either. I see no reason to kill a cat. I think i want to undo the decades of cat killing that up in the favorite pastime so in mitotic spindle is sleeping gas. Sleeping cats right there. The point of it is when you havent yet opened the box, schrodinger says look, apparently by the way, schrodinger didnt like any of this. He invaded his equation. He liked his equation that at the time that he invented it he didnt have this interpretation of the equation that you squared it and got the probability of something. Once you realize thats what it was for, he said i wish had nothing to do with the. He did not return the nobel prize here to get that. Schrodinger is according to my equation, if the wave function of the radioactive force is a superposition of having decayed and that the net, then the wave function of the detectors under supervision of having detected and having that, the wave function of the box of having open and having it, the way function of the cat was in a superposition of being awake and being asleep. His result, his conclusion from this was, surely you dont believe thats what really happened but thats what his own equation says. Lets use this to illustrate the difference in recent between classical physics and Quantum Mechanics. Im going to introduce a notation, so when i have things in square brackets that means their classical somehow, devon value, and if theyre in parentheses then there quantum. Classically, i would say the cat is alive or dead. The cat is awake or asleep. I might not know which it is. I might be uncertain but theres some fact of the matter the cat is either awake or is asleep. Quantum mechanics has no, no, no. The a whole nother said a possible with the cat is in a superposition of being awake or asleep. Thats what schrodingers equation predicts. If you taken Quantum Mechanics as an undergraduate and taught the textbook interpretation, what you are taught is there quantum mechanical systems come in this case the role of quantum system displayed by the cat, but there are classical observers, the observer lives some any classical world. The observer doesnt have a way function. They just observe things and get answers, the observer has definite value. The justification for this is have you ever been in a superposition . No. You think you know its going on in the world. You dont feel like youre in a superposition. Theres something definite about you but this is a picture, the godfather of Quantum Mechanics and a pioneer of the copenhagen interpretation and he is playing the role of the observer. In the textbook version of schrodingers cat you would open the box, the wave function of the cat would collapse and either youd have the cat was awake and joined the observer see the catholic, or the cat was asleep and the observer saw the cat asleep. I tell you this because i want to contrast it with the quantum many world version of this. There was no collapse, there is only one way function and that includes you. Theres no classical observers, no dividing line between the classical and quantum realm. You are part of the wave function of universe. You can be in superposition. Everything is in parentheses so this experiment starts with the capping the supervision, and an observer in this case the observer is played by hugh everett competent the observer opens the box and open box isnt anything mystical, doesnt have anything to do with consciousness pick opening the box just means i saw the equation and i had a physical interaction between whats outside the box and whats inside the box, obeying the schrodinger equation at all time. What does the schrodinger equation predict when open the box . Heres what we know. We know if you open the box in the wave function of the cat was entirely awake, you would see and wake cat. Lets agree on that. If the wave function of the cat was entirely asleep, you would see an asleep cat and thats all the information you need to know exactly what you would observe if the cat was in its superposition. Namely, the world, the way the function of universe evolves into a superposition of the cat was awake and the observer saw the cat awake, but the cat was asleep in the observer saw the cat asleep literally nobody in the world disagreed with the fact that this is the prediction of the schrodinger equation. They might disagree you should be using the schrodinger equation but thats the prediction. This is why no one believes everett because he said he just to pay the schrodinger equation and if youve seen all that it sounds like i myself evolve into superposition and i observe quantum things before and never felt like i was in a superposition. I didnt feel like isis superposition hopping left and popping right. I felt like i hopped left. There seem to be some definite fact of the matter. Going on . Well, i think like everett got it right, circa 1957 but he didnt have any right to get it right. The real reason what makes this respectable is the idea of what we now call decoherence which was a big debt until the 70s and 80s. It stems from the same philosophy of how to think Quantum Mechanics, namely, there is only one way the function for the entire universe and you notice we didnt include the entire universe here. You have a cat and on observer. What about the rest of the universe . Technically we should put the rest of universe in pick you might think that doesnt matter but you would be mistaken. We call the rest of the universe the environment, the environment is a technical term we use to mean me the entire rest of the universe where we are not keeping track of everything that happens. We are in a room with particles of light, photons, atoms and molecules in the air and so forth. I dont know the position and velocity of every atom or molecule, location of every photon. I wouldnt even know if they changed a little bit. Just dont that all into the five it. The point is the environment is both inside and outside the box. Theres air and light and box and outside. If the cat start out in in a superposition of awake and asleep, it interacts with the environment right away before you open the box, theres this process called decoherence in which the state that there quantum system becomes entangled with the environment. Basically the cat and environment wave function, part of the way function, evolves into a superposition of the cat is awake and the five it is whatever would be with the cat awake in the cat asleep in the pilot is whatever it would be thin. Then you open the box, thats the management process and you see an answer. This is the true wave function of universe, slightly colorful depiction. Auppercaseletter, environment of the catholic, observer saw the cat awake and likewise the cat asleep. Why would it matter in the slightest that he keep the environment in there . Its because thats what he really mean by measurement its that anything to do with the human being. Not anything to do with a video camera or an earthworm for any semi conscious creature. Measurement occurs in in a very scientific physical thing. When a quantum system that is in a superposition becomes entangled with the outside world, becomes entangled with the pilot. Thats what decoherence is. When that happens, the following wonderful thing happens. That is the person in the part of the wave function who saw the cat awake says is there a hole in the universe, i hope another part of the wave function with the cat was asleep . Is an experience i can do to detect that . I might be affected by that other part of the wave function . The answer is no because the environment is so dramatically different that this part of the wave function from the first part, the awake part, cannot affect and is not affected by the second part of the wave function. In other words, just to the absolutely inevitable movement of the wave function according to the schrodinger equation, these two possibilities have become noninteracting with each other, as it may be, separate worlds. So everett said bryce dewitt said you dont we should do to get more publicity, we should call this the many worlds interpretation. Him him the problem is the words many worlds interpretation make you think that adding extra worlds to Quantum Mechanics to help make sense of it. But you saw at no point did it add a world. Although i did was force the wave function to evolve according to the schrodinger equation. The worlds were always there, as another physicist once put it, every of the formulation of Quantum Mechanics is a disappearing world formulation of Quantum Mechanics. All everett wants to do is say the worlds are there and thats okay. Thats the therapeutic move. There are many questions and get a refer you to this excellent book that just came out but there are many questions about the details of many worlds Quantum Mechanics like how many worlds are there . There are lots, okay . Thats really all i can say. Theyre very well could be an infinite number of worlds. The truth is we dont know. This is part of the embarrassment that we have not been for the last several decades doing the work we should be doing trying to understand Quantum Mechanics. We let questions like other infinite number of world or just a finite number go by the wayside. One what are the other there are many of them. The way i want you to think about the world and the branching is time is going from the bottom to the top when this branching process happens, its not that i double the universe because then people get worried about questions like Energy Conservation and what is all the energy, are all these extra universes . Its much more like theres an existing amount of universe and think its subdivided. It gets sliced. Theres what i call and a book the weight of the universe which is just the wave function squared in total. That stays the same according to the schrodinger equation. It remains the same amount but as branching happens in universe splits, the individual branches become thinner and thinner. Dispatches question you might have it by both and ever ready in and also a utilitarian. I want the greatest good for the greatest number. Should i spend all my waking days splitting the wave function of universe to create more people and, therefore, more happiness . No. Shouldnt do that. Because that should be balanced by the fact youre making the universe thinner and thinner. Think of the universe splitting and is happening so often, so frequently come every time and adam inside you decays like theres an adam everett actively decays inside your body roughly 5000 times a second. Thats not in every second you make 5000 more universes. 5000 times the second second you split the universe in two. You make two to the power 5000 universes every second just in your body and thats lower limit because every atom in your body that doesnt dk also contributes to givers because another universe in which it did. Rather than individual discrete how events with universe branches, you should think of this as an ongoing constant process of swoosh but dont worry, theres plenty of room, plenty of room for all the universes. Theres math you can do to convince yourself of that. Thats not really what it want to talk about. I want to go over some of the prospects, some of the good news about many worlds and the good news is basically one when you start think about more carefully, maybe its help us answer other questions. Let me get some objections out of the way very quickly. Heres a bad objection. Thats too many universes. Where can we fit them all . I already answered that. Theres the same amount of quantum mechanical stuff in the manyworlds interpretation and in every other interpretation. There is room in the space of all possible way the functions for a very large number of universes. Dont worry if you believe the superposition of a real, plenty of room for the universe to be in in a superposition of many, many different possibilities the only question is whether you let those superpositions describe reality. You might also worry it cant be tested. I cant see any of these other universes. If you read a smidgen of philosophy of science you thought scientists, bless their hearts, have only ever read a smidgen and if it only read one smidgen, they havent read popper but the red that popper once said to make a scientific theory it needs to be falsifiable. That is his income i could in principle imagine an experiment that if i got a certain outcome that experiment which only the theory was wrong. Not that it is welcome not that it is false but in principle it is falsifiable. Its the theory of falsifiable that it is not sites can set popper. We know better now. That was a good attempt but their details popper didnt get right but even at a relatively naive level, that is not an objection. You might say wait a minute, i cant falsify the existence of all these other universes, remember. Is not the other universe. There are predictions of the three, not input industry. The input is there are wave function of the evolve according to the schrodinger equation. In order to falsify the manyworlds interpretation all you have to do is show a wave function of all things in contradiction to the schrodinger equation even though it is not being entangled with anything else. There are ongoing experiment is to do this. There are other alternatives to many worlds that predict that are different physical consequences. In fact, one of the fans of the manyworlds interpretation was karl popper. He thought the interpretation was monstrosity and your shot physicist would take it seriously. He didnt love the manyworlds interpretation because he had his own interpretation that didnt go very far but as far as scientific testability come possibility is concerned, it is as testable as you want a theory to be. I want to emphasize as much as i like the manyworlds interpretation we are not done. We havent done the work that we need to do. There are perfectly good worries to have that many worlds might not be right. Happily, secret science club is given me the six hour slots i can tell you about all of the other interpretation of Quantum Mechanics. [laughing] i can do that but i will tell you what the words are about manyworlds. My favorite, one of the worries is why do we get probability in this theory at all . In the copenhagen interpretation theres a possibility, when you observe, its put in. Everett just as theres an equation of that equation is deterministic. Theres nothing probabilistic about it. If you give me the quantum state of 110 can i know the quantum state of universe at all the times. Why is there talk of the possibility of getting certain outcome for different measurements . The other one is that the classical world the verge . This is an important problem but its one that very few people are paid attention to because we cheat our way around it. We live in a classical world and we put in by hand. I think that is cheating and we need to do better, and by doing we can learn something. Let me rush through, really rushed through question one and chat about question to make. For probability, part of the answer is because manyworlds perfectly deterministic, whatever probability is, its not a truly chance element of the dynamics of the universe. It has to be what was called epistemic. It has to be our ignorance is somewhat causing us to use probability talk. You might say but if i knew the exact wave function, i know everything, and there you are wrong. Thats the wonder of manyworlds interpretation even if you know the exact wave function, there might be something that you dont know that youre a a good about and, therefore, you have to assign a probability. That thing is where you are in the wave function. Remember the story we told worry had the cat in the superposition, environment, the observer. The first step was decoherence. The cat became entangled with the environment. The important thing about the step is the observer has not yet become entangled with the cat, right . The cat became entangled with the environment but the observer has not yet become. I can still treated as two different branches of the wave function, but on those branches the observer is identical. The observer doesnt know which branch they are on. There was one observer, now there are two. Neither one of them know which range they are on. Even though they know the perfect wave function of the universe, the best they can do if you ask them, are you on the branch with the cat is awake or asleep, they said i dont know. Theres a probability. And you write papers and flossie joss and say is at the billy . It turns out to be exact to the rule that was invented back in the 20s, the probability is the wave function squared. Now again that everyone agrees. His people are wrong but thats okay, they can cite my papers when they are disagreeing. Thats called the scientific method. The problem that is richer in some sense and still less salt on the probability issue is citing the classical world. This is one of the things where i first need to convince you there is a problem and then convince you youre making progress toward solving it. You are like what you mean classical world . Here it is, i see it, chairs, tables, peoples, plan, puppies. The classical work is all around us. Its very, very natural as human beings to think about the world classic and even human beings will take in Quantum Mechanics course. We can to privilege what we see people receive electron making a little track, part of our brain since electrons making a little track. Thats not the dumbest thing in the world. If you are out there hunting your liens or whatever and you thought i i see the line theret maybe its spread out, you will be evolutionary selected away from the gene pool. [laughing] as a result we tend to privilege what we see. So we start with leaves of grass and people, and in the physical pleasure we what is called quantizing it. We have some classical system with its cats for electromagnetic waves, set of rules that physicists can apply and say im going to invent a wave function of the cats for the grasp of electric Magnetic Field probative. Mathematically that wave function as an element of a space. I do a threedimensional vector space your. Thats what it is, okay . This is what we teach our students. This is what we do everyday. We start with the classical system, we quantize it. Presumably, nature doesnt. It really doesnt start with the classical system and then quantize it. Nature just is quantum from the start. The real way we should think about it if were emulating a nature works is to start with the quantum system and say in certain circumstances under the right condition there is a good proximate story we can tell which we call classical mechanics. What we should be able to do is start with a mathematical object, a vector any jillion vector space to think about what is done, i was evolving, what its dynamics are and say yes, thats a cat. Thats a person, thats a leaf, et cetera. Finding the classical world and extracting it from the wave. This is twopart and no one thinks about it. Were just beginning on this path that a think we can see a way forward. Most of the work is being done by the idea of locality. The idea that space, this threedimensional space that we live in, is so enormously special in all of laws of physics. The way it is special is things bump into each other when that the same location in space. There is no real spooky action at a distance, as feinstein said. If you want to communicate, you send a signal, placed by place, you can teleport things after than speed of light, okay . Why is this important . Think about the cat. Think about why when you open the box you see the cat awake with a cat asleep. After all, these are just quantum states, vectors. Theres a perfectly good quantum state, awake plus asleep. Another, awake my sleep and all the different combinations. Yet when you open the box we only ever see awake or asleep. These are the preferred states of the cat. Why is this . Remember the wave function branches when the photons in environment of the box bump into the cat. What do they bump into . Different photons bump into the cat differently for the asleep cat on the ground in the awake cat of trying to get at. Heres a picture that would hit the cat were it awake but would miss it were it asleep. So the reason why the way the wave function branches is, is into systems of definite physical location, because that some interactions work in physics. Interactions pick out locations in the world, okay . Even if i handed you a very abstract wave function and said what is it . The first thing you do say can identify at this wave function into little pieces, some of which interact with each other and some of which you dont, and i would call the pieces that interact with each other nearby in space. I would call the ones that didnt interact far away in space. You can imagine building up the concept of space just from the way the wave function evolves over time. Again this is that what we do because we live in space and you think its all right there given to us and all the rest of physics, space is a prerequisite. Space is the arena, a stage that the actors of the world play out on in this advanced formulas and will have to find space. Rather than saying interactions are local in space, what we will be thinking is space is a set of variables and which interactions are mobile. Lets see if we make progress of that. The other thing we know that space is it is current professor einstein taught us this. I do in church or pictures find he is old and hair is sort of gone but when is a young man invading these great ideas he was there sharply dressed. This is a lesson. He looks smarter than you. He didnt look frumpy like your uncle. Einstein had this idea that when you and i think of gravity, its infestation of the curvature of spacetime, spacetime even if its a stage, its not a static stage. Its one of his modern stages moving parts like hamilton in the circle and all that stuff. The stage is a player in the game. Space time response to matter and energy by getting curved and matter and energy feel that coverture into orbit around the sun are what other things people do, things do in the presence of gravity. The problem is, in every problem of course is an opportunity, problem is that gravity is one part of our understanding of physics that we havent made fully quantum mechanical. Everything else, electricity, magnetism, the Nuclear Forces, so forth, we have a good quantum mechanical theory that seems to work to arbitrary access. For gravity we have a case so, so three that works like the moon moving around the earth but not in place like black holes or the big bang or anything like that. My own feeling is the reason why we havent been able to find a a quantum theory of gravity is because we keep starting einstein classical theory in trying to quantize the i think thats a mistake. Rather than try to quantize gravity we should try to find gravity within wanton mechanics. In other words, why in the world should we be surprised that we dont understand quantum gravity we dont even understand Quantum Mechanics. Maybe we just got lucky and were misled by the fact we could find quantum theories of electromagnetism and so forth. How in the world of the going to do that . Its that were moving completely lively. We need to get some hands from what we know works. Quantum field theory is a best current understanding of nongravitational, the physics of electromagnetism and the Nuclear Forces and so forth says its not even really articles that we are quantizing to wear quantizing fields, space, which i think of as the particle is just a place with field is more energetic than you thought it was. In a particle point of view you might think theres empty space and literally nothing is happening in empty space. But with our particles, something is happening. The quantum field theory point of view says something is happening everywhere, even in empty space here there are feels better vibrating. We can precisely characterize those vibrations. Their vibrating in a certain way and to take one of the and vibrate it were, it would look like a particle. The same story of particles moving and get the same experimental prediction but its different ontology, a different way of looking at the world. And guess what, these regions of empty space are entangled with each other. Of course they are. Entanglement is everywhere in Quantum Mechanics. Even into the space, even what we call the vacuum, theres literally nothing different if you were living there he would say theres nothing there. Theyre still little vibrating quantum fields at their entangled with each other in the obvious way, in nearby regions of space, the vibrating quantum fields are highly entangled with each other. In distant regions they are only a little entangled with one another. That is the lesson of quantum field theory as we know it and love it and use. What i want to do is turn it around because im saying we dont know what space is it we dont know what distance is. We do know the geometry of the universe. Maybe we can define distance using entanglement. Entanglement is a feature of the wave function in its own right. Theres no relied on preexisting classical conception. Distance is a preexisting classical conception to maybe we can say when regions of the quantum wave function are unintended with each other, they are far away. When they are very by, sorry, when they are very entangled their close by. If you could imagine doing that for all of the subsystems that make up the wave function you would define and terry geometry on this emergent space. If i know the distance between any two points in space, if i know the size of a triangle and ankles inside, et cetera, i know the geometry of space. Thats what einstein wants us to talk about. I claim, this is just hurts but come not something we tested and it was true, this is a guess, a hypothesis that were exploring the consequences of. Lets imagine we can extract geometry from entanglement. Theres something that we do know for sure that entanglement is related to entropy. I give a whole nother talk on entropy. I love entropy but the quantum version of entropy has certain special properties. Went to systems are entangled with each other, either one of them separately has entropy. You can think of entropy as how much you dont know about the state of the system and he said went to systems are entangled, either one of them is in one depth and quantum state by itself. So john von neumann said thats kind of like we dont know what state a is in. Its not true that we dont know its kind of like its an analogy that theres a formula when the systems are entangled you can quantify the amount of entanglement by calculating the entropy of the different substance. Finally, theres a relationship between entropy and energy. Remember i said when you see particles in quantum field theory you picked out a little vibrating quantum field and just made vibrate more. Youve also broken unit of entanglement between that little vibrating quantum field and the rest of the field around it. You decrease the entanglement. Youve you increase the entropyd just increased the energy in that region. There is another equation, i wont show you, but theres a mathematical relationship between the amount of entanglement in a region and the quantum field theory and the amount of energy in that region. I know this is all going fast, all going by, but here is what we learned. Theres a a relationship betwen geometry and entanglement that we are positive because we think would be cool if some of space emerge from features of the quantum wave function. The relationship between entanglement and entropy because von neumann said so and you give us an equation. Theres relationship between energy and entropy that we can drive in the right circumstances and something that close to quantum field three. Therefore, theres relationship between geometry of space and energy. That should sound familiar from your general relatively coarse. That something what einstein says when he invented the three of general relatively, that the geometry of spacetime is covered by the amount of energy in that region, broadly construed. Theres more math than that. Very quickly and so forth. This is einstein said equation but the more of this equation is the more energy of in the region, the more it curves the spacetime around it. What im saying it is rather than being einstein and positing that relationship directly, we can posit that the idea of geometry emerges from the quantum wave function and derived the fact that geometry is governed, is driven by the energy in the universe. We can hope to derive einstein secretion for general relativity from fundamental features in Quantum Mechanics. We can imagine alternate history were einstein never lived and we develop all quantum field theory and Quantum Mechanics and ever ready in many world formulas and we discovered general relatively just by thinking really, really hard about Quantum Mechanics. Now i know we are done. This is the end of it. Theres a lot that happened there, a lot of stuff went by very quickly picked my advice is [laughing] its explained in greater detail here but thats okay. If my goal were really to make you perfectly understand this, then i would be crazy because nobody perfectly understands this. Rather, i wanted to get you thinking in a new way, okay . I started by saying that physicists have been making mistakes for the last century and not trying as hard as they could understand Quantum Mechanics. Those with trying to let half of the century to quantize gravity without a lot of progress there. My particular strategy for reconciling these things may or may not work but do what you do is what everything you do for living, stop doing that and start trying to figure out where spacetime comes from in Quantum Mechanics, whether professional physicists or not you have a leg up on the professional physicist is they know too much and are doing the wrong thing and are embedded in that, okay . So were trying to think in new ways to get may or not work but it is our responsibility to figure things except because what matters is not actually making predictions or experiments. What matters is understanding how nature works and theres only one way to make progress on that and thats what i think we are doing. Thank you very much. [applause] thank you to sean carroll. [applause] something deeply hidden. We will come around and get your questions if sean will indulge. We were, what i eat side and dont forget the book is for sale back there where you are heading come and sean will be signing them after. You can even get them inscribed i believe. We will head down and take your questions. Should i pick people or do you want to pick people . You can pick them if you want. So the most agreedupon three of cosmology predicts that were fulsome praise can write . No. Go on. I can fill it in. Keep going. To my question was, does the manyworlds interpretation of Quantum Mechanics make this problem worse . Because now theres many quantum states that have many [inaudible] yes. For those of you who dont hang out on the wrong street corners, the idea of a boatswain for prit come if we live in the hightech sequel of a box of gas that lasted forever, i guess it is that atmosphere industry basically stays smooth and straight up in something close to equilibrium, but the individual molecules upon regret in random patterns. If we waited long enough, all of the molecules would move to one side the room. Or all of the molecules would make a little cat, or to make a little brain. So if the universe were like that, if the universe were number one made at a little tiny pieces that fluctuate around randomly, and number two, lasted literally forever, then over the course of eternity there would be random fluctuations and all sorts of things, planets and people, and the minimal thing that would count as a conscious observer would be enough brain fluctuations were adults were created that made to bring those conscious enough to go look remco empty space, then it would die. These are called the question is, theres so many more of those than the are of us, how can this possibly be right . People argue whats right and whats wrong with the short answer is, most people say, therefore, one of hypotheses is wrong. Even at the universe doesnt last forever, or the universe is not made of little randomly fluctuating things. Settle down to a true static back in space. What i i would say about the challenge of bolts and brains this is a to construct cosmological theory predicts that most living things are random fluctuation, then throw that one out. The point of of the ones that do that. As to manyworlds, doesnt make the problem any worse pick manyworlds is that the idea of the thing happens. If the idea the wave function as a base the schrodinger equation brick fest point things happen in manyworlds and theres even more things that happen with a very, very, very rarely. All the prediction for typical occurrence in manyworlds are exactly the same as it wouldve been in a in a single universey with truly random sarcastic brains. We have one over here. It occurs to me that you have may be discovered a new conservation law and that is conservation law of embarrassment. And the sense that the previous explanation seems hard to believe and so is this one anyway. So wouldnt it be easier to not let go of maybe schrodingers equation and try to think like classical a again next to get superseded . Can we think of the Something Else out there other than schrodingers equation that maybe makes less embarrassing explanations . Yeah, look, be my guest is the short answer. The little glib answer to that. Everyone in the world would be thrilled to find a version, a physical threat of fundamental nature of reality that we produced all the prediction of Quantum Mechanics without having extra worlds. Im not into the existence of the world. I i accept the other because my favorite physical theory predicts them but it turns out that constructing such another theory is hard. So its okay. [laughing] dont worry about it. Everything will be fine. Yes . You have to back electrons that came from higgs boson at untangle and pick for a partner you measure one and the other one has a certain date and thats like the spooky action. So they say. If the geometry is emerging because things are entangled with each other, so things are entangled a lot of closer together, thats how youre solving the problem. Like these things are entangled and, therefore, there geometrically close together. Us know. Its a very good question if i had more time i wouldve been more careful about this. The whole story of when things are more entangled their closer together is a story of the vibrational mode of quantum fields in empty space. Its not a sort of particles. Once you have two particles they can be equally entangled like this electron and positron, no matter how close or far away they are. But the number of things in the universe, the number of quantum mechanical degrees of freedom is overwhelmingly dominated by the degrees of freedom of empty space like him even at the center of the sun, like quantum field three steps, the center of the sun is empty space. The number of particles there is enormous and smaller than the number of quantum field modes in their vacuum state. So you first had this whole conversation weve been having compassing taken between modes and it is based and a version jump to spacetime and you can just tack articles on top of that. Thats a good district the bad is is it doesnt help you with any puzzles or stealing share the spooky action of distant quantum. You mentioned an order for a branching universe to be consistent with conservation of energy some property has to be thinner as a branch as i was just wondering what property you are referring to. I contend that. When the back in days when we believe the copenhagen interpretation . The probability of getting answer is the wave function squared. That quantity of the wave function squared over every possible outcome is the thickness of the prince. When you break into two possibilities, one over square root two, come to squared which is a half possible each you are splitting one the best of universe into two half thicknesses and so forth. This is the quantity which is over the evolution of the wave function according to the schrodinger theory. In Quantum Mechanics, is a such a thing as the clear dynamic death of universe . Sure. Are you waiting for the death of the universe . Yes, its going to happen. Most of the traditional productions of thermodynamics or so forth will be just as true in Quantum Mechanics as in anything else. It is relevant to the previous question about boltzmann brain. Not on expanding but excelling. It is acting out at a rate which we think is never going to go away. So the best current theory we have of cosmology says weve had 14 billion years in the past from the big bang and today. We have considered the years in the future. All of which will be a story of getting emptier and if you. So the universe go to a heat death and the quantum version of that is the universe will still down to its back in quantum state and it will just sit there quietly forever and there will be no living beings around to think about it and be set. So live your life now because you have not ten to 15 years left before the last star burns out. Sorry. [laughing] we have one over here. I was wondering what you thought of the von neumann wagner interpretation, and like broader, like the role of consciousness and experienced this in quantum physics . Right. So when i went back year, when he mentioned the puzzles here, one of them was is consciousness really part of it . In the textbook interpretation of Quantum Mechanics we are told there Something Special that when you observe, when you measure, when you look at a system, that sounds like consciousness might be involved. He took that to its logical conclusion is that maybe consciousness is really crucial to understanding Quantum Mechanics. Part of this, theres an old joke that the relationship between consciousness and Quantum Mechanics come from the fact that no one understands Quantum Mechanics and no one understands consciousness so maybe they are the same thing some of. Wagner tried to make it more respectable than that but honestly he later said he was wrong but he said that was a bad idea, stop thinking that. Any more people listen to when he suggested it and what he said no, hes wrong, stop thinking that. So there are still people who try to draw a connection between consciousness and Quantum Mechanics. Its not the craziest thing in the world because we have lack of understanding in both domains. But i think there is zero evidence that we should be connecting consciousness to Quantum Mechanics. Theres room to do because consciousness is complicated so theres no need to do it or anything we know about either consciousness or Quantum Mechanics. My question is do you give any i guess do you entertain any simulation three possibilities . And do you think the nature of Quantum Mechanics could increase the probability that this is a relation because you could i guess conserve large method information without having to render everything and do you think much larger scales, do you entertain the possible . Its the ideal look, were building computers. Theyre Getting Better and better. Well get Artificial Intelligence at some point. You could imagine that we will build computers are so good that there are little artificially conscious creatures in the computers, not knowing that we exist, right there just talking to each other and living their lives and for all possible criteria we would count them as conscious and then you go my goodness, maybe thats me. Maybe im a little creature and someone elses computer and the fact you might imagine both living creatures in the universe are in a simulation and, therefore, probably we are. I dont buy it that i think that to the extent you would have predictions for what the universe would look like were we to live in a simulation, those predictions do not come true. But its possible. I certainly am open to the possibility of it. My personal feeling is that it has zero to do with Quantum Mechanics. I think that if i were simulating things i would just make and classical. Really the best way, you know, the information you need to keep about a quantum state with all these entanglements between all these different subsystems is enormously bigger than the information you need to keep in the classical state. Thats why Quantum Computers might be much more powerful than classical computers. If youre only criterion was saving cpu cycles into a a simulation i would not do your selection of Quantum Mechanics at all. We have one in the center here. Thank you very much for the talk. The two puzzles you mention where one was a management problem and the other one was where do we find the classical world in Quantum Mechanics. I do all the statistics and i thought of an analogy which is probably wrong, just understand congress to white trunk. With respect to the measurement problem when you do something simple like a survey, we have a point estimate and theres a constant arent we dont consider that controversial but we just think thats an extensive we dont think theres thousands of other worlds in which they could be different. Why is that the incorrect analogy i can we to just say te same thing about the wave functions where sampling . And your second point about what was on the classical world, again, in probability to read the measure phenomena. Maybe the classical world is just infinite samples world and so thats what it appears so stable. Thats a very natural way to go and thats on the lines of thought that einstein wouldve been thinking back in the 1920s. It doesnt work, lisa does work and most straightforward ways. The easiest way to see that is that the probability of getting an outcome is not the wave function. Its the wave wave function sq. The wave function can be negative picky can even be a complex number and you might ask yourself, why do we need to bother with the wave . It is the wave function an interview with itself. Different parts of the wave function can add up either constructively or destructively. A true, simple probability is a set of numbers that are nonnegative. Probability distributions dont interfere with each other but in quantum experiment is easy to see the wave function interfering with itself. That is the first clue the wave function is not just a way to get a probability distribution. Its really real in some sense. There are plenty of people who still try to avoid this conclusion. Im a path of least resistance kind of guy. I had a question, you were saying that you really think that things are splitting off based on different actions that might take place. Im wondering if you visualize with your own life that there are other versions of your life taking place, and what the impact is i mean, you seem very you know, contribute your ideas and stuff, but is that something that could freak people out or could it make their lives better . Like, if this gains if your ideas gain more cultural attraction what is the impact of that . So my own view is freaking people out is not a bug, its a future come in the sense that what were trying to do is understand reality at its most fundamental foundational central piece. What weve been trained on is our everyday experience, which is a tiny insignificant sliver of reality. Its been expanding our view of reality and the total story we tell about reality becomes weirder and weirder. Because its intrinsically weird but because it is further and further away from our everyday expenses and intuition. So the fact that the manyworlds formulation of Quantum Mechanics predict something that is so weird and freaking out, i think thats good. I think that says all right, if nevertheless, despite the witness this is the best fit, the simplest theory that fits the data, thats the reason to be like pro that degree, not against it. Of course, it is free to do. Of course it does. What are you talking about when i was a kid when it first or think about cosmology the thing to freak me out is what is the universe has never existed . Thats what we keep me up at night. I do know the answer to that. Yet get there other versions of me that hop right and so forth, its hard to get it right, its hard to come up with exact right way to think about these Different Things but it dont think its existentially worry. I didnt know there were any. You used this concept to construct the concept of space. How would you use this concept to construct the concept of time . Oh, thats a whole other lecture, the concept of time. Very good. Einstein says that gravity is the curvature of space and time and the fact that space and time are two different aspects of one underlying fourdimensional thing. The thing i talked about constructing or merging out of the way is really space. Now, there are ways you can also get time to emerge and the short version, again, you use entanglement. What if time wasnt real, what if it had to emerge. What does it mean . What it possibly means is the subsystem of the universe and tangled with the rest of the universe and has the property that the subsystem acts like a clock. Depending what the subsystem is doing and measure it to be its entangled with something the rest of the universe is doing in such a way that its as if the rest of the universe is evolving with time according to what the clock actually reads. So it can be done, but its know the at all necessary. Its entirely possible that deep down base and time are different from each other and the fact that they appear to be part of one underlying fourdimensional manifold. To us its a phenomenon in the macro scopic world. Its the kind of thing we should have figured out 50 years ago, but are still just tackling now. I think were going to give sean carroll a break on the public questions now, but hell sign copies of something deeply hidden and signing. Hell be signing the book and you can get it inscribed. Thank you. [applause] book tv has live weekend coverage of the southern festival of books from nashville, tennessee starting saturday at 11 a. M. Eastern featuring Chris Edmonds with his book no surrender, a good provider is one who leads, and paul with his book, and a memoir how we fight for our lives. It continues on sunday at 1 p. M. , and Susan Niemann discusses her book learning from the german, former ambassador to the United Nations Samantha Power talks about her book. And david cady, religion of fear. Watch our live coverage of the southern festival of books starting at 11 a. M. Eastern saturday and at 1 p. M. Sunday on book tv on cspan2. Today the center for Immigration Studies hosts a discussion on two reports. Examining the cost of Health Care Benefits to illegal immigrants. Live coverage begins at 9 30 a. M. Eastern on cspan2. Yesterday vicepresident pence visited iowa and made