Science club north. For anybody who is a first timer for secret science club events we are a series that brings scientists of all disciplines out onto the public stages where they can be part of the cultural life of the city and for people like you can, and interact directly with them and be informed at the same time energized by scientific ideas and discoveries. A regular hangout is that the bellhouse in brooklyn. [applause] we have got the bellhouse fans, very nice but secret science club north back here tonight for the kickoff of our season here better fit for many seasons for the secret science club north. We are also happy to kick off the season right behind the new republic as always. We want to thank the staff particularly kathy landau joined the thompson and darren criss the Rebecca White and merry meet for helping us in that. They are the best and the very special thanks to the bar for creating the quantum cocktail exhibit a. It has in it Bourbon Maple syrup and a topless women. Very delicious im here to tell you when you can get it at the bar is off to the left there. Now is the time to go and do a a pretty want to give a heads up that is part of her many seasons we will be back december 3 with astronaut kathy sullivan, cat tom sullivan. She is a former nasa astronaut the First American woman to walk in space and also a former direct your of n. O. A. A very timely. You might have read some of her thoughts yesterday in the paper. If youd like to know more about the secret science club and her Upcoming Events visit our web site at secret science club. Blog. Come. We have a blogspot. You can sign up for mailing lists there. On to tonights event first off we want to say our wonderful speaker today theoretical physicist sean carol has a new book out and affected came out today and thats why he needed the quantum cocktail. Its a book party. The lovely folks at nyc are our booksellers tonight and sean carroll will be signing copies after his talk and q a with you our wonderful audience. We are pretty excited to have sean carroll with us tonight and we are also excited to have a very special guest to introduce sean carroll. Brian green is a physicist, a mathematician, professor at Columbia University and your other center for theoretical civics. Hes also a playwright sometimes an actor in the bestselling author of several science books including the elegant universe in the fabric of the cosmos. He is hosted to Emmy Awardwinning miniseries based on his books. He is also the founder of the world science festival. Please welcome dr. Brian green. [applause] thank you. Thank you very much. The quantum cocktail. I was shocked that i did not follow up i sang you get it at the h bar. I will leave now. Youve been a great audience, thank you very much. Tonights focus with sean carroll is on Quantum Mechanics and as i think many of you know in the early years of the 20th century we have a wonderful quite straightforward understanding of the universe are classical physics, right . Tell me how things are today and i use the questions of newton or the equations of maxwell or even the equations of einstein to figure out what they will be like tomorrow. Then it all changed. The early decades of the 20th century beginning with the work of einstein himself. A paradigm change and now the new way of thinking about the world is you tell me how things are now the best we can do is create probability of what they will be like tomorrow. That was not an easy transition for physicist in that era to take on board. It was an emotional upheaval for many of them to make this transition but heres the thing. Sean no doubt will describe for you in more detail the laws of Quantum Mechanics even though they were problematic can be in use to make predictions. Decimal point digit, due to downward nine or 10 decimal places in that agreement between theory and experiment is so potent and so powerful that people begin to stop thinking about what the theory actually means and at what it us about the nature of reality and they used it as a wonderful structure to make protections about the world to begin to control the microworld and all the wonderful technological gadgets that we walk around with all the time. In fact its more than that. It got to the point where anybody who really is a physicist want to think about the meaning of Quantum Mechanics and what it was really telling us about how the world works, they were looked on as somebody who had lost their way. It wasnt something that we were supposed to do. There are a few people who say that and im trying to figure out in particular how we transition to the definite reality that we all experience in many ideas were put forward, wild ideas. In fact sean is going to talk about perhaps the most wild of those ideas the possibility that we are part of a multiverse, many worlds, parallel universes. A very strange idea but i will say this. Ever since the events at least i have found in talking about this ever since the events of november 8, 2016 people have a much easier time understanding the concept of a parallel universe. And without a gives me great pleasure to introduce tonights speaker. You all of course know him from his many bestselling books on the nature of time and the hicks particle, the nature of reality. We physicist known love sean is one of the great leaders and pioneers in understanding cosmology and quantum physics. Tonight you will have a great trees here from one of the profound thinkers who are willing push in the meaning of quantum physics to figure out what its telling us about the nature of reality so please give a warm welcome to my friend and colleague, sean carroll. [applause] thank you brian. Who do i need to thank . Thank you secret science club. Thank all of you folks for figuring out the secret and figuring out you can come here. I dont know how that happens but im happy that it does. When you become a physics professor they teach you that what you teach other people even if its an abstract physics concept its best to do demonstrations and bring it down to earth. Im going to start by doing a demonstration. Im going to push above, i phone which will send a signal over the internet so laboratory in switzerland will send a photon particle of light down the tube and it will hit a splitter and go either left or right but 50 50 probability and depending on whether its observed to go left or right the signal will come back here and it will tell me whether i dashed to the left or the right. Here we go. The photon is amended. The universes are split. Ready . Thats the demonstration. Thank you. Why is this demonstration worth anything at all . Its because in my favorite version of Quantum Mechanics the many worlds of Quantum Mechanics which i will tell you about it protects and i actually believe it is true that there is an entire other reality where i hop over there and the person standing right there theres a different version of me that did something different. Like i said i actually believe this is true. Now what you should be saying is what kind of crazy person would leave this is true . That is why we are here, to figure it out. Let me see if i can do the technology. Technology is a good thing. The reason why we are talking about these things is because Quantum Mechanics is brian alluded to to is anonymously successful. We needed to understand lasers and transistors, particle physics why the sun shines and even white chairs and tables dont collapse. But as my illustrious predecessor at caltech says Richard Fineman i think i can safely say that nobody understands Quantum Mechanics. They usually dont like to appeal to authority but by bringing up other physicist but when the claim i am making is that nobody understands something the person who understood the thing the best is a Good Authority to say that nobody else understands it anyway. How when the world can it be possible that even though we use Quantum Mechanics to make these predictions someone like Richard Fineman who says we dont understand it. Because we can make predictions but if you ask the professional physicist what is going on, what is the reality its predicting they will say i dont know. In fact they would say i dont want to know. Who cares about reality . Im a physicist and we make addictions. This is a terrible attitude and he should be embarrassed. Wasnt always like this. No one would have said this 100 years ago but only since Quantum Mechanics came on the scene that people are tempted and single only reasons for physics is to make addictions and not to understand how nature works to give them we dont understand Quantum Mechanics what you would imagine a since Quantum Mechanics is so important the path to understanding Quantum Mechanics is the most important thing of all of physics. The people who specialize her superstars of physics. We have in the room tonight several of the worlds leaders in understanding the foundations of Quantum Mechanics. These people could be millionaires and living in penthouse apartments. They are not. They are great people and they are underpaid and undervalued. Its not only that we dont understand Quantum Mechanics, its that we havent even tried. There are complicated complicated set of reasons why but thats for a different talk. Right now i want to remind you of aesops fables. The fox season grapes and once the grapes that are juicy and delicious and pops up trying to get the grapes that they are too high in the fox cant get them so the boxes you know what why but i didnt want this grapes anyway. They are probably sour. In case the parable was not perfectly clear the fox represents a physicist and the grapes of represent understanding Quantum Mechanics. We tried and we couldnt do it so we said we never wanted to understand Quantum Mechanics anyway. Until tonight. Everyone is going to understand Quantum Mechanics. Im going to do a very whirlwind tour of why we came up with Quantum Mechanics in the first place and white let us to these crazy suppositions that im going to try to entertain not particularly accurate. History is messy and we dont have time for that stylish tell you when and relatively brief period of time. Scientists are putting together the picture of the atom. Everyone has seen this picture. The picture of an atom. As a nucleus, theres a center and today we know the nucleus is made of protons and neutrons. They didnt know that. They knew there was a nucleus and orbiting around, orbiting around the nucleus like the planets orbit the sun are these particles called electrons. It also cannot possibly be right the reason why and brian mentioned before Quantum Mechanics came along we had a theory called classical mechanics. The theory that was given to us by isaac newton and his followers and the classical mechanic makes the prediction that we take an electron charged particle and send it around in circles are jiggling up and down it emits radio or infrared or physical electromagnetic waves. All the light you are seeing comes from electrons jiggling up and down so here you have electron zooming around being accelerated. They should lose energy and what they should do is according to classical mechanics they should spiral into the center and collapse into a nucleus. The timescale for this to happen you might say doesnt take a longtime . Less than a pico second which is a very sharp period of time. So if you the chair youre sitting on an everything you see in the world would collapse. It would collapse into a black hole. Apparently doesnt. Scientists had a gut eerie it was conceptually completely inadequate family needed to do better. It was hard to do better. Theres a long set that im skipping but eventually they came up with the following radical idea. Maybe electron is not a particle. Maybe the way to think about electrons is as waves, not as particles. There was previously a long debate about whether light is particles. Someone said the electron is a particle. It is wave flights in certain way. We call the waves to represent the electron the wave function the least romantic name but thats what we called it. We said there is a wave that spreads out around the nucleus concentrated in the middle and then it fades away and basically you can do the math problem saying what is a different way that unlike tom wave can settle down into an atom. Even though the wave itself is energetic waving back and forth there are certain discrete very specific shapes the wave can have where it has a specific energy that can just sit there and not change. The electron settle into this data and i think this is the only time the talk i will tell you any data. This is the picture of an electron around the helium matter where its located. Its not in some simple elliptical orbit. Spread out to what we know call the wave function. This way of electrons dont behave. They arent actually moving but i want you to think as electrons is not a little point of the circle. It really is this function, this cloud, this wave and the wave can be static and unchanging and thats why it doesnt radiate. Thats pretty good tree thats progress. More progress can come years later as an equation. I need to show you the equation because of the quiz we are having at the end. You are going to have to solve the quiz with boundary conditions and i hope everyone is happy with that. Conceptually its not that hard. Conceptually the greek letter pi indicates the way it functions and on the left you have a question that is asked of the wave function namely how much energy does he use . On the right you have an answer which says how fast are you moving . As a typical wave function will have a different part to it which has different energies the equation simply says the highenergy parts change rapidly in the low ngugi parts change slowly. What matters is the arizona case equation. Scientists love equations and physicists love equations. An equation is full employment for scientists and the student who do the homework in solving the equation. The equation says now that i know this particular circumstance of i can figure out what the wave is in any situation. It gives scientists the ability to say how things develop in time. Everything is looking good except for one obvious huge somatic flava says when you look at what comes if you are not hightech and this is a very recent picture of reconstruction based on delicate stuff usually when you look at electrons they dont look like waves. They look like particles. This is actually a movie of a chunk of uranium that is radioactive soot emitting particles and this has been a Cloud Chamber which means when a charged particle sees a string of opals every one of those little lines it created is the result of a charged particle being emitted by the radioactive uranium. I showed you mostly because its cool but what i want you to learn from this picture is the prediction of the equation is when the uranium atom is hit with regular tivoli is embedded in a spherical shell that goes off in all directions equally. Its not what you see when you look at it. What you see is a little particle like saying. Thats why we call them particles in the first place. And on the right and then take a picture of it, you dont see that cloud and then a particular location burqa why is that . The measurement process so there is something that happens this is what was figured out thats what they told themselves in 1926 to 28 people. It was codified it was the copenhagen interpretation and this is what we teach our students today. There are two sets of rules. And if youre not looking at them then they do another kind of thing and the probability and near the peak is relatively large this is what we teach our students. And it is Utter Nonsense and clearly unacceptable this clearly cannot be the right answer i will highlight two of the problems one is the oncology problem. To talk about what it is real. Not just what you observe but not observing and then we slid around on that question. That is that function with the reality is is that only part of reality . Has nothing to do with reality to do all these things to do not agree and then the measurement problem what do you mean . Looking at things changes them what about something nonliving quicksort video camera . In the agency and consciousness from those that believe all of these things so there is a problem so what are you going to do . There is wellestablished tradition of highlighting and never telling you how to get it right and a graduate student in 1957 and what he said was you are working too hard. So chill out a little bit. Okay . We have some good look one dash looking rules. So they obey a lot of the time clearly the most straightforward thing and what it does is obey the equation all the time naturally he left academia right away because it is interesting and they said no its not. So here is the interpretation of Quantum Mechanics. There is one set of rules that applies all the time no matter what is happening and through every other theory of physics general relativity positions of momentum or fields and they are to the equation and all of this stuff of Measurements Get rid of it. You dont need it. Okay. So that stuff about measurements you follow the picture with the particles. With that version of Quantum Mechanics to possibly match our experience. Now here is a little feature called entanglement. So now to put it into modern terms i also wrote a book about take out your phone right now to order that. Thats okay. But the only particle we have ever detected that has zero that has zero it is very much similar to the spin of the earth so the spin is zero. So one way is that the electron and positron. And then to spin one half so it must be the case that the spin of the two electrons cancel out from each other because a has to add 20. So the electrons spin up or down electron number two could be up or down but they must be opposite thats what we know. So the way that happens in Quantum Mechanics is that into a superposition and there are two possibilities. Either electron one but its not that we dont know just like one electron with its function to be spread out so what this means that the quantum wave function that the two electrons are entangled with each other. We dont know if that is spin up or spin down. But if we look at the spin of electron number one we know number two will be the opposite so they have to cancel each other out. So they are not separate from each other. And with Quantum Mechanics there are not separate states for individual parts of nature. There is only one wave function of the universe and it describes the probability of measuring everything all at once. You may think we are trained for classical physics that Quantum Mechanics says there is the wave function of the universe and the combination the possible answer from one particle related to the other. What does this have to do for her measurement . And with that thought experiment. And with that radioactive sort and then there is a Geiger Counter and it is particle there is a probability that it clicks and when it does it opens the box and gas will come out and then it is poison gas and then to save my father just did not like him. [laughter] so i see no reason to kill a ca cat. So theres a happy sleeping cat so if you have not open the box by the way should injure did not like cats he like the equation but at the time he did not have the interpretation about the probability. That is what his own equation was for. He did not return the nobel prize. He kept that but according to my equation if the wave function was not enough the wave function of the box the wave function of the cat in the position to be awake or asleep. So as a result to see whats really happening so use this with classical physics and Quantum Mechanics. I know this is everyones favorite part. So that means they are classical with definite value and in parentheses they are quantum so practically the cat is alive or dead or awake or asleep i do not know but there is a fact of the matter it is awake or asleep Quantum Mechanics says no there is another set of possibilities besides awake or asleep so if you take a little bit of Quantum Mechanics as an undergraduate. You are taught there are quantum mechanical systems that then there are classical observers that lives in a classical world to observe things to have definite values that justification is you thank you know whats going on in the world. There is something definite about you the godfather of Quantum Mechanics. And then to play the role of the observer so the textbook version you open the box the wave function of the cat would collapse and either they cat is awake or the cat was asleep. There is no collapse in only one wave function that includes you. There is no classical observer or dividing line. And then you can be in superposition. Everything is in parentheses. But then they open the box to do anything mystical or a consciousness it just means i saw the schrodinger equation and to do outside the box are inside the box and then to obey at all times. So it is a schrodinger on would injure equation predict if i open the box . If it is entirely awake you would see the awake cat if the wave function was entirely asleep you would see the asleep cat and thats all you need to know what you would need namely the wave function of the universe is the cat awake but its asleep nobody in the world disagrees of the schrodinger equation they may disagree if they should be using it this is why nobody believes if you disobey and you follow that sounds like i observe quantum things before hop right hop left there was some different fact of the matter. That he really didnt have any rights so the real reason it makes Quantum Mechanics respectable is the idea of decoherence which was in figured out until the seventies and eighties but how to think of Quantum Mechanics there is only one way function for the entire universe and noticed he did not include the entire universe. What about the rest of the universe . Technically we should put them in you may think that doesnt matter but we call the rest of the University Environment that is a technical term to mean the entire rest of the universe that we are not keeping track of everything so we are in a room with lights and photons and molecules in the air i dont know the polite velocity and position of every adam i would even know if they changed it inside and outside the box if that starts out it interacts with the environment right away before you open the box with the state and that system becomes entangled with the environment. So that way function is in that superposition so was the cat awake then you open the box that is the measurement process so this is a true wave function of the universe and then the cat is asleep so why does that matter in the slightest because they keep the environment in their. It has nothing to do with the human being or with a video camera or an earthworm. And then to become entangled with the outside world to become entangled with the environment. And when that happens so the person is there a whole other way function and then to be respected by the other part of the way function and the answer is no it is so dramatically different that this part of the way function is not affected by the second part of the way function so of that movement according to the schrodinger equation it is as if it becomes separate worlds and you know what we should do and also theory of the universal wave function but now the problem is that many world interpretation that i am adding extra worlds to Quantum Mechanics but at no point did i add that was just according to the schrodinger equation. Now another physicist once put it every other formulation is a disappearing world formulation to say the world is there and thats okay. Now there are many questions about the details like how many are there cracks thats all i can say there could be an infinite number of worlds but we dont know thats part of the embarrassment over the last several decades we have been doing the work we should be doing. Trying to understand Quantum Mechanics and then just the finite number so time goes from the bottom to the top because then people get worried like energy conservation. It is like there is the existing amount of universe there is the lift of the universe that is according to the schrodinger equation but when it splits it becomes thinner and thinner to also the utilitarian greatest on greatest good for the greatest number to split the wave function of the universe you should not do that it should be balance that you make it thinner and thinner. It is happening so often and frequently and then it radioactively decays inside your body but then you make 5000 more universes to to the power of 5000 every second. And also contributing to the splitting and thats what you did. So how do you think of this as an ongoing constant process . No worries. There is plenty of room for all the universes. Thats not really what i want to talk about but the prospect of the good news that once we start thinking then it will help us to answer other questions. Lets get some objections out of the way very quickly. That is too many universes. Where we put them all . I already answered that. The same amount of quantum mechanical stuff every other interpretation for a very large number of universes if you believe they are wheel on real theres a position for many different possibilities you might also worry it cannot be tested even if you read as smidgen of science of the scientists, bless their heart and they only read one but they read what he once said that needs to be viable and then to say i can imagine an experiment that would show me that the theory is wrong. Not that it is but in principle is falsifiable. So that was a good attempt of the details. At that naive level is not the objection for Quantum Mechanics by the existence of all these other universes but its not the other universe but there are wave functions with the shrewd injure equation all you have to do is show that way function even though it is entangled with anything else there are other alternatives too many worlds that predict there is different physical consequences one of those interpretations is the copenhagen interpretation he had his own interpretation that did not go very far as it is he wants the theory to be someone to emphasize we are not done we havent done the work that we need to do so happen the the sixhour club with all those other interpretations but now i cannot do that but i will tell you i say there are two of them one of the worries why do we get probability in this theory at all . In the copenhagen interpretation when it collapses with a certain probability they say there is the equation there is nothing probabilistic about it so why is there any talk of a probability of an outcome of a different measure . The other is how does the classical world emerge cracks its much more interesting problem that very few people paid attention to so to live in a classical world then we need to do better and then we can learn something so for probability part of the answer is to be perfectly deterministic it is not an element of the dynamics but what brought this epidemic of our ignorance is to use probability talk but there you are wrong that is the interpretation even if you know that exact way function there may be something you are ignorant about that thing is where you are in the way function. The observer the environments so the cat is entangled with the environment so the observer has not yet become entangled but the observer has not yet so you can still treat that is two different branches of the wave function but on those two bridges the observer does not know which they are on first there was one now there are two. Neither know so even though they know the perfect way function of the universe the best they can do is to say i dont know. There is a probability but then you say what is that and then you say thats from back in the 20 of the wave functions scrape on squared. But thats okay now they can cite my papers they disagree with them that is the scientific method. [laughter] so now to be richer is to find the classical world this is one of the things where there is a problem so here it is. I see it. Classical world is all around us. Thats because its very very natural as human beings to see the world classically. Went into privilege what we see its not the dumbest thing in the world if youre out there hunting your lyons than it you necessarily wouldnt be selected away. [laughter] so we tend to privilege what we see and weeds of grass and people and then we do what is called quantitative easing it and there is a set of rules to invent the wave function and mathematically have a little threedimensional space but thats what it is. So what we do every day presumably in the real way to think about it and to start with the quantum system and that is classical mistakes and to think about what its doing and to say yes. So that is super hard. So we are just beginning on this path on this way forward most is done with the idea with that space that we live in east so enormously special that things bump into each other the same location and space as einstein said if you want to communicate you actually cannot teleport. So after all these are just quantum states there is a week plus asleep there is another form from all the different combinations. We only ever see awake or asleep it is a preferred state. Why is that . And then the photons bump into the cat what do they bump into . And if they bump into the cat differently . Here is a picture of photon of the cat if it was awake but would miss it if it was asleep. The way the wave function branches is into definite physical location because that is how interactions work they pick out locations in the world. So even if i handed you a very abstract function and said what is it the first thing you do is say can i divide this up into pieces some of which interacts in some dont then the rest is nearby in space so you can imagine building up just the way that it evolves over time that it has given us to face a prerequisite and that the world plays out so rather than saying interactions are local in space but to think those are in. A set of variables and the other thing we know about space is it is curved. Everybody shows pictures of einstein but as a young man to say he was very smartly dressed. And einstein has this idea that when you think of the gravity is a manifestation of the curvature even if its a stage it is a player in the game to matter and energy and then to do orbits around the sun for what they do in the presence of gravity. But the problem is it is one part of our current understanding that we havent made fully quantum mechanical. Everything else has good quantum mechanical theory. So the theory that works for the moon revolving around the earth but not anything else that the reason that we have it if you find the quantum theory of gravity as it starts with einsteins classical theory, i think thats a mistake but to find gravity within Quantum Mechanics. So why in the world should we not be surprised when we dont even understand Quantum Mechanics maybe we are so lucky we find electromagnet magnetism and so forth so how do we do that . But we do need to get some hints of what we know works. So the best current understanding of non gravitational physics. So to say its not even the particles and what you think of as a particle but just to be more energetic than you thought it was so from the particle point of view you may think it is empty space but where it is happening the quantum field theory is that something is happening everywhere. So they are fields that are vibrating and we can characterize those vibrations a certain way and if you take it and vibrated more than it was like a particle. So the same story of those predictions but a different oncology and looking at the world so these world regions of empty space some of course they are there are entanglements everywhere Quantum Mechanics. And theres nothing there is empty but there is so many on little that are entangled with each other in nearby regions of space to be highly entangled with each other and distant regions only a little entangled that is as they know it and as they use it so i want to turn it around and we dont know the geometry of the universe to define distance with entanglements that is a function of the wave of their own life from the preexisting classical conception this is a preexisting classical conception and of that quantum wave function that they are very close by if they are entangled if you can imagine doing that and with that if i know the distance of any complaints in space of the triangle and the angle in the geometry of space this is chutzpah. This is a hypothesis of exploring the consequences but extracting geometry from entanglement. There is something we know for sure but the version of entropy has properties so the hungarian mathematician shows when two systems are entangled with each other either one separately you can look at entropy how much you dont know so when those two systems are entangled one isnt all by itself so we dont know what they say but its true so its like it is an analogy to be super entangled to be quantified with that amount of entanglement. So finally so with the quantum field theory you pick out this quantum field and also broken the amount of entanglements with the rest of them around them see you decrease entanglements and you increase the entropy and you increase the energy. Another equation that i will not tell you but there is relationship between the amount of entanglement. Now here is what we learned. Is the relationship between geometry and entanglement because we think it would be cool if space emerged from each of these functions and there is a relationship between entanglement and entropy and the relationship between energy under the right circumstances. Therefore there is a relationship between geometry and space and from those general relativity courses. And when he comes up with the theory of general relativity that is governed by the amount of energy to be broadly construed with greek letters and so forth this is einsteins equation so the moral of this equation is the more energy so what im saying now so with this relationship directly we can become positive that the idea of that quantum wave function with the fact that it is the energy in the universe but for general relativity and fundamental features of Quantum Mechanics and all that quantum field theory and then wed escort one discovered general relativity. So now i know we are done, this is the end of it but there is a lot that happens and it comes by very quickly so my advice is. [laughter] it is explained in greater detail here. But thats okay. If my goal was to make you perfectly understand this that i would be crazy because nobody perfectly understands this. I want you thinking in a new way. Physicist have been making mistakes for the last century. So without a lot of progress there. So this strategy that may or may not work so whatever you do for a living, stop doing that and start trying to figure out were space time comes from an Quantum Mechanics. [laughter] dont know professional physicist they know too much and they are indebted. So were trying to think in new ways that may or may not work but that responsibility without actually making predictions for experiments to understand how nature works and then to make progress on that. Thank you very much. [applause] now we will go to questions. The book is for sale. And sean will be signing them after. The most agreedupon theory of cosmology predicts. No. But keep going. So my question was do the many worlds of Quantum Mechanics make it worse because now there are quantum states quick. Yes so if you dont hang out on the wrong street corners the idea is we live in the high tech equivalent of a box of gas that lasts forever basically it stays spread out with equilibrium but then coming around in random patterns all of the molecules go to one side of the room so if the universe was like that or was number one or that we lasted for ever, then over the course of eternity there are random populations that would count as a conscious observer but that was conscious enough but then it was done. And the question is there are so many more so how can we possibly be right . But the short answer is most people say therefore one of the hypotheses is wrong so what i would say about the challenge is the guideline to constructing theory that most living beings so that doesnt make the problem any worse its not the idea that everything happens its the idea there are plenty of things that dont happen and even more things that happen very very rarely. And with all of those predictions for a world and the things that they would have been in a single universe theory. It seems to me you have discovered a new its hard to believe and then to be superseded that there is Something Else out there. Yes. Be my guest. [laughter] so everyone in the world would be thrilled to find a version the physical theory to reproduce all the predictions i am not into the existence of the world. But it turns out disrupting such another theory is hard. Dont worry about it. Everything will be fine. So if geometry is emerging that is how you are solving that problem are they geometrically held together . No. Because the whole story is the vibrational modes its not a story of particles that is not equally entangled no matter how close or far away but the number of things in the universe with the degrees of freedom but even in the sense of the sun and the particles there of those quantum field modes. With those modes of empty space so thats a good news so the bad news it doesnt help with those feelings you may have. You mentioned with conservation and energy so what property are you referring to quick. Remember back in the days of the copenhagen interpretation the probability of wave functions squared over possible outcome so when you branch into two possibilities so then you are splitting one part of the universe so this is according to shorting jurors one shorting others. So with Quantum Mechanics and the universe quick. And of those dynamics it is relevant to the previous question and it is emptying out at the rate we think will never go away and to have 15 billions from the year infinity years in the future so the quantum version of that and to sit there quietly for ever so now only ten or 15 years left. So i was wondering so of that interpretation and that role of consciousness. So when i went back here one of them is consciousness part of that . So we are told that sounds like it might be so another noble one nobel prizewinning physicist that it is crucial so part of this is an old joke that Quantum Mechanics comes from the fact nobody understands Quantum Mechanics. They tried to make it more respectable than that but said that was a bad idea stop thinking that. Many said stop thinking that. There are many people who tried to draw connections its not the craziest thing in the world with a lack of understanding of both domains but there is zero evidence and theres room to do it because consciousness is complicated but theres no need to do it by either consciousness or Quantum Mechanics. So do you think that nature increases the possibility because large amounts of information with a much larger scale quick. So yes with that hypothesis we are Getting Better and better you can imagine we would build computers that are so good that theyre just living their lives in all possible criteria but then you say oh my goodness maybe thats me and then in fact you might imagine i dont buy it to that extent we have predictions for what the universe would look like that they do not come true but it is possible i am open to the possibility but my personal feeling that i would just make them classical the state of all these entanglements that is like Quantum Computers so if youre only criterion was and i would not use that at all. Thank you for the talk. Where do we find the classical world . I do a lot of statistics so im just trying to understand why. So if we do something simple like a survey but we dont think that there are thousands of others. And then to the second point of the classical world and at the classical world and thats why it appears so stable. Thats a way to go and that cell lines of einstein was thinking. In that probability of getting an outcome the wave functions squared so why does this work with the probability and the answer is the way interferes with itself to add up constructively or destructively but the true simple probability distribution there are numbers that are not negative. We dont disagree but it is a wave function. But that is the first clue its not just probability but it is real. So i have a question so that things are splitting off with different actions. So im wondering if you visualize there are other versions of your life taking place and what the impact is . If this does gain cultural traction. That is not creeping people out it is a feature so what were trying to do is to understand reality of a post fundamental feature in what we have been trained on of the everyday experience to expanding a review of reality and that becomes weirder. And then to predict something that is so weird, i think thats good nevertheless this is a simple theory must be pro not against it. And when i was a get is first started to think about this what freaks me out what if the universe never existed quick stats what would keep me up at night paraguay didnt know the answer but there are other versions of me but its hard to get it right it is almost a theorem that how you should live your life in this view of reality. We have a centrist back here. Use this concept to construct the time a space what about the concept of time. Thats a whole other lecture but the concept of time. But you did test me. Very good einstein says the curvature of spacetime is that they are two different aspects of one underlying dimensional thing but that thing that i talk about so there are ways to emerge in the short version is entanglement what if that was . What that could possibly mean there is a subsystem and has the property that acts like a clock depending on what its doing to hold up to what the universe is doing in such a way according to what the clock actually read so what can be done it is entirely possible and they are different that they appear to be that manifold to go on in that type of world. And natalie are tackling right now. He will be signing copies in the back talk to him there. Give him a hand and maybe next time hell come back to talk about time. [applause] you can have it signed and inscribed