#1352 - Sean Carroll

Sep 16, 2019

Sean Carroll is a cosmologist and physics professor specializing in dark energy and general relativity. He is a research professor in the Department of Physics at the California Institute of Technology.His new book "Something Deeply Hidden" is now available and also look for “Sean Carroll’s Mindscape Podcast” on Apple Podcasts.

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The Joe Rogan Experience trained by day Joe Rogan podcast by night all day

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hello Sean hey guys thanks for being here again man I really appreciate it so over the weekend I got in your book whoo yes yes it's great thank you I mean I really appreciate someone like you who's trying to break down quantum mechanics and quantum physics for someone like me it's very hard to follow and there was a lot of backing up and trying it again and backing up and try it again and like going over paragraphs and trying to figure out exactly what it means but it's it's really excellent and really perplexing at the same time well thank you and you know it there are different styles when it comes to writing popular books I think there should be different styles and my particular style is look it's not going to be a breezy page-turner but if you read it carefully like there's not prerequisites you don't have to come into it as an expert what do you have to come into it is someone who's willing to sit and think about every paragraph and then hopefully you'll be rewarded

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truly understand what's going on after doing that well it is rewarding because it is fascinating and the history of quantum physics is also pretty fascinating cause I've always wondered like how did anybody even want to come up with this stuff like the S and the fact that it was so long ago those what the beginnings of it were the 19th century night well 1900 is the typical literally that year the turn of the century when box plunk first cut the first hints of it and then yeah it was took another 27 years to put into final shape now for regular people that don't have a background in physics or the don't this is like the whole idea behind it is so bizarre it's like why would anybody try to figure out something that one of the things that you said that's really interesting is that you quantum physics is used all the time it's used with exact calculations but yet

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we don't really understand it yeah yeah no that's the main message of the book really because physicist of course do quantum mechanics every day whether it's you know straightforward quantum mechanics Quantum field Theory Quantum information Quantum Computing clearly we're pretty good at it you know like transistors and lasers depend on quantum mechanics the sun shining figuring that out depends on quantum mechanics the Higgs boson etcetera so to claim that we don't understand quantum mechanics is a little bit weird but then we have quotes from people like Richard Fineman saying nobody understands quantum mechanics right and so if he says that then there's some Authority behind it and the reason is what we have is some sort of a black box right we say you know what I think what I said in a New York Times article I wrote recently is physicists understand quantum mechanics in the same way that someone who owns a smartphone understands the smartphone like they know how to use the apps they can call people they can make phone calls they can take pictures they don't know what's going on inside and that's physicist with quantum mechanics

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State they use it they can make very very precise predictions but if you ask them what is really going on like what is actually happening what are all the details are like you know that's not our job let's just stick to prediction but to someone like me that's so terrifying because like the very nature of reality is being examined by people like if if it is US of smartphone it's being examined by people like me yeah who don't really understand the smartphone I have no idea what what's going on inside a smartphone I've no I know some words that have you used to describe RAM and process so the electrons moving around in there right but yeah and I think and it's in some sense that's fine like most of us don't need to know what's going on inside the smartphone to use it but somebody should know right and my argument in the book is look the 500 years from now when historians write the history of 20th century physics they will say two things

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one is my God these people were so brilliant and creative to invent quantum mechanics and then they were so afraid to really take it seriously and try to understand it like they said like stop asking questions about the meaning of reality and what the world is doing in my mind what physics is all about is understanding reality and what the world is doing it's not just about making predictions making predictions is good but we do that you know mostly because we're curious about what the world is doing well for people outside the world of Academia when I read someone like you saying that you were discouraged from pursuing this and you literally told that you should be pursuing your work in cosmology and gravitation is That's Where It's At a serious work yeah that seems to me be so crazy it's like if anybody should be pursuing it should be people like you yeah I mean I want to

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fair so of course 20th century physics was incredibly successful and there was part of the attitude was look we have to understand nuclear physics and particle physics and you know a lot of it was the center of physics shifted from Europe to the US and Europe is much more philosophical and you willing to think about the Deep ideas and Americans are pretty pragmatic and want to build things right in particular at the time they wanted to build nuclear weapons and so the idea of just really putting aside deep philosophical issues and putting stuff to work was attractive and and the other issue is you know okay let's say we do demand that we understand quantum mechanics better how do you do it like what experiment is it there that you can do is as far as we know the cookbook that we have even though we don't understand it works pretty well like what what could you type into your smartphone that would help you understand what's going on inside it's kind of hard to figure out so I think those attitudes were wrong but at least you know they're not completely crazy it's not just that they were afraid of the truth or anything like that and

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I also think that it is finally changing now I think that there's slowly slowly slowly more people are appreciating the understanding quantum mechanics is important what do you attribute that to a couple of things one is I mean there's good news and bad news part of the good news is technology has gotten better so we're trying to build quantum computers for example and guess what you know some of the ad hoc rules that we had for doing quantum mechanics might not be up to the task we need to understand the details a little bit better the other satyr thing is that so much of fundamental physics is kind of stuck right now right we haven't we literally have not been surprised by a new experimental result in fundamental physics since the 1970s wow the what is one exception to that which is the universe accelerating in 1998 which is the dark energy we've had amazing accomplishments in experimental and observational physics we found the Higgs boson we found the top

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Mark we found gravitational waves the microwave background many many things but they were all predicted decades ago right so progress is driven by being surprised and it's been a long time since we've been surprised so some people including myself say well one of the things to do in that situation is to take a step back and re-examine the foundation's maybe maybe we can take a broader look and think that we were walking down the wrong path now for people who don't have any background in physics there there's a bit of an issue with public perception and one of the things about public perception is films like what the bleep yeah that sort of throw this sort of cultish monkey wrench into the you know quantum physics is weird enough as it is yeah without adding that movie was literally created by a Channeler right my friend of mine David Albert was one of the leading philosophers of physics and I should also give credit to philosophers here because they've been taking quantum

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seriously longer though that businesses have to be honest so David is one of many people who got a PhD in physics and then switch to philosophy because he cared about the foundations of quantum mechanics and no physics department would ever hire him right larious and yeah I tell the story going through the back door yeah I tell the story in the book like he wrote a bunch of influential papers as a graduate student and then he went and said I would like to you know make these papers my PhD thesis and they said no that's not really serious physics and they punished him by making him write this incredibly technical mathematical paper on Quantum field Theory just to prove he could do it and then he's like this I can't take this anymore I'm switching Fields but anyway he was in that film he was in what the bleep and they lied to him they misrepresented themselves they said we're doing a documentary about quantum mechanics and they sat him down for three hours and asked him all these questions you leading questions like doesn't this mean that we're bringing reality into existence by looking at it and he's like no that's not what it means let me explain to you then in the final

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all film there's like 30 second clips of him going yes that is a really important question right like completely misrepresenting what he said and so he went public after that and complained about and about the film and he did in a hilarious story there was a vent some sort of convention put on in Santa Monica by supporters of the film that they thought would be fun to get all of the people who are in the movie what the bleep do we know and get them at you know and talk to them and charge people money to listen to them but these people were not affiliated with the filmmakers so they didn't know the David Albert had been completely misrepresented in the film so they invited him and he goes to this event in Santa Monica and he gave a talk you know he decided he wondered like should I just go at all but okay why not let's reach a different audience and he gave a talk and he said look there's two things you can do when you are faced with fundamental puzzles of reality one is you can face up to

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what the world is trying to tell you and you can accept it and take it as what it is no matter what you like the other is you can choose to tell a flattering story about yourself and the people who made this movie have decided that the mysteries of quantum mechanics are really stories about how they are powerful and have influence over reality and so forth but it's all nonsense and the punchline is the audience loved it they went nuts because what they wanted was a guru of some sort and like he was just as good a group with anybody alright so you know he had a better story to know reality based reality Guru yeah yeah so I think you're right I mean I think that quantum mechanics I've said before is of all the theories in the history of science the most easily distorted misrepresented in the popular mind we you've done an amazing job in this book of trying to boil it Down For Dummies like me but it's hard it is it is a complicated and insanely nuanced subject yeah and it's one of those things where it

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like this many worlds theory for one example the the just the possibility that there's like explain that explain for people that don't understand what quantum mechanics even means give them just like a little bit of that and then explain many worlds Theory yeah good this is what I'm here to do so thank you you know an electron take an electron quantum mechanics should apply to the entire universe but it becomes unmistakable when you look at little tiny things right so we always are talking about electrons or atoms and so forth and electron has a position and well sorry let me not even say that that even that was wrong it's just so hard to correctly talk about where I can mix right if you were Isaac Newton before there's quantum mechanics there was classical mechanics and basically quantum mechanics and classical mechanics are the only two big Frameworks that have ever existed in physics you know classical mechanics was so good that everyone thought that was just right and it's all better filling the details until quantum mechanics came along and changed

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things in classical mechanics and electron is a point it has a position a location in space and has a velocity it's moving somewhere and from that you can predict what's going to happen Okay quantum mechanics says no no no the electron has a wave function so there's a wave you know sometimes you hear this debate about are things like electrons and photons particles are waves the answer is that they are waves and the wave function has this weird property that when you're not looking at it it's a wave it's all spread out or it's localized somewhere but it'll bazin equation the Schrodinger equation so far so good just like regular physics there's a thing the wave function it'll be is an equation the Schrodinger equation You can predict what's gonna happen next but the weird thing about quantum mechanics is that there's a whole separate set of rules for what happens when you look at the thing when you observe it when you measure it that's where things get squirrely with people describing it right yeah and that's where they want to go woo on you it's an opening to be woo right way

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say like what do you mean observe something like does have to be a conscious being going to be a video camera you know that's just right here right is it the act of measuring the changes things well this is the puzzle okay this is what is called the measurement problem of quantum mechanics that the rules we teach our students at Cal Tech or anywhere else when we teach them quantum mechanics in their sophomore year of college the rules say when a system is observed when it is measured its state its wave function changes dramatically suddenly and unpredictably now let me ask you this how do we know this based on if if you're measuring it and it changes how do we know because we didn't measure it before like what What observations are we making that we understand the state of it before it's measured without measuring it good there's a couple of ways so let me make things even simpler forget about where the electron is located and

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think about the electron is spinning right electron is spinning just like the Earth spins it's really exactly like that it's like a little spinning top except when you measure the spin you can sort of send the electron through magnetic field and we'll get deflect either up or down depending on whether it's spinning spin up or spin down you only ever get one of two answers it's either going up or going down is nowhere in between this is an empirical measured fact okay so that's a part of quantum mechanics that that's the quantum fact that there's discrete set of possible answers to this question is it spinning clockwise or counterclockwise yes or no that's just those two possibilities nowhere in between so if you're if you have a magnetic field that is oriented vertically send your electron through it it gets deflected up you say oh it's spin up so now I've measured it spin now I know what it state is if I send it through another magnetic field oriented vertically it will always be deflected up every single time we know what it is we're going to measure it measuring it in this case doesn't change

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it's in exactly that state we know it okay now let's send it through a magnetic field that is oriented horizontally so it's going to be deflected either right or left we know exactly what state it's in it's spinning this way but when you send it through that magnetic field that's oriented horizontally it gets deflected left or right 50/50 unpredictably there's no way we can predict it hmm and then once it is so okay now it's been spinning up you measured it spin left let's say send it through another magnet that is going vertically and now it's 5050 again it could be spin up or spin down so somehow even though we knew exactly what state it was in we couldn't predict what would happen next that is part of quantum mechanics so the act of sending it through these things where it makes it vertical or horizontal in what is what is happening to it when it's going through these things so in quantum mechanics what we say is that it's not that we don't know whether the electron is spinning clockwise or counterclockwise

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it can be in a superposition of both that's just the spin version of the position of the electron can be spread out in a wave right it's it's truly not just that we are lacking some knowledge is that the knowledge really isn't there and again this is how we teach quantum mechanics in textbooks and then I'm going to correct it because many worlds is much better but this is the standard textbook version there's a wave function the wave function for a spin is it's either up or down or some combination and then there's a rule that says when you measure the spin you only get up or down you don't see the wave function just like the cloud that you have for the electrons position when you look at it you see it at a location so another way to get to make the same argument is take a little piece of I have a nice little image of this when I give talks a little piece of uranium so it's a radioactive little chunk of metal and you put it in a bubble chamber so it is emitting radioactive particles and you did

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the particles you can see a little streak of motion when the particle leaves the uranium okay well like I said when you're not looking at it this electron is supposed to obey an equation the Schrodinger equation and you can ask what the prediction is when when a radioactive nucleus decays and gives off an electron what is its wave function going to do what is the wave function electron going to be in the answer is it goes off in a spherical wave it goes off in all directions at once evenly yeah all directions evenly but you never see that is that Railway based on the shape of the piece of uranium does it vary no because the electron gets from one individual nucleus of an atom right so the what they let the uranium was doing doesn't matter it's just that one atom matters and the easiest thing for the electron to do is just to go out in a sphere doesn't have to in go out and higher energy states but the point is it's not going out in a straight line but when you look at it you see a straight line right that's the fundamental mystery of quantum mechanics that

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we describe the thing when we're not looking at it is different than what we see when we look at it so when you're in pursuit of an understanding a deeper understanding of quantum mechanics what you when you're thinking about people from the 1900s that are just sort of basically getting the first steps going to understand this stuff when you're talking about this lack of funding and the lack of encouragement for people to pursue quantum mechanics you strongly feel like there are answers to these questions yeah that's right that we just need better tools and a better understanding better equations more time yeah me and Einstein think this right so Einstein is one of the secret Heroes of the book because he has this reputation as someone who just couldn't quite accept quantum mechanics the title something deeply hidden is a quote from Einstein when he was talking about when he was a kid and he had a compass right and he was given his first magnetic compass and he could rotate it this way

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that way and it always pointed North and you and I would go ha that's cool but he was Einstein he's like wow this is amazing why how does it know where North is right and he said there must be something deeply hidden that explains why it's doing this mysterious thing and he felt the same way about quantum mechanics that it we have we gave these set of rules Orchard called The Copenhagen interpretation of quantum mechanics one set of rules for when you're looking at it one set of rules for when you're not and Einstein was like oh come on clearly this is not the final answer to the nature of reality right he wanted to know God's thoughts he's like I want to know everything we're not done yet there must be more going on and so many worlds is one of the proposed answers to what could be going on it's not the only one there's Alternatives but it's definitely my favorite is definitely the easiest one to write down let's put it that way okay so hit us with this many worlds Theory okay so think about this electron you're going to you you say that it could be either spin up or spin down it's a combination of both that's its wave function you

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RIT you only ever see spin-up or spin-down so Copenhagen says that's because the wave function suddenly changed snapped into place when you observed it don't ask me what it means to observe something that's not what Copenhagen lets you ask okay many world says what you're missing is two things number one you're a Quantum system you are obeying the rules of quantum mechanics you're made of atoms and electrons and so forth you have a wave function to okay so you're secretly treating yourself as a classical thing when you make that measurement but you really should be treating yourself Quantum mechanically right that's one thing and the other thing is something that Einstein invented namely called entanglement when quantum mechanics says there's a wave function for a system it doesn't say there's a separate wave function for every particle right it says that there's only one way function for the whole universe so the way I like to say it is

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imagine two particles come in and bounce off of each other either one has a wave function and it's you know unpredictable exactly what angle is going to go off at so both of them both of the particles that go off you don't know where they're going but because momentum is conserved you have they came in at equal velocities will go out of equal velocities in opposite directions if you measure one then you know where the other one is going right that's entanglement The observed state of one system can be related to The observed state of another system so those are the two ingredients you're a Quantum system and Quantum systems could be entangled with each other so Hugh Everett who was a graduate student when he invented this idea in the 1950s said look when you measure that electron

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what happens physically like forget about your a person you're conscious all that BS like you're a physical system you obey the Schrodinger equation you you are quantum mechanical system you obey the laws of physics so you look at the electron your wave function changes it used to be you're just a person doing whatever you do but then after you look at the electron you become entangled with it and it splits so there is one part of the wave function that says the electron was spinning clockwise and you measured it spinning clockwise and there's another part of the wave function that says the electron was spinning counterclockwise and you saw it spinning counterclockwise now everybody knows this like that that far it's not controversial at all that's clearly the prediction of the equations of quantum mechanics but everyone else said well that means that I'm some weird combination of I saw it spinning one way and I saw spinning the other way but I've never felt that way when I look at real electrons I see them one way or the other that can't be right that can't be the final answer the wave function must somehow

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collapse and Everett said know what you're missing is there's now two separate worlds both of those part of the wave function are real but they're different worlds they will never interact with each other again what happens in one part of the wave function will not affect what happens in the other part so now there's a version of you that's all the electrons spinning clockwise and there's another version of you that saw it spinning counterclockwise and that's just taking seriously the prediction of quantum mechanics it's not adding any extra stuff any extra World anything like that that is the part where my brain broke all right the idea that there's a you that observes it going clockwise and the you that observes it going in a different direction like that is so hard to understand do you apply this in your regular life like do you think like when you go home and you say hi to your wife and you open the refrigerator do you think of yourself as this Quantum being that's existing in this super state so I mean there's a couple of answers to that one is you know

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sure if I think about it like I really do believe it you know I have a chapter in the book which my editor resisted it at first but then he let me get away with it which is a dialogue between a young philosopher and her father who was a physicist and the father is skeptical about all this philosophical nonsense and she tries to explain how many worlds Works to him and at the end you know his last question is do you really believe this is how you really taking this seriously and look that's a perfectly at a good question it's a very respectable question because it is many world it's not crazy or weird or bizarre but it's certainly very very far away from our everyday experience right so what it's asking you to do is to say I have these equations they are really really good at fitting what I do observe in the world and making predictions you know I can build the Large Hadron Collider etcetera I will take them seriously even for things

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that I can't directly observe because at the best equations I have right until a better set of equations come along I will believe these equations and the implication of that is yeah there's a whole bunch of Worlds like a huge number like a real you know Jai humongously unimaginably big number may be an infinite number may be finite we don't know of different copies of you and they're being created all the time the good news is that it doesn't really affect how you go through life it doesn't really imply that you should behave any differently than you would if you just lived in one world but do you think of each choice that you make possibly changing everything about the world that you exist in the how are you how are you looking at it if you don't know nothing because you you are a guy who will probably understands it as good as anybody that's alive so as weird as this stuff sounds to me it sounds like a mean it's almost impossible for me to comprehend so I'm trying to filter it through your understanding of it

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well I think that he's jacking off we're going to see I know it's getting hot in here like physics is eating us up

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yeah I'm not exactly sure how to say that the best you know it doesn't it doesn't change who you are it's certainly not true that you making a decision is what branches the wave function of the Universe I guess that's the right thing to say because I want to stop all whoo yeah you can't afford it happen everyone you know believe the bricks the joke about how certain political choices imply that we're living in the wrong branch of the wave function has been made many many times right but you that it's not that your choices create different universes different universes get created and maybe you're different in them by a little bit in fact I you know I like to point out there is an app you can download if you have an iPhone called Universe splitter which will Branch the wave function of the universe for you and then if you agree ahead of time to do one thing in one branch to another thing in another Branch then there will be multiple copies of you who are living different lives then you can deal with that and your therapist however you like but what's the application exactly doing

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what it's doing is basically a version of measuring the spin of it's called the universe splitter Universe Splitters only for iPhones I'm gonna grab this right now sorry Android people yeah sorry it's not even a web page is only a only an app there's an equivalent web pages but okay I'm pulling it up right now yeah and what so would you can do basically it sends a signal to a lab that coincidentally is located in Geneva Switzerland but has nothing to do with the Higgs boson or anything like that they send a single Photon down a pipe to what's called a beam splitter so the wave function of the photon goes 50/50 It Gets Sent left it gets sent right and if you agree and so then it sends back whether you ended up in the branch of the wave function where it went left or where it went there you go $1.99 come on yeah the power of changing the universe is in your hand I download it I got it I paid for it I got it right here yeah right so if you have any tough choices you can type in like you know I want to have pizza or I want to have Chinese food for dinner tonight what's this in one Universe I will take a chance

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in the other one I will play it so yeah but you can you can correct those you can fill in whatever you want really yeah that's the good part but what is what is happening when I will ask her to marry me I will not ask her to marry me so I will accept this job I will go somewhere else equivalent of a Quantum fortune cookie yeah but except that all possible fortunes remained in different universes the bad news is you can't ever find out how things went in the other universe so Cox is a different universe that's the problem right so the problem will be paralyzed by analysis that's why it's you should act to the same as if you just lived in one Universe because you can never talk to the people in the other ones hmm so but now let's hit the brakes on the woo again yeah because people would like to believe that there are I mean are there an infinite number of use existing legal ethics at the exact same time making various choices which send you off in a different direction so number one we don't know if it's

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infinite number or just really big but there's certainly a really really big number it's big enough to be you know big enough for whatever you want but it's not everything it's not the theory does not say everything happens somewhere right the theory says the Schrodinger equation is obeyed there's an equation that is obeyed so electrons will never convert into protons because electrons are negatively charged and protons are positively charged and nowhere in the Schrodinger equation can you violate the conservation of charge right so there's plenty of things that don't happen but then there are plenty of things that do happen and some things are more likely than others for you to experience so again it's sort of a you know it's a mind-bending thing but it's a straightforward prediction of the equations and it doesn't affect our lives it there's no rule that says you know to be a moral person to be a good utilitarian and make the world happy knowing that the world the wave function is branching into multiple copies I should acted differently somehow it's it's exactly the same as it would be in the Ordinary World so you and you are the Ordinary World no matter how copies how many copies of you there are

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he versions of you there's are nothing so when all these copies are being made there's no essence of you that is traveling through one of the copies right like all these people are separate people so I use the analogy it's like identical twins they were the same zygote or whatever and now they're different people okay so that's the same thing like you are you now and if you hit the button and Branch the wavefunction they'll be two different people both of whom used to be you but not the same person anymore because different things happen to them now when people think about the concept of quantum mechanics and the way you're talking about describing things in the micro and the macro you think of your existence itself very similar in a very similar manner that the way you think of electrons the way you think of things being Quantum is that you are a combination of all these Quantum things yeah so you don't operate in some sort of static State that's

► 00:37:42

hurry like here and now and and and carbon and you can put it on a scale and it will never change there's constant versions of you yeah it's kind of like a wishing where you know more and more versions of you are being created all the time and it's an interesting thing because even the best trained physicist sort of think intuitively classically like look here's a table there's a bottle right after the yeah you had like come to the brakes and this is how we evolved and how our brains work right and like I said you know many worlds is one respectable version of quantum mechanics there are other respectable versions more respectable than the textbook presentation but they all all the other ones somehow lean on our classical experience and the textbook version certainly does it says like your classical person observing a quantum mechanical system and so forth and Everett when he was a graduate student you know he was he had arguments across the ocean with people in Copenhagen you know who tried to push their way forward and he's like

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why do you get to be classical and the electron has to be Quantum like why aren't you Quantum like why isn't everything what's so special about you really write and he was trying to think of the quantum mechanics of the whole universe right where he is not a separate Observer outside because he's doing the whole universe all at once and so everything had to be Quantum and I think that that's another thing that is pushing us to appreciate the foundations of quantum mechanics a little bit more is that we're trying to understand quantum gravity trying to understand Quantum cosmology the universe all at once obeying the rules of quantum mechanics and the conventional Copenhagen theory is just not up to it when I was reading it I was thinking I thought came across my mind that it's almost like the human brain is a radio that's picking up a distant signal but getting better and better at tuning into it all the time and that we are thinking of ourselves in this very limited primitive biological way because that's how we evolved but slowly but surely through people like you and through work on this stuff

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we're gaining this more comprehensive view of what reality is itself and that we're experiencing these stages of comprehension and that that's why you know again going off of what you're saying about your being potentially discouraged from pursuing these things that's why this is so important is like for most people like myself we don't have a background in this at all that the signal is so distant but it seems like the more you folks study it in the clothes the more the Large Hadron Collider in CERN and more these experience get done the closer we get to the better signal just a little bit better signal and we might be talking about Generations from now right exactly yeah but no I like the analogy very much because the human brain did not evolve to understand quantum mechanics right didn't understand did involved understand science at all like we're in some of my best friends are human beings but we are wonderful bundles of

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impulses and heuristics and shortcuts and ways to rationalize our behavior and stuff like that and the idea that we can aspire to be logical and to develop theories and reject them and to develop theories that are very very far away from our everyday experience is a relative latecomer on The evolutionary scene and we're still not really good at it we're getting better at it and this is part of it you know quantum mechanics is the biggest challenge that we have in physics to our intuitive understanding of the world and so there's a question how should we try to understand it how much of it should be lean on our intuitive understanding and how much we just accept that the world is fundamentally super duper different and I think that's a perfectly good question I'm not trying to Prejudice the answer one way or the other I mean our experience is limited but it's all we have right you know we have to we have to be based on that and so some people wonder is quantum mechanics just impossible to understand like as the human brain not

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up to the task the current human brain the current human brain short but I think that no I think that that's totally wrong I think that number one quantum mechanics certainly is very understandable and number two I don't think that anything about nature is impossible to understand for the current human brain I mean maybe it is there's no way of knowing for sure but there's zero evidence that we will fail in our ambition to try to understand the universe it's just hard and it takes time look a hundred years ago we didn't have one mechanics at all like we've made enormous progress in a hundred years is nothing even in human life human history much less cosmological history so don't be impatient take time but it just seems to me that the the human understanding of the world we live in is obviously radically changed over the last 500 years and if we continue to exist in this current state or a slightly better State as things move on it's going to get better but quantum mechanics and quantum theory to me almost seems like

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like an ant trying to understand the choices on Netflix it's like those choices exist but the ant really lacks all tool being without people like you especially especially describing the computations and what's been done and what we currently understand for a regular person with no background or even no knowledge of it no no no one's ever explained it to them at all yeah it's almost outside of the realm of our capacity for reasoning now I got to disagree okay I think it's just hard I think there's a difference I think that and I could be wrong about this but I think that you know there was a phase transition there was some you know how we talk in computer science about a certain kind of computational machine being touring complete maybe you don't know this but this is something we say please explain that torso a touring machine Alan Turing the great computer scientist who bro codes and things like that he also thought a lot about like what computation was and he invented the Turing test for

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Consciousness and stuff like that fear AR and for AI yah and but the touring complete is basically there's a certain kind of computational device that can essentially do any computation that can be done like anything you can ask if you can do this problem then you can also do that problem and they're sort of a maximal hardness to problems and so it turing machine can do that probably if you give it enough time and there's some problems at our undoable so no machine can do those but the Dual ones can be done on a turing-complete machine so in some sense this is not a rigorous fact by any stretch but I think there's an analogy with human reasoning like at some point where a little bit smarter than dogs and cats but it's not just we're a little bit smarter wear a different kind of smart like we did pass a threshold we can use language we can reason symbolically and abstractly we can write things down and pass them down through generations we can imagine Futures in ways that they can't so even though you know the number of neurons or the number of Connections in our brain might not be that different

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between the human being and a chimpanzee it's a different kind of reasoning that has been opened up we've been become capable of this kind of thought and I think that's enough my idea is that we are smart enough to understand the laws of physics whatever they turn out to be quantum mechanics or something Beyond quantum mechanics and to the person on the street who's never learned anything about quantum mechanics you know it is so different from how you experience the world that it seems bizarre and you do have to like read the same paragraph over and over again sometimes but I think it is absolutely understandable if people make the effort I don't think there's any person who you know can balance their checkbook but not understand quantum mechanics they just need to put the timer yeah put the time in and take your time and go back open like don't ask that the real thing that holds people back I think is a insisting ahead of time that they know how things work right that reality should work in a certain way yes and you have to least be open to the possibility that the way reality works is way different than

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what you had in mind if you're open and you're willing to put in the work you can understand that's why I was curious as to how you apply it in your actual physical life your knock on wood ring a doorbell you know drive a car physical life yeah if I was thinking about quantum mechanics and I was driving my car things will be much worse than they are and that's because the classical world is a really good approximation and this is something I'm also interested in yeah you know that's this is important emergence right I talked about this in the last book in the big picture thing about this when we talk about the earth going around the Sun forget about quantum mechanics just to just do classical mechanics Isaac Newton Earth orbiting the Sun okay we can predict that we can write down the equations we can tell you where the Earth was a million years ago or million years in the future right but think about how amazing that is the earth is made of something like 10 to the 50th Adams okay in principle to tell you what the Earth is

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Ling I should tell you what every one of those atoms is doing all right yeah but I have no idea what every one of those atoms is doing all I actually in the real world need to tell you to predict what the Earth is doing is to tell you the center of mass of the Earth where it is and where it's moving so only using an incredibly tiny amount of information I can make incredibly precise and accurate predictions I have this enormous handle over what the world is doing ignoring almost all the data that there is about this persistent about the specific state of the world so that's emergence when you don't need to know almost anything about a system you have certain very very special High leverage pieces of information that you can use to make accurate predictions so really now that we know quantum mechanics all of classical physics is like that the fact that you can throw a baseball and know where it's going to land and stuff like that the fact that can get a rocket to the moon or drive a car is because without knowing quantum mechanics is because Newton's laws of physics are really really

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approximation that led you make predictions without knowing the quantum wave function of the car you're driving right and if you needed to know the quantum wave function the car you were driving on be helpless it's just you know computationally intractable so the world appears to us in a way that it is very convenient in some ways we need to know so little about the world to yet understand quite a bit of it otherwise you couldn't get through the day the idea that everything is in motion is also very difficult for people to wrap their brain around you see a stationary Rock On The Ground yeah you you think that rock is still but it is not nothing is still you know it's pretty still but it's a part of the earth pretty Earth spinning sure the Earth is spinning that relatively in terms of the universe everything is in motion in some way shape or form well you know this is a very this is you know there's a lot going on here actually because on the one hand Einstein teaches us you know when you say something is moving you have to say with respect to

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you what right right so if you're standing next to the Rock it's not moving with these back to you right if you just stationary there there's also what I try to squelch in the book one of The misunderstandings about quantum mechanics is the idea of quantum fluctuations the idea that an electron sitting in the the orbit of an atom is really jiggling around there and you don't know exactly where it is that's not what quantum mechanics says like if you're good Eveready in any way a good many worlds person there's a wave function to the electron in the wave function is sitting there not moving it's really not changing appreciably over time if you were to observe the electron you would see it somewhere and if you have to observe it multiple times would be in different places so it looks to you like it's jiggling around but when you're not looking at it it's not jiggling it's just sitting there quietly according to Quantum Mechanics so is this confusing description based on our limited ability to perceive it's actually based on the fact that we inevitably attach a notion of reality to what we do perceive right

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so in quantum mechanics what we perceive is different than what really is and that really bugs people because I just saw it I mean how much more real could it be right the way that we describe you know I'd like to go on a rant in a whole chapter of the book like the Heisenberg uncertainty principle that there's uncertainty to either your position or your velocity you can't know both of them at the same time it's not that you can't know both of them at the same time is that neither one of them exists tradition and velocity are things you measure they're not the elements of reality that quantum mechanics uses and there's a difference there and people don't like that but by the way I wanted to bring up in a whole nother aspect of the not moving thing which I think is fascinating and it's nothing do with quantum mechanics but it is a future Frontier for physics I think you know we can look at the bottle of water and say like it looks pretty stationary it's not really changing I can also look at you and you're sitting there pretty quietly you're not really changing but there's a

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Mendez difference because this is stationary not moving because all of its pieces are stationary and not moving I'm this is liquid so it's not the best example the table would be a better example but you and I are sort of macroscopically stationary trying to sit here more or less quietly but inside is a lot of churn going on right there's you know a lot of cellular biology there's ATP is being created and destroyed and you know signals are going from our brain and back and forth and someone like Antonio damasio the neuroscientist emphasizes this idea of homeostasis that there is stuff going on beneath the surface but it regulates our particular configuration so that we are more or less macroscopically stable and and amazingly you know human beings last for a century like you were born and we are bodily Integrity last 400 years which is which is kind of crazy but it doesn't do that by in having its individual Parts remain quiet and stationary it does

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through the arrow of time in the growth of entropy in the fact that we eat food and get sunlight and we use up enormous resources for the purpose of apparently maintaining our integrity and I think it have that whole story works and fits together is something physics doesn't understand very well but will be important going forward the idea that there's an enormous number of you making various choices yeah and that these various choices will ultimately affect how long you exist in some branches so there is a weird thing called Quantum immortality which I think is a bad idea and I don't like to talk about it but people hear about it so I sometimes need to mention it Max tegmark who is a friend of mine a very smart guy popularized this idea he said look what and it's a little bit Macabre sorry about this little bit you know weird the experiment but imagine you're doing you're playing Quantum Russian Roulette

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so you have your Universe splitter okay you have your app on your iPhone and you can split the universe and if it goes one way you don't do anything if it goes the other way faster than you can react machine is activated that kills you instantly okay so you you don't even know it you don't even perceive it you don't have any pain you just instantly dead and you do this over and over and over and over and over again so in most branches of the wavefunction you're dead but in those you're dead you don't know anything you don't you don't feel like you're dead you know there's no regret after the fact the only version of you that survives is the one that was lucky enough to be in the branch where you didn't die every single time so take Mark's argument was that the if you do this over and over again and you survived you should take that as good evidence that the many-worlds interpretation of quantum mechanics is correct because in other versions you probably just died right I don't think that's quite right I don't think it's a good way to go through your life I think that the reason why we don't want to

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I is not just that we will experience pain but that sort of prospective lie right now the idea of being dead in the future bothers me right like if someone said you know you're going to die in this and that date might be useful information but I'd be sad right at that date was soon and I think the same thing is true in the quantum immortality experiment I don't buy the move that says well in all the branches were you're dead it doesn't matter because you're dead you don't feel anything like I think did right now it's okay for me to be bothered by the prospect that in many future worlds I will not be there so I you know I think that at the end of the day once again you should act in quantum mechanics just like you act in the regular world are there competing theories to this that this many worlds theory that you've embraced and then discarded yeah yeah yeah their abs there's two big ones that are that are quite popular one is more or less what Einstein had in mind which are called hidden variable theories so basically you know if you have

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an electron and you say look when I'm not looking at it it's wave like when I look at it it's like particle like maybe it's both maybe there is a Wade and there is a particle so in a hidden variable Theory there's a wave function just like there is in many worlds but there's also another set of variables saying there's really a location of the electron right maybe I don't know where it is but there really is an electron located somewhere and that location of the electron is pushed around by the wave function but it's a whole new part of reality so there's not so that they're separate branching of the wave function and all that stuff but that none of that is reality where reality is is where the particles are and this is now called bohmian mechanics David Bohm in the 1950s developed the most respectable version of this it's sort of

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therapeutic if you don't like all the other worlds it's basically you know the equations are the same as many worlds except there's new equations and new stuff so it complicates the theory by adding new variables but the good news is it says only one of the branches of the wave function is real I don't need to worry about the other ones the problem is it's very hard my particular problems it's very hard to reconcile these ideas with modern physics like if you thought the world was made of individual particles it would be do okay but these days we use quantum field Theory and quantum gravity and things like that and those more modern ideas are harder to attach hidden variables to so hidden variables are you know an old idea but there I think that they're hard to make work the other idea which is more dramatic a little bit more fun is every single electron has a wave function and it seems to you that when you observe it it collapses but maybe what's really going on is the following that there's a random probability every second that every electron will just spontaneously collapse so it's all spread out but its way

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function just randomly localizes to some particular region of space very very rarely like if you have one electron and you wait for it to happen it will happen like once every hundred million years okay but if I have lots of electrons like in a table there's way more than a hundred million electrons in this table there's there's you know billions and billions of billions of electrons so somewhere in the table all the time an electron is localizing at one particular position and because that electron is entangled with all the other electrons the table maintains a location in space hmm and this is called spontaneous collapse or grw Theory after the initials of the people who invented the theory and the great thing about grw theory is that it's experimental e distinguishable from many worlds because it says that if I have a collection of atoms even if I'm not observing it even for not and tangling it one of the wave functions should spontaneously localized occasionally and that will heat it up energy is not conserved in this Theory so people are doing experiments to test this

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really you know legit experimental science Adams the current perception by the general public of atoms is that it's mostly empty space this is not idea this is not true well or not correct or not it's certainly not with many world says right so this is you know there are two enormous problems with our current way of presenting quantum mechanics one is the measurement problem which is this question like what do you mean look at it what do you mean observe like what actually happens when does that happen that's the measurement problem but the other problem is what I unhelpfully call the ontology problem as ontology is the philosophy of being of what is real what is actually existing so we just talked about hidden variable theories so in Everett what's real is the wave function the wave function of the universe describes the universe exactly and completely in many whirl in Hidden variable theories there's a wave function

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and there's also particles so there's extra ontology extra pieces of reality so the question of is the atom mostly empty space

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depends on what you think is real so the wave function of the electron fills the atom so if you're a many worlds person like me you think what is real is the wave function it fills up the atom and the atom is not mostly empty space the atom is the wave function it has that size right you get the feeling that elect that atoms are mostly empty space because you think that really the electron is a point and the wave functions just telling you where you might see it when you measure what well yes so many worlds says there's no such thing as where it is there's only a probability of seeing it everyone knows that but people kind of died at they talked as if there really is a location of the electrons even if they should know better so people who generally people who say that atoms are mostly empty space are just being sloppy they're just really thinking of the electron as a little tiny dot rather than a wave function there is an exception to that because there is a fourth version of quantum mechanics that is somewhat popular I said three

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many worlds hidden variables and spontaneous collapse there's another version that just says look the wave function has nothing to do with reality in many worlds it's all a reality in spontaneous collapse it's all of reality but it obeys different equations and hidden variables the wave function is part of reality but there's also particles in the other approach which is called an epistemic approach to Quantum Mechanics the wave function is just a way of talking about your personal knowledge of the world your knowledge or lack of knowledge or ignorance of the world so your wave function just a tool you use to make a prediction for what the experimental outcome is going to be right and that's more or less what we teach our students and this approach says don't bother about reality what we should concern ourselves with is the experiences of agents who make predictions and update their probability expectations of the world and so someone

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that if you ask them you know how is an electron located in an atom or how is it an atom mostly empty space I think if they're honest they would say don't ask those questions those are the way we don't ask reality questions we'd ask what are you going to see kinds of questions but I think that some of the less honest ones will say sure nanum is mostly empty space because electron has location somewhere we just don't know what it is

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why do they approach it in this what you the way you're describing a sloppy way why do you think that is so common

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well you know it is part of the attitude that physics is physicists have adopted that we use quantum mechanics but we don't try very hard to understand it so you can talk to plenty of physicists on the street and they will tell you to your face that understanding reality is not their job and I think that's terrible but it but they will say it and so when you press them too much on questions like you know is the atom mostly empty space you know what happens when you make an observation they just kind of get uncomfortable and say no you're asking the wrong questions let's ask questions about what will we see at the Large Hadron Collider if we smash protons together right and those are perfectly good questions too but I think that the what's really going on questions are also interesting so because they don't care about these questions they will often be sloppy and answering them right they don't you it is hard like like like you said it's hard when you read the book it's hard when you write the book it's hard to think about these things as a professional physicist it's it's not

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natural it's not easy it's not intuitive so even if you're a super duper expert at solving the equations and making predictions understanding what's going on is a whole nother activity that a lot of physicists don't try very hard to do now how was all this stuff verified or argued like say here come you're sitting down you're having a conversation with someone who espouse has a competing Theory how are you guys working this out good I think that if everything were going along really really well we would be making experimental predictions and testing them but I think the theorists have sort of dropped the ball here in the sense that the theoretical physicists should have since the 1930s been developing these Alternatives like many worlds in variables whatever and make using them to make predictions but we really haven't they were neglected they were back Waters there were a few people few Plucky Souls who really put their

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efforts and understanding these many of them got pushed out into philosophy departments but that's what we need to do we need to like catch up on the last 70 years of lost time and work out what the implications are of these ideas so it's in the ball I think is in the theorist Court the experimenters are working hard experimenters are doing amazing things with lasers and Adams and learning about how to manipulate Quantum systems at a delicate level but the theorist had not given them sharp experimental questions that they would really illuminate the foundations of quantum mechanics so honestly what it is is a bunch of people get around a table and talk to each other they're like alright I think that what happens when the wave function branches is this so a typical question will try to address is

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in ordinary quantum mechanics we say if I send the electron through one way or I send it through the elect the other way there's a 50/50 chance that I will see it go left or go right and someone says what do you mean 50/50 chance especially in many worlds where there's a 100% chance they'll be a world where it goes left and a world where it goes right at what is the meaning of the phrase there's a 50/50 chance what is the nature of probability in this game where everything is perfectly deterministic right so that's not the kind of question that you act answer very easily by doing an experiment you have to think about it right so that's what the kind of thing that we argue about how often do you guys get together yeah you know it happens there's conferences it's a small community someone asked me just the other day because I know the book came out something deeply hidden last week and been on book tour so I was on I was being interviewed in someone said how many people do you think in the world are would classify themselves as working on the foundations of quantum mechanics

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maybe a hundred something like that not a very large number like if you say how many people would classify themselves as particle physicist to be tens of thousands so I remember there's a woman who came to the Comedy Store the after the last podcast that we did and she apparently is also working on it and she was trying to explain it to me her version of it you know after hearing your version of it was very similar but I believe she was from Romania she was struggling a little bit with England she was so excited to discuss it it's so fascinating when you see someone who's like for the limited number of how many of you guys there are and gals there are out there I mean whatever the number is when that spark gets ignited and other people start tuning into it she was so excited that this was being discussed on a podcast and she wanted to talk to me about to say you know please have more people on please talk about this more in a we need support we need you know

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it's it is it's it does baffle me a little bit how difficult it is forming a pill to get more support for this kind of thing because it is just an enormous privilege to be able to call your job thinking about the fundamental nature of reality right like you know I gave you my first book tour talk was last Tuesday and I had dinner the night before with several philosophers of physics in the New York area of you know from Columbia and NYU and ever and and you know we're all friends and we could talk about you know our cats and our cars but every single word discussed at the table all night long was about the philosophy of physics it because you guys work in isolation essentially and then when you get together you just you're so pumped up to be discussing these things are like-minded souls you know in part yeah I mean I there's no one else in the physics department at Caltech who cares about these issues I mean some of them care in the sense that they are happy that I'm doing it but no one does it but it's just yourselves yeah well

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is a couple other people in the philosophy Department who care about these and a lot of most folks you're saying get pushed into philosophy and why is that I mean is it just because it's so complex that it's so esoteric there's so many people that just they don't this is the the support for it's not there but the support for philosophy is more common in mainstream yeah you know there's different kinds of support one kind of support and Academia is who do you hire right what what areas do you want like a physics department will generally say yeah we should have some people doing particle physics some people doing astrophysics some people doing condensed matter in solid state physics and then and then it becomes hard to we need people doing biophysics do we need people doing this and by the time they get to the foundations of quantum mechanics there's there's usually very little support philosophers there their job is being patient and clarifying difficult conceptual questions and so they get that quantum mechanics is fertile territory for philosophy like

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you know one of the big problems in philosophy compared to science is that many of the questions that they're asking cannot be tested experimentally right what is infinity well you know okay it's hard to do an experiment there but it's an important question right and so you need patience but also it's harder to make progress because it's easy to be trapped by your intuition right like when it's just you thinking and trying to think hard and be rational and so forth it's easy to fall into a trap of well this looks reasonable to me and quantum mechanics doesn't look reasonable to anybody so it's a wonderful corrective It's a Wonderful reality check when you think well reality has to be this way and then someone can say well look at quantum mechanics that's different than what you said so philosophy and quantum mechanics they sort of the they share some sort of a border yeah oh yeah absolutely I mean the things so I was always a big fan of philosophy ever since I was an undergraduate I discovered it for the first time

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When I Was An undergraduate and my favorite philosophy classes were like the philosophy of morality or political philosophy right I took philosophy of science classes but they seem to be kind of dry to me because they were all about how scientific theories are constructed and chosen you know the structure of scientific revolutions is the famous book that everyone reads people like Thomas Kuhn and pole fire Abend and so forth and okay that's interesting but it's sort of meta science right it's like how science is done not how the world works and it wasn't until you know Circa 2000 that I discovered that there are philosophers of physics who are kind of really doing physics you know they're not asking how physics Works they're asking how the world works but they're asking in a way that is Comfortably located in philosophy departments in right now not so much in physics departments there was a part of the book that that shocked me because I had a ridiculous idea once and this idea was not my idea apparently La Paz

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very similar idea as a thought experiment I had an idea once that if one day there was a computer that was so powerful that it could accurately describe every single object on earth that we would be able to figure out the past and La Paz was saying that not only that which he proposed for the entire universe like every single object electron everything in the atom in the entire universe that you would not only be able to show the past but also predict the future that's right so this is called lip glosses demon although he never called it that pierre-simon LaPlace was a brilliant guy he deserves to be much more well-known so I based I think I've mentioned him his name in every book I've ever written for totally different reasons he helped invent probability as we currently understand it for example but yeah so Isaac Newton came up with the rules of classical mechanics in the 1600s but it wasn't until LaPlace around the year 1800 that this implication of classical mechanics

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X was realized it's A Clockwork universe that the way classical mechanics works is if you tell me the state of a system right now at One Moment by which In classical mechanics you would mean the position and the velocity of every part and you knew the laws of physics and you had arbitrarily large computational capacity LaPlace said a vast intelligence okay then to that vast intelligence the past and future would be as determined and known as the present was because that's the Clockwork universe is deterministic everything is fixed once you know the present moment now quantum mechanics comes along and throws a spanner into the works a little bit if you're a many-worlds person

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the place is demon is still possible so if you know the wave function of the universe exactly and you have infinite calculational capacity you could predict the past and the future with perfect accuracy but what you're predicting is all of the branches of the wave function so any individual person inside the wave function still experiences apparently random events right so you can't predict what will happen to you even if you can predict what will happen to the entire universe Wu-Tang Sean Carroll my goodness there's a lot of people pausing this podcast right now just shaking their head like you know I wrote a little article that just appeared in Quantum magazine which by the way if anyone here is a science fan Quantum magazine is the best online magazine for Science these days they have really really good high level are articles but all sorts of things and so I wrote an article called what is probability because you know again this is a philosopher's kind of question like your business this will just put it to use and get all

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their lives philosophers will say well what do you really mean by probability the traditional answer is if you're flipping a coin and you say it's 5050 what you mean by that is that if you flipped it an infinite number of times half the time it would be heads half the time it would be Tails that's what you mean it's called the frequent assist idea probability but then what do you say like well what is the probability that Donald Trump wins re-election that's not going to happen infinite number of times you're not going to do the experiment or even better what was the probability that Lee Harvey Oswald actually was the Lone shooter of JFK that already happened that's in the past right but we can easily say well I think it was an 80% chance that that's true right so this is called Bayesian probability where rather than thinking of an infinite number of things going on you're assigning a degree of confidence to your lack of perfect knowledge right like I don't know exact there's a tree describe something yeah there's something going on I don't know what it is so I assign a probability and that

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like the frequency that you know those the Creedence as we say that you assigned to these different ideas is a positive number then all the greens is add up to 1 because something happened so in quantum mechanics is probability more like frequentist probability or is it more like Bayesian probability the answer is it depends on what your favorite version of quantum mechanics is in one of these spontaneous collapse theories it's very much like a frequency like you know you just things happen randomly and it's purely objective in something like many world well sorry I should say in something like hidden variables

► 01:14:09

it's LaPlace is demon all over again so the place is demon doesn't work in a spontaneous collapse Theory because you the laws of physics are not deterministic you don't know when things are going to collapse all by themselves in a hidden variable Theory the hidden variables and the wave function of all deterministically but you don't know what the hidden variables are so you can assign some probability to having them be different things so there's some ignorance involved many worlds is the coolest idea because it's kind of in this is what is kind of hard to wrap your mind around on the one hand there is only the wave function it describes the universe exactly but imagine that I measure the spin of an electron okay so I actually do know what the wave function is going to evolve into it's going to evolve into a 50/50 split of I observed that spinning up and I observed it spinning down and then but I only ever find myself in one side or the other so there is always a moment

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between when the wave function splits and when I know about it it splits much faster than I can know about it the the rate the speed of a wave function branching is some incredibly tiny number 10 to the minus 20 seconds or something like that and the time scale of things happening in my brain is like 10 to the minus 3 seconds at best okay so there will always be a time when there are two copies of me

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one on the branch with the spin was up one on the branch where this been was down but they're both identical they don't know which branch there on yet so they need to be good Bayesian 's and say well what probability should I sign that I'm On One branch or the other and it turns out that the probabilities work exactly like the textbook quantum mechanics tells you the probability should work out now how is that the wave function squared is the probabilities so there's a new function Square this is a rule called the born rule after Max born who was a physicist who invented it so I mean read the book of course but like you said it to very start the history of quantum mechanics is just so fascinating and hilarious Schrodinger Erwin Schrodinger of Schrodinger's cat Fame invented the idea of the wave function and wrote down the equation that it obeys okay but what he hoped was that if you had the wave function of electron all by itself if you solved his equation it would sort of show that the wave function becomes localized peaked at one location the electron kind of

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acts like a point particle and that's why we see particles that was his hope what actually happens when you solve the equation is that the electron spreads out all throughout the universe so he was his Hope was dashed and then he's like all right I have this equation what is it like what is the wave function do and it was Max born hold another guy who said what the wave function does is you square it and that's the probability of seeing something somewhere like if the wave function looks like this it's some spread out thing there's very small probability over here and large probability over there because the probability is the wave function squared and Schrodinger said like oh my God that's awful I'm sad I had anything to do with it he regretted being involved with this whole idea of probabilities and collapses and all that stuff do you see an increased interest in this subject among students is this is seems like I do very yeah I do but you know with things like that it's always hard to you know protect against my own biases right like I see the the people who

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interested come to me because I keep talking about it right and maybe I'm ruining their lives by getting them interested in it you know when I have real graduate students I try not to let them work on topics like this too much like a little bit and get their foot wet but they got to work on respectable stuff that will get them a job also that's interesting so you're protecting them oh yeah no I have I'm I really try mixed success of course but I tried very hard to

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be a good advisor in the sense that you know challenge them intellectually and get them through interesting things but in a way that will lead to a productive career in part of that is get a job right like you know I'm not a believer in being such an idealist that you stop doing physics by the time you're out of graduate school you know keep going do you think it's possible to boil this down to a documentary that isn't filled with whoo like a just a response to something like what the bleep some sort of entertaining yet clear version of what you're saying I think so yeah know if it has any producers out there who want to opt in my book Champion you know I think it's especially these days when computer Graphics are really good right and we can visualize thing yeah them couldn't be sure I would help yeah and that was I in fact I think that you got a copy of my book that didn't have any figures in it right and you get the I believe so yeah it makes it much harder the real the real book has pictures okay

► 01:19:03

that doesn't make that out or is yeah I'm sorry I should have brought a copy is that out today last week okay so it is out now we'll send you a copy little that'll be better but honestly all the pictures in the book were made by me using Adobe Illustrator and this is not really my area of expertise so it's not like high-level Graphics it's just barely functional yeah especially you know there's so much history in there I had the idea before I actually wrote this book I was seriously contemplating writing a novel about the boar Einstein debates because they were nominally about the nature of quantum mechanics but they were really about the nature of reality right and there's all sorts of the history is interesting you know there were Nazis we talk about the 1930s right you know Einstein fled Germany the personalities are very different and you'll bore Niels Bohr is this amazing figure I had David Albert on my podcast on mindscape and the same David Albert who appeared in what the bleep and we talked about Quantum

► 01:20:03

and it's the measurement problem and you know he said he put it really well he said like if there's a figure from history who I would like to have dinner with it would be Niels Bohr and because like he was certainly a very an amazingly good physicist very very influential but over and over again SuperDuper smart people would get together and talk to Niels Bohr and come away spouting nonsense about the foundations of quantum mechanics somehow he had this magic Charisma that worked in a bad direction to like make people just become crazy about quantum mechanics in a bad way and that's part of the reason why we haven't dug into the foundations of quantum theory why what was it about him he was just incredibly charismatic in a weird way because he was a terrible writer you know there's this story where he Einstein wrote this paper about entanglement and spooky action at a distance and bore responded to it and everyone said you know because by this time 1935 people were already bored

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foundations of quantum mechanics and they didn't want to think about it so if anyone said well what about Einsteins worries they would just say oh bore wrote a paper don't worry about it and boars paper was reprinted in this you know book you could buy and then you could read it and the pages were printing the wrong order and no one noticed and is like it's just hard to make sense of what he said so he was even pretend to understand what I was saying even though it was in the wrong order it's that's a weird it is yeah that's and that's how bad a communicator he was but in person everyone loved him like John Wheeler who was you Everett's advisor was a sort of an acolyte aboard he their sentences he said like I never knew what people meant when they talked about people like Jesus or Socrates or Buddha until I met Niels Bohr

► 01:21:55

hmm so he had some magnetism he had that's why that's why David Albert wanted to like meet him he's like what what did that guy have like what was it like to talk to him that people loved him so much even though he's kind of wrong about the foundations of quantum mechanics but it's at least someone who's charismatic who has that sort of enigmatic personality at least it could spark interest yeah that's right so you know part of the reason why I wanted to write this book is it's very much like you know another thing I do is go around and talk about science and religion and I'm an atheist myself so I say that you know science leads us to not believe in God and I talked about this two very different audiences churches and things like that sometimes how's that go well it depends very much on the age of the person in the audience is the thing older people like they made up their minds they're not they're not going to change but young people even a very very religious young people are fascinated by what I have to say it's not that they change their mind right away but it's like I've never heard someone

► 01:22:54

it that way before right and maybe they do change their mind later maybe not but at least they've heard a perspective that they were not exposed to earlier I think the same thing is true with quantum mechanics like there's a buttload of books about quantum mechanics on the market there's no shortage of books about quantum mechanics but they're mostly with this Spirit of isn't this bazaars and this weird will never understand it and I think that that many many people who up to be physicists this is what they're doing when they're 12 years old the reading these books right and so I wanted to write a book which said like actually we could maybe understand is if we just tried it's not inevitably mysterious lets lets you know be embarrassed that the field of physics is not put its effort into it and make an effort here and so maybe that will so that's what my you know most ambitious hope for book like this is that 20 years from now will be a flood of young physicist who think this is really interesting yeah well the number what would you estimate it would be currently like how many people do you think yeah certainly

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order a hundred that's it I think so yeah like you know when we have conferences is often 12 people there are 20 people holy shit maybe there's more because I haven't met them all but it always depends on how you draw the boundaries also whereas you know there's thousands or tens of thousands of people in most subfields of physics so I mean why would you go into the sub field where there's no money or promotion chance it's it's it's yeah gasps but still that's stunning when you hear that it's somewhere around a hundred yeah I mean we have here in California we have sequin the California Quantum interpretation Network which is a group of us you know the people we know in California who care about these issues and we need to talk about them and it's like 15 people wow and we could think and it depends on where you draw the boundaries and so forth but when you guys kicks the bucket I know it's how we get to bring get new blood in there yeah it's a but I like I said I do think it's it's growing its expanding and I'm optimistic I-10

► 01:24:54

optimistic you know there is this alluded to it before but let's emphasize it we turned on the Large Hadron Collider in 2009 we turned it on in 2008 and then it exploded we fixed it and turn it on again in 2009 and it found the Higgs boson the 2012 and it didn't find anything else

► 01:25:16


► 01:25:18

that's bad that's bad for physics in a big way because it's great that we had a theory that was the king true with the Higgs boson but in some sense we learned from the Large Hadron Collider the smallest amount it was possible for us to learn there's a Higgs boson and that's it about quark-gluon plasma yeah that's great but we knew it was there I mean we will learn details about it but the fundamental underlying laws that give rise to that we've known since the seventies mmm so there's a million things we learn about you know like for the gravitational waves for measuring the Higgs boson we pinned down numbers we measure the cosmic microwave background the leftover radiation from The Big Bang but you would like something more that you could bring to people saying that this is very valuable intangible stuff well not just that I wanted to make progress right so we had good reason to think that there should be a bunch of other particles that you discover at the Large Hadron Collider and they weren't there meanwhile we have very good reason to think that 25

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end of the matter in the universe is dark matter only 5% of the energy in the universe and we had very good reason to hope that we could detect it by now in an underground laboratory and we haven't and it's there but it's beyond our reach somehow so it's just so hard to make progress under these circumstances and meanwhile we have big cool ideas like string theory that are hard to connect to the real world so this is the last third of the book to me is you know again like I have my favorite ideas but there's a bigger picture about what kinds of ideas we should pursue and how we should pursue them so the last part of the book is maybe we need to understand quantum mechanics to better understand quantum gravity in the theory of everything you know like what should how should we expect to understand quantum gravity if we don't understand quantum mechanics come on right and what was the motivation behind starting your podcast it's called mindscape mindscape yeah line scape um yeah I've been having lots of fun with the podcast it's been great and several episodes about

► 01:27:18

quantum mechanics most recently just last week I did a whole two hours solo episode on how space-time can emerge from quantum mechanics the I'll tell you the the motivation was when I wrote my previous book the big picture it was a sprawling book so it's not only physics but also philosophy and Neuroscience and biology and math and computer science is a whole bunch of things in there that I'm not an expert on I'm a big believer that people should talk about things they're not an expert on but they should talk about them in some sense of humility that I don't understand everything here so I will talk to some experts right so I went around talking to experts I you know I interviewed people and I had so much fun because I was writing a book I can literally just email a Nobel prize-winning biologist and say could I drop by and talk to you for an hour and they would say yes and when the book was done that went away I can't I can't I don't have the license to just call people up randomly and say can I talk to you for an hour but if you but Papa you have a podcast and suddenly yeah people want to talk to you right so I've gotten you know

► 01:28:18

I talked to Wynton Marsalis the the trumpet player right you know the the grammy-winning trumpet player I talked to Seth McFarland the other day I talked Nobel Prize winners MacArthur Prize winners philosophers biologists documentary filmmakers it's I just really have a blast so yeah this podcasting thing I think is going to take off you should look into it yeah well for me I mean there's no way I would be able to get someone like you to sit down explain things like this without a podcast well it is a it's taking advantage I think right I mean I'm not telling you this let's say we're telling the audience this but it's your we can talk songs we want right let you take advantage of this better than anybody and it's different it's doesn't replace things like books okay but like books are always where you can get into the weeds a little bit like maybe a little bit more specific a little bit more careful but there's a long road you know there's a lot of books out there I'm not going to read all of

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that was the other motivation behind starting my own podcast is that I had a stack of books I wanted to read and to force myself to read them I would invite the author on in the podcast but I can't read all those books which book should I read you know there's there's a whole you know journey to saying oh like this is important enough I should dedicate myself to a week of my time to reading this book and hearing people talk about it in an informal setting is you know both Illuminating but also like oh yeah there's ideas in there I really need to get to so I'm a big believer in diverse ecosystems I like Twitter I like little YouTube videos I like podcasts I like books I like talks there's all sorts of ways to get this information yeah I think it's opened up the interest in a far broader group of human beings to because and having conversations like this with you or with you know the hundreds of people that I get to talk to on a regular basis it's Sparks ideas and people that you know in their seemingly mundane existence maybe just would never get

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there and it allows these new areas of inquiry and the new areas for them personally to go look into and I get messages and I meet people all the time I tell me how much it's changed the way they view things because they've now been exposed to interesting information that's sort of sparked their their their view of the world in a different way knighted different parts of their imagination and absolutely and including me like literally yesterday one of the areas that I had hoped to get onto mindscape podcast is economic some variance in economics but I realized I don't know crap about economics like I'm not interested in you know the trade deal or what interest rate the FED should set and the problem of Economics is it's too relevant to the real world so people want to talk about you know monetary policy and things like that but I want to talk about the underlying theoretical ideas right and I realized I just it's hard to get those

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so I downloaded some economics podcasts and I started listening to them and I just happens to me all the time when this new a good podcast I'm in the car and I have to stop it to think about what just happened because you know they gave me they said something and it gave me an idea and the great thing about being a physicist is there's some relationship between what I do for a living and almost everything else right like whether it's economics or biology or philosophy so I can always hide like hmm that's an interesting idea I wonder if I should you know write a paper about that so and I wouldn't have done that very easily without the podcast format yeah no it's a really interesting time it's a really exciting time to spread information it's a really exciting time to find things that you're interested in yeah you know and also you know I always noticed this about the internet in general which is that it calls you on your crap a little bit right like before the internet you know you could have opinions about things that you could spout off to your friends and you know over the dinner table or whatever over drinks and suddenly when I started having

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the blog and I would spout off and people would say like yeah you're full of shit like what are you talking about how you can say then I just you know sit back and think like oh maybe I am full of shit like where did I get that idea right yeah and I think that despite all the misinformation Etc that's out there if you are intellectually responsible and want to get things right putting your ideas out there in public to be critiqued is a wonderful tool it really does go oh yeah so like it helps you figure out like what I do understand and know and what just were kind of vague ideas that somehow got into my brain For No Good Reason yeah if you're open to the the floodgates that's the problem is there's so much feedback it's really hard to separate the wheat from the chaff it is yeah and you know different people have different strategies like when I talked to Seth MacFarlane he it was interesting he reads the comments like he wants to know we have like 12 million Twitter followers and he and he hates it he's like it's

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listen toxic and but he reads that and and you know for good reasons he's like look I'm creating entertainment yes if I don't know what the people I'm trying to reach think about it what is the point is like much like me and physics like the kind of physics I do is not building better machine or curing cancer right it's only because human curiosity leads us there so if I don't tell other people about it what's the point and but we did have a conversation about blocking people on Twitter because I was like the only reason why I like Twitter because I block everyone who's a jerk you know like if they make my Twitter experience Less Pleasant they get blocked right away yeah that's a good move yeah there's a

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a loud noise and there's a lot of wonderful people I've met wonderful people like half of my podcast guests come because I got to know their Twitter feeds yes I'm fascinated yeah yeah I've read a lot of other people's things I don't read any of my stuff like any of the stuff is coming at me it's just you got to overwhelming after a while and it also would it interferes with the time that you have to put stuff out because people get wrapped up in responding to their mentions or reading their mansions and this is an extraordinary amount of time that you can waste doing that yeah I mean that's the secret like people ask like you know how can I spend so much time on Twitter and like what are you talking about like I spend five minutes a day on Twitter yeah tweeting and maybe another 15 minutes reading other people's tweets and zero time responding to tweets that's the secret like if you yes Twitter's a terrible medium for conversing right it's you just can't be precise you can easily misunderstand and people easily become aggressive jerks right what's the worst possible way to have a back-and-forth unless you already know somebody

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and are just trying to clarify something so I use it for linking to things like I say Twitter is for linking not for thinking business like the hierarchy of communication top of the food chain is one-on-one talking just two people having a conversation and especially without any sort of heightened sense of importance or anger or frustration with another person just two people talking that's number one like it with no gravity right number two is probably phone calls like calling someone they don't see them it's not as good you know but like being in front of someone physically 121 is the best way to do it which is one of the reasons why I love podcasts as well as because you get a chance to put that energy out there the energy of a one-on-one actual conversation with people as opposed to writing an article like you know if I'm sure you've had snarky articles written about you it's it's weird it's like well that would

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why are you saying it that will do you determine my thoughts and and I've almost gotten to the point where I never respond to those like a lot of them I mean I got a lot of them by were when you started the podcast was it always in a studio or did you do things remotely back in the day it's always we've only had a few conversations remotely through Skype and one of them was with this egyptologist John Anthony West who was in poor health he's since passed away and then we eventually did get him into the podcast Studio but I started doing it in my house and just with friends because it wasn't there was no Grand ideas when this ain't got started was just Comics fucking around and then slowly but surely a big one of that guy would talk to me and and then it became now then it became what it is yeah I am still a hefty portion of my interviews are still remotely because like I want to get this person there or Oklahoma and yeah whatever

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but I totally think that you know it's much better if you're in person so yeah never I can do that yeah like I luck by little podcast portable podcast Studio around so if I like going to Boston in a few weeks I'm going to try to get like 10 people on their guests so now that's great man I'm excited you're doing it and and thank you for writing the book and thank you for coming in here and talk about it and if people want to get your podcast it's available on iTunes its everybody casters old yeah anything else many things but you know this is good yeah okay the podcast in the book or the things I'm hearing all right well always a pleasure Sean thanks very much for being here bye everybody

► 01:37:36

thank you everyone for tuning into the show and thank you to our sponsors thank you to policy genius life insurance folks you need it and you can get it it's the best time to get it right now because the prices are the lowest they've been in 20 years and policy genius has made it easier than ever and they don't just have life insurance they can make life insurance easy that can also help you find the right home insurance auto insurance disability insurance the policy genius team will handle all the paperwork and red tape it's the easy way for you to shop for life insurance online policy genius the easy way for you to compare and buy life insurance go to policy genius.com get quotes and applying minutes and you could do the whole thing on your phone right now policy genius.com we are also brought to you by stamps.com all of the amazing Services the US Post Office with none of the hassle you can buy and print official US postage

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► 01:41:05

I hope you guys recovered from that podcast it's a brain Bender he's too smart for us but we got through I hope you enjoyed it his book is excellent I really do I really do recommend it it's any also has an audio version that he reads himself so you can back up and try it again something deeply hidden by Sean Carroll all right thank you folks appreciate you all much love to everybody bye