Physics & Philosophy with Sean Carroll & Neil deGrasse Tyson

foreign [Music] this is Star Talk Neil deGrasse Tyson here you're a personal astrophysicist I got with me my co-host Chuck Nice Jeff hey what's happening all right it was good to have you there man especially when we have Cosmic queries oh fan favorites oh yeah fan favorite we love them uh you get to ask a question with sort of entry-level participation in our patreon program just five dollars a month that we collected them and you know in advance what you're asking about because today's topics involve physics and philosophy people love just talking about stuff for which there is no answer of course you know why because it makes them feel like they have a stake and a say and it's like because nobody has the answers yeah nobody has the answer so I'm just as right as you are right like no you're not you're still an idiot okay see I have a PhD in philosophy and physics I have what's called an informed opinion you on the other hand went on the internet saw somebody on Joe Rogan's show say something about something else and now you think you're an expert shut up shut up right okay that's the end of our show well we we we're bringing into this uh an old friend and colleague Sean Carroll Sean welcome to StarTalk hey thanks for having me on Neil welcome back to Stark talk I see I should say this is you've been on at least four or five times uh you are one of the world's experts on not only physics being a physicist but you're also that subcategory of physicist who cares about philosophy and have engaged philosophers on the frontier of our understanding of physics so it's great to have you for this Cosmic queries and dare I say we crafted this Cosmic queries around your expertise so I don't have to give you nothing but the correct true answers so okay otherwise chuckle get on your case don't don't make me go on another diatribe so you're the Homewood professor of natural philosophy at the Johns Hopkins University right there in Baltimore and you have a joint appointment at the Santa Fe Institute now that Institute everything I know about it those are deep thinkers about things that it's like what like you twist your head like a dog hearing a high pitch it's like what and you're the fractal faculty at the Santa Fe Institute and your expertise in quantum physics space time cosmology love it emergence um entropy Dark Matter Dark Energy symmetry origins of the Universe um and perhaps most people who know you know you through your mindscape podcast so always good stuff happening there those things that make you uh tilt your head and scrunch up your eyes like that's my Lane that's what I do that's you with that oh I'm gonna keep them in it okay so I say this lovingly and crazily stay in your lane okay and full of crazy people but I'm I'm in it so tell me what is uh First Natural philosophy I'd last saw that term with you know 17th 18th century philosophers natural philosophy was the then term for what today we would call physics right because political philosophy and religious natural philosophy was physics so what why isn't that just physics professor there's a joke in philosophy circles that once an area of philosophy starts making progress it gets spun off to a completely different field so it never looks like philosophy actually makes progress but you're right Newton Galileo those folks would have called themselves philosophers the idea of a physicist hadn't been invented yet but what happens is that Academia loves to categorize and Silo people so they invent a physics department and a philosophy department and they examine what questions you could ask and they decide which is which but what that does is that it means that all the in-between stuff because it's really a Continuum here not a interstitial ideas and things those just get lost and we're at a point in physics right now where questions like you know what is an observer what is infinity why is the past different from the future what is emergence like these are physics questions but it clearly was different from all other nights so you are there to clean up the pieces is what you're saying well I'm actually there to understand the Universe I think that the common thing uh within natural philosophy is we're not studying the process of science or anything like that we're studying nature we're studying reality but there's a way of doing it that it's kind of foundational that you know takes a step back look physicists plus their hearts you've met physicists Neil I know this uh and ask them by the way Chuck anytime someone prefaces something by bless their heart bless your heart they're about to insult them in some nothing nothing good ever you know it's just in the same sentence as bless their hearts especially if you're an old white lady from the south you know what I mean they said oh bless her heart she's just a little that's all Sarah you know it's true that's how it goes okay I started a book by saying uh you do not need a PhD in theoretical physicists in physics to be afraid of quantum mechanics but it doesn't hurt and physicists don't want to dig into the deepest questions about quantum mechanics they want to calculate their differential equations they show up and calculate you shut up and calculated and that's the opposite of what I like to do myself so the Philosopher's uh humor me on that so just to be just to make sure all our audience is on the same page quantum mechanics is is amazingly successful at predicting and and and and describing reality but that reality defies all our common sense and you reach a point where you just say okay I'll just live with that and continue to calculate and Sean you're telling me you're not satisfied with that you want to understand crazy Quantum phenomena on some level where we can sit down and say okay now I understand it is that what's driving you yeah absolutely just like it drove professors Einstein and Schrödinger back in the day but there was this uh consensus that developed in the 1920s and 30s by physicists where like you say we have some equations we can solve them we can calculate them we can make predictions and book beautiful Exquisite agreement between the calculations and the predictions without knowing what's going on without freeing right actually happening in the world and there's a whole bunch of physicists who will say oh no understanding what is actually happening in the world that's not my job I'm just here to make predictions I strongly feel that's not right I'm here to help understand what is going on right so you you're the show your work part of this whole equation explain your work show it unhide anything no scene yeah it's okay to come up with the answers but we got to know how we got there absolutely yeah so Sean what's been in all the buzz in recent years is a quantum entanglement all right and let me offer my best explanation and you correct it and then but then give me your understanding of it all right you can create two particles simultaneously that have sort of complementary properties Quantum properties to them and they can separate and they know about each other there I use the word no they they know about each other's existence and and the moment you make a measurement of one of them the other particles properties manifest to whoever is observing them and they manifest instantly transcending the speed of light and so we know that happens but Sean you're going to tell me that you understand it or will you not well I think that we have multiple competing ways to understand it we have not agreed on the correct way my way is like I said Chuck in the bar you just have the beer and nobody agrees right that's the difference but like like you said we can make the prediction to Exquisite accuracy people tested the prediction they won the Nobel Prize for it last year that was what the physics Nobel Prize was given for and by the way the whole reason we know and care about entanglement was because Einstein in 1935 was trying very hard to figure out what really is going on right and he didn't quite succeed he didn't get the answer there but it's that drive to understand that led here and ultimately what we can say I think with some confidence is that what the world is is not a bunch of separate particles doing their own thing it looks like a bunch of separate particles under certain very clear circumstances but in other circumstances like this entanglement business it doesn't it's more holistic than that so people like me who are Advocates of the many worlds interpretation of quantum mechanics we have a very simple straightforward way of talking about entanglement but there's other people out there who talk about it differently and you know that's great that's what Academia and intellectual curiosity is all about remind us of the many worlds hypothesis because I think that's now 100 years old right we're we're on the Centennial decade of the major discoveries of quantum physics the 1920s so if you can just remind us what the many worlds I think it was once explained to me then I said what are you smoking I think that's for sure that's what I said tell us when we teach undergraduates quantum mechanics we say that a Quantum system has two different ways of evolving there's one way it can evolve when you're not looking at it and that's what Schrodinger and Heisenberg and their friends figured out back in the day well just to be clear I just to be precise I know how you're using the word evolve but to a biologist the word evolve means something completely different so you mean it unfolds yeah the events unfold yeah it's it changes it has its Dynamics whatever it's doing whatever its behavior is but then there's a whole nother way that we need to describe that behavior when we make a measurement when we observe the system famously in quantum mechanics you can't predict deterministically precisely with 100 confidence what answer you're going to get you can predict a probability distribution over different possible answers so the Einstein said God does not play dice that's what Einstein said yes and the universe or so it kind of looks like you are playing dice I'm just saying I'm just and by the way what a uh what a presumptuous statement on Einstein's behalf I mean who knows Sean didn't Niels Bohr say I stopped telling God what to do exactly I mean who's to say that God's not down to one knee going popping these a new pair of shoes you don't know that you don't know that so it wasn't me it was more somebody said it to Einstein who was it I think I think it was Niels boy I think the better advice would be like don't play dice against God you're not going to win if that's yeah okay there you go that that makes sense so what is this going on with this weird thing you don't expect measurements observations looking at things to be part of the fundamental nature of reality right you know it never was before quantum mechanics came along so you can ask yourself what if like all that was unnecessary this whole idea that we need a separate rule for what happens when we measure something what if you just erase that from the rules of quantum mechanics and the answer is that what do you find is that every possible measurement outcome comes true but in a different world in a different part of the overall Quantum Universe you get parallel worlds where different measurement outcomes are true that's when I asked what the guy was smoking wow now wait so that these different worlds are in the same realm is that the case or are we talking about completely different um unfoldings that create completely different scenarios that make the whole thing work or another way to ask that do you have access to these other worlds there you go thank you you have iPhone you can download an app called Universe splitter and if you're ever stuck on what decision to make you know should I have a hamburger should I have pizza for dinner tonight or whatever ask the universe splitter and we'll come back with an answer and you can be guaranteed that there's a whole nother Universe which you can never interact with or talk to in which you do the opposite thing it's split in that instant right in that instant yes yeah at the decision instance okay okay it's a physical Quantum process but and and that's because of the entanglement because they couldn't exist simultaneously they have to exist in those positions at the time of the decision so that when one does it the other does the opposite or when one does something so there's a there's an action and there's a reaction but there can't be action action it has to be so that they're existing and then reacting differently Sean Chuck is about to blow a gasket and no because you're freaking me out man you are free get me out this is not anything that we uh bump into in our everyday lives if it doesn't make you a little bit uncomfortable you're not taking it seriously okay all right I am wow all right sure let's get to the questions okay man this is already good stuff boy I'll tell you right I'm so mad I didn't have an edible before this show I really should have taken the gummy before this one dog gone again these are from our patreon supporters thank you all for what you do for us it allows us to experiment and bring new and creative content to you that's yet to be proven to be commercially viable so that's what would that's what's going on here all right Chuck you got your your iPad there all right I do so here we go hi I'm Neil deGrasse Tyson your personal astrophysicist and I'm Lindsay Nix Walker senior producer of Star Talk and Neil and I just co-authored a brand new StarTalk book coming out September 12th yeah this is the third in a series of collaborations with National Geographic books and this one is titled to infinity and beyond and it's available for pre-order from the StarTalk website startalkmedia.com books if you pre-order it you get to gain access to a live stream that Lindsay Walker and I will do from this office and you have the occasion to submit questions that we will answer that's right if you pre-order from startalkmedia.com books we'll answer your questions about the book The Universe Neil's favorite kind of cheese whatever you want all right so we'll see you there and we'll see you then this is from Psy uh says hello Dr Tyson Dr Carol Dr haha uh first time patreon member I know right first time patreon remember here a huge huge fan uh I am Sai anurag U from India uh Chuck if you get my name right I swear to God I will double my patreon membership exactly yeah well I I guess you have no you're in no danger there are you yeah I think he's gonna have it after what you just did to his name but all right that was funny uh my question pertains to Dr Carroll's research which says that the universe is infinitely old and big bang is just one of many events resulting from Quantum fluctuations of a vacuum energy in a cold this litter desitter space please throw some light on what kind of space is this how can I visualize it better in order to understand it more fully ooh good very good I love it you know hanging out on the wrong street corners I don't know where they where they picked these things up but yes this is all driven by the very famous philosophy question why is the past different from the future why is there an arrow of time because the fundamental laws of physics have no Arrow of time in them the answer is entropy and the second law of Thermodynamics the universe used to be more organized lower in entropy the whole history of the universe is just entropy increasing disorder and Chaos developing all around we're all gonna die that's the it's not your fault necessarily but you're contributing to the disorder and Chaos all around us and that started about 14 billion years ago near the Big Bang at the moment of the beginning of the universe our universe was exquisitely orderly it doesn't necessarily look that way but you run through the numbers and it's true why why is that true why was the early universe so orderly and so uh I've long wondered about this and I wrote a paper years ago now with uh uh a woman who's a graduate student of mine at the time Jennifer Chen where we proposed that the Big Bang was not the beginning of our universe other people proposed that in different contexts but we made the case that you don't need a fine-tuned special organized low entropy beginning of the universe the universe can be Eternal it can last forever but what happens is it empties out just like our universe is doing a universe can be completely empty the future of ours will be but it still won't be perfectly quiet there are still Quantum fluctuations that can lead to whole new universes coming into existence and as that happens they all start in low entropy conditions and the entropy uh grows and gives that little part of the universe a narrow of time and the fun part is the far far past the same thing happens but in the other direction so there's sort of a symmetric shape to the universe where the future is a story of more and more universes being rated and the arrow of time pointing in that direction the past is the story of more and more universes being created with people in them who think that we are in their past I I'm gonna tell you right now uh if if Psy understands what the hell you just said and they need to be the co-host of this show so Sean what you're saying is there's some symmetric point among these universes and these time continua where in One Direction we're entropy increases but in principle there's a whole other Realm where entropy decreases from our point of view from the people living in it they will always see entropy increasing because we always Define the past as the direction in which entropy was lower so it's a big U shape that is perfectly significant now so now that so we're in their past because they're looking at us and seeing a decreasing entropy which is and which is indicative of traveling backwards because we're moving towards a more ordered universe but we cannot be moving towards a more ordered Universe if we're moving into the future because we are always moving towards entropy so if you are observing that then you are in my I am in your past so because you're looking at me going towards order Chuck gets it we're done yeah man [Laughter] Chuck you're blowing out the volume level one that's insane okay wait so so Sean before we get to the next question what um these are ideas is there any way to experimentally verify any of this well we're trying but the short answer is we don't know yet we don't have uh it's not like a no just say it oh it was very much not a no oh okay but all the words deal these all the words matter here okay yeah and this but this is a more a broader idea right um there are plenty of tentative preliminary scientific ideas which are too ill yet I'm with you predictions Einstein's um gravitational waves Einstein's gravitational Rings yeah I'll give you that we'll get there we will get there send money we'll we'll do it just trust us yeah in your lifetimes yeah every time it's getting shorter every year so I don't know yeah your life expectancy is dropping every year yeah yeah all right Chuck what else are you at all right let's go on to Doug Sherman Doug Sherman says hi Neil hi Sean Lord nice uh the Doug this is Doug from Frisco Texas all right all right Doug says I thoroughly enjoyed Sean's debate on God and cosmology against William Lane Craig although I'm still trying to get my head around everything Sean explained once one amongst many arguments I found interesting was Sean's rebuttal against Mr Craig's technological argument that the finely tuned Universe was evidence for the existence of God I don't recall the specifics but I believe Sean stated that in some models the probability of a finely tuned Universe approaches one and then it's oh man he he must have cut and paste because it drops out then he so he he he the finely tuned Universe approaches then he says could Sean once again go through the perspective of the fine-tuned argument I also reject the technological argument but for more simplistic reasons than my flawed Brink can rationalize so just for context William link Craig is a proponent of um basically a god-created universe and he's not the Bible thumping person in such a conversation as others might be he's trying to stay grounded in the natural world taking you to a precipice where you say Okay God must be there so I I'm pretty sure Sean wouldn't debate just anybody on that subject so William Lane Craig has some some uh debating respectability in that regard do they characterize that you're not going to throw down with Pat Robertson or Jimmy Swaggart that's right it's not on the debate stage no okay I do think that the what is called the fine-tuning argument did I characterize your your opponent accurately would you say yeah that's fine um but the the fine-tuning argument for the existence of God is what I think is the best argument for the existence of God I also think it's a terrible argument but still it's the best of the ones that they have so I've read when they refer to it and the idea is that you look around the world the world in which we live the universe we find ourselves in and you say there are features of this universe that need to be the way they are in order for life to exist if they were different life couldn't exist but it they easily could have been different right that the things like the amount of energy in empty space could have been so large that it would rip planets apart before they ever formed but we seem to have gotten lucky we seem to find ourselves in a universe that allows for our existence and so the argument is I know why it's because God did it because God created a universe in which that's possible a very common counter argument is well it also could just be a Multiverse right there could be many different parts of the universe and we just are finding ourselves in the hospitable one but there's two things you're not in all the others to have this conversation right so they help play an explanatory role in in accounting for why our universe looks so fine-tuned so two things going on here one is the proponents of this argument tend to exaggerate the degree of fine-tuning that they need and that's what the questioner is referring to there's certain things that William Lane Craig and others say oh that I just don't get it that's so fine-tuned but you can raise your hand and say actually physics has completely explained that one now we don't need to go beyond the realm of physics to account for that so but in other ways it still looks fine-tuned and and my favorite rejoinder is actually this is a great argument for the non-existence of God because if God existed and God created life God is not beholden to the local laws of physics God can create life however God wants to because he's God God can do anything you don't need the physical conditions to allow for the existence of Life unless God does not exist all right now let me let me let me just ask a question here because I uh just just to further clarify by what if uh instead of needing the laws of physics the laws themselves are a reflection of what God has done so it's not necessarily that the that the laws are needed it's that the laws exist because they just happen to be a byproduct of the creation itself that is completely possible and Neil will raise us in here and say how do we observationally test that hypothesis okay listen I'm 100 with with I'm on board with that okay good I just wanted to make sure that that could that that could be an argument to be here it smells like Spinoza's God right which is that the whatever God is to you the laws of physics are the manifestation of it oh so I'm not that smart somebody already thought of my question could have been Chuck's argument but nice is god um but look for the last 500 years as science has done more and more to explain why the universe is the way it is the role for God as an explanatory move has gone away has diminished right and so you are continues to do so yes and so you're left with if you want to believe in God and there's plenty of very very smart people who do they they tend not to rely on God to account for the things that we observe in the natural world what is called natural theology as opposed to Natural philosophy natural theology is not so popular anymore gotcha all right fascinating stuff all right Chuck keep going we've only gone through two or three questions let's see if we can speed up okay we just have to have Sean back that's all this stuff is too good we can't rush we cannot rush through this at one point get a double wide episode with him maybe yeah well yeah yeah absolutely all right this is Tom B Knight hello I'm a patreon supporter of both Star Talk and mindscape we're great to see Sean on the show uh do voids in the cosmic web like the iridonis uh supervoid violate the cosmological principle what could be the cause of these structures thank you for your service okay good one every dinosaur is a constellation I think it's a waterfall or is it has something to do with water my memory serves but anyhow uh Sean what you got there this is a great question but there's a lot going on here I'm going to try to keep it brief here you know there's something called the cosmological principle that says that if you squint and look at the Universe on very large scales everything looks the same everywhere right the same number of galaxies and whatever it's a Dopey thing to call a prince simple because it's not a principle it's just a fact that you see about the universe it could easily have been otherwise especially because it's not exactly true and that's what the question is getting at there are places in the universe where matter is very dense there's places where it's very empty and so forth the way that modern cosmologists think about this question is to say the early Universe it was even smoother than it is now it was very very smooth there was only a difference in one part in a hundred thousand as you went from place to place number one why was it not perfectly smooth but number two why was it pretty darn smooth and number three how did it evolve using the word evolve again from that condition 100 000 years after the big bang to our conditions now the last one how it evolved is the one we have the best handle on it was gravity doing the work gravity turns up the contrast knob on the universe so if you have a slightly emptier region it empties out you have a slightly heavier region it collects matter onto it and so we went from very faint ripples if you look at the cosmic background radiation to these very Vivid voids and Galaxy clusters that we see today we still don't know where those first ripples came from inflationary cosmology is a is a favorite thing to talk about but that's a whole nother episode wow I like the way you said that you we this we observe these fluctuations about apart in a hundred thousand and you say well how come it's not perfectly smooth how come it's one part in a hundred thousand and how come it's not anywhere near that today that's a fun way to think about that problem because it's easy to say oh here's the answer and then move on but wait a minute why isn't it something else yeah right and not enough of that goes on I think well it's it's a Once Again a reflection of the fact that the early Universe had low entropy because gravity was so strong in the early universe uh more common generic random configuration would have been wild fluctuations like black holes here and empty space there and so the fact that it was so smooth does kind of demand an explanation and we're not sure what the explanation is all right keep this going Chuck uh this is Malcolm Marfan and Malcolm says hello Dr Tyson Dr Carol and Chuck maybe okay um okay I love these people they love you Chuck no matter what they call you I know nobody I know [Laughter] well Malcolm marfon here all the way from Trinidad and Tobago and this is nice he says Dr Carol I came across your 2018 paper why is there something rather than nothing and thought wow this guy's really dedicated to a lot of brain power to the concept of nothing now since you've clearly become an expert in nothingness can you shed some light on the various layers of nothing uh specifically how do these layers of void stand apart and how are they intertwined with the head-spinning Realms of cosmology and quantum mechanics P.S can I get a philosophy or Physics degree with nothing from with nothing for my thesis I think our questioner missed the point of the title of my paper which is that there is something like you know we can contemplate that there wouldn't have been anything and there's just nothing but what I say in the paper is can we really contemplate that I mean I think that we have this informal training from our everyday lives right where we have boxes with things in them and boxes with nothing in them and so we think that there's an option there can be things that there could be nothings but when the it comes to the universe it is not at all obvious that there is an alternative to the universe existing what does it even mean for nothing to exist how does nothingness even exist I mean that's kind of what I'm getting at in the paper which is that it's not at all clear that the reason why the university exists is the kind of thing that has an answer to a why question uh maybe we maybe we just have to accept it as a brute fact and be lucky about it so I do think this stuff is fun to talk about but I I don't think that uh it is nearly as down to earth and simple and physical as certain physicists to like to talk about this uh make it out to be it's a it's a fun mentally a philosophy question wait but Sean uh if there were no quantum physics in principle you could talk about space as having no particles and none of these virtual particles that quantum physics forces into it you just say remove the atoms and all known particles that's as pretty good and nothing as anyone would hope to describe isn't it no it's something it's space it has because you have a word for it okay you you call the empty space space and I call the empty space nothing aren't we just semantically differing there not fundamentally differing is empty space three-dimensional I don't know you just don't want to answer it because okay so let's say let's say it's three-dimensional and and exists on a time continuum sure it's oh it has a property then it's not nothingness it is there's a way it could have been different you invoke a way to measure stuff in it I wouldn't call that an inherent property of the empty space it's it's different than four-dimensional empty space okay so how about this how about this okay uh again one of the reasons why I don't like arguing with philosophers because ultimately it comes down to how you're defining the words that you're using in your sentence in so many of those arguments so let me just say if we Define something versus nothing as something is there's a thing there and I take everything out so that as Chuck said there's as you said there is no thing nothing there then that's nothing okay now we're now you're saying there's a grid system there that we can invoke or it's inherent so that's a thing okay so now I add to my inventory of a thing particles plus grid systems okay fine then that's there no so now we have to ask can we take away the grid what I think is a more interesting question is do the laws of physics apply in that volume and therefore can't be entirely nothing because laws of physics apply even though there's nothing there to manifest them ooh now you're getting deep so I like it because you're invoking not what the system is but counter factual properties of what would happen to the system if you changed it a little bit which is fine it's a fine thing to do look you're absolutely right that there is no pre-existing definition of the word nothing to which we're referring here you could have different ideas I think that the deepest level of this question is why is there a universe at all versus complete non-existence not even space I mean even you had to preface your question by saying like imagine there was no quantum mechanics and for that matter secretly imagine there's no general relativity either because okay yeah you're throwing away all of known physics to even ask your question but of course within known physics you can ask plenty of questions about why isn't space empty why is space three-dimensional those are perfectly good physics questions it's a little bit different than the question of why there's a universe at all you can ask the post them separately it's not a right or wrong thing to ask right yeah all right well that's all right cool what a great question yeah yeah because when someone says why is there something rather than nothing and I look out in the universe which is mostly nothing I say there's a lot of nothing in the universe I just so whatever something we have that's is side by side with a lot of nothing and until you start invoking other definitions for what nothing can be so that's all that's my only point there well there you have it Malcolm uh we have discussed your question and we have uh we have achieved nothing okay [Laughter] all right all right keep it going this is Javier Ortega who says hi you guys are just the best greetings from my artificial limbs development lab in Panama just a quick question that will not let me sleep till to the speed of light we can only see the past while looking into distances of the cosmos how do we know we are in the quote unquote real present we sense everything with delay even short distances also there's a delay between our census and our brain are we sure that we perceive now as now maybe it's just something relative to us like movement maybe we are five hours in the past or 200 million light years in the past According to some other arbitrary timeline or other alien beings that could be TR that could travel absolutely everybody's been smoking before they said let me tell you man I told you I told you but he says I hope you read this message from the past please keep looking up he makes an interesting point that what is what is the present even mean if everything we do to interact with the world has some kind of time delay yeah I'd like that idea of the brain or understanding our senses our that's true our uh you know my hand is not as it is it as it was a billionth of a second ago so what does it even mean to talk about the present yeah there's a scientist here and a philosophy answer here I'll give you the science answer because it's quite good uh our brain does not perceive the present our brain puts together a picture of the world that is on a slight time delay like our brain wants to be able to bleep out things that it doesn't like if you watch someone dribble a basketball and they're right next to you you will see the basketball hit the ground and you will hear the thump of the basketball against the ground and they coincide they go along with each other if that person walks away still true you see and hear the same thing at the same time even though the light gets to you much quicker than the sound and what happens is if they keep walking away suddenly they will go out of sync the vision of the basketball hitting the ground and the sound of it because that happens suddenly so your brain has correcting for it holy because your brain corrects for it as long as it's near enough your brain says this is all now and you can even measure how much it is it depends on what sense you're talking about and what perception but roughly think about 40 or 50 milliseconds of time is a little window in which your brain collects things and says I'm going to put this together into a picture of well millisecond is a thousandth of a second so forty to fifty thousandths of a second would be like five hundredths of a second there you go good method excellent yes right so what you're saying is there's a point where the brain just gives up uh recreating the present and said I can't compensate for this it's too hard it's too much I can't do no more so you do deal with it oh God you can't take it no so so so this is an experimental result Sean you know look as as I'm sure you are already know Neuroscience biology psychology that's a whole Frontier right there they like it way harder than physics or astronomy way harder way harder oh yeah okay I did not know this so uh interesting so the brain constructs a present so that we can help make sense of the world in our own moment that we make decisions it's actually doing that with everything all the time your brain because there's just too much input for your brain to actually process in real time so most of what it's doing is uh kind of creating a construct and then painting a picture of what it is and then it looks for changes in that construct wait so Sean this tells me that if the brain can't complete the picture it'll make stuff up to fill out the picture absolutely that's why there are so many black men in prison right now that's one example I was going to say optical illusions but sure yes racial incarceration uh inequalities that's another one yes this is the philosophy part of the answer which is that there is there's a real world out there I mean there there is objective physical reality but there's also the picture the image the model of the world that our brain puts together and they're related but they're not the same and our brain is doing a lot of work to take all the many sense inputs that it has and sew them together into cohere in picture yeah and a clever a clever optical illusion will hijack that ability and make you think something that is not very far from true as being true very but it doesn't quite make sense yeah yeah all right we've got time from one last question chuck oh my God this is over already I know right right yes we got to do this again this is fantastic I think he's got other stuff to do you know he's working on books you know the man writes books Okay now what's his latest book you just wrote um on right now during this episode yeah I'm almost done [Laughter] oh that's excellent wait you've got to book the biggest ideas in the universe volume one and you're working on volume two and this is a physics book where you you got equations in there and you and you are you are not apologetic about it no I mean we don't assume that you know any math we teach you the math so I teach a calculus and what have you know just in case you miss calculus you know in your school it's in the first couple of pages right a couple chapters but yes and then you move on and you learn tensors and differential geometry and uh Einstein's equation for general relativity and this is for the public you just want to boost the Public's math literacy a bit I and their self-esteem I love the public I want them to feel like they can get they can get this stuff into their heads it's not so hard really I love what you said to us Offline that when you were 16 you wished someone had written A Book Like This for you to consume at that time of your life the quantum mechanics and Quantum field Theory and particles and symmetries and Gage Theory had you had such a book imagine how much smarter you would be yeah it's all out by now I let one last quick question go okay this is uh Hamed who says this hi Star Talk uh this is Hamed from uh Montreal Canada my question are we still Chasing the Dream of a unified theory of physics or is that just a dead end should never be achieved love it Sean still chasing it because there is the universe the universe is telling us what it does it's just up for us to think up to us to figure it out so Sean it's a philosophical bias that you presume everything can be explained under one field equation and everything derived that's a isn't that a bias maybe the universe is fractured in this way with multiple forces that can't talk to one another yeah that's completely fine I I did not say it was just going to be one equation I was just about to say it might be a terrible mess we don't have any right to say that the final theory of the whole universe will be simple or elegant or easily understandable by us but we can shoot for it we can try and we can give it our best shot and see what happens that's what we're trying to do because we got bad history there in astronomy where Kepler has he's a mathematician and he's he knows that geometry is beautiful and perfect and there's certain number of platonic solids kids there's like the cube and the pyramid and the dodecahedron and he thinks that relates to the orbits of the planet and he embeds one in the other he is philosophically driven with some idea that the universe is beautiful and perfect and he spent 15 years wasting his time until he threw it all I said no planets just have weird elliptical orbits and sure enough that's the answer so we we've had to be we've been through this in my field uh John I'm just telling you Hill's artist Kepler I'd be very very happy okay yeah all right we got to call it Chris there Sean it's been a delight to see you again and chat with you and Chuck always good to have you man always a pleasure Neil deGrasse Tyson here you're a personal astrophysicist I'm beating you to keep looking [Applause] [Music]

Channel: StarTalk

Views: 479,126

Keywords: startalk, star talk, startalk radio, neil degrasse tyson, neil tyson, science, space, astrophysics, astronomy, podcast, space podcast, science podcast, astronomy podcast, niel degrasse tyson, physics

Id: vmlyQ0PjLzY

Length: 46min 41sec (2801 seconds)

Published: Thu Aug 31 2023