Cosmic Queries: The Multiverse with Neil deGrasse Tyson | Full Episode

this is Startalk this is Startalk and I'm your host Neil deGrasse Tyson your personal astrophysicist and I'm I hail from the American Museum of Natural History right here in New York City where I also serve as the director of the Hayden Planetarium my first planetarium as a kid when I was 9 years old and I was never the same since then I think the universe found me for this edition of star talk it's the ever favorite cosmic queries fielding your questions on a pre solicited topic and today's topic is the multiverse I know you've read about it I know you've heard about it and I know you're itching to know more and I've got my co-host Chuck nice Chuck a nail help you're gonna help me get through this that's right I have the questions right am I very high solicited from all over the internet wherever our fans may be found and maybe they're inquisitive little minds want to know all sorts of things and and I need a backup for this cuz I know a little bit about the multiverse but I had claimed no particular expertise in it so we get on the horn and called what my old friends and colleagues Paul Steinhardt Paul hey welcome to Startalk well thank you professor physics Princeton University yes and you are a proponent of one of the multiverses that people have been talking about well I'm not sure I put it quite that way but I'm actually a proponent of alternatives to the multiverse oh so I'm not a big fan of the multiverse oh okay the multiverse destroyed one of my favorite ideas oh oh the problem for you from me okay so what was your idea that the multiverse destroyed well it's an idea that we call cosmic inflation hmm so one of the long-standing problems that we've had in trying to understand the universe is why the distribution of matter and energy is so uniform on large scales and we thought we had well in other words I look to one side of the universe there's statistically a number of galaxies and stuff and any direction I look it kind of looks like that that's right so and you're saying it shouldn't look like that well according to our initial idea of the Big Bang the universe should have emerged from some random quantum state and been very had a very uneven distribution of matter and energy and space itself should have been curved and warped and all that should have happened is that you just stretched that out over time very very slowly so that if you looked at the universe today you should see remnants of that unevenness and war things like an area where there's tremendous amount of matter and other areas where there's hardly anything yeah and and bizarre curvatures of the space-time continuum yes like a fire yeah unpredictable in the way it moves it has certain burn patterns and so you would look for that to see where the fire how it progressed in certain air but it wouldn't be like a very uniform I hadn't thought of using fire but yeah I guess if a room would not burn uniformly because some things others are more flammable than others let me tell you something you have no idea I just bailed you out but I was just like the way you looked at me I was like ah the bed again Cho will try to come wrap our heads around this okay continue Paul okay so we thought that the idea for solving this problem was to have a period of very rapid acceleration accelerated expansion occurs right after the bang so that instead of expanding and that sort of slow modest rate that would preserve this unevenness instead you would stretch it at such a space at such a fast rate that the matter and radiation would all that existed before would all be spread out dissipated all you'd have left is the energy that would be driving this expansion this super expansion and then when that energy decayed into ordinary matter and radiation that we see today because it made the matter and energy or one in the same MC squared tells us that yeah but it also includes light and other forms all forms of energy then you would discover that the only energy that was left was very uniform yet very uniformly distributed so that was the initial idea that seemed to be a sweet idea for explaining how you would get physics this universe we see the universe we see which is has its peculiar and unexpected uniformity okay so then we came up with another added idea to this which is in this description I just gave you I didn't include anything about quantum physics so I said just stretching the universe would make it uniform but quantum physics resists uniformity it produces fluctuations random fluctuations that that that prevent perfect uniformity and they would lead to some regions of space ending inflation slightly before after the average so you wouldn't end up with a perfectly uniform universe you'd end up a universe with a specific non uniformity in the distribution of matter you can predict that you that we thought we could predict okay that seemed to be predictive it seemed to be something you could work out on the back of an envelope you could work out on the back of my supercomputer equals you in the back of your envelope okay but the and and curiously enough those naive predictions agree with what we've observed when we actually look out in space with the pattern of unevenness that existed in the early universe it's uh it's not as uneven as it might have otherwise been yeah it has the right amount of unevenness that's consistent with the hypotheses this not with this naive calculation so this is what's wrong okay the problem well there are a couple of things wrong with this idea that as we've discovered the first is that it presumed that after the Big Bang it would be easy to get this inflation that just by introducing the right forms of energy hypothetical energy into the universe you could automatically start inflation and so you could begin with a very random uneven state and start the influence inflation to occur when you needed it to match the universe that we know yes but you also need to start the inflation it needs to ignite if you somehow and we can we phonology to flames yes we thought it would be easy to ignite but we discovered actually the opposite is true so as an analogy imagine that I was trying to I told you at a theory for how to become a billionaire and I am very interested I thought you I'm right one might think I'm taking notes okay so I have a theory how to become a billionaire and I show you a little part of my theory which tells you how to invest some money and sure enough it demonstrates that it could make some money by following that procedure and so you buy my theory and I give you the book which which explains the theory and you open up to page 1 it says page 1 let's assume that your parents were billionaires so basically this is Trump University right I've become a billionaire to start with a billion dollars right well this is essentially what happened the story of inflation we thought originally just simply stretching the universe would be easy an easy start but we discovered actually we only under very rare conditions essentially the conditions you needed you need to start with Universal which was already smooth enough and unwarped enough only then can inflation start so it's just like saying I need to have a billion dollars in order to become an order to make a billion dollars okay so that was the first big problem and we've never gotten around that up to the present time we've known about this for 30 years but we haven't been figured out despite lots of clever attempts how to get around that 30 years now I'm waiting waiting is it because the problems harder because you all just aren't smart enough it's because probably it's actually not a good way of smoothing the universe out okay I would say it's probably not a good idea it's probably not a good book that I that I gave you for the billionaire right recipe then the second problem that we found is well suppose I let you start as a billionaire okay I'll give you the conditions you need to start inflation okay but and I let you choose your inflationary energy to have whatever properties you want we thought that you could then calculate as I said on the back of an envelope what the predictions would be but there's a little something that we left out of the story that we didn't realize when we thought about these quantum fluctuations that slightly change the rate at which inflation ends one place to another inevitably there's also going to be regions which are going to have large quantum fluctuations there are not going to just delay the end of inflation by a little bit but by a huge amount and the longer you delay because it's inflation is stretching the universe so fast the bigger those regions become so a typical region is not the region you thought it was which just had tiny fluctuations a typical region in terms of where most of the universe is is one of these huge regions which continues to inflate and then itself it will repeat the process we patches of it will end inflation but patches of it will continue so that alters within it within it and so it'll keep producing patches and patches and patches with most of the universe continuing to inflate and only rare patches where it ends we don't see these patches we and mote according to this idea we would live in one of these patches but these patches are not all the same this is where the problem begins to break down looking around we don't see such non uniformity in the universe you only think yeah you see we see uniformity we don't see any evidence what's our entire universe is one of these patches which is that which is the that's one kind of multiverse but that is one patch of the multiverse right and that is and but the problem is that so just to be clear yeah this is not a universe in some other dimension right no no no this is all one universe area volume whatever in a meta universe and we think in it's our own it's our thing right yes we think it's everything right but but outside of that our patch if you went far enough out would be more inflating universe and finally you did another patch that patch would have different property right due to fluctuations lots of fluctuations would cause different properties in that little pack that means you can actually travel within this universe from one patch to another and then experience different slightly different laws of physics too bad and the reason is because this between these patches is growing so fast it's continue to inflate that light or neither you in a rocket nor light could make up the difference so we can't overcome the expanding boundaries between us yes yeah beat the expansion right you can never get ahead of that expansion right so you're never gonna reach that patch right Wow so it's completely it's there and it's like no because you don't want to wander into a place that has slightly different laws of physics yeah for example where all the molecules in our body would decay into radiation that wouldn't be a good news perhaps I show up in the wrong outfit okay how would you ever test this well it's actually hard to test this idea because one of the consequences of this idea is over time you produce patches of ever ever increasing variety so that every conceivable possibility that can occur will occur in some patch so the patch that has a slightly different law of physics will have patches that are slightly different from it yes will have patches slightly different from it right Wow so it's a theory where you're freaking us out here that is freaking crazy man well I think it is because our goal was to explain why the universe is the way it is and we haven't exams are exploding but yours had exploded long ago would you just cool with it you know you know what's what's also like blowing my mind is that I mean it's so incredible that you're able to conceptualize this as all a part of like you say the meta universe one expansion where where as our our common perception of a multiverse is we're making jumps and leaps to these parallel universes that are existing on different planes your saying no it's this is like whirlpools in a giant lake yes yeah that's amazing that a connected space yes yes okay we're not done with you here no I know here we go of course we always start our queries with a patreon patron these people who paid to get their question first yes because even fair listen that's all we know life is not fair their supporters of the show support the show and so we support them back ok I giving them preferential treatment mutual back scratching you got it Oh same reason why my parents like me better than my siblings at least they pretend to here we go Christopher Cohen from patreon says hi dr. Tyson how far do you think we are away from determining the theory of everything ie a theory of quantum gravity what will we need to perform experiments that could prove or disprove a particular hypothesis Chris and Samantha Cohen from hard Worth New Jersey so Paul how interconnected is a theory of everything to what's going on on the frontier of multiverse thought well I think it's intimately connected in the sense that one of the problems we talked about already was how you would start the universe off so a presumption of the this conventional picture is the universe has a beginning the only only cosmologists get to sound like God well this is how we're gonna make the universe this way the power that they wield yeah so so the question is how so that so the idea is that at some point there was nothing no space no time no matter no energy that's the presumption that's the presumption which we can question but that's the presumption then suddenly it bursts into something space-time filled with energy that was first quantum and then suddenly became later a few Instructor large enough and became classical described by general relativity now those are words what actually happened there what's the theory that explain that creation event or that replaces it with a better idea let's go to the tape that reminds me of the you know the Syd Harris cartoon where the two physicists at the chalkboard and it's filled with equations and then at the end of the bottom right-hand corner it says then a miracle occurred so the other physicists um more detail here for what happens at this stage that's the theory of everything so that's what we're looking for it's a so it would dovetail into what you're trying to describe would happen after yeah a full theory would would have to incorporate a quantum theory of gravity and an explanation of either this creation from nothing or something that replaces it with a different idea so you hear people talk about the eternality of matter like that it just it's not about that it came from someplace that it just always existed I mean I've actually heard that as people that try to explain that's how everything started and that this just goes over and over again well so the idea of this creation idea of this Big Bang that's traditional Big Bang ideas if there would have been no matter right there would have been no space for matter to even exist in so matter already presumes a notion that exists in some space background but we don't know that this creation idea is right right so so there are some of us and and their self included myself included who have been who have been rethinking the creation scenario yeah and thinking that maybe what we thought was a Big Bang was really a Big Bounce that we universe went through a period of contraction and then bounced to expansion so that space would not have had a created created moment but would have existed before during and after that's what I was trying to say yes there's your analogies at least in space what do you call this idea well there there are different versions of this idea so the Big Bounce is one is just describing this event like that two syllables yeah a version of it the universe undergoes not just one bounce but periodic bounces so we call that a cyclic universe so the universe goes to if you if you are into your Greek one version of that is called an erotic universe another version of worst name ever thank you thank you by the way once you get done with the app erotic universe want to make your way over to the enema universe so ik products for the Greek woman means what what are those words from out of the fire so actually an ancient Greek idea was the idea of a universe when and went under regular periods of creation evolution and then Cataclysm disappear and then a new universe would be created an act parodic universe so with phoenix universe maybe i phoenix is another version of this otherwise you're just showing off that you know greek and imagine if the Big Bang had been called something else yes something with multi-syllable eyes at first right then it's it would not have caught on that's chin popular culture and parlance absolutely bang black hole this kind of thing this is true so marketing is important market very important we're gonna take a quick break okay and we come back to Startalk cosmic queries edition we've got Paul Steinhardt physicist at Princeton University and he's our expert in house on the multiverse see in a moment we're back on Startalk cosmic queries edition today's topic the multiverse topic I would not dare tackle on my own so I brought in Chuck nice of course Chuck knows everything about the multiverse alright Chuck is reading questions from you our fan base and I brought in a ball of Steinhart Princeton University professor yes physics it's been a fascinating conversation thus far and he's been doing some thinking of his own as a multiverse so we it's a quick question you're a crayon ik universe which is repeating bouncing you remove the need for singularity is that correct yes so as time would exist Barbra Cheerilee far back maybe infinitely far back in time it's maybe space and time existed forever we're just in the latest most recent cycle I'm gonna ask you a philosophical question did you come up with this idea because the singularity was too hard and so you needed an easier way to understand the universe or did you have compelling reasons to go there actually it's a very practical reason I didn't have a philosophical outlook at all it was to get rid of the multiverse problem because the multiverse caused the multiverse got two in the back of the head that's right and then Paul went leave the gun take the cannoli that was the motivation though he actually was the motivation because the multiverse essentially as I was saying at the outset destroyed an idea which I thought explain how the universe could have been smooth in uniform just because we didn't properly understand the effect of quantum physics and that due to these rare quantum effects that totally changed the structure that we instead of getting a smooth universe we expected to get we got this patch universe which every outcome is possible so I just want to you know I want to explain it in a sentence that feels comfortable with me and this patchwork universe where you have causally separated regions that cannot know about one another they are nonetheless connected in the fabric of space-time yes we cannot and should not think of them as some separate parallel universe in another dimension as is so commonly thought of in movies and the rest yeah okay that's that is really just a bit mind-blowing ratably mind-blowing concept all right this one from Greg Fischer on Facebook says hi dr. Tyson at all I remember reading a while back that in a quantum state electrons were shown to not only have spin but we're kind of able to jump or teleport between and within their shells while this still seems a bit far-fetched and I'm not a physicist hey thanks for that Greg thanks for letting us know I was for one I was very concerned what's new and what can be explained about this so Paul it's not specifically multiverse but if you're worrying about quantum phenomenon it's got to show up at some point we know that when electrons jump energy levels or even when particles what we call tunnel from one state to another state yes the time delay is basically zero isn't that correct and the particle can show up in one place having traveled from another place if it tunneled there it got there faster than the speed of light isn't that correct that's the wrong way to think of it I think it's the wrong way to think about it I think there's a period of time during which its location is uncertain and if you account for that that lost time that's the time it would take for that would be longer time that would take four or equal to the time take light to travel from its first location to the other so it's like you would see it here and then there'd be a period if you weren't watching that it would suddenly appear here and then that would that period of uncertainty would account for the light travels ok now the period where you're not watching that's an area that's a necessary part of this phenomenon yes right it gets to see it would mean you'd have to be shining light on it to see it now you'd be cheating you'd actually be kicking the electron and you'd say oh the reason why it went from here to here is because I kicked yeah yeah just the like it's important that you don't look because then you're not studying the tunneling phenomena that's like the old joke I I know how the teleport and they say prove it and you say okay I'm gonna go to San Francisco right now I'm back okay so just you said something fun and deep as you have been doing in this time you've been sharing with us that for a particle to disappear from one place and reappear in another spontaneously via some kind of tunneling phenomenon it does that because you stopped looking at it the act of having looked at it you look the act of looking at it so it keeps it in that quantum state if you will and this is some kicks it out or kicks interact with it now you're setting a different effect right right and this is happening all the time for everything it's just that we can be illuminated by light but our mass is so high that we don't jump to another quantum state body and soul but an electron is such low mass and it has this interaction capacity with a photon that you can't shine a photon on it and expect it to stand there and smile for you yes okay okay yeah that's pretty awesome so the act of trying to measure it changes what you're trying to measure right you can't measure it because once you pull out whatever it is you're measuring that actually affects it right and the New Age movement completely misunderstood this thinking that it's your consciousness that's somehow affecting it and it's a human thing no it's the act as the active measurement is a thing whether or not the human is doing it you have a machine right whatever doesn't matter and this spontaneous process by the way is the same idea that's involved with petition the multiverse it's a similar tunneling or decay like process this case it's a decay of inflationary energy into matter and radiation that's occurring randomly due to quantum effects and in fact it's random and sometimes proves is a huge banshan is all part and parcel of this quantum uncertainty randomness not you quantum is some badass let me tell you that's that's crazy it's a powerful thing yeah and the fact is that I'm going to be very honest I don't understand any other I'm just letting you know nobody but you don't have to by the way I mean I said was it firemen so one of the one of the Great's of yesteryear said the day you say you understand quantum physics is the guarantee that you do not because as Lee said it's not something to understand it just is oh okay well then that feel much better we were freaking out we our our our historical brethren who discovered this that they they were freaking out just like you are right now oh my god a particle a wave why who what Einstein said God does not play dice and people will freak out even Einstein you in good company even today even today people still there's still a community of people that debate the interpretation of quantum mechanics and then there's another community of us who just say just get up and computed exact I mean that common that camper by the way Jim by the way if I had a time machine and I somehow found myself in the 1920s I would be the greatest Herald er of the discovery of quantum physics which I think did not get much public play back in the 1920s when most of the foundations of it were laid to paper let me think about newspapers of the day aren't saying a new branch of physics has just been discovered it's not there it's only when it became useful for the IT revolution and I are tire the creation storage and retrieval of information has anyone been able to fully appreciate what came out of that error that's pretty well transistor to you needed you know partly and parses because it was a lot of confusion as to how to interpret the idea and exactly what a pointer was convey what it meant and what point it was convincingly true so the point is as a as a professional physicist you you study quantum physics which historically had only been applied to the small now as a cosmologists when the entire universe was once small you're invoking the the rules of quantum physics after now effect the entire universe Wow and the effects how that's pretty awesome the thing about right because when the large were small quantum physics is kicking cosmic butt okay and you know what does particle but and that's in the Bible the law be small in the small hey this is Matt even right quest race book that was a great question that we Matt Eli from Facebook and also from San Antonio Texas a little more it wants to know this a little more existential why should we take the multiverse Theory seriously in the first place might there be extraordinary evidence for this extraordinary claim who is not the least bit skeptical I like this question it's it's you gotta admit Paul to assert multiple universes is extraordinary and if you're not on the tail and you're a theorist last I checked so you're not even well of course good theorists think of how to test and hypotheses have you good theorists do this do you yeah well I think I've already sort of played laid out my cards and said that I think the multiverse is a sign of breakdown of this inflationary idea it's a failure it's a failure mode of the theory something we didn't expect it wasn't designed to produce a multiverse it's something we discovered after the fact and the problem is that because it produces an infinite number of patches of every possible variety if you ask what the theory predicts the answer is of nothing or everything or anything that's so it's a little bit I now again if it explains everything then in fact it explains nothing yes that's what that's so in my view that makes it no longer a scientifically interesting theory so it's not testable even if it's true it's just not interesting it's not interesting because anything you'd measure you could say oh we live in that patch of the universe and then you measure something else tomorrow and it doesn't fit that patch they must be the natural wear both of those are the fact yeah that's right yeah and according to the multiverse idea if it's physically possible and obviously our physical world is one of the possibilities then it must exist somewhere else we're a simulation you can't get away once you have a bad idea alright so there you have it okay hey Matt nice question wait so you agree that it has it doesn't really set the standard yet for a testable theory I think by construction it does not and if you read what the proponents of the multiverse say that's exactly what they'll tell you so what about what about the quantum foam bursting forth multiple whole other universes from the very early universe and these would-be universes that you would be able to see in a higher dimension but they don't interact and they're perfectly separate fabrics pretty fabric so yeah I don't know what to make of that that's another untestable idea in principle so it's it's another version of a if well so there are two possibilities one possibility is that those different fabric regions have completely different properties again like the multiverse and you and it's just random chance patchwork multiverse to capatch work multiverse in which wouldn't in which again you everything could possibly everything that could happen will happen in which case it has no scientific predictive value or it could be that you have a theory which says actually the same thing will happen each time every time you produce one of these fabrics so that if I suddenly transport it to the other one imagine doing that it would look familiar to me mm-hmm that's a different story that's a predictive theory but the problem is you can't get there it's what you're saying yeah and and so it doesn't have a meaningful scientific value and isn't it true for reasons that I never learned because I never took advanced field theory and graduate school but my wife did and okay she is a PhD mathematics I know I know your wife and she's smarter than you so but from what I've been told gravity is not contained in the space-time in which it is formed in which you have it so in other words the the effect of gravity can leak out of whatever is the membrane that it's contained and be felt by other universes outside of that so unlike electromagnetic radiation which is trapped within the space time gravity is not I've heard that so I think you're referring to theories like in string theory you have extra dimensions and where we might live in a membrane like surface in which we seem we think we're living in a world of three space dimensions there's actually extra dimensions which we our particles can't access there our light can't move there so electromagnetic radiation can't move there but gravity would be felt even along that extra dimension so that you we so that for example if there were another similar membrane parallel to us now they are thinking about this idea of parallel and something were happening over there it let's say a matter lumped together to form a star right or a black hole or something like that that would be felt its gravitational effect why isn't that dark matter it's a dark matter our users would be ordinary matter in a parallel universe is leaking into ours and we're mysteriously inventing stuff to account for it when in fact is just ordinary matter I think that's that's a conceivable idea that it could be matter on the other side another brain and another membrane that's a small distance away it couldn't be like our matter because if it were it would also when it gravitationally clumped it would produce radiation and that radiation would affect us as well in a way that we know we know there aren't those sources of radiation there and the dark matter one of the things about dark matter compared to ordinary matter is dark or Denari matter collapses to form stars and stick together and stick together and sits in a halo a very diffuse dark matter if this dark matter were like us but on the other side it would also collapse and it wouldn't form the halo which you know of dark matter that we observe we infer from measures and there's another little factor a gravity drops off as one over distance squared but if you're feeling gravity from another universe that's gravity permeating through other dimension yes and then therefore gravity from another universe would have to drop off faster than one over R squared okay so little but ever so as of course the foremost authority on this in the room let me just say what the hell are you it's time for commercial breaks you lost me until one over ours gravity thing there that live if you're spilling out and you got to go through another dimension to for it to be felt right then your equations have to somehow wreck it recognize that fact I got you the dilution of gravity as you get so in other words gravity the surface area of a sphere as it grows up you're thinning out whatever the fabric was by the the square of the distance so I got a fear that's three times bigger so cuz the sphere is expanding as nine times the area and so you see so it's thin it whatever was there before is now 1/9 is there so gravity thins out at that rate okay but now that makes sense of gravity I'm thinking of this as a blowing up balloon okay if you want to think way out into a whole other dimension and that equation can't just be one over R squared gotcha now that makes it let me just go Paul was i okay with that except for those of you listening at home you're welcome comes back more on the anatomy of the multiverse we're back on Startalk and I'm here with Chuck nice Sarah and an old friend and colleague of mine from my Princeton days Paul Steinhardt professor of physics and Lord of the Phoenix universe so Paul is this your does your chair have an endowed name to it it does what is that it's called the Albert Einstein professorship in science excuse the hell out of it that's pretty that's pretty rough man okay I'm thinking with some name there's a rich guy that just gave money oh no that Albert Einstein okay so do you realize you could only be a disappointment that's the price cause Macquarie's what else you have multiverse cosmic first we are talking about this is somewhat in that range but Michael Ranger from Twitter says this reality is granular I love how people put their own little stuff there things do it let them do that how then I can say the Earth's gravity reach infinitely far wouldn't it eventually wink out ooh so let me let me recast that question yeah it's a good question in a quantum construct of the universe you cannot get arbitrarily small things you cannot have arbitrarily short time intervals because there's a quantum size that limits it do we agree ok so if you have gravity dropping off ever so slowly' 1 over R squared and that means R gets bigger and bigger gravity gets smaller and smaller but there's always something there you can always calculate how much is there is there some calculation where the gravity is so low it goes from some quantum higher-level to apt to zero did I say that did I make sense in that question was that a fair interprets a fair interpretation okay I wasn't sure if you were talking about time or space though you're talking about just gravity yes gravity it's really a from the go away from Earth so it's gravity right right right you know it's you know it's like it's like cleaning up broken glass there's like a gazillion pieces that you'll never get it all but eventually there's the last piece of glass you've cleaned and there's no more glass left even though it's felt infinite at the time so is there a last piece of gravity that Earth is expressing into the universe they're very I'll give you one interpretation of that question let me see if that it will will help answer it so it's important to appreciate that the earth hasn't always existed it came into existence so before it came to existence there was no gravitational field associated with it okay there was matter that was going to eventually come together to form the earth so if you go far enough out and so that if you go far enough out in space you would not know that the earth was about to form ooh we got to wrap my head around that so earth is about four and a half billion years old yes if you go four and a half billion light years away there's a point where Earth had not yet assembled yeah from the void yes if you were looking for a field of gravity oh you measure man okay I'm telling you right now there are people listening to this and they're just like I am never doing drugs just take up cosmology people I'm telling you right now so what you're saying is you could be there and you would watch the formation of a source of gravity in front of you even though it's too far away to see right you would feel you'd measure this gravity arise yes so it'd be like you know throwing a rock in the in a puddle and and eventually the wave is going to meet you is going to reach out to you and then you'd be aware that Iraq if you weren't using your eyes you're just feeling the water you'd be aware that something happened except the rock hitting the puddle was a spontaneous thing as the Assembly of the earth where the slow was slower and piecemeal that's right okay okay so that's that's an awesome reply but I think it still avoids the question yes is there a point where the gravity of something quantum drops to the strength of gravity something quantum drops to zero from some quantum level above it when I say quantum I don't even mean to I don't even mean quantum physics so much as can it's smoothly go to 0 asymptotically or not that's really the question and you could say I don't know yeah you're gonna say they even though you're Princeton professor you say you know I don't know well the question could mean I'm more confused because the question could mean various things so let me mention another issue which is there in the the way let me just say I am glad that right now you guys are not two surgeons to figure out how we should approach this open heart situation is that we think there is a deep puzzle which is if you if you buy this idea at the universe began from a quantum beginning which rather than a bounce one of the puzzles there is how do you go from a quantum world to a world which is described by your 1 over R squared force and by the laws of general relativity how do we go from quantum to classical and at this point what proponents do is simply wave their hands and said something must do it and so we'll just you know sometimes you work on one side of this something sometimes on the other but exactly how that occurred is a mystery and is another reason to be suspicious of this set up of a Big Bang leading to a classical expansion okay all right we'll give me another question here we go there we go I'm going to say I'm sorry I lost his name I've wanted to answer him yeah Michael here's the deal we didn't answer your question at all so so no his race a say we turned it into a better question that we we turn to question into a better question uh here we go here we go Maria Simon from Facebook would like to know dr. Tyson what our perception of time be the same throughout the multiverse Thanks I can't wait to see you live on Monday what are you going on Monday I have no idea with his child oh no actually that this shows being recorded next week I'm I'm in the Pacific Northwest I'll catch some public talks all right there you know maybe one maybe one of your flock to be Eugene Oregon or to Seattle but okay so I'm sorry the question so she's talking about the perception of time oh yeah yeah is that going to be consistent so Paul we know from relativity that the passage of time is relative to an observer yes so other than that which we're kind of we live with and we live with in fact daily you realize the GPS satellites at their elevation above Earth experience a different strength of Earth's gravity than we do here and I Stein's general theory of relativity prescribes the difference in the rate at which it's clocks tick compared with hours and so well so what that means is when it is telling us what time it is we have pre corrected the change in its time because of Einstein's general theory LeTip e so that we all have the same time here on Earth's surface gotcha the same time as that no that's and that makes sense general relativity at work right at work okay so Paul so we got this and if you go to another one of your multiverse pockets could just time have a whole other kind of thing going on well certainly there would be no way to synchronize it compared to our time so for example sample one patches would be born at different times so the period the time the time they would have transpired since the creation of our patch to reach a point where there's earth and people would be different maybe in this other patch it might have just been born and their calendar would be bp4 before patch yeah so it would be simply no way to to correlate our time so unlike the case of the satellite where we can send signals back and forth to the earth to synchronize and to make this correction and only by having that communication because we can't communicate with one another there's no meaningful way to synchronize it in the quantum fluctuations in the quantum fluctuations of these patches could time mean something different there could a quantum fluctuation change what time is conceivably it's not part of the usual multiverse picture okay it's rather conventional in that sense that the patches would more or less have normal space and time like we think about here although some of them could be in some cases the space could be space time could be so warped that time could never lose its quantum its quantumness it might remain quantum and have a sort of no classical meaning in some patches that's conceivable and that's a kind of version of what you're what you're asking like that so time would just not be even fit not even a thing it may not they may not even be yeah right they could figure out some other way to meet you they put it in a bottle I couldn't meet you at the corner because space wouldn't have a meaning either oh the corner would the corner wouldn't be there yeah we got time just for a quick lightning round okay soundbite answers naggy Jonathon Agee went from Twitter wants to know this well quantum gravity means ER is incorrect since qf t is based on flat space-time and gr is a curvature he's just showing off yes yes that's question Gabriel from Twitter wants to know this what if anything is stopping gravity waves from traveling faster than the speed of light yeah hmm well relativity you are really good at this part okay we gotta take it as an answer because this is the lightning round look it up in other words relativity does not allow anything to go faster than light therefore gravity waves are not traveling faster than light correct even though they be gravity and not light that's right okay all right Don's Dayton's own quick Twitter says this chemists telescope be made to see so far that it sees the Big Bang what is the limit of telescopes including the ones that we launched into space because light takes time to move in one location to another it means as you look out in space you see things not as they are but as they they were and as you just take that far enough back yes in principle you can see the birth of the universe provided that there is matter out there that is as old as the universe ok so now the reason why we have any evidence of the Big Bang at all is because we have this expanding horizon that is washing over parts of the whole universe that was born 13.8 billion years ago here's what would scare the daylights out of me if all of a sudden the Cosmic Microwave Background began to disappear Oh would mean that our cosmic horizon would be entering a region of our universe where there is no longer any matter we'd reached the physical edge of our universe and then that wave would is coming our way no then then there would be no cosmology because we would have no information about what happened in the past that's why we can see the Big Bang at all okay yeah you okay with that Paul well Microwave Background is disappearing right if it's it's being redshifted away due to the expansion of the universe so in fact it is fading from view but that's not because we've reached the edge it's because over time that's going to happen just because the universe is continuing - yes yes so because of the expanding universe the we are diluting the evidence of the Big Bang yes that is coming to us from that from from the part of the universe that we are seeing being born right now yes however if that is not fading simply at the rate of the universe expansion but if it's fading at some faster rate than that that could be evidence that we are running out of matter in the universe for our horizon to engulf all right we are way over time here you've been you've been listening and possibly watching Startalk the the cosmic queries addition on the multiverse let me thank my friend and colleague Paul Steinhardt Princeton University Chuck nice yes I think of Chuck Norris said calm and calm and confused alright you've been listening to Startalk possibly even watching it I've been your personal guide through this universe my name is Neil Tyson and as always I bid you to keep looking up this is Startalk you

Channel: StarTalk

Views: 658,836

Rating: 4.8692694 out of 5

Keywords: Chuck Nice, Neil deGrasse Tyson, Paul Steinhardt, cosmology, multiverse, quantum physics, quantum tunneling, Big Bang, Big Bounce, general relativity, universe, spacetime, cosmic inflation, theory of everything, quantum gravity, Albert Einstein

Id: Qd28YfV5ZAY

Length: 50min 38sec (3038 seconds)

Published: Mon Sep 25 2017