The Fabric of Spacetime with Neil deGrasse Tyson – Cosmic Queries

foreign this is Star Talk Neil deGrasse Tyson here your personal astrophysicist today we're going to do a cosmic queries grab bag Edition so Chuck what what does that even mean well you know what it means it means that anything that people want to know we just throw it in a bag and they get a chance to do it we used to call it Galactic gumbo that owns them a company having a gumbo in a while but last I had it yeah it did kind of have pretty much everything in it yeah man uh whatever might have been left in the fridge overnight but okay well let's do it you got him yeah we got the question that's right co-host yes thank you so let's jump right into it uh let's go to Chris Hampton who uh says easy name here Chuck hey thanks Chris what the hell I should really read these before before this show thanks Chris anyway uh do you think future scientist Neil will look back at our particle colliders and think that they were somewhat barbaric uh I.E smash smash smash which would also imply that they found a better way to observe particles um and parts of atoms uh while they're still intact what what do you think is I like that question yeah it's really that's a very nice um you know peace loving question it is yeah because Adam Smashers and particle accelerators they're entirely designed to smash particles now I don't think particles have feelings so to be worried about them right and to think that we're committing violence upon them right I'm not so here's how to think about it yeah rest easy you little particle pacifist Sparkle pacifist if you if you smashed a particle and then it was destroyed and it would never then okay but what when you smash a particle what you're doing is you're putting energy into the system empowering it to make other particles so so atom Smashers particle accelerators they their means of infusing a system with high levels of energy to see what pops out the other side because some particles exist only under those conditions so what you'd have to say is is there a way to observe those conditions without being barbaric to arrive at them yes there is you know what that would be go back to the Big Bang ah okay there you go with your microscope or with your telescope go back to the Big Bang because those are the conditions we are trying to duplicate in the laboratory the the conditions of density and temperature and pressure these are the conditions of the big bang and this this is what started the field of Astral particle physics astral particle physics it deals with what happened in the early Universe when the universe was small and very hot and you couldn't have matter as we know it you know physical object objects everything was a particle soup of seething back and forth between energy and matter and this is what we're trying to create in the laboratory so these Laboratories are actually um portals back to the origin of time itself look at that so basically they're giant replicators is what they're doing exactly exactly and really he shouldn't have to be we're not going to one day find out that particles have feelings I'm pretty sure about that yeah exactly no need to have a protest for particles you know no justice no peace yeah we don't we don't it's gonna be all right all right all right let's keep going here uh oh wow fontanez there you go that's I think that's it that's it no matter what that's it it is what it is now that's what it is says hello my people this is well Korea or while Kira from Georgia originally from the Bronx Neil in the house there you go if gravity pulls everything down then how do clouds defy gravity and how do clouds stay up oh uh I love that yeah I love that so let me let me ask a different question that's exactly the same okay gravity pulls everything down why do helium balloons go up oh there you go so you can ask the question what does a helium balloon weigh what does a cloud way right it doesn't have negative weight you have to take a scale and put it upside down above it and have it press upwards does it have negative weight okay that's the question it's the same question all right yeah it's weight relative to something exactly exactly so so we as physical objects called humans are so much denser than air and you mean that as as in a physical sense yeah because you know the other the other part is true too I'm kind of dense the other kind of dense is also true when did dense become like you can't learn anything against to me means you have a lot of information in there there's a density of Enlightenment see and that it lets you know who you are okay because you look at dense as a good thing as in um a a great deal of information compacted pack it in right pack it in and where whereas dense as in thick-headed it's about getting it in there oh the density is the barrier the density of the bearing you're a thick-headed dolt okay so it's a thick scold it's a thick skull right don't implicate the whole head here just it's okay I didn't I swear to you I did not know that yeah okay yeah the density of the barrier of Entry of information into your mind there you go so so you can ask what so we are so much denser physically denser than air we don't think about how much less we weigh in air right air has a buoyant force that makes you weigh a little bit less but we don't care about it we don't even think about it how about water okay we are almost the same density as water so some people float right and those who sink they don't sink very fast right so how much do you weigh in water well if you're floating do you weigh zero so what's happening here is everything has weight unless you're floating in something okay so the helium bleedness balloon is lighter than air if you started evacuating all the air of the earth then all the helium balloons however many are still up there the Chinese balloon whatever whatever balloon is up there it will come to Earth and then you can stick a scale under it and figure out how much it actually weighs with no buoyant force assisting it now you filthy now you pour air back into our atmosphere and things lighter than air will float above it but that doesn't mean they're weightless look at that yeah that's awesome and by the way there's a lot of videos on social media right now circulating that speak to this question and gravity because of things that float and uh the fact that there are things that are uh on parts of the earth that they say are upside down so it's keeping you upside down but yet at the same time the same so-called supposed force is allowing these other things to float around so okay so so this is a case of a person who thinks they know about enough about a subject to believe they're right but they don't know enough about the subject to know that they're wrong there you go look at that in all the lands down under you know that's because like Civilization and so the dominant forces of cultures have all been like in the northern hemisphere right right so we have Northern Hemisphere bias on Southern Hemisphere resonance and we say that they're upside down and even any of us if we saw a map with South up we would say that's upside down and that's look how deep that bias is because space don't give a and that's what I was about to say in in the in the Blackness of space when you're floating in a void right is there really any up or down right no it's no up or down correct right correct uh and so well you can point to places that locally will have an up or down where they are okay but where you are no so up or down is relative there you go it's relative to where the center of gravity is of your closest object so anyhow all I'm saying is if you're floating it's because there's a buoyant force that's all and I did I once did this calculation for 150 pound person uh what would that be in in kilos that would be you know something like 75 kilos okay it's 2.2 2.2 pounds all right okay so uh that person you know there's a few I mean it's it's an it's a measurable amount but no one cares right you know is it 100 grams less because of the buoyant force of air here like I said we don't typically think about that because it doesn't really matter to us that's all okay all right there you go next one fantastic let's move on to Michael Ranger cool name Michael Ranger uh is particle a placeholder word for things that are so small we don't know what they are yet oh it's particle a placeholder yes but only for one particle the electron aha every other particle well every other party we play with in the in the in the laboratory every other particle that we control and play with has a measured size an electron we have never measured how big an electron is and as far as weak no it's infinitesimally small this is a profound point of mystery in particle physics we don't dwell on it because we can still invoke it we still make current in electricity we can still do all manner of things with an electron this thing we call an electron but it is a spot in space-time that we have never measured all we measure its charge that's it wow yeah I just learned something I did not know this you didn't know that about electron I did not know this about electrons I have an entire video course with the teaching company which they changed their name to the Great Courses uh what what I do in each lecture is I take you to the frontier of our ignorance and then I just drop you there and I said here's nice peer out and your guess is as good as mine okay what's going on out there so like I I take the viewer to the edge of the unknown in astronomy and physics uh it's it's in um the Great Courses series check it out if you're interested in there I talk about the fact that we have no idea how big an electron is that is fascinating I mean wow neutrinos are pretty elusive as well and we do manipulate them and I haven't I don't know the latest on those and what size we have ascribed them maybe they're equally as intractable in our ability to measure their Dimensions but we do know the size of protons and they're composed of quarks three quarks protons and neutrons and and how big is a quark I I don't know what our latest thinking is on that but the fun one is electrons because we've all heard of electrons we've right we all know what they are they're they're they're they're the satellites of of the nuclei yeah yeah that's right nucleus well yeah yeah they quote orbit the nucleus right and but we didn't want to use the word orbit because that applies to planets um and so we we invented a new word orbital so they uh they have orbitals right put a little distance between it and astronomy yeah wow look at that dude what a great little question you had there Michael Ranger thanks for that man yeah okay all right here we go uh this is Michelle Star Girl watch out watch out now Michelle Star Girl star girl that's her name that's that's what she wrote that's what she wrote that's what she wrote I'm not going to judge her because okay she broke uh she goes greetings this is Michelle from NYC now that the James Webb Space Telescope has seen mature galaxies not long after the big bang that under current knowledge shouldn't exist could these galaxies possibly be a window into another Universe oh I like that oh what a lovely like that thank you star girl so um you know when I was a kid one of my favorite cartoons was Astro Boy astro boy back man they didn't I didn't know that yeah throw a boy bombs away you're on our mission today rocket High to the sky okay anyway so let's back up so after the big bang where there was this particles matter soup uh everything was too hot to make stars and so but then there's a point where things cooled so that the Universe became because the universe was glowing back then it called and became transparent but it still was not in this ready to make stars so it would have to wait I I forgot how long but long enough so that we have a word for this era and it's called the Dark Ages where you know there's no there's no stars no galaxies right James Webb Space Telescope is exquisitely tuned to observe the birth of galaxies so we turn on the telescope look back to this era and we find red-blooded galaxies doing the backstroke in the Dark Ages wow so that freaks us all out because it's like okay who ordered that right and nobody ordered that okay so either our entire understanding of the big bang and expansion and cooling of the universe is wrong or these are varieties of galaxies that we haven't seen before and we're mistakenly putting them in a place where an ordinary Galaxy would have been with those same properties but could there be a different kind of Galaxy with those same properties that is otherwise unfamiliar to us this happens all the time by the way so you you say oh I know who you are because you're standing there and you're doing XYZ because I'm using information that I think should describe fully who you are turns out you're not that you're something completely different so all my understanding of your look of you being there is is wrong is completely wrong so so uh if you're a betting person I would not bet against the Big Bang exactly I see what you're saying so it's it's it's kind of basically like uh uh when you're looking back because you're looking back in time but you're looking back in time through different wavelengths as well correct yeah correct and right and we have our catalogs of everything that we understand right and we're looking to a place we've never looked before in wavelengths that we never received from that part of the universe and we see objects hey these look like our galaxies that don't belong there maybe they're not our galaxy maybe they're not our galaxy maybe there's nothing in this catalog that we have created of everything nearby to us right right maybe there's a whole new early Universe completely different yeah it's like looking at an ultrasound and uh you you see a baby but the baby is like watching TV and smoking a cigar right you're like hey something's wrong with this thumbs up but it doesn't necessarily mean that it's not a baby in there you know it's right yes I don't know what the hell that would be but dude that's so great all right well let's close this out this first segment and when we come back more Cosmic queries grab bag oh and StarTalk returns we're back Cosmic queries grab bag these are fun I like grab bags Chuck yeah exactly I got Chuck Nice we think oh Chuck I have something to add to that question how much does a cloud weigh okay I'm gonna add something to that so generally if you look up Wales in in you know in a in a book or on a Wiki page it'll say how much they weigh all right right okay and there's a lot they're the heaviest animals that ever existed but is it really fair to say how much they weigh because you know what you're doing you're taking them out of the water right putting them on and measuring them on dry land immersed in air you big blubbery fat butt stuff [Laughter] [Music] face exactly so the point is the whale doesn't live on land right it lives in the water so what matters here is not the air buoyancy it gets which would be irrelevant as it is for us what matters is the water buoyancy right so in water a whale weighs zero okay it can move up and down freely the way a perfectly neutrally buoyant balloon could move up and down freely in our air so to a whale a whale weighs nothing wow that's kind of cool yeah because in in the medium it weighs nothing right there you go yeah it is that's very cool okay all right here we go let's keep moving on with keep on moving we're going to keep it moving with this is Rebecca I'm gonna say Fuchs okay yeah spelled could be a bunch of different things but I'm gonna go with Fuchs I'm fine all right uh she says hello Dr Tyson Lord nice Rebecca from Connecticut here uh could you please explain in the simplest terms possible please why do we think that space and time are emergent and not fundamental I don't know what that means oh oh oh I don't even know what she means by that oh um so there's been some murmurs about it being the consequence well so I I tell you the little bit that I know okay okay actually I think that question might have come in when we had Stefan Alexander here who was a sort of cosmologist particle physicist dude and maybe he would have been better equipped to answer that but let me tell you what I just learned in a conversation with Brian Greene who's right up the street from us in Columbia University our buddy Brian the author of the best-selling book The Elegant universe and he followed it up with the fabric of the cosmos anyhow here's what he told me and I it's blew my mind all right so you gotta like hang with me for this okay so quantum physics tells us that there's no such thing as empty space okay that in empty space where you would classically say there's zero energy because there's nothing there quantum physics says there's always a chance of there being some energy everywhere hmm okay and and this is called vacuum energy of the universe this is where the source is called okay so how is this manifested so if you run through the quantum physics equations you get particles out of that energy popping into existence matter anti-matter particle pairs that then rejoin and make energy again okay so energy is coming and going with particles and it's a seething soup within the vacuum of space okay these are called virtual particles so no one denies that they're there even though we've never measure them because a very natural prediction of quantum physics and what quantum physics everything else quantum physics is predicted is turned out to be correct right so we're sticking with this explanation now it turns out these particle pairs since they were created together know about each other ah they know about each other in a quantum entanglement sort of way okay okay well if they know about each other because they're Quantum entangled and quantum entanglement means if something happens to one particle over here the other one knows about it instantly and the only way we can think about that is if there's some kind of Wormhole between the two of them where it doesn't have to then travel through the physicality of space some kind of Wormhole because then you can get to two places instantly without quote violating the the speed of light rule so here's what he told me that there's some emergent thinking that suggests that the very fabric of space-time is the network of these wormholes created by the seething soup of virtual particles so that those wormholes are themselves the fabric of the universe they're weaving together the fabric of the universe wow and that blew my mind so because we we speak of the fabric as distorting and it's sort of metaphor right and you know but is it literal is it a literal thing that could be true so so there's that okay so now about time what I do know is that we measure Time by things that repeat okay right Cycles if cycle right if nothing repeats you can maybe know what happened before something or after something but you wouldn't be able to measure the time between it so I don't know about time as being emergent relative to what I just learned from Brian Greene that the very fabric of space-time might itself be emergent and a property of the vacuum so I lost a few nights of sleep on that one that I don't blame you uh she's I'm losing like just brain cells listening to it that is freaking trippy and so Chuck this word emergence yeah of course has its own meaning in biology in biological circles and evolution absolutely because you could look at a bird like pecking away on the ground and you can study every atom and molecule of that bird and you probably would not know that a group of birds will flock together by analyzing a single Bird right so that flocking is sort of an emergent feature of a group of birds that you would never learn by studying one bird we don't as far as we can tell you wouldn't learn it so so emergent property maybe Consciousness is emergent exactly they're worried about AI you keep programming up AI if you get enough data points coming together with enough computing power then all of a sudden it's not that you made it intelligent enough to become sentient it just becomes that yeah because it works right I just saw the the preview again for that movie Megan oh my God I love that movie oh no I don't I can't see the movie after that preview that's a little oh God I love that forever so much so so that's an emergence but here in in the universe the emergent would be something that was not there from the beginning right we just show up later because something else happened so so this is this is how we're using the term in physics which is a bit different from how it's been commonly used in biology that's all cool cool man yeah all right well Rebecca what a great question thank you thank you that was very cool all right let's go on to Catherine B here and Catherine B says good day all my name is Catherine and I'm from a small insignificant town near Ottawa Canada [Laughter] around the world got to put us down we're like we're number one all right she says I have a question that I have not been able to find the answer to and I know you can answer it Neil or at least you'll have a theory about it if time speeds as we leave Earth's gravity and slows with velocity how will astronauts traveling to Mars be affected once they leave Earth's gravity does it no longer slow so they will only be impacted by the speeding up of time because of their velocity if that's so how long will a three-year Earth journey be for them I love them making sense right now completely completely so there you go so this is a combination of a bunch of things we know that the closer you get to a source of gravity the slower time ticks for you right the farther away the faster it takes the faster you move the slower time ticks for you right so if you are not only moving farther away from Earth's gravity which would speed up time but now you are traveling fast that would slow down time you got to run the equations and see which equations win right which is greater which is a greater pull which is a greater and I have I can't do that in my head I could do that on paper I can do it but here's one I did do already and that's for GPS satellites so GPS satellites orbit the Earth at very high speeds so relative to us their time is slowing down okay if you only factor in their high speeds but they're also much farther away from Earth's surface than we are right so the time is speeding up and the speed up time is about twice what the Slowdown time is so the speeding up wins gotcha speeding up of the time wins against the slowing down the slowing downtime for its orbital speed right which means the GPS satellites do not keep the same time we do right and they have to be pre-corrected before you get the time signal from your phone company wow yeah so these factors are all in work working in either conjunction or against whatever against at all times at all times at all times and it's cumulative it's cumulative so okay if you're gonna if you're on a mission for three by the way it's very tiny it's cumulative but tiny okay you want to know how much younger or older is your twin astronaut sibling who went to Mars it would be fractions of a second gotcha yeah there you go just off the top of my head wow all right still fascinating because it's not a perception of time that's speeding up the actual time itself yes time keeping devices your heartbeat your brain thoughts everything everything is so great yo all right hey Catherine B thanks for that that's very cool look forward to some more uh information for the coming about your trip to Mars Catherine because I know that's why you asked I actually got a plan I know you got a plan I'm from nowhere Ottawa but I'm going tomorrow so how about that okay let's uh move on to okay man you just messing with me this is Kathy Lee don't pretend like you do with that oops that's a good act there yeah okay all right that could that sounds like it could be okay go ahead hey Neil hey Chuck I'm new to patreon but a long-standing welcome Star Talk I have a very basic question why is string theory so unprovable and if so why are we still trying to prove it you know every time I see Brian Greene I slap him upside the head and say Ryan why haven't you string theorists solve this problem yet and his answer is well it's a very hard problem well so was general relativity and Einstein did it all by himself and he took 10 years which was a long time for an Einstein brain but he solved it and here all y'all that's the plural of y'all right it's all y'all y'all okay here's all y'all strings theorists there's dozens of them probably not much more than that but I'd say dozens of them in the world they're working on it for 40 years and so I why don't you all so I said why don't you just confess to yourselves you are collectively too stupid to figure it out well I said this to his face or that or or that it's not the problem that you should be solving and the actual solution is something else that nobody's thought of yet oh yeah I was in his face oh my goodness yo that's that's hardcore bro it was now I'm bigger than him so I knew that I could yeah you kind of called him to question the you know the veracity of his entire life's work that's a little rough man that's a little rough it's a little rough uh yeah I did it to be of course purposely of course but it was um how long are you gonna say the problem is just hard rather than we are barking up the wrong tree so that's so that's kind of how I think about it plus it assumes that there can be one coherent theoretical understanding of all phenomena in the universe it assumes that and you're putting your philosophical mission statement on the universe that you're investigating and the history of that exercise has never proven to be successful I'll give an example uh Copernicus says you know I think the sun is in the middle of the universe and not earth and so let me create us a sun-centered universe so he does it and he puts the sun in the middle and Mercury the orbits of Mercury Venus Mars Jupiter said the asteroid belt wasn't discovered yet but uh on out it does this okay do you realize it was still wrong because he assumed that the universe is per God made the universe the universe is perfect God because God is perfect so clearly God made orbits that are perfect circles because a circle is the perfect circles right so that was a theoretical expectation placed upon his ideas about what the unit how the universe is put together wow and it was just wrong the the orbits are squashed circles and they're all squashed differently in the most squashed Circle among objects known as planets or formerly known as planets is Pluto Pluto's word is so squashed it crosses the orbit of Neptune right this is hardly the handiwork of someone who really cares about perfect circles all right so so I just like to take a step back and stay open to the possibility that there's a whole other idea that could supplant everything they're doing that wouldn't take 30 people 40 years to try to figure it out because that's a lot of brain power going in there in all fairness to them they made certain progress with their string theory in interpreting using it to interpret things that we Now understand more deeply okay so that works and by the way uh how close are we to proving it experimentally some predictions it cannot what are forever in the future will never ex no okay but that some of it is interdimensional like yeah I'm gonna go there you're holding your chin like you're contemplating interdimensional yeah higher Dimension I got this one all right the point is you can have a hypothesis that is untestable in its core but if the hypothesis is true some other things might be true that you can then test all right so you can test the edges of it all right and that can still make progress on the thing that you're waiting to test if you can't do it today I got you that I mean that makes perfect sense and what you're saying is they're not even close to that damn that's rough man yeah so Einstein said so here's what Einstein said Einstein said um he has something called the equivalence principle deep and profound statement that that the mass that gravity sees when it pulls on you is identically equal to the mass that a force sees when it accelerates it through space okay these are these two masses there's no reason in Heaven and Earth why these two masses have to be the same right but they sort of seem to be the same and Einstein said let us declare them to be the same and if they are the same here's something that would be true and what is that if I'm in an elevator and you cut the cable and I let go of a ball right I will fall the elevators falling the ball is falling and it'll stay stay stationary in front of my face right you'll be falling at the same rate and then also Einstein will have to face murder charges at the end of the year at the end of that experiment it's only if you've got the cable yeah he's probably too smart to cut the cables himself to be honest right okay so the point there is I am in free fall okay right fine but if I had so I'm zero g but if I'm standing on Earth watch this I'm standing on Earth and I let go of the ball it falls I'm in 1G okay so now watch now I have rockets on the back of your ship and I accelerate you through the universe at 1G and you holding a ball you let go the ball it'll fall down to the ground you cannot distinguish whether you were in a rocket accelerating through empty space or standing on a planet under that same 1G force that is such a like elegant little thought experiment elegant and profound and you can do it really is experiment it's a thought experiment you could do the experiment you can actually do it right on the edges on a train or I think that's what they did though yeah that's so cool okay gotta take another break uh when we come back more Cosmic queries the grab bag Edition we're back StarTalk Cosmic queries grab bag Edition so Chuck why why do we stop calling it Galactic gumbo because that was fun I think maybe uh people got tired of me um imitating uh Paul puto yeah Paul put them Galactic gumbo they're there but is he the one that spoke like that I don't know if it was him I just know that that guy was on PBS and he was amazing because we're going to do it and put that whatever that guy was that's the guy okay we don't know who we're going to add some Kion pepper okay that was amazing that dude he was okay awesome so we got some more questions Bring It On All right here we go here this is Captain James Reilly okay Captain Riley says if a photon is a particle which it is can't it just sit still why does it always have to be moving at the speed of light oh wow look at that okay so here's what we have concluded and this might sound like a cop-out answer okay objects that have mass can never attain the speed of light oh and objects that do not have mass right only exist at the speed of light that is how that is the hand we're dealt in this universe wow so it's a massless particle that ceases to exist when it stops traveling at the speed of light while you can't not it's okay if not right yeah right so what will happen is so it has to hit something exactly so if it's gonna if that if the energy of that particle is going to become matter right then the matter has to be moving slower than the speed of light but the energy budget Remains the Same we're fine right energy exactly because you've got a little exchange going on there exchange going on MC squared yeah so I'm not I'm not answering it with a y I'm just declaring that that is the universe we live in now now you want to hear something profound okay I think okay this this is profound um you may know that time slows down as you go faster and faster and stops at the speed of light exactly okay okay well neutrinos there's something called the solar neutrino problem where everything we understood about thermonuclear Fusion in the core of the Sun told us how many neutrinos it should be making we build detectors on Earth and we were detecting only a fraction of the predicted neutrinos okay this was this went on for decades and people say maybe we don't understand Fusion but it worked out we're getting the energy and budget for the Sun that seemed to work maybe there's something wrong with the detector no we got the detector thing so what's going on okay here's what we found well plus we didn't quite know how fast do neutrinos move could they be moving the speed of light okay we don't know here's what we found there's more than one species of neutrino oh and the neutrinos emitted by the Sun change species on route to Earth so the detectors we built were detected to find only the kind of neutrinos that the sun made not the kind of neutrinos that ended up landing and arriving here on Earth it'd be as though I tossed you a basketball right and you received a football look at that but you set up detectors only for basketballs right okay so now watch wait wait so that meant that it's called neutrino um was it term for it in physics but basically it decays into another species okay gotcha okay wait a minute if it knows to do that after a certain amount of time then it can't be traveling at the speed of light because if it was at the speed of light it would have no concept of time and would not know when to change to transition exactly it could not know because traveling at the speed of light means that it can only exist as it is while it's traveling at the speed of light correct because there's no time clock there's no time to tell it what to do correct yeah so in one we're looking for the wrong neutrino and the neutrino does not travel at the speed of light it travels very close close to it not the same but not the same that is fascinating yes this is science too this is crazy fun interesting thing really is yeah I just love that the neutrino is like um Tom Cruise in the mission impossible okay it leaves the Sun and then it gets to Earth and it's just like it pulls its face off like it was me all in love oh you can't detect me [Laughter] so you got another question all right wow that was really good stuff thank you by the way so our crack team of researchers behind the camera reminded me of the the simple physics term so when when neutrinos change species the golden neutrino oscillations we call them neutrino oscillations that is so cool but it will only know to oscillate from one species to another if there's an internal clock and it can only happen until the clock if it's going slower than the speed of light it's that simple all right here we go this is um Walker foland and Walker says gentlemen this is Walker from West Branch Michigan I don't know why I think he sounds like that but he goes if two objects travel parallel on a sphere three-dimensional sphere they will eventually converge at a point yes if we extrapolate that the fourth dimension does that roughly explain behavior of gravity in our universe so if we extrapolate that to the fourth dimension does that roughly explain the behavior of gravity in our universe yeah so first the fourth dimension is time and so I'm not quite getting where that would land but let me just remind people that how we learned in grade school perhaps certainly by Middle School that parallel lines never intersect no no that's only if the space in which they're embedded is completely flat right but if it's a curve like a surface parallel lines and a line is very rigidly defined as uh if you cut through that line that cut will go through the center of your your sphere okay that assures you that that's a proper line a geodesic it's called or great circle route if you're taking an airplane Okay so two lines that are parallel will ultimately intersect in two places on a sphere okay which is odd because not odd which is interesting because we refer colloquially to lines of latitude as parallels lines of latitude do not intersect and we're we're borrowing the concept of non-intersecting lines being parallel and applying it to the the surface of the Earth and calling latitude lines parallel but they're not parallel because they're not authentic lines there's only one authentic latitude line in the world and what line is that the Equator the equator because even cut through the equator all the other Cuts do not go through the center they're not legitimate lines and that's why airplanes don't go along latitude lines because it's not the shortest distance between two points wow yeah you ever see the airplane trajectories it's always well why are you looping up like that right let's just go along this straight line here on your Mercator map which completely distorts how you got to get from one place to another wow look at that yeah that's very cool yeah so but did I I don't think I answered the question what what was the question well because he's saying that we were if we were to strap like that out to the fourth dimension which is time with that explain gravity in our universe yeah I don't I don't feel that I don't feel what I do know is that as you go back in time the universe was smaller so if you take imagine our universe as the surface of a sphere that is expanding just we're all just on a Surface okay so I've lost a dimension just for the sake of this explanation so if you go back in time the universe was smaller and then smaller and smaller so you can follow a Time Arc backwards and all time arcs will meet at the center of the balloon okay so if you ask on the surface of balloon where is the center I say it is nowhere on this balloon the center of our universe exists in time right 14 billion years ago let's find that Center and now you go back in time as the balloon shrinks and there it is infinitesimally small that is the center of everything that is the center of the universe wow that's that's that's fascinating so time has a center in a way right exactly right right right yeah yeah that's all the time that was a mind-blowing moment oh man these people came they came with it today boy out of the bushes for that one yeah it really did it was good stuff yeah all right thanks everyone for those questions great to have a new patreon member coming in on the Q a and uh all right and by the way these are all patreon members correct all pension members yeah this has been start talk Cosmic queries the grab back Edition Chuck always great to have you there always a pleasure I am Neil deGrasse Tyson as always wishing you looking up [Music]

Channel: StarTalk

Views: 260,110

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, Einstein, Brian Greene, clouds, gravity, emergence, emergent properties, quantum entanglement, fundamental, JWST, early galaxies, dark ages, big bang, photons, speed of light, time, time dilation, neutrino, solar neutrino problem, parallel lines, GPS, equivalence principle, unprovable, relativity

Id: as49_LNf3VA

Length: 47min 39sec (2859 seconds)

Published: Thu Jun 08 2023