Speaker 1: Inside space? Is there a place where the matter ends
Speaker 1: and it's just empty space? And then path that space?
Speaker 1: Is there something else that's not space? Can space have
Speaker 1: an edge? Right? And so that to me is the
Speaker 1: is this concept of the universe, all the matter in
Speaker 1: all the space, things beyond that space, if there is
Speaker 1: anything there I would consider not part of our universe.
Speaker 1: Oh I see, So we could like there could be
Speaker 1: through stuff and maybe at some point we run out
Speaker 1: of stuff and there, but there're still there could still
Speaker 1: be space, There could still be space. Hi. I'm Daniel
Speaker 1: and I'm Horhan, and we're here to explain the universe.
Speaker 1: Today we're going to talk about the biggest question in
Speaker 1: the universe, the biggest question you could even possibly imagine.
Speaker 1: How big is the universe? Like really, how big is it? Like?
Speaker 1: Does it go on forever? Is it just a little
Speaker 1: bit bigger than we can see? Does it wrap around
Speaker 1: on itself? Is it some other crazy thing. That's what
Speaker 1: we're going to try to tackle today. We went out
Speaker 1: in the street and we asked people what they thought
Speaker 1: about this the biggest of questions. Oh man, it's pretty big,
Speaker 1: Like I'm pretty sure it's like unmeasurable because like we
Speaker 1: don't really know much about it, so I'm pretty I
Speaker 1: wanna say, like pretty big, like it's really unmeasurable. Tend
Speaker 1: to do something article do you want, like a number
Speaker 1: or whatever you think is appropriate. Um. I remember reading
Speaker 1: someone where that's like it's always growing, so it's like infinite, right,
Speaker 1: So most people seem to feel like, wow, the universe
Speaker 1: is pretty big. Some people thought it was like infinite,
Speaker 1: and some people thought just just really big. Nobody thought
Speaker 1: it was small. Nobody's like I can see the end
Speaker 1: of it. It's just about it's only my town. It's
Speaker 1: only as far as I can see. That's right, And
Speaker 1: ask really, that's really interesting because I bet like if
Speaker 1: you ask prehistoric man how big is the universe, they
Speaker 1: would just like say, like, look around you, this is
Speaker 1: what there is, and they couldn't even really imagine. So
Speaker 1: let's break it down. There's all the stuff right as
Speaker 1: part of a right you know, this matter and energy,
Speaker 1: all that stuff feel and touch and see m But
Speaker 1: I think there's one other component which I think it
Speaker 1: a little less usual for people to think about, and
Speaker 1: that's the space. Space. I would think of the universe
Speaker 1: as all the stuff and all the space that it's in. Okay,
Speaker 1: and then like the stuff we can actually move around in, Yes,
Speaker 1: the place we can move around in the space we
Speaker 1: have at some point that space um ends. Yeah, the
Speaker 1: space could end right now. Somebody out there listening, you smart,
Speaker 1: good looking listener, you might be thinking, what how good
Speaker 1: space possibly end? He's talking about space like it's a thing,
Speaker 1: like it's water and the fish could run into the
Speaker 1: end of it or something. But briefly, we should just
Speaker 1: remind people that space is not just emptiness. It's not
Speaker 1: just a backdrop. It's not just the nothing in which
Speaker 1: stuff happens. It's stuff. It has properties that can bend
Speaker 1: and expand and ripple and do all sorts of weird
Speaker 1: crazy stuff. And so we know that it's a thing.
Speaker 1: It's a dynamic, physical thing that could do stuff. So
Speaker 1: we have to consider the possibility that it ends like
Speaker 1: That's part of the question how big is the universe?
Speaker 1: Is how much space is there? And can it end? Right?
Speaker 1: It's like for fish and we're asking how big is
Speaker 1: the ocean? Yeah, yeah, okay, exactly how big is the
Speaker 1: I wonder do you think fish? Wonder about how big
Speaker 1: is the ocean? I think fish wonder about um not
Speaker 1: getting eaten by other fish, right, and fish fish might
Speaker 1: also wonder like are there other oceans? Right? That's the
Speaker 1: all diverse for fishes. But in our universe you're saying, uh,
Speaker 1: space might have a limit to it, like there might
Speaker 1: be an end to it. Um, Yeah, but is it
Speaker 1: like a wall or is it like a what does
Speaker 1: it mean for it to be at the edge of space? Well,
Speaker 1: there could be an edge to space, and um to
Speaker 1: think about what that means, we have to think about
Speaker 1: what space is a little bit more like to think
Speaker 1: about whether space can curve or if space is flat
Speaker 1: right right, And this kind of stuff is really hard
Speaker 1: to think about in three dimensions, like what does it
Speaker 1: mean for space x y z space right x y
Speaker 1: z being one to three dimensions, the curve really hard
Speaker 1: to think about it because it's hard for us to
Speaker 1: think about that about space curving in some higher dimensions.
Speaker 1: So usually it's best if we think about it in
Speaker 1: two dimensions so we can think about it it's curving
Speaker 1: in that third dimension. So imagine that we are two
Speaker 1: dimensional scientists, were like living on a sheet of paper
Speaker 1: where we can only move in two dimensions, like x
Speaker 1: and y and then we can ask those two dimensional
Speaker 1: scientists can ask is our space curved? Is our paper
Speaker 1: universe curved? And and that changes the answer, Like say
Speaker 1: you discover that it is curved and it has a
Speaker 1: positive curvature. Positive curvature would be like on the surface
Speaker 1: of a sphere or a planet. Right, if it has
Speaker 1: positive curvature, that has consequences for its shape, because if
Speaker 1: it's positively curved, it can't go on forever, right, like
Speaker 1: the Earth. You're standing on the surface of the Earth,
Speaker 1: and you know the Earth is curved, and that means
Speaker 1: that Earth can't be infinitely big, right right, right, So
Speaker 1: you're saying, at the edge of the universe, maybe the
Speaker 1: space space is curved, and or maybe it's a possibility
Speaker 1: you have to consider that maybe space is curved everywhere.
Speaker 1: If the universe had curved space and it was positively curved,
Speaker 1: that would mean that it could be um sort of
Speaker 1: looped on itself very naturally, the same way the surface
Speaker 1: of a planet is, and you could travel around it
Speaker 1: through space and not really get to the edge, right,
Speaker 1: Like where is the edge of the Earth? Well, the Earth,
Speaker 1: the surface of the Earth, the two dimensional surface doesn't
Speaker 1: have it like people in historic times. Maybe they saw
Speaker 1: the earth around them and they thought, oh man, this
Speaker 1: is pretty big. It probably goes on forever, but they
Speaker 1: didn't know that actually land curved. That's right, And and
Speaker 1: it turns out that we're actually kind of on this sphere.
Speaker 1: And if you keep going in one direction and you
Speaker 1: kind of loop back around, that's right. Yeah. And it's
Speaker 1: not like you get to the edge and you get
Speaker 1: magically transported back to where you started or something. There's
Speaker 1: no you know, shortcut or magic there on the surface
Speaker 1: of the earth. You to keep walking, you come back
Speaker 1: to where you started, connected back onto itself exactly. That's
Speaker 1: the key. So that's a big curvature space like space
Speaker 1: that we're in. Could kind of like if you keep
Speaker 1: going in one direction and a spaceship, you'll come back
Speaker 1: around to the same spot exactly. And the way you
Speaker 1: said it was perfect. It's the connection. So we like
Speaker 1: to talk about space by using this analogy of living
Speaker 1: in two dimensions and thinking about it being curved in
Speaker 1: a third dimension. Now pop that up to three dimensions, right,
Speaker 1: because we know our space is at least three dimensions,
Speaker 1: and popping an aspirin because it's now I'm getting it.
Speaker 1: Did we work on getting addibility to support this podcast
Speaker 1: because we're sending them a lot of customers. My god,
Speaker 1: that could be a great um sponsor. That's right, um,
Speaker 1: So pop that up into your three dimensional space, right,
Speaker 1: and then you can ask, well, what does it mean
Speaker 1: for three dimensional space to be curved? Well, it's not
Speaker 1: that we imagine that it's curved in some other fourth dimension.
Speaker 1: It's not that it's hanging in four dimensional space and
Speaker 1: has a curvature in it. It's how space is connected.
Speaker 1: We call it intrinsic curvature because it reflects how one
Speaker 1: part of space is connected to another part of space.
Speaker 1: So without hanging in four dimensions, you can be connected
Speaker 1: in a way that space is curved and you look
Speaker 1: back on yourself without ever really noticing. So when we
Speaker 1: talk about the size of the universe, we mean that
Speaker 1: it has made some kind of edge, but made that
Speaker 1: edge is not like how we think of a nedge,
Speaker 1: is like a stub or a wall. Maybe it's just
Speaker 1: kind of looped around, and so the size of it
Speaker 1: is kind of like this blob of space, right, yeah, exactly.
Speaker 1: And the possible answers for the size of the universe
Speaker 1: depend on how it's curved. Right, If it's positively curved,
Speaker 1: then it can only really be like a big sphere,
Speaker 1: which means it's finite. Right if it would negative? What
Speaker 1: if it's not right? Um, if it's flat. If space
Speaker 1: is flat like it's um, doesn't curve intrinsically, then it
Speaker 1: could potentially go on forever. If space is negatively curved,
Speaker 1: that's like the shape of a of a saddle, the
Speaker 1: negative curvature, then it could have all sorts of really
Speaker 1: weird shapes, but it could still be infinite. Okay, so
Speaker 1: the options are infinite or not infinite. That pretty much
Speaker 1: categorizes the options for everything. How big is your house? Where? Hey?
Speaker 1: Is it infinite or not infinite? I want to see
Speaker 1: that option actually on Zillo from Yeah, I would love
Speaker 1: to have infinite square feeda house, would you really? Because
Speaker 1: then all and you have to look forever for your
Speaker 1: kids shoes? Right, where'd you put them? I put them
Speaker 1: in room numbers somewhere between here and infinity. Yeah. So
Speaker 1: let's talk about the possibilities of what could be beyond
Speaker 1: the observable universe. I mean, we talked a little bit
Speaker 1: about before about maybe it's infinite, Maybe it's not infinite. Um.
Speaker 1: Do we really have no idea whether the actual universe
Speaker 1: is just a little bit bigger than the observable universe,
Speaker 1: much bigger than the observable universe, or it could be infinite.
Speaker 1: We really have sort of no indication of which possibility
Speaker 1: it is. We have a few clues, they're kind of indirect,
Speaker 1: and I want to talk about that some more, but
Speaker 1: first let's take a quick break. One clue comes from
Speaker 1: the curvature of space. We talked earlier about how the
Speaker 1: curvature space affects the how the size of the universe
Speaker 1: could be. And if the space is curved positively or
Speaker 1: negative or flat, that limits the options, right, So that's
Speaker 1: something we can measure. We can measure it here. We
Speaker 1: can look around us and measure how curved is space
Speaker 1: in our universe? Um. And that might be a bit
Speaker 1: of a puzzler, right, like, how does that mean? How
Speaker 1: could space be curved? How could you possibly measure it? Um?
Speaker 1: And to think about that, it's best to go back
Speaker 1: to the two dimensional example. You're living on the surface
Speaker 1: of a planet. For example, if you were a two
Speaker 1: dimensional scientist living on the surface of a planet or
Speaker 1: or some surface and you want to know is this
Speaker 1: surface curved. What you could do is make a triangle,
Speaker 1: because triangles are very sensitive to curvature. For example, you
Speaker 1: draw triangle on a sheet of paper, you add up
Speaker 1: the angles, then you get a degrees every triangle, every
Speaker 1: flat surface, no matter what. Beautiful results basic geometry. That's right. Yeah,
Speaker 1: Now imagine that triangle sitting on the surface of a
Speaker 1: tennis ball. You can draw triangle on the surface of
Speaker 1: a tennis ball that has three right angles on it,
Speaker 1: because triangles behave differently are a curved surface, Yeah, it
Speaker 1: could imagine that it could be ninety degrees, meaning that
Speaker 1: it adds up to two seventy degrees. Yeah, exactly. So
Speaker 1: let's take a break, so everyone can go get a
Speaker 1: tennis ball and sharp. You try this at home, and
Speaker 1: we'll be right back when you have your tennis ball. Alright,
Speaker 1: assuming you're holding a tennis ball and you've annoyed your
Speaker 1: partner or your spouse or your child by drawing triangles
Speaker 1: on it, you can see the triangles behave differently on
Speaker 1: a curved surface. It looks kind of bloated. Yeah, yeah,
Speaker 1: it looks distorted. And so if you just make a
Speaker 1: triangle and add up the angles you can see whether
Speaker 1: or not the space you're in is curved or flat?
Speaker 1: Is that kind of crud to think about the curvature space.
Speaker 1: It's kind of like a distortion of space. Yes, Yes,
Speaker 1: it's a distortion and how the pieces of space are
Speaker 1: connected to each other, which changes how you move through space.
Speaker 1: Changes like how you can get from one spot in
Speaker 1: space to another spot in space. Yeah, like I think
Speaker 1: I'm going straight, but I'm actually kind of being distorted
Speaker 1: one way or the other. Yeah, it changes what straight means. Okay,
Speaker 1: So so then the curvature might give some clues as
Speaker 1: to whether, like we wrap around in ourselves or whether,
Speaker 1: um we don't. I mean, that's all it can tell us, right,
Speaker 1: it's whether we're on a sphere or we're not on
Speaker 1: a sphere. Well, there's one other option, which is that
Speaker 1: we're on a sort of a saddle. Space is negatively curved.
Speaker 1: Imagine you have a sheet of paper that's forms sort
Speaker 1: of like a bowl or the opposite of a sphere,
Speaker 1: and you're in the middle of that bowl. You can
Speaker 1: draw a triangle in that and it will have angles
Speaker 1: of less than eight degrees. Can really measure the chunky
Speaker 1: had distortion. Yeah, yeah, not quite a bowl because that's
Speaker 1: just the inside of a sphere, but something that has
Speaker 1: a sort of saddle shape. Um. And so you draw triangle,
Speaker 1: you make a measurement, and that tells you. And so
Speaker 1: we've done that. We've made those triangles and we've measured
Speaker 1: them to very high precision in three dimensional space. Like
Speaker 1: any answers on this the the sheet of the universe, Yes, exactly.
Speaker 1: We've done it in two different ways, at least that
Speaker 1: I can think of at the top of my head.
Speaker 1: One is that we looked at giant cosmic triangles in space.
Speaker 1: You know, we've looked at the cosmic microwave background radiation,
Speaker 1: this leftover photons from the birth of the universe, and
Speaker 1: drawn these triangles and measured the angles and and they
Speaker 1: come out to degrees. It seems like space is flat.
Speaker 1: Flat were flat? Yeah, And that's a puzzle. It's really interesting.
Speaker 1: There a lot of people wonder like, why is space flat?
Speaker 1: We've measured to be flat to within you know, like
Speaker 1: point one percent, and for a long time that was
Speaker 1: a mystery. But some people don't think that space could
Speaker 1: be curved, like what would why would what would that
Speaker 1: be weird. Yeah, and well that that leads perfectly into
Speaker 1: the second way we've measured the curvature of space, which
Speaker 1: is you might ask what causes space to curve? Right,
Speaker 1: why would you expect space to be curved or flat
Speaker 1: or negatively curved. And the answer is that the thing
Speaker 1: that curves space is matter. Right. You put stuff, matter
Speaker 1: and energy into space, and it curves it. That's what
Speaker 1: general relativity tells us that that gravity is in fact
Speaker 1: the curvature of space. So we know that space gets curved.
Speaker 1: Like you put the Sun in the center of the
Speaker 1: Solar System, it curves space so that the Earth very
Speaker 1: naturally moves in a circle around it. Right, that's an
Speaker 1: impact of the curvature of space. There, nobody's turning the Earth.
Speaker 1: Nobody's like driving the Earth around the Sun, right, but
Speaker 1: constantly turning. It's moving in what it considers to be
Speaker 1: a straight line. But space is curved, so it's it's
Speaker 1: just moving constantly in an orbit, not like a force
Speaker 1: pulling the Earth towards the Sun. But gravity is more
Speaker 1: like it's distorting the space around the Sun so that
Speaker 1: the Earth just can naturally goes around it. That's right,
Speaker 1: that's that's a great way to think about it. And
Speaker 1: so matter distorts space and causes curvature of space, and
Speaker 1: so you can ask is there enough matter and energy
Speaker 1: in the universe to curve space or to make it
Speaker 1: negatively curved or positively curved? Right? And um, if space
Speaker 1: is totally empty, if there's no matter in it at all,
Speaker 1: and then it's negatively curved, you have to add energy
Speaker 1: and matter to make space zero have zero curvature. And
Speaker 1: so we've measured this. We've measured the total energy naturally
Speaker 1: wants to be negatively curved, but if you add stuff
Speaker 1: to it, then it gets a straighter. That's right, Um,
Speaker 1: Space with no energy density in it at all would
Speaker 1: have negative curvature, and so you add stuff to it.
Speaker 1: In fact, if you add I think it's six hydrogen
Speaker 1: atoms worth of energy per square meter, then space has
Speaker 1: zero curvature between five and six. And so we've measured
Speaker 1: the amount of stuff that's in the universe and it
Speaker 1: all adds up to be just about the right number
Speaker 1: to make space be not curved, which is seems like
Speaker 1: a weird coincidence, right, It seems like an important clue,
Speaker 1: like why does all the stuff in the univer has
Speaker 1: happened to add up to the number that's just right
Speaker 1: to make space not be curved. Would that let's take
Speaker 1: a break. We'll be back in just a short minute.
Speaker 1: Space seems to be flat, at least space in our
Speaker 1: part of the universe seems to be flat. It could
Speaker 1: be that other parts of the universe it's curved, right,
Speaker 1: But in our part of the universe it seems to
Speaker 1: be flat. And we think that's sort of that it
Speaker 1: maybe extends out to as far as we can see. Yeah,
Speaker 1: it seems to follow the same rules, and so you're
Speaker 1: absolutely right. That rules out, you know, the potato universe
Speaker 1: that we're living on the surface of its huge cosmic
Speaker 1: potato or bubble universe, whatever, and rules out the saddle universe.
Speaker 1: With the universe is negative curvature. Seems like space is flat,
Speaker 1: which is going on direction forever? Um, I'll just keep going.
Speaker 1: Not necessarily right, we know space is flat. That doesn't
Speaker 1: necessarily mean that it's infinite. It's a natural idea, right.
Speaker 1: If space is flat, then it doesn't curve on itself.
Speaker 1: And so it seems like you could be able to
Speaker 1: go on forever, but earlier that you can't just have
Speaker 1: a wall. You can't just have a wall. But since
Speaker 1: we don't know what space is, we don't really know
Speaker 1: how it works. We don't really know how it's connected.
Speaker 1: It's still possible that it could be flat but connected
Speaker 1: in a weird way. So where one edge is connected
Speaker 1: to the other edge, like you go flat you're moving
Speaker 1: through flat space, but it just loops on back on itself.
Speaker 1: It's like it is connected in that way like an
Speaker 1: asteroids game, you know, you go at the edge of
Speaker 1: the screen, you appear on the other side, but like
Speaker 1: a teleport to the other side. Yeah, yeah, and not
Speaker 1: necessarily teleport, Like that could just be the way space
Speaker 1: is connected. So that's weird that that wouldn't feel u
Speaker 1: you mean, like an asteroid games are like pac Man
Speaker 1: where you walk off one side of the screen and
Speaker 1: suddenly appear on the other side like that. It's possibility.
Speaker 1: Physicies are like, hey, that could be true. That certainly
Speaker 1: could be true, yes, absolutely, But the other possibility is
Speaker 1: also true, which is maybe it just goes on forever. Right.
Speaker 1: It could be that the that space goes on forever um.
Speaker 1: And that's also kind of weird because that's infinite space, right, yeah, yeah,
Speaker 1: and it could be the space is flat, but it
Speaker 1: just ends because we can't see past the observable universe,
Speaker 1: and so we have intuition and ideas and speculation and
Speaker 1: we think, oh, this would be more natural, or that
Speaker 1: would be more natural, or I wish the universe looked
Speaker 1: that way, but at this point that's all we can do. Um. Yeah,
Speaker 1: So it's a it's a fascinating concept infinity because, as
Speaker 1: you say, if things go on forever and then you
Speaker 1: get infinite number of tribes at everything, then that means that,
Speaker 1: given quantum randomness, you really do get every possibility out there.
Speaker 1: So that means it's somewhere out there, there's a universe
Speaker 1: where we're recording podcast and I'm named Jorge and your
Speaker 1: name Daniel, and you know, another universe where every possible
Speaker 1: thing you can imagine happens. That's really true, I mean,
Speaker 1: it's actually happening. If there is an infinite universe with
Speaker 1: infinite space, it means it could be really far away
Speaker 1: and we could never get there and prove it. But
Speaker 1: if that is reality, then it's really happening right now,
Speaker 1: which is crazy to think about. Right right, we just
Speaker 1: will never see it we'll never see it, yeah, or
Speaker 1: if we wait long enough, maybe we would. But but
Speaker 1: it's also so it's on one hand, like really crazy
Speaker 1: to imagine infinite universe with infinite stuff in it. On
Speaker 1: the other hand, it's sort of natural, right, like what's
Speaker 1: the simplest explanation? Is it simpler to imagine an edge? Right,
Speaker 1: like a limited amount of stuff? Um. I find those
Speaker 1: ideas to be sort of weird, and they sort of
Speaker 1: call back to, you know, geocentrism, the idea that we're
Speaker 1: the center, we're an important place in the universe. It's
Speaker 1: much more natural for me to think the universe just
Speaker 1: goes on forever and we're just at one dot in
Speaker 1: a random spot in it. Um. Otherwise they have to explain,
Speaker 1: like why the universe began here, Like imagine the scenario
Speaker 1: the infinite space but finite stuff scenario. Then you have
Speaker 1: to ask, why did the Big Bang happen here and
Speaker 1: not fifty billion light years to the left or to
Speaker 1: the right in that infinite space? Why is that clump
Speaker 1: matter here where we are? Yeah? So my personal preference,
Speaker 1: based on no science at all, is the infinite space
Speaker 1: infinite stuff universe because it sort of puts to rest
Speaker 1: some of those questions, right, It doesn't raise weird questions
Speaker 1: or inconsistencies. Yeah. Yeah, it just asks you to imagine
Speaker 1: creation of an infinite stuff in a moment. I mean
Speaker 1: that's not too much currently. I don't know if anybody
Speaker 1: who has such clever ideas for ways to determine whether
Speaker 1: the universe is infinite or finite by just looking at
Speaker 1: stuff around us. So the only way we could do
Speaker 1: it is direct by looking at the universe, which of
Speaker 1: course we can't. So currently it feels impossible. But you know,
Speaker 1: we always have to leave a little bit of an
Speaker 1: open door there for some future physicist more clever than
Speaker 1: us comes up with a clever way to probe whether
Speaker 1: the universe is find out or infinite just by looking
Speaker 1: at clues around us. You might say that, um, there's
Speaker 1: plenty of room to grow there. Certainly is there? Certainly
Speaker 1: is cool. Well, I hope you guys enjoyed that discussion. Um. Yeah,
Speaker 1: And maybe when you look out at night into the stars,
Speaker 1: you think about the idea that maybe the universe is
Speaker 1: infinite or maybe we're seeing all that there is, and regardless,
Speaker 1: it's a beautiful, gorgeous universe out there. And if you're
Speaker 1: into views, the best view out there is the night
Speaker 1: sky on the top of a mountain, where you can
Speaker 1: see billions of light years across. Amazing business. So however
Speaker 1: big the universe is, go out and enjoy it. Do
Speaker 1: you have a question you wish we would cover, Send
Speaker 1: it to us. We'd love to hear from you. You
Speaker 1: can find us on Facebook, Twitter, and Instagram at Daniel
Speaker 1: and Jorge One Word or email us to feedback at
Speaker 1: Daniel and Jorge dot com.