Speaker 1: One of my favorite things when we give our lecture
Speaker 1: about what we don't know about the universe is the
Speaker 1: questions we get from people in the audience. The best
Speaker 1: questions always come from the youngest audience members. I remember
Speaker 1: one time I gave a talk about liquid nitrogen in
Speaker 1: front of elementary school kids and some kid asked me
Speaker 1: the question. He said, if lightsabers were real, would they
Speaker 1: be made of liquid nitrogen? And Uh, that's I don't
Speaker 1: even know how to answer that question. I was like
Speaker 1: totally stumped by like a six year old. Wait, wait, wait, wait,
Speaker 1: Star Wars is not real. Lightsabers are fictional. Horr heead fictional? Yes,
Speaker 1: so you need to find some other defense against the
Speaker 1: invading arm sampire. So the questions are a fantastic way
Speaker 1: to understand have I really communicated anything? Have people really
Speaker 1: understood what I'm doing? And so that's why I love
Speaker 1: the live aspect of a presentation, because you get that
Speaker 1: feedback from the audience. They're getting it, they're asking fall
Speaker 1: up questions, or they're totally confused and they're asking you questions.
Speaker 1: It seemed to make no sense. Yeah, if only you
Speaker 1: had jedim line tricks, Daniel, These are not the questions
Speaker 1: you're looking for. This is the podcast you're looking for. However. Hi,
Speaker 1: I'm Jorhan and I'm Daniel. Welcome to our podcast. Daniel
Speaker 1: and Jorge explained the universe in which we try to
Speaker 1: make the universe understandable to you, and this time we're
Speaker 1: really going to do our best. Yeah. Today on the program,
Speaker 1: we're going to be answering questions from you the listeners.
Speaker 1: That's right. People have been sending us questions over email,
Speaker 1: and some of them really tickled our brain and said
Speaker 1: we thought let's dig into them because we thought other
Speaker 1: people must have the same questions. Yeah, we have questions
Speaker 1: here about the speed of light, about using giant lasers,
Speaker 1: and about where is the center of the universe. That's right,
Speaker 1: And these are just three questions that we chose from
Speaker 1: the pile. There are other questions I wish we could
Speaker 1: dig into, but we don't have time, like some of
Speaker 1: the joke questions. Yeah, and so as a reminder, if
Speaker 1: you have any questions even after today, after we answer
Speaker 1: some of your questions, if you're a different listener and
Speaker 1: have a question, you can always send us a question
Speaker 1: at Questions at Daniel and Jorge dot com. That's right.
Speaker 1: Send us questions about anything, life, the universe, dating, bananas, whatever.
Speaker 1: We don't promise to be experts in all these fields.
Speaker 1: You don't want to answer dating questions. Yeah, we can
Speaker 1: give an answer about dating, but you know, maybe you
Speaker 1: shouldn't follow dating advice from a cartoonists and a physicist.
Speaker 1: I don't know that you're any more or less qualified
Speaker 1: to give dating advice than anybody else out there giving
Speaker 1: dating advice. Horror, everybody's only got their own experience. You know,
Speaker 1: you should definitely not get dating advice from me because
Speaker 1: I haven't dated anyone since I was like sixteen. But
Speaker 1: it was a success, right, So there you go, you
Speaker 1: have a hundred percent success, right, I have a yeah, yeah,
Speaker 1: I have one data point Every date you take leads
Speaker 1: to marriage, right, Yeah, there you go. Um yeah, so
Speaker 1: listener questions so um, And this is one of your
Speaker 1: favorite parts of teaching and giving cogs, right, Daniel. We
Speaker 1: give a lot of talks across the country in other
Speaker 1: countries about our book, and we always get great questions
Speaker 1: at the end, right, Absolutely, we always get great questions.
Speaker 1: Sometimes people show up with a question already. You can
Speaker 1: tell they're burning to ask some physicists, um, and sometimes
Speaker 1: they have a question that's inspired bout what we've said.
Speaker 1: And you know, sometimes the questions are pretty random, but
Speaker 1: it's always a lot of fun because you can really
Speaker 1: try to explain it to the person and when they
Speaker 1: get it, you can see that light go on in
Speaker 1: their eyes when they finally the pieces of clicked together
Speaker 1: and they have some understanding. And I love that feeling
Speaker 1: of like having an idea in my head translating into
Speaker 1: land waves which then wiggle across space and get translated
Speaker 1: back into an idea in their brain. I mean, it's incredible,
Speaker 1: right that you can even translate an idea from one
Speaker 1: brain to another. So when it's successful, I feel I
Speaker 1: feel pretty good. Yeah, we'll enjoy that feeling before um,
Speaker 1: you know, we're all plugged into the matrix and it's
Speaker 1: just all automatic, that's right, And then we won't need
Speaker 1: podcasts because we'll all know what everybody knows all the time.
Speaker 1: There'll be no privacy. All right, let's just jump into
Speaker 1: the questions, alright. Our first question comes from Sandy from
Speaker 1: New York and he has a question about the speed
Speaker 1: of light. Hi Daniel and Horror. My name is Sandy Delone,
Speaker 1: originally from New York City. I was hoping you can
Speaker 1: talk about whether the speed of light has always been
Speaker 1: the same or whether it is a function of space time.
Speaker 1: How do we know whether or not the speed of
Speaker 1: light has been slowing down over time? Wow, that is
Speaker 1: a great question. Yeah. Well, first of all, he said
Speaker 1: he's originally from New York. What does that mean? That's
Speaker 1: so mysterious. Where is he that? Well, right now he's
Speaker 1: on a rocket ship and at nearly the speed of
Speaker 1: light hitting someone hoping speed right away. This pressing question.
Speaker 1: Wherever he is he can get the podcast, so he
Speaker 1: can't be that far away unless he's from the future,
Speaker 1: that's right, in which case, he invited time travel and
Speaker 1: he knows more about the speed of light than I do,
Speaker 1: so I should be asking him, would be asking him questions. Yeah,
Speaker 1: you're saying these questions. Come to my house and show
Speaker 1: me your time machine. But this is a great question. Basically,
Speaker 1: it's the question of whether the speed of light has
Speaker 1: ever changed. But the first thing I thought was, holy cow,
Speaker 1: can the speed of light change? Is that even possible?
Speaker 1: Is that something that might actually happen and not totally
Speaker 1: break down the universe. Um, all right, So I'm gonna
Speaker 1: make a classic mistake by saying, yes, all right, so
Speaker 1: it's possible for the speed of light to not always
Speaker 1: have been the same. However, as a classical mistake, because
Speaker 1: those people are just gonna hear that and then go
Speaker 1: off and say this physicist said the speed of light
Speaker 1: might change. It's possible. And however, nobody takes that idea
Speaker 1: very seriously. It's pretty well understood that the speed of
Speaker 1: light is fixed, and we assume that it's not changing
Speaker 1: in time. We have no evidence to say that it
Speaker 1: is changing in time, and we can dig in a
Speaker 1: minute to the experiments that we've done, and the evidence
Speaker 1: we have to suggests is constant. However, you know, there's
Speaker 1: a limit to the kind of things we can know,
Speaker 1: and some things are based on assumptions, and so the
Speaker 1: speed of light is one of those things, like we've
Speaker 1: never seen it change. We have no reason to imagine
Speaker 1: it would have changed or will change. But you know,
Speaker 1: there are things we don't know. So, for example, we've
Speaker 1: measured the speed of light a bunch of times, but
Speaker 1: we don't know why it is what it is. You know,
Speaker 1: it's a number three times tend to the eight meters
Speaker 1: per second. We have no reason to feel like it
Speaker 1: should be that number or some other number. You know,
Speaker 1: if we had measured it to be a different number,
Speaker 1: we would have been like, Okay, that's the speed of
Speaker 1: light instead of this other number. So it's not like
Speaker 1: it has a special value. There's nothing in the math
Speaker 1: attics of the laws of physics that'd say the speed
Speaker 1: of light has to be this as far as we know.
Speaker 1: I mean, somebody could come up with a deeper theory
Speaker 1: of physics that doesn't have the speed of light as
Speaker 1: an arbitrary parameter that predicts the speed of light, you know,
Speaker 1: that says it has to be this way because space
Speaker 1: is made out of these quantum loops and that's and
Speaker 1: they oscillated some certain frequency, and that determines the speed
Speaker 1: of light. Maybe right, But we're not there yet at
Speaker 1: this point. It's just a number we measure about the universe,
Speaker 1: and I physicists love doing that. We go and we
Speaker 1: measure these constants because we think there are clues about
Speaker 1: the way the universe is put together. Yeah, but I
Speaker 1: guess what would happen if the speed of light did change?
Speaker 1: Like if suddenly it was twice as fast as it
Speaker 1: is now. Would anything change for us right now, like
Speaker 1: in our everyday lives. Well, if it changed, so the
Speaker 1: universities fall apart. Yeah, like suddenly, wow, suddenly, a sudden
Speaker 1: change in the speed of light. That is an awesome
Speaker 1: thought experiment. Um, I think a lot of things might
Speaker 1: break because, um, you know, we assume speed of light
Speaker 1: is the speed of light, and we use that for
Speaker 1: lots of things, like in the Internet, for to measure
Speaker 1: timing of stuff. You know, we assume things travel as
Speaker 1: certain speed. Wait, wait, wait, it might affect my web surfing. Right,
Speaker 1: that's right, that's all right, let's don't even think about that.
Speaker 1: That's too scary. Yeah, but you know, and on a
Speaker 1: deeper level, if you're like a philosophical kind of person,
Speaker 1: you can ask even deeper questions like do we know
Speaker 1: that the laws of physics themselves change? You know, we
Speaker 1: have these laws like general relativity and quantum mechanics, and
Speaker 1: they're pretty well established over you know, hundred years of experiments, etcetera.
Speaker 1: And they don't seem to be changing. But that doesn't
Speaker 1: mean they won't, right. The assumption that experiments are repeatable
Speaker 1: is foundational concept of empiricism we have in science is
Speaker 1: itself an assumption. You know that the universe has laws,
Speaker 1: and those laws don't change over time, so that we
Speaker 1: can bit by bit do experiments to reveal them. That's
Speaker 1: just an assumption. It seems to work, it works great,
Speaker 1: it works amazingly. We've never seen hints of things changing.
Speaker 1: But we don't know why the universe has laws that
Speaker 1: are discoverable and then don't change. So that assumption is
Speaker 1: based on a lot of data, but it's not based
Speaker 1: on like a bedrock principle. It's like, there's no fundamental
Speaker 1: reason why, and so it could certainly change, or it
Speaker 1: could be changing really gradually over time. So we haven't
Speaker 1: noticed yet. So it can change, but we just haven't.
Speaker 1: We don't think it's changing, that's right, But I guess
Speaker 1: the question is has it ever changed in the past, Like,
Speaker 1: how do we know it wasn't different before? Right exactly?
Speaker 1: And so we have this awesome tool for looking into
Speaker 1: the past, and it's called the universe. So you can
Speaker 1: look out intil the night sky and you can see
Speaker 1: what happened eight minutes ago. If you look at the sun, right,
Speaker 1: don't stare directly at the sun of course. But you know,
Speaker 1: the Sun you're looking at is not the Sun as
Speaker 1: it looks like now. It's how the Sun looked eight
Speaker 1: minutes ago. And the further out you look, the further
Speaker 1: back in time you look, and we can see all
Speaker 1: the way back to the very early moments of the universe,
Speaker 1: and we can see physics happening. You know. We see
Speaker 1: things rotating, we say things orbiting, we see things smashing
Speaker 1: into each other. And we apply the laws of physics
Speaker 1: that we learn about here on Earth in our environment
Speaker 1: to those systems that we see deep in the deep past,
Speaker 1: and things make sense, and they make sense using the
Speaker 1: same speed of light. So we see the speed of
Speaker 1: light unchanged way way back into the history of the universe.
Speaker 1: So that gives us a lot of confidence that things
Speaker 1: haven't changed. Oh I see, So we when we look
Speaker 1: at a star that's really far away, we're seeing the
Speaker 1: results of physics not only that far away, but that
Speaker 1: long ago. Yeah, exactly, And so that gives us confidence that,
Speaker 1: you know, the universe pretty much works the same way
Speaker 1: now as it did billions of years ago. That's right.
Speaker 1: And you know the concept that the speed of light
Speaker 1: may have been different a long time ago UM is
Speaker 1: sometimes proposed by advocates of creation theory. You know, they say, well,
Speaker 1: the universe is only a few thousand years old, and
Speaker 1: then they have a problem. They have to explain, how
Speaker 1: do the light from stars get here if it's if
Speaker 1: they're so far away in the universe is only six
Speaker 1: thousand years old, right, this night sky should be totally black. Um.
Speaker 1: And so they proposed that maybe the speed of light
Speaker 1: was super duper fast a long time ago, so the
Speaker 1: light sort of here and then it's slowed down and
Speaker 1: then you know, and then and that's the way the
Speaker 1: light got here in such a short time. So, you know,
Speaker 1: that seems kind of crazy to me, but that's one
Speaker 1: motivation for imagining the speed of light might have been different.
Speaker 1: And there are other ones that are, i mean, they're
Speaker 1: still on the on the on the fringe, but they're
Speaker 1: not as fringees creation theory, and they have to do
Speaker 1: with the very early moments of the universe, the inflation,
Speaker 1: because you know, we can look out into space and
Speaker 1: we can see the speed of light is basically unchanged
Speaker 1: until the fairly early universe a few hundred thousand years
Speaker 1: after the Big Bang, but before that is very hard
Speaker 1: to see because the universe was trent, was not transparent
Speaker 1: back then. And we have these questions about what happened
Speaker 1: the very early universe. And one of the theories is
Speaker 1: called inflation and explains how the universe got so big
Speaker 1: so quickly, right and and and it's so smooth. And
Speaker 1: one way that people explain that is that the universe
Speaker 1: got really stretched out, the space itself got stretched out,
Speaker 1: and that's called inflationary theory, says the universe expanded really
Speaker 1: rapidly early on um. And but there are other ideas.
Speaker 1: And one of those other ideas is that in the
Speaker 1: very first moments after the Big Bang, maybe the speed
Speaker 1: of light was much much faster, and that account for
Speaker 1: how things moved more quickly in the first few moments
Speaker 1: after the universe was born. Oh, I see, but you
Speaker 1: don't need that if you have the expansion of space itself. Yeah,
Speaker 1: Inflation is a much more comprehensive theory. Explains a lot
Speaker 1: of things that's been tested much more rigorously. This is
Speaker 1: sort of a crazy idea people think about, and I
Speaker 1: totally encourage crazy ideas. I mean, crazy thinking is what
Speaker 1: leads to breakthroughs, not every time, not every crazy theory
Speaker 1: is the right theory. But you've got to allow for
Speaker 1: people to think outside the scientific mainstream in order to
Speaker 1: you know, sometimes generated crazy idea which turns out to
Speaker 1: be true. We've had revolutions in physics and those came
Speaker 1: from crazy ideas. All right, So Sammy from New York,
Speaker 1: that's your answer. We know because we can see well
Speaker 1: into the past, and we have theories that project well
Speaker 1: into the past, and that that tells us that the
Speaker 1: speed of light hasn't been changing. That's right with that,
Speaker 1: Let's take a break. Our next question comes from Ariel
Speaker 1: from Russia, and he had a question about, or more
Speaker 1: like a suggestion about what we could do if there's
Speaker 1: a big asteroid coming to kills All. Hi, Daniel and Jorge.
Speaker 1: My name is Ariel. I want to ask you what
Speaker 1: if instead of using a projectile launched from Earth to
Speaker 1: intercept an incoming asteroid, we use an array of lasers
Speaker 1: and blast asteroid without living Earth. Wow, a great suggestion.
Speaker 1: I think Ariel just wants to build a huge laser
Speaker 1: and point out in the space. Right. That is an
Speaker 1: awesome question, um, and it's pretty wild. I wonder what
Speaker 1: he was doing when he thought of this question, he's
Speaker 1: probably building a huge laser and preparing to point out
Speaker 1: in his face right right. So the background year, of course,
Speaker 1: I mean, why would you want to shoot a laser
Speaker 1: at asteroids other than that sounds really fun, um. And
Speaker 1: the reason is that we did an episode about death
Speaker 1: from space or death from above, right, the danger from
Speaker 1: killer rocks floating out in space, landing on Earth and
Speaker 1: wiping us all out like the dinosaurs. And in that
Speaker 1: podcast we talked about what we could do if we
Speaker 1: see one coming at us, and we talked about how
Speaker 1: we can send rockets out there to kind of deflect
Speaker 1: the asteroid or blow it up or try to break
Speaker 1: it up. Right, that's right, um. And one of the
Speaker 1: challenges is finding the asteroid early, because the sooner you
Speaker 1: find it, the less you have to deflect it. Right,
Speaker 1: If it's really far away, you can give it a
Speaker 1: pretty tiny nudge, and by the time the asteroid gets
Speaker 1: to Earth, that tiny nudge is going to turn into
Speaker 1: a big deviation in its path. If you only find
Speaker 1: it like one second before it hits the atmosphere, then
Speaker 1: a tiny nudge is going to do nothing. So the
Speaker 1: earlier you spotted, the smaller the nudge has to be.
Speaker 1: And then one problem is, say you spot this asteroid.
Speaker 1: If you want to send up a nuclear weapon or
Speaker 1: a gravity tractor or something to tug it off, course,
Speaker 1: you have to get it up there and get it
Speaker 1: to the asteroid really fast, right, because every second counts.
Speaker 1: And so I think that's what motivated Arial's question. He's thinking,
Speaker 1: let's get something there that travels at the speed of
Speaker 1: light like light, right, and using lasers, can we build
Speaker 1: a death star? Can we turn the Earth into a
Speaker 1: death star? You know, have the guys in the black
Speaker 1: helmets pull that lever, have the green laser shootout and
Speaker 1: destroyed the asteroid. That's right, this fully operational battle station exactly.
Speaker 1: That's everybody's fantasy to pull that big lever. You know.
Speaker 1: I love pressing buttons and pulling levers, and the same
Speaker 1: things happen, So that would be a lot of fun. Um. Well,
Speaker 1: great question, Aril, and we didn't cover our podcast. You're right,
Speaker 1: and the reason is that it's a fairly new idea.
Speaker 1: So there's a short answer to your question. Yes, it's
Speaker 1: absolutely possible. People are working on it right now and
Speaker 1: they're developing this technoques. Yes, it's a grown ups working
Speaker 1: on this. Yeah, there are grown ups building death rays
Speaker 1: to shoot at rocks in space. That is somebody's job.
Speaker 1: I mean people, if you work hard, if you study,
Speaker 1: you could get to work on that kind of question.
Speaker 1: And there's a labit. You didn't realize that was an
Speaker 1: alternate career path? Should build gine a death star lasers? No?
Speaker 1: I didn't know. Yeah, well you know my life would
Speaker 1: have been so much different. Yeah, we should educate children
Speaker 1: about all of their options. Um, there's a labit you see,
Speaker 1: Santa Barbara that's working on exactly this. And the reason
Speaker 1: it's not one of the older ideas. You don't hear
Speaker 1: about this when you read like books from the seventies
Speaker 1: or eighties about asteroids and asteroid deflections is that only
Speaker 1: recently do we have lasers that are powerful enough to
Speaker 1: make this efficient. I mean, you've got to put a
Speaker 1: lot of energy into a laser if it's gonna blast
Speaker 1: something super far away. Right, lasers are really focused, right,
Speaker 1: the photons are almost parallel. But if you shoot a
Speaker 1: beam of light, it's going to get wider and wider
Speaker 1: and wider as it goes, which means less and less intense. Right,
Speaker 1: For example, you can shine your flashlight at the Moon
Speaker 1: and you can hit the moon no problem, right, because
Speaker 1: by the time you're the beam from your flashlight gets
Speaker 1: to the Moon, it's huge. It's wider than the moon. Right,
Speaker 1: So the key one of one of the photons you
Speaker 1: shoot is going to hit the moon, exactly. But the
Speaker 1: idea behind laser asteroid deflection is that you want to
Speaker 1: heat up a spot on the side of the asteroid,
Speaker 1: so it warms up to like three thousand degrees and
Speaker 1: then it's going to shoot off a jet of gas
Speaker 1: like molten rock and and gas coming out of the asteroid,
Speaker 1: which is going to act like a little rocket, pushing
Speaker 1: it to the side. Right. So if you can heat
Speaker 1: up one side of the asteroid, you basically can push
Speaker 1: it off course, so you would aim it to the
Speaker 1: side of it, not directly at it. Yeah, I mean
Speaker 1: you're imagining like compu compue compute, Right, I'm shooting these
Speaker 1: things out of the sky direct hit. We're like, We're like,
Speaker 1: but we don't have we don't have powerful enough to
Speaker 1: blow them up, right. The key is to heat it
Speaker 1: up on one side. So you're saying laser technology has
Speaker 1: been improving all these years and now we can actually
Speaker 1: maybe build a death star rate. Yeah. Well, we can't
Speaker 1: blow up planets, right, um, so we can't make disturbances
Speaker 1: in the force like the way you maybe imagining, but
Speaker 1: we can shoot lasers at pretty far away objects and
Speaker 1: deposit significant energy. Um. And so the people have been
Speaker 1: doing studies and the best plan they have so far
Speaker 1: is to build a space based laser right. Right. You
Speaker 1: don't want to shoot the lasers from the ground because
Speaker 1: then they got to go through the atmosphere and they
Speaker 1: get defocused. So you have to have an orbiting platform
Speaker 1: of powerful lasers. Right. And if you're thinking laser gun,
Speaker 1: if you're thinking, yeah, that's not going to be misused
Speaker 1: by by some politicians space gun literally space gun? Yeah,
Speaker 1: I mean, do you want to build this and then
Speaker 1: put in the hands of the next president, whoever it's
Speaker 1: going to be, you know, over of Jay Z or
Speaker 1: Kid Rock or whoever is gonna be the next president.
Speaker 1: Make sure you can't point it back, you know, like exactly,
Speaker 1: it only works you pointed away from the Earth. Anyway,
Speaker 1: you gotta point it from space. You've gotta point it
Speaker 1: at the asteroid and you gotta hit it, and you
Speaker 1: gotta cook it for a little while. I mean, because
Speaker 1: by the time the laser gets there, it's going to
Speaker 1: be more diffuse, right, So you've got a deposit enough energy.
Speaker 1: So the studies that I read, they estimate that depending
Speaker 1: on the power of the laser, it could take between
Speaker 1: a year and ten years to push the asteroid off
Speaker 1: course for like a planet killer asteroid. Yeah, and so
Speaker 1: that's a long time, which means you've got to see
Speaker 1: this thing coming well in advance. And in our podcast
Speaker 1: we talked about how there isn't really a lot of
Speaker 1: danger from asteroids in our Solar system because the biggest
Speaker 1: ones we've seen, we know where they are, we know
Speaker 1: they're not coming for us. The real danger is from
Speaker 1: comets because they're big, they're fast, and we don't necessary
Speaker 1: we haven't necessarily seen their orbits, and we might just
Speaker 1: have like less than a year of warning. And they're
Speaker 1: they're supposed to be made of ice, right, Yeah, they're
Speaker 1: there's like a huge snowball, right, and that would be
Speaker 1: pretty dangerous and we have less than a year of warning,
Speaker 1: so that that's not terribly optimistic, right. The other plan
Speaker 1: is to launch the lasers and then send them to
Speaker 1: the asteroids so they can get closer up and then
Speaker 1: you can have smaller lasers. But you know, then you
Speaker 1: have to spend time getting them to the asteroid, and
Speaker 1: it gets pretty complicated where it's the laser itself. You
Speaker 1: shoot it from Earth would get there the speed of light.
Speaker 1: It would get there to the speed of light, but
Speaker 1: it would be less intense, right, you need a more
Speaker 1: intense laser if you shoot it from further away. On
Speaker 1: the other hand, then you can have your space laser
Speaker 1: and you can use it for whatever you want. You know,
Speaker 1: you can write your name in corn fields a mile
Speaker 1: long right in Europa, basically exactly. You could you could
Speaker 1: carve your face into um, you know, Mount Rushmore from space. Yeah,
Speaker 1: that would be pretty awesome. You could add another eye
Speaker 1: to the jupid jupid, make a smiley face or something.
Speaker 1: That's right, you got the red dot and then you've
Speaker 1: got my dot. Yeah. You could change literally change the
Speaker 1: face of the Solar system. Yeah, so these are dangerous technologies.
Speaker 1: There are actual labs working on this idea, Yeah, exactly.
Speaker 1: There's uh. I think the leading one is that you
Speaker 1: see Santa Barbara and it's called the Directed Energy Planetary
Speaker 1: Defense Lab. You couldn't just call it the laser gun Lab.
Speaker 1: I think probably some students in there wanted to call
Speaker 1: it the death Star Lab, but that was probably over
Speaker 1: ruled by the puy you know. M hmmm, uh so
Speaker 1: Ariel from Russia. The answer is yes, you could do that,
Speaker 1: and there are people working on it, and if you'd
Speaker 1: like to contribute, you just need to apply to the
Speaker 1: physics program. But you see, Santa Barbara, this is a
Speaker 1: perfect point to take a break. Okay, So our last
Speaker 1: question in this episode comes from Russell. And Russell didn't
Speaker 1: say where he was from, which means we can guess
Speaker 1: where he's from. Where do you think he's from? I
Speaker 1: think he's probably on an asteroid headed to Earth. How
Speaker 1: about you? He's gonna guess, pig, but I like your
Speaker 1: your answer. Um, okay, So Russell has a question about
Speaker 1: the expanding universe. Hey, guys, my name is Russell and
Speaker 1: I really love the podcast and I've got a question
Speaker 1: for you. If the universe is constantly expanding, where is
Speaker 1: it expanding from? Does it have a center? Thanks? Guys,
Speaker 1: this is a great question. It's actually a common question
Speaker 1: that we get. Yeah, but it's kind of tricky. I mean,
Speaker 1: a long time to sort of get on my head
Speaker 1: around this concept. Right, Like the idea is that if
Speaker 1: everything is moving away, is growing, it's stretching, doesn't that
Speaker 1: mean that there's a point that is not growing or
Speaker 1: moving do you know? Do you know what I mean? Like,
Speaker 1: if you explode a grenade in space and you see
Speaker 1: all the bits flying off, if you track the motion
Speaker 1: of all the bids, you could track down where all
Speaker 1: those bids came from, which is sort of like the
Speaker 1: center of an explosion. And so if if somebody tells
Speaker 1: you the universe exploding or it's expanding, isn't that doesn't
Speaker 1: that mean there's a point in the universe that is
Speaker 1: not growing or expanding. Yeah, in your grenade theory of
Speaker 1: the universe, that would be correct. Yeah, So if the
Speaker 1: universe is a grenade, then there would be a center.
Speaker 1: But and this misconception comes from thinking about the origin
Speaker 1: of the universe the Big Bang as an explosion, right,
Speaker 1: but it's not really an explosion in the sense that
Speaker 1: just matters is flying through space. It's also an explosion
Speaker 1: of space. Right, Space itself is expanding, and it's expanding
Speaker 1: everywhere at the same time. So it's like everything is
Speaker 1: exploding at the same time. So rather than thinking of
Speaker 1: it like an explosion, you should think of it like
Speaker 1: an infinite ruler. An infinite ruler suddenly starts to stretch right,
Speaker 1: and it's stretching everywhere all at once. Right, But isn't
Speaker 1: doesn't the ruler have a center? If the ruler has
Speaker 1: a center of mass, like a point where you could
Speaker 1: balance it on your finger. Okay, So where is the
Speaker 1: center of mass of an infinite ruler right in the middle? Right?
Speaker 1: Where is the zo at every point? At every point
Speaker 1: you have an infinite amount of mass on both sides, right,
Speaker 1: so it balances the same way everywhere. Yeah, but I guess,
Speaker 1: but you're assuming the universe is infinite. What if it's
Speaker 1: not infinite, wouldn't that mean it has the center of mass? Right? Okay,
Speaker 1: So let's break the answer into two different possibilities because
Speaker 1: they're very two very different answers. One is, let's assume
Speaker 1: the universe is infinite, right, that beyond what we can see,
Speaker 1: it just goes on for ever. And in that model,
Speaker 1: I think the most common scientific understanding is that the
Speaker 1: Big Bang happened everywhere same at the same time. Right.
Speaker 1: The Big Bang was not like at some location, you know,
Speaker 1: corner or Fifth Avenue and Broadway, um, and then everything
Speaker 1: expanded from there, but that it happened everywhere at the
Speaker 1: same time. So there was a big bang over there's
Speaker 1: a big bang over here. It's all at the same time.
Speaker 1: And so you can think of it like you know,
Speaker 1: the surface of a balloon expanding. Right, there's no center
Speaker 1: to the surface. Every point on the on the surface
Speaker 1: is expanding simultaneously, right, obviously the center to the balloon.
Speaker 1: But here this is too d example, We're just thinking
Speaker 1: about the surface of the balloon, right, like everything came
Speaker 1: from nothing everywhere. Yeah, well, what came before the Big Bang?
Speaker 1: That's a whole other question, right. But if you assume
Speaker 1: that somehow an infinite universe exists, right, and that then
Speaker 1: the Big Bang started, the Big Bang being just this
Speaker 1: expansion of space, the stretching of the very fabric of
Speaker 1: space itself. Um, then that happened everywhere at the same time.
Speaker 1: There's no preferred location, And it's an important concept in
Speaker 1: physics that everywhere in the universe is equally preferable to
Speaker 1: everywhere else. Right, we're very democratic in physics when we
Speaker 1: think about space. We we don't like to think about
Speaker 1: any place being special, right, But like in a balloon, Um,
Speaker 1: if I'm inflating the balloon, there's a point the part
Speaker 1: where I'm holding it and blowing error into it, that's
Speaker 1: the part that's not moving. That's true, You're right. I
Speaker 1: guess I was imagining a balloon without a without whore
Speaker 1: his lips on infinitely exactly. And you know, the universe
Speaker 1: doesn't have to be infinite for this to work. It
Speaker 1: just has to be sort of closed, right, Like we
Speaker 1: talked in our podcast about the size and the shape
Speaker 1: of space. The universe could be infinite, but it could
Speaker 1: also be wrapped around itself like a game of asteroids,
Speaker 1: where you go off in one direction and you loop
Speaker 1: back around the other way without any discontinuity. And that's
Speaker 1: the way, like the service of a balloon is, right,
Speaker 1: you walk along the service of a balloon. You can
Speaker 1: do it forever and everyone ever. You just come back
Speaker 1: to where you started. There's no end. And in that
Speaker 1: concept also there the big bang is not in any
Speaker 1: particular place. It has no center, right, I see, like
Speaker 1: a balloon would have the center of the balloon. But
Speaker 1: you're saying like it's a kind of kind of a
Speaker 1: three D balloon. Yes, exactly. It's like a three D
Speaker 1: balloon where only be on the center of the balloon,
Speaker 1: and expanding balloon really doesn't have a center. Like if
Speaker 1: you're an ant walking on it, you'd be like, we're
Speaker 1: the center. Yeah, exactly. Like on the surface of the Earth,
Speaker 1: there's no center to the surface. Right. Every place on
Speaker 1: the surface of the Earth is the same relative to
Speaker 1: the Earth, right, it's the same radius and whatever. All right,
Speaker 1: So if it's infinite, then it could have no center,
Speaker 1: yeah exactly. Um, but we don't know that, right, And
Speaker 1: that's the lovely part about questions about the universe is
Speaker 1: that we know so little about these large contextual questions,
Speaker 1: you know, like what have we seen about the universe?
Speaker 1: We've seen what's inside a sphere, a sphere that's big
Speaker 1: enough for light to have traveled from those things to
Speaker 1: us since the start of the universe. It's a little
Speaker 1: bit more complicated than just being the speed of light
Speaker 1: times the age of the universe, because there's some actual
Speaker 1: stretching of space. But we can hand away that for now,
Speaker 1: so we call that the observable universe, right, that's everything
Speaker 1: that we can see right. And what we don't know
Speaker 1: is what fraction of the universe is. That is that
Speaker 1: most of the stuff in the universe. Is that one
Speaker 1: bajillions of the universe or is that basically one over infinity?
Speaker 1: Because the universe is infinite. So it's certainly possible that
Speaker 1: the universe is finite, that there's you know, at some
Speaker 1: point it runs out of stuff. Um, you know, space
Speaker 1: could be infinite and the stuff could be finite, right, Yeah,
Speaker 1: So there's all these possibilities. But um, there's basically like
Speaker 1: infinite or not infinite, right. And if it's not infinite, right,
Speaker 1: if there's a finite amount of stuff in the universe,
Speaker 1: well then we don't know where the center of that
Speaker 1: stuff is because we can't see all of it, right,
Speaker 1: So we have no way of knowing. Um. But if
Speaker 1: there is a fine amount of stuff in the universe,
Speaker 1: and yes, it would have a center somewhere, right. Um.
Speaker 1: But the thing I love about that is that of
Speaker 1: the observable universe, the center is you, right, you are
Speaker 1: literally at the center of your observable universe. I'm more
Speaker 1: like in the center of my kids universe. It seems
Speaker 1: that's right. You just just a little orbiting moon right
Speaker 1: around there, some like egos Um. Yeah, but we all
Speaker 1: have different observable universes because our heads are in different places,
Speaker 1: and so we can all catch photons from the early universe.
Speaker 1: It's slightly different times, and so like another alien species
Speaker 1: would have their own observable universe that's a sphere around
Speaker 1: their planet. So the short answers to the question is
Speaker 1: that we really just don't know. If the universe is infinite,
Speaker 1: then it has no center. If it's finite, then we
Speaker 1: don't know that it is finite, and we can't see
Speaker 1: enough of it to know, you know, what would the
Speaker 1: average location of all that stuff be. But there could
Speaker 1: be a hypothetical center to the universe. I mean, if
Speaker 1: it is finite, there could be a center to the universe. Yeah.
Speaker 1: Currently most of our models assume the space goes on forever,
Speaker 1: and everything we see agrees with that. I think if
Speaker 1: the universe was finite in the sense that it was,
Speaker 1: the size of the universe was only a little bit
Speaker 1: bigger than the observable universe, so that what we're seeing
Speaker 1: is basically most of it. I think we would see
Speaker 1: effects of that, you know. I think that the gravitational
Speaker 1: forces would be tend towards one location or in one direction, right,
Speaker 1: rather than pulling things everywhere. And what we see now
Speaker 1: is very homogeneous. We've never seen anything that prefers any
Speaker 1: one direction or any one location, and so the universe
Speaker 1: seems to prefer no direction and seems to prefer no location.
Speaker 1: So that suggests doesn't seem like we're orbiting around something. Yeah,
Speaker 1: that suggests that things are either infinite or really really
Speaker 1: big compared to what we can see. Right. Of course,
Speaker 1: we can't tell the difference between those two things. But
Speaker 1: if I had to place a bet, I would say
Speaker 1: the universe is most likely either infinite or huge jungu
Speaker 1: is compared to what we can see, huge, dude, Jungus. Yeah, exactly,
Speaker 1: ginormous compared to what we can see, which would be
Speaker 1: for all practical purposes, would be infinite. And so from
Speaker 1: those from that perspective, uh, the universe wouldn't have any
Speaker 1: well defined center in either case. The fact that it's
Speaker 1: it's space itself that's like spanning, means that you don't
Speaker 1: need that sort of center of the grenade, Like, yeah, exactly,
Speaker 1: everything's space itself is expanding. Literally, would sort of look
Speaker 1: the same, whether we're here or we're in Andromeda, or
Speaker 1: we're billions of lighters away, it would all just sort
Speaker 1: of seem like it's expanding away from us. Yeah, exactly
Speaker 1: every point in the universe. It seems like everything is
Speaker 1: expanding away from you. So everybody feels like, hey, why
Speaker 1: is everybody going away from me? And that makes me
Speaker 1: wonder about a little b about Russell's motivations, like why
Speaker 1: is the center of the universe important? Like why do
Speaker 1: we care? It's not like from a scientific point of view,
Speaker 1: it doesn't necessarily have any meaning, right, It's not like,
Speaker 1: you know, are we living at the center? Are we
Speaker 1: in the best real estate in the universe or something?
Speaker 1: Or maybe it's a question an attempt to understand, like
Speaker 1: the origin, like this special place. If there was a
Speaker 1: center to the universe, you could ask why they're right.
Speaker 1: Imagine space is infinite, the matter is not that the
Speaker 1: universe is like a finite blob of matter that exploded
Speaker 1: in space at some point fourteen billion years ago. Then
Speaker 1: you could ask this question, why that spot and not
Speaker 1: a billion light years to the left or billion light
Speaker 1: years to the right, And that would be an interesting question,
Speaker 1: would be just include that there's something that happened here
Speaker 1: and not somewhere else. So if space did have a center,
Speaker 1: then you can ask interesting questions about it. Right. I
Speaker 1: thought you were going to say that the reason Russell
Speaker 1: was wondering what everything is moving away from him was
Speaker 1: that he needed some dating advice. You've gotta be nice
Speaker 1: to our listeners, for here, they are the reason we
Speaker 1: get to keep doing this, right, Russell, They're going away
Speaker 1: from you because they're also intimidated by your good looks
Speaker 1: and charisma. That's what's going on in your ability to
Speaker 1: ask great questions. Seriously awesome question, Russell. Thank you very much,
Speaker 1: and your tasting podcasts and your tasting podcast is exquisite. Alright,
Speaker 1: those were all super great questions. And I think you know,
Speaker 1: it just kind of generally points to the curiosity of people,
Speaker 1: you know, just like you listen to this podcast like
Speaker 1: this one, or watching the Science Show and you just
Speaker 1: you can't help but have questions, deep questions about the universe.
Speaker 1: That's right, and we are here to talk about them,
Speaker 1: and we don't always have the answers. But sometimes it's
Speaker 1: even more fun when we don't know what the answer
Speaker 1: is and we can talk about all the crazy possibilities.
Speaker 1: So please don't hold back. If you are listening to
Speaker 1: this podcast and you have a question you want us
Speaker 1: to talk about, send it to us at questions at
Speaker 1: Daniel and Jorge dot com. And if you need dating advice,
Speaker 1: just write as a dating at Daniel and Jorge dot
Speaker 1: com or just shouted at your window late at night
Speaker 1: and Jorge will eventually hear it. Or just build the
Speaker 1: death star and write it on the surface of the moon.
Speaker 1: We'll we'll, definitely. I do not endorse that advice, by
Speaker 1: the way, that is purely from rhead. I'm gonna have
Speaker 1: my lawyers cleared me from liability from your moon moon
Speaker 1: vandalism suggestion. There we need we need to disclaimer at
Speaker 1: the end, you know, like movies have disclaimers. Yeah, please
Speaker 1: sign this way. This is a work of fiction. None
Speaker 1: of the opinions podcast. We can't say it's the work
Speaker 1: of fiction. I'm supposed to be talking about things that
Speaker 1: are real. None, none of the opinions expressed by the
Speaker 1: cartoon is should be taken seriously. I'm sorry. By listening
Speaker 1: to this podcast, you accept responsibility for all of your actions,
Speaker 1: even if we suggested them. All right, Thanks everybody for listening.
Speaker 1: Please don't go out and vandalize cosmic features of our
Speaker 1: solar system and ruin them for everybody, and keep asking questions.
Speaker 1: That's right, See you next time, See you next time.
Speaker 1: If you still have a question after listening to all
Speaker 1: these explanations, please drop us a line. We'd love to
Speaker 1: hear from you. You can find us at Facebook, Twitter,
Speaker 1: and Instagram at Daniel and Jorge that's one word, or
Speaker 1: email us at Feedback at Daniel and Jorge dot com.