Latest / Daniel and Kelly’s Extraordinary Universe / What came first matter or energy?

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What came first matter or energy? · Daniel and Kelly’s Extraordinary Universe

• 0:02
  Speaker 1: Y Daniel, I have a deep philosophical question for you. Awesome,
• 0:12
  Speaker 1: let me just get some Banan appeals ready over here.
• 0:15
  Speaker 1: It is a slippery question, so watch out all right.
• 0:17
  Speaker 1: So which came first? Physics or math? Oh, tough one.
• 0:22
  Speaker 1: I'm inclined to say math because people have been doing
• 0:25
  Speaker 1: that since there was like money. I think there are
• 0:28
  Speaker 1: cuneiform tablets they have found with receipts for like cows
• 0:31
  Speaker 1: that somebody bought in two thousand BC. So economics came first? Well,
• 0:35
  Speaker 1: you know, economics is doing math to describe the physical
• 0:39
  Speaker 1: world like cows. So in a way they're secretly physicists,
• 0:43
  Speaker 1: aren't they. I see, you're just trying to point it
• 0:45
  Speaker 1: all back to physics. So even if I buy a Hamburger,
• 0:48
  Speaker 1: I'm being a physicist. Well, you know, if you spend
• 0:50
  Speaker 1: money doing it, then I guess you're like a Mathematterian.
• 0:53
  Speaker 1: We're already saying that I eat math or I eat mathematicians.
• 0:57
  Speaker 1: That depends on your ethical framework. Man, what came first?
• 1:00
  Speaker 1: Ethics or physics? Philosophy came first? Would you get a
• 1:03
  Speaker 1: doctorate in those? I think podcasts definitely didn't come first, Hi,
• 1:23
  Speaker 1: am or Hammay cartoonists and the creator of PhD comics. Hi,
• 1:26
  Speaker 1: I'm Daniel. I'm a particle physicist and a professor UC Irvine,
• 1:30
  Speaker 1: and I definitely liked math before I liked physics. Really,
• 1:33
  Speaker 1: math is your first love or just your first experience
• 1:38
  Speaker 1: with the academics. Well, you know, you learn math in
• 1:41
  Speaker 1: elementary school, but they don't really teach you a lot
• 1:43
  Speaker 1: of physics in elementary school. I mean maybe you do
• 1:45
  Speaker 1: a little bit of like this is what it's inside
• 1:47
  Speaker 1: of rock, but you definitely don't talk a lot about
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  Speaker 1: astrophysics in elementary school. I see, so Daniel Whiteson was
• 1:53
  Speaker 1: a mathematician before he was a physicist. Yeah, my dad
• 1:57
  Speaker 1: was really into math, and so I learned a lot
• 1:59
  Speaker 1: of math at home and I really enjoyed math and
• 2:01
  Speaker 1: elementary school. I was definitely a math nerd before I
• 2:04
  Speaker 1: was a physics nerd. That kind of makes me a
• 2:06
  Speaker 1: little sad. I feel like that's like learning that Michael
• 2:09
  Speaker 1: Jordans really wanted to be a baseball player and not
• 2:11
  Speaker 1: a basketball player. I think that's true, actually, isn't it.
• 2:16
  Speaker 1: It is true? Yeah, his first love was baseball. But
• 2:20
  Speaker 1: I'm pleased with any analogy that puts me in the
• 2:22
  Speaker 1: same phrase as Michael Jordan. I'd like to be the
• 2:24
  Speaker 1: Michael Jordan of anything. You are full of air hot
• 2:28
  Speaker 1: air sometimes. But you know, don't they say that all
• 2:30
  Speaker 1: babies are kind of physicists when they're born. You know,
• 2:32
  Speaker 1: they're trying to explore the physical world around them, and
• 2:34
  Speaker 1: they're trying to, you know, learn the laws of physics
• 2:37
  Speaker 1: in a way. Yeah, it sounds to me like you're
• 2:39
  Speaker 1: saying everybody who's curious about the world is a physicist,
• 2:43
  Speaker 1: not just curious about the physics of the world. You know,
• 2:45
  Speaker 1: like how do I stand up? Or what happens if
• 2:47
  Speaker 1: I dropped this ball? Or how do I get more food?
• 2:50
  Speaker 1: Although babies come from biology, so made biology came first?
• 2:53
  Speaker 1: Now I'm confused. It's all philosophy in the end. But anyways,
• 2:55
  Speaker 1: Welcome for a podcast. Daniel and Jorge explain the university
• 2:58
  Speaker 1: production of I Heart Radio, in which we treat the
• 3:00
  Speaker 1: entire universe as one grand physics question. We ask how
• 3:05
  Speaker 1: does it work? Why does it work this way and
• 3:07
  Speaker 1: not some other way? And how will it work in
• 3:10
  Speaker 1: the future? And most of all, we ask is it
• 3:13
  Speaker 1: possible for our tiny little mathematical biology? Economics philosophy, loving
• 3:18
  Speaker 1: brains to understand it. Yeah, it is an amazing universe,
• 3:21
  Speaker 1: and it makes me wonder if we are still just
• 3:23
  Speaker 1: kind of babies in it trying to figure out the
• 3:25
  Speaker 1: basics of how it works, or are we PhD holders
• 3:28
  Speaker 1: who pretty much are going to understand everything there is
• 3:31
  Speaker 1: to know about the universe right now. It is fun
• 3:33
  Speaker 1: to look back at that sort of history of physics
• 3:35
  Speaker 1: and how it developed, people stumbling forward, having silly ideas,
• 3:39
  Speaker 1: having to backtrack, having new ideas, and then bursts of progress.
• 3:42
  Speaker 1: It really is similar to the way kids develop. I mean,
• 3:46
  Speaker 1: physics are just like banging blocks together, you know what,
• 3:49
  Speaker 1: You know what, that's kind of what you're doing, just
• 3:51
  Speaker 1: banging particles together seeing what happens. Yeah, well, there definitely
• 3:54
  Speaker 1: are false leads and stumbling blocks, you know. I was
• 3:56
  Speaker 1: reading some history of physics yesterday, and even after are
• 4:00
  Speaker 1: like the Michaelson Morley experiment that light travels at the
• 4:03
  Speaker 1: same speed no matter who measures it. Most physicists still
• 4:06
  Speaker 1: believed in the ether for years and years afterwards. It
• 4:10
  Speaker 1: takes physics a long time sometimes to change direction and
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  Speaker 1: figure out a new course, the same way it takes
• 4:15
  Speaker 1: kids time to break old habits. Yeah, tell me about it.
• 4:20
  Speaker 1: We tried telling a kid what to do or try
• 4:23
  Speaker 1: to instill the habit of cleaning up the room. Impossible, impossible.
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  Speaker 1: And so I hope that we are still babies when
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  Speaker 1: it comes to the physics of the universe, because that
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  Speaker 1: suggests we're going to grow up into some new, deeper
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  Speaker 1: understanding of the way the cosmos works. That in our
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  Speaker 1: future are some revelations. Yeah, we're gonna get PhDs in
• 4:40
  Speaker 1: PhDs or something, But there is still plenty to understand
• 4:45
  Speaker 1: about the universe and all the mysteries of the cosmos,
• 4:48
  Speaker 1: how it works, how things swirl around each other, how
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  Speaker 1: things form, how they burn, how they die, generate questions,
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  Speaker 1: not just in the minds of academic physicists, but in
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  Speaker 1: children and in everybody out there. Yeah. Maybe in a
• 5:01
  Speaker 1: way before math or before physics or biology or philosophy
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  Speaker 1: came just asking questions like that's kind of how everything
• 5:08
  Speaker 1: starts by a human asking a question about how something works. Yeah,
• 5:12
  Speaker 1: proto humans asking questions like how fast do I have
• 5:15
  Speaker 1: to throw my spear to get that mammoth? Yeah, that
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  Speaker 1: it sounds like more of an engineering problem, Daniel, We're
• 5:22
  Speaker 1: all proto engineers. Is that what you're saying before asking questions?
• 5:26
  Speaker 1: We're engineers. We ask questions and the answers lead to
• 5:29
  Speaker 1: engineering problems, like all right, I need a spear this long,
• 5:32
  Speaker 1: somebody build me one. Yeah, well, I'm regardless of who
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  Speaker 1: came first. What's important is that we ask questions. That
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  Speaker 1: seems to be a very common human trait that everyone doesn't,
• 5:41
  Speaker 1: no matter how old you are or where you come from,
• 5:43
  Speaker 1: because we all look at the universe and we wonder like,
• 5:46
  Speaker 1: what's going on, how does it all fit together? And
• 5:49
  Speaker 1: what's going to happen next? And if you're listening to
• 5:51
  Speaker 1: this podcast, probably you're the kind of person who desperately
• 5:54
  Speaker 1: wants to know the answer to these questions. Feels like
• 5:57
  Speaker 1: there is a truth out there about how the universe
• 5:59
  Speaker 1: works and how it began and what its future holds,
• 6:02
  Speaker 1: and we want to know it because we believe that
• 6:05
  Speaker 1: if we apply our minds, we can understand the universe. Yeah,
• 6:08
  Speaker 1: and it's not just physicists asking these questions. It's people
• 6:11
  Speaker 1: like you asking these questions. And sometimes listeners like you
• 6:15
  Speaker 1: send their questions to us, and we invite you to
• 6:18
  Speaker 1: send your questions as well. If there's something about the
• 6:21
  Speaker 1: universe you don't understand, or you'd like to hear us
• 6:24
  Speaker 1: talk about and make silly jokes about. Please write to
• 6:27
  Speaker 1: us two questions at Daniel and Jorge dot com. Yeah,
• 6:31
  Speaker 1: Daniel answers every physics questions he gets, even if they
• 6:34
  Speaker 1: are crazy out there, right, that's right, And not just
• 6:36
  Speaker 1: physics questions. AHI answer every message I get from our listener,
• 6:40
  Speaker 1: even funding requests. He takes that funding requests. I guess
• 6:44
  Speaker 1: you can always answer it. No, I'd always answer no.
• 6:46
  Speaker 1: Sometimes people ride in with life advice questions like I'm
• 6:50
  Speaker 1: forty years old and I'm a computer programmer, but I
• 6:52
  Speaker 1: always wanted to be a physicist, and is there a
• 6:54
  Speaker 1: way for me to get there? Cool life advice, career
• 7:00
  Speaker 1: advice from a physicist, Life advice from somebody who doesn't
• 7:03
  Speaker 1: really know how the real world works. Yeah. So sometimes
• 7:08
  Speaker 1: we get these questions, and sometimes they're so interesting Daniel
• 7:11
  Speaker 1: puts them up to answer on the podcast live in
• 7:13
  Speaker 1: front of a studio audience. Who's the studio audience exactly
• 7:17
  Speaker 1: by the laugh track, Now it's the studio in my head.
• 7:22
  Speaker 1: We have a live audience in my head in front
• 7:24
  Speaker 1: of the studio audience of nobody know. Sometimes I get
• 7:27
  Speaker 1: a question that I think we'll be fun to talk about,
• 7:29
  Speaker 1: or I suspect other people will want to hear the
• 7:32
  Speaker 1: answer to, and so then we get audio from that
• 7:34
  Speaker 1: listener so we can talk about it here on the podcast.
• 7:36
  Speaker 1: Yes to the On the program, we'll be tackling listener questions.
• 7:45
  Speaker 1: Remember that's the six episode in which we answer questions
• 7:50
  Speaker 1: from listeners. That's right, and last time we did this,
• 7:52
  Speaker 1: or hey, you had so much fun, you said we
• 7:53
  Speaker 1: should do this more often, And so here we are again,
• 7:56
  Speaker 1: just a couple of weeks later, doing it more often.
• 7:58
  Speaker 1: Oh man, I didn't know I had that kind of
• 8:00
  Speaker 1: influence in the universe. Should I wish for more things?
• 8:03
  Speaker 1: Oh man, Daniel, I wish I had a bazillion dollars.
• 8:06
  Speaker 1: You can submit a request to the Daniel Science Foundation,
• 8:08
  Speaker 1: but they usually say now do they ever say yes?
• 8:12
  Speaker 1: What's their track record? Zero percent? We responded to all requests.
• 8:18
  Speaker 1: I see response rate zero percent, affirmative response. We have
• 8:23
  Speaker 1: issued of our foundation of bank account, have issued knows
• 8:29
  Speaker 1: in your operations. That's right. But anyways, we're so we're
• 8:32
  Speaker 1: answering questions from listeners today and we have some awesome
• 8:35
  Speaker 1: questions here today, some from kids about the Solar system
• 8:39
  Speaker 1: and the planets in the Sun and the moons around us,
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  Speaker 1: and also some interesting questions about asteroids that may or
• 8:45
  Speaker 1: may not kill us, and also about matter and energy
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  Speaker 1: at the Big Bang. We're going all the way back
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  Speaker 1: to the beginning. That's right. We want to understand everything
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  Speaker 1: about the universe from the way it is today to
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  Speaker 1: the way it started. Yeah. So we have awesome questions here,
• 8:59
  Speaker 1: and the first few are from a couple of kids
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  Speaker 1: who listen to the podcast, and they have questions about
• 9:04
  Speaker 1: kind of our immediate neighborhood. So the first one is
• 9:07
  Speaker 1: from Kendall, who is seven years old. Hi, my name
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  Speaker 1: is Kendall. I'm seven years old. I would like to
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  Speaker 1: know why our stars so hot? Or hey you're a star,
• 9:16
  Speaker 1: why are you so hot? I don't know. You know,
• 9:18
  Speaker 1: I work out, I eat well, a mom cartoonists. I
• 9:22
  Speaker 1: think that adds to that air of you know, attractiveness. Yeah,
• 9:25
  Speaker 1: so great, another piece of life advice from somebody who
• 9:28
  Speaker 1: doesn't live a typical life. That's right, someone who doesn't
• 9:32
  Speaker 1: leave their house very much. But thank you Kendall for
• 9:35
  Speaker 1: sending in this question. That's awesome. That you're curious about
• 9:38
  Speaker 1: the Sun, about stars, about what's out there in space.
• 9:41
  Speaker 1: That's amazing And it's a great question because it sounds
• 9:44
  Speaker 1: like a simple question on the surface but actually gets
• 9:46
  Speaker 1: into a lot of really interesting physics. And it's not
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  Speaker 1: that simple a question to answer. WHOA see, Kendall, you
• 9:52
  Speaker 1: just dumped the footy seven year old physicists. So Kendall's
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  Speaker 1: question is why our stars so hot? I guess star
• 10:00
  Speaker 1: are pretty hot? Right, They're not cold. Stars are pretty hot.
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  Speaker 1: The reason we can see them is because they're so hot. Remember,
• 10:06
  Speaker 1: everything in the universe glows, and the frequency at which
• 10:11
  Speaker 1: it glows depends on its temperature. So the Sun is
• 10:14
  Speaker 1: hot enough to glow in the visible spectrum, which is
• 10:17
  Speaker 1: pretty cool or pretty hot. Well, it's interesting because I
• 10:20
  Speaker 1: guess you know, maybe people your age and mind associate
• 10:24
  Speaker 1: light and something bright is something being hot, right, because
• 10:26
  Speaker 1: light bulbs are hot. You don't want to touch a
• 10:28
  Speaker 1: light bulb from from when we came from. But nowadays,
• 10:31
  Speaker 1: you know, with LED lights you can have like cool lights, right,
• 10:34
  Speaker 1: you can have a cold light bulb. Yeah, because the
• 10:36
  Speaker 1: light generated by an LED is not like black body radiation,
• 10:40
  Speaker 1: the way light from like a tungsten filament is it
• 10:43
  Speaker 1: comes from a quantum mechanical process, which is pretty super cool.
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  Speaker 1: But one of the interesting things about stars is that
• 10:49
  Speaker 1: they are hot, but in order for them to even
• 10:51
  Speaker 1: get formed, they have to actually start out very, very cold.
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  Speaker 1: So they have a really interesting sort of thermal history
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  Speaker 1: to them, right, right, because I guess all star us
• 11:00
  Speaker 1: out there in space in the universe started off as
• 11:04
  Speaker 1: cold clouds of gas, right, That's how they all started. Like,
• 11:07
  Speaker 1: the gas isn't hot, it's just like it's just floating
• 11:10
  Speaker 1: out there in space, and space is really cold, so
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  Speaker 1: really it comes from cold gas. It comes from cold gas.
• 11:15
  Speaker 1: And if you have a big cloud of gas, if
• 11:17
  Speaker 1: it starts out too hot, it can't form stars because
• 11:20
  Speaker 1: remember stars are formed by gravity pulling together all these
• 11:24
  Speaker 1: little bits of stuff. But gravity is super duper weak.
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  Speaker 1: So for gravity to succeed pulling together a big cloud
• 11:30
  Speaker 1: of gas, it can't be too hot. If it's too hot,
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  Speaker 1: it'll just ignore the gravity. So cloud has to cool
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  Speaker 1: down enough for gravity to be able to take over
• 11:39
  Speaker 1: and compress it. And so if a cloud is more
• 11:41
  Speaker 1: than like ten or twenty degrees kelvin, it just can't
• 11:44
  Speaker 1: form stars. So a star starts off as cold gas,
• 11:48
  Speaker 1: and then gravity makes it all sort of clump together
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  Speaker 1: into one kind of smaller ball of super hot gas exactly,
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  Speaker 1: And it's that gravitational pressure that provides the heat. A
• 11:59
  Speaker 1: lot of people think that stars are hot because they
• 12:02
  Speaker 1: have fusion going on, because they are burning, but it's
• 12:05
  Speaker 1: the other way around. Stars get hot from gravity and
• 12:08
  Speaker 1: that temperature allows fusion to happen, and then the fusion
• 12:12
  Speaker 1: sustains them. But the reason that they're hot is that
• 12:14
  Speaker 1: gravity takes the gas and squeezes it into a smaller
• 12:17
  Speaker 1: space and that heats up the gas. Just maybe step
• 12:21
  Speaker 1: us through a little bit, because that's kind of a
• 12:22
  Speaker 1: tricky step. Like when you start off with a big
• 12:24
  Speaker 1: cold cloud of gas, well, why does crunching it together
• 12:28
  Speaker 1: make it hotter. It's an interesting bit of chemistry, right,
• 12:30
  Speaker 1: If you compress something, you make it hotter. And that
• 12:34
  Speaker 1: feels weird because you're like, hold on a second, it's
• 12:36
  Speaker 1: the same amount of stuff. I'm not doing anything. I'm
• 12:38
  Speaker 1: just squeezing it down. You're just like storing it closer together. Yeah,
• 12:42
  Speaker 1: it feels counterintuitive to think about it getting hotter, and
• 12:45
  Speaker 1: it's helpful to think about the temperature of that gas
• 12:48
  Speaker 1: as like the speed of the molecules of gas flying
• 12:51
  Speaker 1: around in it. Temperatures are really complicated topping. We have
• 12:54
  Speaker 1: a whole podcast about just that. But a simple way
• 12:56
  Speaker 1: to think about it is that a temperature is like
• 12:58
  Speaker 1: a spedometer of the particles in a gas. So a
• 13:00
  Speaker 1: hotter gas means particles moving faster, and a colder gas
• 13:04
  Speaker 1: means particles moving more slowly. So when when you take
• 13:06
  Speaker 1: a big cloud of gas and you squeeze it together,
• 13:08
  Speaker 1: somehow that makes the molecules, the little gas particles inside
• 13:12
  Speaker 1: in the in the cloud move faster exactly because what
• 13:15
  Speaker 1: you're doing when you squeeze it is that you're pushing
• 13:17
  Speaker 1: in on it. You're providing energy. You're actually putting energy
• 13:20
  Speaker 1: into that gas by squeezing it down. Think about, for example,
• 13:24
  Speaker 1: throwing a tennis ball against the wall. It comes back
• 13:26
  Speaker 1: at the same speed as you threw it. Cool, But
• 13:29
  Speaker 1: what if you threw a tennis ball against the front
• 13:31
  Speaker 1: of a train, Then when it comes back it would
• 13:33
  Speaker 1: be going faster. So if you're a tennis ball inside
• 13:36
  Speaker 1: a box and that box is shrinking, then every time
• 13:38
  Speaker 1: you hit the wall, you're gonna bounce off with more energy,
• 13:41
  Speaker 1: and so very gradually, as the box gets compressed, the
• 13:44
  Speaker 1: balls start moving faster and faster and they have a
• 13:46
  Speaker 1: higher temperature. Interesting. Now, just to be clear, candles seven
• 13:50
  Speaker 1: year old should not be throwing balls in front of
• 13:52
  Speaker 1: moving train. Right, that's a parenting question. I'm not going
• 13:56
  Speaker 1: to step in because I don't have realistic life advice.
• 13:59
  Speaker 1: That's right as your parents first, always for all things.
• 14:03
  Speaker 1: But that's interesting, and that's an interesting analogy. Like if
• 14:05
  Speaker 1: the walls are closing in on you, they're going to
• 14:07
  Speaker 1: be imparting some energy on the balls hitting the walls.
• 14:11
  Speaker 1: But I guess in space there's there are no walls.
• 14:13
  Speaker 1: It's just gravity moving things together. So where does that
• 14:15
  Speaker 1: extra energy come from? Right? Well, gravity is pulling stuff together,
• 14:19
  Speaker 1: and the way it creates more pressure is that it's
• 14:21
  Speaker 1: like pulling gas on the outside of you in you know,
• 14:24
  Speaker 1: So the wall is like the next layer of gas,
• 14:26
  Speaker 1: which is less and less pressure, but effectively it acts
• 14:29
  Speaker 1: like a wall. So gravity is pulling everything and it
• 14:32
  Speaker 1: creates this gravitational well which makes it harder for the
• 14:35
  Speaker 1: particles to leave. So each shell of gas is sort
• 14:38
  Speaker 1: of compressing the next shell of gas. Interesting, all right,
• 14:41
  Speaker 1: so then you have a big cold cloud of gas
• 14:43
  Speaker 1: that gets compressed. Then that gets hot, and at some
• 14:45
  Speaker 1: point it gets so hot it starts to explode in
• 14:48
  Speaker 1: the middle. Yeah, if when it reaches like twelve million
• 14:51
  Speaker 1: degrees kelvin internally, it can start to fuse hydrogen into
• 14:55
  Speaker 1: helium and that releases a bunch of energy, and that
• 14:57
  Speaker 1: helps us start stay hot and actually also EAPs the
• 15:00
  Speaker 1: star from collapsing further. If you just let gravity do
• 15:03
  Speaker 1: its thing, it would turn those particles into a black hole.
• 15:06
  Speaker 1: But fusion pushes back, and then you get this balance
• 15:08
  Speaker 1: between the energy released from fusion, the outward pressure and
• 15:11
  Speaker 1: the inward pressure of gravity, and the star burns for
• 15:14
  Speaker 1: a few million, billion or trillion years, depending on its size.
• 15:18
  Speaker 1: I see. So then I guess the answer to Kendall's
• 15:20
  Speaker 1: question is that stars are hot because they can't have
• 15:23
  Speaker 1: to be Otherwise you won't have a star, Like you
• 15:26
  Speaker 1: can't have a cold star, right, You can't have a
• 15:28
  Speaker 1: cold star unless you call it black dwarf, a star
• 15:31
  Speaker 1: which is a remnant from a white dwarf that has
• 15:33
  Speaker 1: cooled off. But yeah, you can't have a cold star.
• 15:36
  Speaker 1: So I guess by definition, right, a star is something
• 15:39
  Speaker 1: that is hot. But I think the most direct answer
• 15:40
  Speaker 1: to this question is that gravity is what makes a
• 15:42
  Speaker 1: star hot to begin with. It ignites the star and
• 15:45
  Speaker 1: then fusion keeps it hot. Yeah, because I guess you know,
• 15:47
  Speaker 1: once gravity crunches everything together, it will stay hot even
• 15:50
  Speaker 1: if there's no fusion, right, true, But if there was
• 15:53
  Speaker 1: no fusion, it would compress into a black hole. And
• 15:55
  Speaker 1: then you get me into questions of like what's the
• 15:57
  Speaker 1: temperature of a black hole? That that's the subject of
• 16:00
  Speaker 1: another podcast. That's a whole rabbit hole. All right, Well,
• 16:06
  Speaker 1: thank you Kendall. Hope that answered the question. And so
• 16:08
  Speaker 1: we have another question from Megan who's ten years old,
• 16:11
  Speaker 1: who is a question about the moon. How my name's Megan,
• 16:14
  Speaker 1: and I'm wondering why they are craters on the moon. Yeah,
• 16:18
  Speaker 1: why are there creators on the moon? Like if you
• 16:19
  Speaker 1: look at the moon, great question, Megan. By the way
• 16:22
  Speaker 1: you look at the moon, it's not like a perfect
• 16:23
  Speaker 1: little sephee or perfect circle. It's not just all one
• 16:27
  Speaker 1: color or one um, one smooth surfer that it has
• 16:30
  Speaker 1: a bunch of holes and pop marks in it. Right, Yeah,
• 16:32
  Speaker 1: there are a lot of craters on the moon. By
• 16:34
  Speaker 1: last count there are nine thousand, one d and thirties
• 16:37
  Speaker 1: seven recognized creators with names nine that's a lot. I
• 16:41
  Speaker 1: have a friend who did her PhD in like moon craters,
• 16:45
  Speaker 1: Like she was in a moon crater when she did
• 16:47
  Speaker 1: her PhD that time. Yeah, suddenly she became a lot cooler.
• 16:52
  Speaker 1: You're right, Yeah, Yeah, there are a lot of these craters,
• 16:56
  Speaker 1: and it's fascinating because you look at the Moon you're like, Wow,
• 16:58
  Speaker 1: the Moon is filled with creators, but the error there
• 17:00
  Speaker 1: is not. And so that's an interesting question. Yeah, we
• 17:03
  Speaker 1: don't have like giants holes here north, at least not
• 17:07
  Speaker 1: not that are visible. And it's not a question we
• 17:10
  Speaker 1: actually knew the answer to. Until we went to the Moon.
• 17:14
  Speaker 1: This was an open question about the source of these craters.
• 17:17
  Speaker 1: Some people thought maybe there was like volcanic activity on
• 17:19
  Speaker 1: the Moon and each crater was like a little mini volcano,
• 17:22
  Speaker 1: and other people thought they were impact from rocks from
• 17:24
  Speaker 1: space and there they were even crazier ideas. And until
• 17:27
  Speaker 1: we went to the Moon and got samples and studied
• 17:30
  Speaker 1: the age of the surface, we didn't know the answer
• 17:32
  Speaker 1: to Megan's question. Interesting, Yeah, they could have been like
• 17:35
  Speaker 1: holes on a piece of cheese. Was that your friend's
• 17:37
  Speaker 1: thesis topic on the lore of the moon cheese hypothesis. Well,
• 17:43
  Speaker 1: now we know that the surface of the Moon is
• 17:45
  Speaker 1: about as old as the surface of the Earth, about
• 17:48
  Speaker 1: four and a half billion years old. But the Moon,
• 17:51
  Speaker 1: unlike the Earth, doesn't have an atmosphere, right, doesn't have
• 17:54
  Speaker 1: like a cloud of gas surrounding it. And so the
• 17:57
  Speaker 1: short answer to Megan's question is that it's rocks from space.
• 18:00
  Speaker 1: Space is filled with rocks that are constantly hitting everything
• 18:04
  Speaker 1: in the Solar System. And if you have a shield
• 18:06
  Speaker 1: like the Earth does, and most of those don't hit
• 18:08
  Speaker 1: the ground, But the Moon doesn't have a shield, and
• 18:10
  Speaker 1: so it gets smacked by every rock that comes its way. Yeah,
• 18:13
  Speaker 1: and it's kind of interesting to think like that happened
• 18:16
  Speaker 1: or is happening all over the Solar System, right, Like
• 18:18
  Speaker 1: there are planets who also don't have an atmosphere who
• 18:21
  Speaker 1: are filled with craters too. Yeah, Basically every surface on
• 18:24
  Speaker 1: the Solar System will get impacted with craters, and so
• 18:26
  Speaker 1: you need some kind of protection if you're going to
• 18:29
  Speaker 1: live there, either an atmosphere or like a really strong umbrella.
• 18:33
  Speaker 1: All right, So to answer Megan's question, the Moon has
• 18:35
  Speaker 1: craters because it gets hit by a lot of rocks
• 18:38
  Speaker 1: from space and it doesn't have a coating of air
• 18:42
  Speaker 1: to kind of protect it. Yeah, and some of these
• 18:44
  Speaker 1: craters are like more than two billion years old. No
• 18:48
  Speaker 1: wind or water on the Moon, so if you form
• 18:50
  Speaker 1: a crater, it will last a very very long time.
• 18:53
  Speaker 1: There's one crater on the Moon that might even be
• 18:55
  Speaker 1: four billion years old, and scientists think that an asteroid
• 18:58
  Speaker 1: more than a hundred d miles across smashed into it
• 19:02
  Speaker 1: about four billion years ago, such a big explosion. It
• 19:05
  Speaker 1: probably rain did debris down on the surface of the Earth.
• 19:09
  Speaker 1: Interesting Also, I think another part of the answer is
• 19:11
  Speaker 1: that there's no lava on the Moon, right Like we
• 19:13
  Speaker 1: have lava here on Earth and that's kind of making
• 19:16
  Speaker 1: the surface move a lot, which kind of gets rid
• 19:20
  Speaker 1: of all of the craters that we used to have.
• 19:22
  Speaker 1: But in the Moon there's no lava, so it does
• 19:24
  Speaker 1: nothing ever moved. And the surface of the Moon really
• 19:26
  Speaker 1: interestingly is covered in this like really fine grain soil.
• 19:30
  Speaker 1: If you look at the astronauts footsteps, for example, you
• 19:33
  Speaker 1: know that they were walking through like several centimeters of
• 19:35
  Speaker 1: what looks like dust, and this lunar dust. It basically
• 19:39
  Speaker 1: the shattered surface. There's been so many impacts on the
• 19:41
  Speaker 1: Moon that its surface is basically covered with shattered little
• 19:45
  Speaker 1: pieces of rock. I guess the question is, like, are
• 19:48
  Speaker 1: there still new craters being formed in the Moon? Like
• 19:50
  Speaker 1: does the Solar system now have fewer asteroids flying around
• 19:54
  Speaker 1: or are there still is the Moon still getting bombarded
• 19:56
  Speaker 1: by meteors. It's still getting bombarded. We actually we saw
• 20:00
  Speaker 1: one happen in two thousand and thirteen which was visible
• 20:03
  Speaker 1: to the naked eye. A nine pound meteoroid strike the
• 20:07
  Speaker 1: surface at like nine thousand kilometers per hour and left
• 20:11
  Speaker 1: a new crater. So it's still happening. Wow, But is
• 20:14
  Speaker 1: it happening faster or at the same rate as before
• 20:17
  Speaker 1: or has the Solar system sort of calmed down a
• 20:20
  Speaker 1: little bit? The Solar system definitely has calmed down. In
• 20:22
  Speaker 1: the very early part of the history of the Solar System,
• 20:25
  Speaker 1: there was the heavy bombardment period when the Solar System
• 20:28
  Speaker 1: was a huge mess. Since then, things have calmed down
• 20:31
  Speaker 1: and larger objects have pulled together to make fewer objects.
• 20:35
  Speaker 1: Since you have fewer rocks out there than you used
• 20:38
  Speaker 1: to see. Yeah, we've made it past purity, right, skin
• 20:42
  Speaker 1: is now going to clear up a little bit more.
• 20:44
  Speaker 1: All right, well, thank you Kendall and Megan for these
• 20:46
  Speaker 1: awesome questions. We hope you keep asking questions, and so
• 20:48
  Speaker 1: now let's get to our other questions about asteroids that
• 20:52
  Speaker 1: might kill us here on Earth and also about the
• 20:55
  Speaker 1: nature of matter and energy. But first let's take a
• 20:58
  Speaker 1: quick break. All right, we are answering questions from listeners,
• 21:14
  Speaker 1: and we've just answered some awesome questions about the stars
• 21:17
  Speaker 1: in our in the moon, and so now let's get
• 21:19
  Speaker 1: into some terior topics like the possible extinction of humankind. Hi,
• 21:24
  Speaker 1: Dani and Jorge, this is Shawn calling from Ottawa, Ontario, Canada.
• 21:27
  Speaker 1: We always hear about asteroids and comets hitting the Earth
• 21:31
  Speaker 1: at thousands of kilometers per second and wiping out life
• 21:36
  Speaker 1: as we know it. But I was wondering, is it
• 21:38
  Speaker 1: possible for a comet or an asteroid two come in
• 21:43
  Speaker 1: and slowly hit the Earth where it won't kill us all?
• 21:48
  Speaker 1: Maybe if we're both on the same trajectory and it
• 21:50
  Speaker 1: can come in and just gently land somewhere on Earth
• 21:54
  Speaker 1: and not destroy everything. Anyways, thanks for the great podcast.
• 21:59
  Speaker 1: All right, some question, thank you, Sean. It's an interesting question, Yeah,
• 22:02
  Speaker 1: because I guess when you think of asteroids hitting the Earth,
• 22:05
  Speaker 1: you usually think of them as coming in fast and
• 22:08
  Speaker 1: crashing on Earth. But he's asking, you know, could one
• 22:11
  Speaker 1: somehow sort of like creep up on us and kind
• 22:14
  Speaker 1: of shem me onto our planet and gently, you know,
• 22:19
  Speaker 1: land in the middle of the ocean or something. Yeah,
• 22:21
  Speaker 1: it's very Canadian. He's looking for like a friendly asteroid
• 22:24
  Speaker 1: that just comes and settles down gently. But yeah, maybe
• 22:29
  Speaker 1: the land in Canada and apologize for causing a disturbance.
• 22:33
  Speaker 1: It is an awesome question. Why do we always think
• 22:35
  Speaker 1: about asteroids? It's basically like bullets aimed at the Earth.
• 22:39
  Speaker 1: Can't we think about them like moving in parallel to
• 22:42
  Speaker 1: the Earth and very gently coming into the surface. It's
• 22:45
  Speaker 1: a really cool question. I guess, um, it maybe seems
• 22:48
  Speaker 1: unlikely that something would just come out of the blue
• 22:50
  Speaker 1: and then just happened to like fly right next to
• 22:54
  Speaker 1: us slowly, And that's the answer. It is possible, but
• 22:57
  Speaker 1: it's much less likely if you just pick like random
• 23:00
  Speaker 1: trajectories for rocks in space that are going to come
• 23:03
  Speaker 1: into contact with the Earth. It's just much easier for
• 23:05
  Speaker 1: those rocks to be going the opposite direction of the
• 23:08
  Speaker 1: Earth or to be going in opposite direction of the Earth.
• 23:11
  Speaker 1: At least at some level. It's possible for a rock
• 23:15
  Speaker 1: from the asteroid belt or the Kuiper Belt or even
• 23:18
  Speaker 1: the Orc Cloud to end up in like the Earth's orbit,
• 23:21
  Speaker 1: but it would take a very special circumstance. You mean,
• 23:24
  Speaker 1: like it is possible maybe for one of the asteroids
• 23:26
  Speaker 1: around us to like suddenly kind of jump into our orbit.
• 23:29
  Speaker 1: It is possible, But everything right now in the Solar
• 23:31
  Speaker 1: System hasn't orbit. The reason it's still around is that
• 23:33
  Speaker 1: it hasn't fallen into the Sun. It's in some orbit.
• 23:36
  Speaker 1: So even to come into contact with the Earth would
• 23:38
  Speaker 1: require it most likely to change its orbit. The collision
• 23:41
  Speaker 1: happens when the trajectory of one of those objects intersects
• 23:44
  Speaker 1: with the Earth right, which is very unlikely to happen
• 23:47
  Speaker 1: in parallel. In order for one of those things to
• 23:49
  Speaker 1: like jump into the Earth's orbit, it would need to
• 23:52
  Speaker 1: change its trajectory, which means like hitting something else and
• 23:55
  Speaker 1: bouncing off. So you need like two things to come
• 23:58
  Speaker 1: into contact and change each other orbits that one of
• 24:00
  Speaker 1: them happens to end up in Earth's orbit and kind
• 24:03
  Speaker 1: of going at the same speed. But I guess couldn't
• 24:06
  Speaker 1: it also happened that the Earth, you know, maybe passes
• 24:09
  Speaker 1: by close enough to a cloud of asteroids that maybe
• 24:12
  Speaker 1: like pulls one along with our gravity. Yeah, that is possible.
• 24:15
  Speaker 1: And in fact, there are some things out there that
• 24:17
  Speaker 1: have been sort of like captured by the Earth. They
• 24:19
  Speaker 1: haven't landed on the Earth when they came close enough
• 24:22
  Speaker 1: to the Earth that sort of now in orbit around
• 24:25
  Speaker 1: the Earth or sharing the Earth's orbit around the Sun.
• 24:28
  Speaker 1: At least one of these things is called the space
• 24:30
  Speaker 1: being because it traces out this weird path relative to
• 24:34
  Speaker 1: the Earth. It's this five kilometer diameter rock where there
• 24:37
  Speaker 1: is a rock like that that it has somehow fallen
• 24:39
  Speaker 1: into our orbit and it is kind of going along
• 24:41
  Speaker 1: with us. Yeah, officially, it's like a quasi satellite of
• 24:44
  Speaker 1: the Earth. It's got a fancy name which I can pronounce,
• 24:46
  Speaker 1: and it has its own elliptical orbit around the Sun
• 24:49
  Speaker 1: that's sort of in residence with the Earth's and so
• 24:52
  Speaker 1: from our perspective, it has this like weird being shaped
• 24:55
  Speaker 1: orbit around the Earth. But effectively it's been captured and
• 24:58
  Speaker 1: in a very similar or bit to the Earth. But
• 25:01
  Speaker 1: of course it's not landing on our surface, right right,
• 25:04
  Speaker 1: but it's interesting that it's possible, right, Like, what maybe
• 25:06
  Speaker 1: can happen again and we could pick up another bean. Well,
• 25:09
  Speaker 1: this one, the closest it ever comes is like seven
• 25:11
  Speaker 1: and a half million miles from the surface of the Earth,
• 25:14
  Speaker 1: which is like thirty times further than the Moon. I see,
• 25:17
  Speaker 1: I see, But maybe it eventually, could it somehow, you know,
• 25:20
  Speaker 1: creep into the Earth, Like maybe not now, maybe, but
• 25:24
  Speaker 1: maybe in a million years, could it somehow, you know,
• 25:27
  Speaker 1: start creeping in and maybe go into orbit around the
• 25:29
  Speaker 1: Earth at some point. It's certainly possible, right if it
• 25:32
  Speaker 1: impacts something or something else comes along and tugs on it,
• 25:35
  Speaker 1: it could change its orbit. And it is possible for
• 25:37
  Speaker 1: something to get even closer to the Earth and eventually
• 25:40
  Speaker 1: even come into the atmosphere. And in theory it could
• 25:43
  Speaker 1: come in slowly, could like gently approach the Earth's atmosphere. Interesting, Well,
• 25:49
  Speaker 1: you said it's not very likely because I guess we
• 25:51
  Speaker 1: have most asteroids out there kind of catalog, So I
• 25:55
  Speaker 1: imagine if any do sort of surprises, it's they're going
• 25:58
  Speaker 1: to be coming in pretty fast. But maybe, just for fun,
• 26:00
  Speaker 1: let's assumed that um Seawan scenario here comes through in
• 26:04
  Speaker 1: which is like make an asteroid appear right next to Earth,
• 26:07
  Speaker 1: we would it kills or would it's just kind of
• 26:10
  Speaker 1: gently bump us. Yeah, I just want to make one
• 26:11
  Speaker 1: more comment and the likelihood of it. Another way to
• 26:13
  Speaker 1: think about why it's unlikely is that these objects are
• 26:16
  Speaker 1: moving typically faster than the Earth. You know, the Earth
• 26:19
  Speaker 1: moves like thirty kilos per second around the Sun, and
• 26:22
  Speaker 1: these asteroids moved like fortify or even faster if their
• 26:25
  Speaker 1: comments from the outer Solar System. And if you think
• 26:27
  Speaker 1: about like two velocity vectors, in order for one of
• 26:31
  Speaker 1: these to catch the Earth, they basically have to be
• 26:33
  Speaker 1: perfectly aligned with the Earth. Otherwise to impact they could
• 26:36
  Speaker 1: have at any angle. So it's just unlikely for these
• 26:39
  Speaker 1: things to be perfectly aligned with the Earth's direction. But
• 26:42
  Speaker 1: you ask a great question, like what would happen if
• 26:44
  Speaker 1: this thing like gently came up to the Earth's atmosphere?
• 26:47
  Speaker 1: Would that actually hurt us? And I like Shaun's fantasy
• 26:50
  Speaker 1: that this thing would like gently sink down to the
• 26:52
  Speaker 1: surface of the Earth so we could like you know,
• 26:54
  Speaker 1: touch it and build a monument to it or whatever,
• 26:56
  Speaker 1: But actually I don't think that's likely either. I guess
• 26:58
  Speaker 1: maybe let's paint the picture a little it better. So
• 27:00
  Speaker 1: the Earth is moving through space, We're spinning, and somehow
• 27:04
  Speaker 1: like another an esteroid kind of like chemis up to us,
• 27:07
  Speaker 1: going at the same speed, in the same direction, maybe
• 27:09
  Speaker 1: in the same orbit, and then just a little by little,
• 27:12
  Speaker 1: just kind of bumps into the Earth. Is that possible.
• 27:14
  Speaker 1: It's possible for it to get close to the Earth
• 27:16
  Speaker 1: and like join our orbit, but then it's going to
• 27:18
  Speaker 1: be captured by the Earth and it's going to fall
• 27:20
  Speaker 1: into the Earth's gravitational Well, remember the Earth itself has
• 27:24
  Speaker 1: a lot of gravity. So if you just like dropped
• 27:26
  Speaker 1: a big rock at zero velocity at the top of
• 27:29
  Speaker 1: the atmosphere, what would happen, Well, the Earth would pull
• 27:32
  Speaker 1: on it. By the time it reached the surface, it
• 27:34
  Speaker 1: would have a lot of kinetic energy. Imagine what would
• 27:37
  Speaker 1: happen if you drop like a penny from the top
• 27:40
  Speaker 1: of the atmosphere. It would be going super duper fast
• 27:43
  Speaker 1: by the time I hit the ground. Oh, I see
• 27:44
  Speaker 1: you're seeing. Like, even if I parked this esteroid close
• 27:47
  Speaker 1: to us, just the earth gravity is gonna pull it
• 27:50
  Speaker 1: in and make it go faster towards us. Yeah, the
• 27:53
  Speaker 1: escape velocity of the Earth he's like eleven kilometers per second,
• 27:57
  Speaker 1: And so that means if you're going at like zero
• 27:59
  Speaker 1: kilometers per second at the top of the atmosphere, then
• 28:02
  Speaker 1: by the time you get to the bottom, you're gonna
• 28:04
  Speaker 1: be going in eleven kilometers per second. So it's a
• 28:06
  Speaker 1: lot of kinetic energy, right. But I guess maybe Shawn's
• 28:09
  Speaker 1: point was that, you know, even if it's going at
• 28:11
  Speaker 1: eleven kilometers per second, that's still not as fast as
• 28:15
  Speaker 1: most asteroids that hit Earth are going. And so maybe
• 28:18
  Speaker 1: it would he's saying it would. Would it might survive
• 28:20
  Speaker 1: the atmosphere, right, not get burned up by all the
• 28:23
  Speaker 1: friction from the error, and maybe it might it will
• 28:27
  Speaker 1: crash onto Earth, Yeah, and I think that's likely that
• 28:30
  Speaker 1: it would make it to the surface of the Earth.
• 28:31
  Speaker 1: You know, it wouldn't actually get to eleven kilometers per
• 28:33
  Speaker 1: second by the time it hits the Earth because of
• 28:35
  Speaker 1: the resistance from the air. It would heat up and
• 28:38
  Speaker 1: parts of it would blow off. But probably it would survive,
• 28:40
  Speaker 1: but it might make a crater when it lands because
• 28:42
  Speaker 1: it would be going pretty fast. But even asteroids that
• 28:45
  Speaker 1: do hit the Earth at high speed, some of them
• 28:47
  Speaker 1: make it to the surface. If they're big enough to
• 28:49
  Speaker 1: survive the trip through the atmosphere. Interesting, I guess maybe
• 28:53
  Speaker 1: then the real answer to Shaun's question of couldn't asteroid
• 28:56
  Speaker 1: hits slowly without killing us? The answer is not, because
• 29:00
  Speaker 1: and a story can hit its slowly. Any asteroid that
• 29:03
  Speaker 1: hits is going to be coming in pretty fast because
• 29:05
  Speaker 1: the Earth's gravity pulls it in and it's going to
• 29:08
  Speaker 1: pick up speed. You might imagine another scenario where a
• 29:11
  Speaker 1: rock comes in near the Earth and it has like
• 29:14
  Speaker 1: negative velocity, like the Earth is catching up to it,
• 29:16
  Speaker 1: but it's running away in the atmosphere gradually slows it
• 29:20
  Speaker 1: down so it lands on Earth. But that's even more unlikely.
• 29:23
  Speaker 1: The Earth would have to like sneak up on this rock, right.
• 29:26
  Speaker 1: It's it's less likely, but much cooler to think about.
• 29:30
  Speaker 1: So you're saying that there could be an asteroids flying
• 29:32
  Speaker 1: through space sort of in our orbit, and so Earth
• 29:35
  Speaker 1: sort of sneak like we sneak up behind it, and
• 29:39
  Speaker 1: we're in such a trajectory, and it's in such a
• 29:41
  Speaker 1: trajectory that it really just kind of slowly touches us.
• 29:44
  Speaker 1: So what you're saying, Yeah, I think that's probably possible.
• 29:47
  Speaker 1: I haven't run the simulation, but you'd have to have
• 29:49
  Speaker 1: a lot of factors exactly a line to make that work.
• 29:53
  Speaker 1: Like what's the slowest it could hit Earth? You know
• 29:55
  Speaker 1: what I mean? Like would it still pick up eleven
• 29:57
  Speaker 1: kilombers per second? Or is there a snario in which
• 30:00
  Speaker 1: it literally like just slowly kind of touches the Earth. Well,
• 30:04
  Speaker 1: there's some things you have to balance there, because in
• 30:07
  Speaker 1: order for it to be going slower when it hits
• 30:09
  Speaker 1: the Earth, you wanted to start with like negative velocity
• 30:12
  Speaker 1: velocity away from the Earth at the top of the atmosphere.
• 30:15
  Speaker 1: But then you know, how is it getting to the
• 30:17
  Speaker 1: top of the atmosphere. It has velocity away from the Earth,
• 30:20
  Speaker 1: so it can't be going too fast away from the Earth.
• 30:22
  Speaker 1: The Earth has like sneak up behind it while it's
• 30:25
  Speaker 1: moving fast away from the Earth, and then the atmosphere
• 30:28
  Speaker 1: somehow slows it down and pulls it in. So it's
• 30:31
  Speaker 1: a pretty tricky set of circumstances. But I bet it's
• 30:34
  Speaker 1: technically possible, and you know, if the solar systems around
• 30:36
  Speaker 1: for long enough, maybe it will happen. Right right, just
• 30:39
  Speaker 1: got to the mass, right, Anything is possible with them,
• 30:42
  Speaker 1: But are you envisioning that this could like literally just
• 30:45
  Speaker 1: like touch down like a spaceship or would it crash
• 30:47
  Speaker 1: land anyways, just because you know the guy is big
• 30:50
  Speaker 1: and it's going to fall. Well, the slower you wanted
• 30:52
  Speaker 1: to hit the Earth's surface, the less likely this scenario
• 30:56
  Speaker 1: is because the faster it has to be going away
• 30:58
  Speaker 1: from us at the top of the atmosphere. And I
• 31:00
  Speaker 1: think technically it might be possible for it to like
• 31:02
  Speaker 1: gradually sink into the Earth's atmosphere if it has enough
• 31:05
  Speaker 1: initial velocity away from us and the atmosphere just sort
• 31:09
  Speaker 1: of like slurps it in gradually. Interesting. That was pretty
• 31:13
  Speaker 1: cool to see a giant rock slowly land on Earth.
• 31:17
  Speaker 1: I don't expect that to happen. And after this, I'm
• 31:19
  Speaker 1: gonna have to go write some code to simulate this
• 31:21
  Speaker 1: too but actually work. But that's my instinct. All right,
• 31:24
  Speaker 1: let's stay tuned. Well that Daniel writes in a scientific
• 31:27
  Speaker 1: paper about it, and when it comes out, we'll we'll
• 31:30
  Speaker 1: let you know. That's right, and Sean will make you
• 31:31
  Speaker 1: a co author. Wow. Nice, See what can happened when
• 31:35
  Speaker 1: you write questions to us? You might become a physicist
• 31:38
  Speaker 1: for real? All right, Well, let's get into our last
• 31:40
  Speaker 1: question about the nature of matter and energy at the
• 31:44
  Speaker 1: Big Bank. But first let's take another quick break. All right,
• 32:00
  Speaker 1: we're answering listener questions, and we've answered questions from kids
• 32:03
  Speaker 1: about the sun and the moon, and also a question
• 32:07
  Speaker 1: about an asteroid slowly killing us slowly with its song
• 32:11
  Speaker 1: that with its a space song. I guess it's telling
• 32:15
  Speaker 1: our whole life with its trajectory. I guess that's that's
• 32:18
  Speaker 1: kind of a philosophical question. If an asteroid is going
• 32:20
  Speaker 1: to come and kills do you want it to be
• 32:21
  Speaker 1: fast or do you do you want it to be
• 32:23
  Speaker 1: slow and you want to see it coming. I definitely
• 32:27
  Speaker 1: want to see it coming so we can potentially divert
• 32:29
  Speaker 1: it so it doesn't come and kill us. What if,
• 32:33
  Speaker 1: like you do, see it's coming, but there's nothing we
• 32:35
  Speaker 1: can do about it. We always have Bruce willis Man,
• 32:39
  Speaker 1: did you see that latest movie with the Leonardo DiCaprio
• 32:42
  Speaker 1: and the asteroid don't look up? Yeah? Yeah, I did.
• 32:45
  Speaker 1: That was a lot of fun. I heard that he
• 32:47
  Speaker 1: couldn't write the equations himself on the board, so they
• 32:49
  Speaker 1: had to have a hand double doing the math close
• 32:52
  Speaker 1: ups for those shots. Whoa that could have been you, Daniel.
• 32:56
  Speaker 1: Now I have a new life, the real Leonard of
• 32:59
  Speaker 1: the Caprio's hand physics hand model. It's like being a
• 33:04
  Speaker 1: stuntman basically, it's just that dangerous, right right, Yeah, you
• 33:08
  Speaker 1: could get carpal tunnel from or I could become a
• 33:11
  Speaker 1: movie star and then I could brag and say I
• 33:13
  Speaker 1: do my own math. Well, let's see what happens first.
• 33:21
  Speaker 1: It's more likely that a huge rock will slowly touchdown
• 33:23
  Speaker 1: the atmosphere than at that any of that happens. Yeah,
• 33:27
  Speaker 1: I guess if you become a movie star that there
• 33:28
  Speaker 1: would be the end of the world. That's one of
• 33:33
  Speaker 1: the signs of the apocalypse, right there, Frogs falling from
• 33:37
  Speaker 1: this guy Daniel co starring in a movie with Leonardo DiCaprio,
• 33:40
  Speaker 1: although Neil de grass Tyson has been in big movies, right,
• 33:43
  Speaker 1: So it's possible there are physics out there that have
• 33:46
  Speaker 1: broken into Hollywood. Oh man, it is the end of
• 33:48
  Speaker 1: the world then. But anyways, we're answering listener questions and
• 33:51
  Speaker 1: our last question of the day comes from Jeels, who
• 33:54
  Speaker 1: has a question about which came first in the universe. Hello,
• 33:59
  Speaker 1: Danny on Jorge, how are you guys? My name's chill,
• 34:04
  Speaker 1: and I was curious about the following. I know that
• 34:09
  Speaker 1: matter and energy are intimately connected, but I was wondering
• 34:15
  Speaker 1: what came first matter or energy. I would appreciate if
• 34:19
  Speaker 1: you guys can address this in your podcast. Thanks a lot,
• 34:23
  Speaker 1: Bye bye. Alright, awesome question. I feel like this is
• 34:27
  Speaker 1: getting back to like elementary school philosophy, you know, like
• 34:31
  Speaker 1: which came first, the chicken or the egg. It's a
• 34:33
  Speaker 1: deep question about the early history of the universe. I
• 34:35
  Speaker 1: love this stuff. Yeah, so gals Um kind of acknowledges,
• 34:39
  Speaker 1: first of all, that matter and energy are really closely related.
• 34:42
  Speaker 1: And I always thought that matter is energy, right, isn't
• 34:45
  Speaker 1: that what E mc squares says That they're the same
• 34:47
  Speaker 1: thing sort of, But it's not entirely symmetric. The way
• 34:50
  Speaker 1: I would explain it is that mass is a form
• 34:53
  Speaker 1: of energy. Right. The reason things have mass, it's because
• 34:56
  Speaker 1: they have internal stored energy. And so you can think
• 34:59
  Speaker 1: about mass is like a form of energy, or you
• 35:02
  Speaker 1: can think about mass is like a little dial that
• 35:04
  Speaker 1: tells you how much stored energy is inside this thing.
• 35:08
  Speaker 1: But you can turn mass into other kinds of energy,
• 35:10
  Speaker 1: like velocity, or you can turn velocity into mass and
• 35:13
  Speaker 1: so you can think about mass it's like a form
• 35:15
  Speaker 1: of energy. But energy is not a form of mass,
• 35:18
  Speaker 1: so they're not entirely symmetric. Oh I see, it's not
• 35:21
  Speaker 1: really an equivalence. E equals mc square. It just says
• 35:24
  Speaker 1: that mass is energy, but it doesn't say that energy
• 35:26
  Speaker 1: is mass. Yeah, equals mc squared tells you how much
• 35:29
  Speaker 1: energy is stored in an object at rest with mass.
• 35:33
  Speaker 1: M I see, So I guess you're saying that matter
• 35:38
  Speaker 1: is a subset of energy, and therefore therefore it can
• 35:41
  Speaker 1: be first, can it. Yeah, that's right. Matter is a
• 35:43
  Speaker 1: kind of energy, so it can't really predate energy. You
• 35:46
  Speaker 1: can't imagine a scenario where you have matter in the
• 35:49
  Speaker 1: universe without energy because matter is a kind of energy.
• 35:53
  Speaker 1: It's like saying an egg is really a baby chicken,
• 35:56
  Speaker 1: so therefore the chicken can first. Not a biologist not
• 36:00
  Speaker 1: going to weigh in on that one. But it sounded good.
• 36:03
  Speaker 1: That sounded good. The mass funded, right, we'll go with that.
• 36:07
  Speaker 1: I'll have to do a simulation later, but yeah, it
• 36:09
  Speaker 1: sounded another paper. Oh man, we are cracking out the
• 36:13
  Speaker 1: assigns here. So I think it's pretty clear that energy
• 36:16
  Speaker 1: came first, because you can't have matter without energy. But
• 36:19
  Speaker 1: it's interesting to think about sort of what forms of
• 36:21
  Speaker 1: energy were created in the universe at what time, When
• 36:24
  Speaker 1: did matter come about, When did we get radiation, what
• 36:27
  Speaker 1: came first, How did that all happen because the history
• 36:29
  Speaker 1: is quite complicated and really nuanced. Oh, interesting because you're
• 36:33
  Speaker 1: saying that, you know, in the Big Bang, maybe there
• 36:35
  Speaker 1: was sort of an opportunity for matter to be more dominant. Yeah.
• 36:39
  Speaker 1: The way we think about it in the very early
• 36:41
  Speaker 1: universe is that you have very high energy density. Right,
• 36:44
  Speaker 1: the universe used to be much more dense, it used
• 36:46
  Speaker 1: to be much more compact, it used to be higher temperature,
• 36:49
  Speaker 1: so things were flying around, they were crazy, and there
• 36:52
  Speaker 1: were such high energy that all the quantum fields were
• 36:55
  Speaker 1: buzzing with so much energy that doesn't even really make
• 36:58
  Speaker 1: sense to talk about particle in the way we think
• 37:00
  Speaker 1: about it. There was a moment very early on in
• 37:02
  Speaker 1: the universe when there's a lot of energy, but there
• 37:04
  Speaker 1: weren't even really particles flying around in the universe had
• 37:08
  Speaker 1: to like cooled down a little bit before you can
• 37:10
  Speaker 1: even start to talk about the quantum fields buzzing in
• 37:13
  Speaker 1: the way that we think about it today is like
• 37:15
  Speaker 1: these little discrete pockets of energy flying around the universe.
• 37:19
  Speaker 1: It was just more like a huge ocean of energy,
• 37:22
  Speaker 1: like pure like everything was just pure energy. I guess
• 37:25
  Speaker 1: the question now that I have is which came first,
• 37:28
  Speaker 1: energy or quantum fields. Yeah, that's a great question, and
• 37:31
  Speaker 1: we don't know the answer. We have a description of
• 37:34
  Speaker 1: the universe in terms of quantum fields. For certain energies,
• 37:38
  Speaker 1: like for the energies that exist today in the universe,
• 37:40
  Speaker 1: which are very very cold, we know that we can
• 37:42
  Speaker 1: describe the universe in terms of quantum fields, and for
• 37:45
  Speaker 1: higher energies like what happens inside the Large Hadron Collider
• 37:49
  Speaker 1: and going back to the early moments of the universe,
• 37:51
  Speaker 1: we can describe that in terms of quantum fields. Beyond that,
• 37:55
  Speaker 1: we don't know, Like we have quantum fields, and we
• 37:58
  Speaker 1: suspect that those theories and the disc oricteen to the
• 38:00
  Speaker 1: universe in terms of quantum fields probably works at very
• 38:03
  Speaker 1: very high temperatures very early on in the universe. But
• 38:06
  Speaker 1: the truth is that we just don't know. One of
• 38:08
  Speaker 1: the reasons we don't know is that we don't understand
• 38:10
  Speaker 1: how gravity works in a quantum sense. So what you're
• 38:13
  Speaker 1: really asking about is like can you give a quantum
• 38:16
  Speaker 1: field description of the universe when gravity was just as
• 38:19
  Speaker 1: important as all these other forces? And we don't know
• 38:23
  Speaker 1: because we don't have a theory of quantum gravity. So
• 38:25
  Speaker 1: we're really pretty clueless about a sort of a quantum
• 38:27
  Speaker 1: picture of the universe when gravity was very important early on. Interesting,
• 38:32
  Speaker 1: I guess you're saying, you know that in the beginning
• 38:34
  Speaker 1: of the universe, at the Big Bang, things were so crazy,
• 38:38
  Speaker 1: so crunched together and so high energy density. Did we
• 38:42
  Speaker 1: really don't know what was going on at that moment? Yeah,
• 38:45
  Speaker 1: in the same way that we don't know today what's
• 38:47
  Speaker 1: going on inside a black hole for the same reasons.
• 38:50
  Speaker 1: Like you send a particle inside a black hole, we
• 38:53
  Speaker 1: think of it like a little wiggle in a quantum field.
• 38:55
  Speaker 1: What happens when it goes inside a black hole? Well,
• 38:58
  Speaker 1: now it's under very strong gravitational pressure. Is it's still
• 39:01
  Speaker 1: a quantum wiggle? Is it turned into something else a
• 39:03
  Speaker 1: new kind of matter? Are there gravitational quantum fields? We
• 39:06
  Speaker 1: just don't know. In the same way we don't know
• 39:08
  Speaker 1: what was the state of the universe when gravity was
• 39:11
  Speaker 1: really strong and very important early on. So it might
• 39:14
  Speaker 1: be that we can describe in terms of wiggles and
• 39:16
  Speaker 1: quantum fields. But it might be that we can't. But
• 39:18
  Speaker 1: we do have a pretty nice picture of what happens,
• 39:20
  Speaker 1: like after the universe drops in temperature to a point
• 39:24
  Speaker 1: where it turns into particles, and we can then think about,
• 39:27
  Speaker 1: like how much of the energy in the universe is
• 39:29
  Speaker 1: in terms of these particles or in terms of the
• 39:31
  Speaker 1: photons that go between them and that kind of stuff. Oh,
• 39:34
  Speaker 1: I see, but I guess before that it starts to
• 39:37
  Speaker 1: cool off. Does it even make sense to talk about
• 39:39
  Speaker 1: energy as we know it? Like inside of a black hole?
• 39:42
  Speaker 1: Does it makes sense to talk about energy? Or can
• 39:44
  Speaker 1: you still, you know, define energy in a such a scenario.
• 39:47
  Speaker 1: We can define energy, but you're right, we don't know
• 39:49
  Speaker 1: if it's the most important quantity. Like people think about energy,
• 39:52
  Speaker 1: it's fundamental to the universe and a really insightful way
• 39:56
  Speaker 1: to think about the state of the universe. Remember that
• 39:58
  Speaker 1: we discovered recently that energy is not even conserved in
• 40:02
  Speaker 1: the universe. Right, It turns out it's something we can measure,
• 40:05
  Speaker 1: and it seems to be conserved in most of our experiments.
• 40:08
  Speaker 1: But we know that in an expanding space, if the
• 40:11
  Speaker 1: universe is growing. If space itself is changing, the amount
• 40:15
  Speaker 1: of energy in the universe is also changing, so energy
• 40:18
  Speaker 1: might not be the right way to think about the
• 40:20
  Speaker 1: nature of the universe. We talked a few weeks ago
• 40:23
  Speaker 1: about what happened in those first few moments of the universe,
• 40:25
  Speaker 1: this inflation theory, and you know, we have some like
• 40:27
  Speaker 1: pictures of what that means. Maybe there was this insulaton
• 40:30
  Speaker 1: field with these influcton particles which decayed into normal matter.
• 40:34
  Speaker 1: So you can possibly think about it in terms of
• 40:37
  Speaker 1: like weird new quantum fields. But we just don't know
• 40:39
  Speaker 1: if any of those theories are at all accurate. They're
• 40:42
  Speaker 1: just more like sketches of ideas that we're using to
• 40:45
  Speaker 1: try to think about it in terms of stuff we
• 40:47
  Speaker 1: already know. But but there's no guarantee that the kinds
• 40:49
  Speaker 1: of ideas we have are the right ideas. Well. I
• 40:51
  Speaker 1: feel like you're saying, like we almost don't even know
• 40:53
  Speaker 1: if math worked at the beginning of he never you know,
• 40:56
  Speaker 1: like maybe one those one was three back then, you know,
• 40:59
  Speaker 1: because energy and things were just popping out of nothingness.
• 41:02
  Speaker 1: It's definitely a very weird situation, and I'm pretty sure
• 41:04
  Speaker 1: there's going to be mind blowing surprises when we figure
• 41:07
  Speaker 1: out how that worked and how to even think about
• 41:09
  Speaker 1: it and how to talk about it. And that's one
• 41:11
  Speaker 1: reason why we do crazy collisions is super high energy,
• 41:14
  Speaker 1: because we want to probe the most extreme situations to
• 41:17
  Speaker 1: see when do our theories break down? When do we
• 41:20
  Speaker 1: need a new kind of structure. You know, quantum field
• 41:22
  Speaker 1: theories themselves are only a few decades old, and they
• 41:25
  Speaker 1: came into play to explain collisions at high energy that
• 41:28
  Speaker 1: we couldn't otherwise understand. And so maybe that a crazier
• 41:32
  Speaker 1: high energies we need a whole new kind of idea
• 41:34
  Speaker 1: about what's going on in the universe, or maybe quantum
• 41:37
  Speaker 1: fields will describe everything up to the playing scale. We
• 41:40
  Speaker 1: just don't know. Yeah, I think that's how I would
• 41:43
  Speaker 1: describe my childhood as well. It's a lot of weird
• 41:45
  Speaker 1: things happen and I'm still trying to understand it. Did
• 41:50
  Speaker 1: you break mathematics? I probably thought I could. Yeah, that
• 41:55
  Speaker 1: broke a lot of things when I was a kid.
• 41:56
  Speaker 1: But I think I think your main point, though, is
• 41:58
  Speaker 1: that we maybe don't know what happened during the Big Bang,
• 42:01
  Speaker 1: were before the Big Bang, were right after the Big Bang?
• 42:04
  Speaker 1: We do have kind of a clear picture of how
• 42:06
  Speaker 1: much of the universe was matter and how much of
• 42:09
  Speaker 1: it was kind of like flying energy, which you call radiation. Yeah,
• 42:13
  Speaker 1: so some mysterious thing happens, the universe exists, and then
• 42:17
  Speaker 1: some other mysterious thing happens. The universe inflates and expands
• 42:20
  Speaker 1: and cools down rapidly, and just after that we can
• 42:22
  Speaker 1: start to talk more concretely about quantum fields. And in
• 42:25
  Speaker 1: that situation, when the universe is still very very hot,
• 42:28
  Speaker 1: but we can talk about it in terms of quantum fields.
• 42:30
  Speaker 1: It's a really interesting situation because every particle back then
• 42:34
  Speaker 1: was massless. This is before the Higgs boson even came
• 42:37
  Speaker 1: into play, and so every particle, the electron, the w,
• 42:40
  Speaker 1: the z, all these particles had zero mass. Whoa, whoa,
• 42:43
  Speaker 1: Yeah that's wild. Yeah, at some point the universe had
• 42:47
  Speaker 1: nothing had mass because the Higgs field hadn't come into being. Yeah,
• 42:50
  Speaker 1: none of these initial particles had mass. You could still
• 42:53
  Speaker 1: have mass by combining particles into some like object, the
• 42:57
  Speaker 1: same way like if you put a bunch of photons
• 42:59
  Speaker 1: into a rage box, it actually gains mass because any
• 43:02
  Speaker 1: stored energy turns into mass. But the particles themselves. None
• 43:06
  Speaker 1: of them had mass in the very early universe until
• 43:09
  Speaker 1: the Higgs boson sort of settled into this weird state
• 43:12
  Speaker 1: that it's in today that gives them that mass. So
• 43:15
  Speaker 1: if it's nothing had mass, that means nothing what not,
• 43:18
  Speaker 1: Nothing mattered kind of in a way like you didn't
• 43:21
  Speaker 1: have matter. Particle physicists talk about the difference between matter
• 43:24
  Speaker 1: and radiation, and it's sort of a fuzzy line because
• 43:27
  Speaker 1: you know, when we talk about radiation chemically, we say, like, oh,
• 43:30
  Speaker 1: electrons are alpha particles, that's radiation, even though they have mass.
• 43:34
  Speaker 1: So we have all sorts of totally inconsistent definitions of radiation.
• 43:37
  Speaker 1: But in terms of like early universe physics, we divide
• 43:40
  Speaker 1: things into matter and radiation. Things that are radiation or
• 43:43
  Speaker 1: things that are traveling at light speed, and things that
• 43:46
  Speaker 1: are matter things that are traveling not at light speed.
• 43:48
  Speaker 1: But in the very early universe everything was massless, so
• 43:52
  Speaker 1: everything was moving at light speed, so it was just
• 43:54
  Speaker 1: a d radiation. Oh interesting, So we don't know which
• 43:57
  Speaker 1: can first, matter or energy, but we know which game second,
• 44:02
  Speaker 1: which is a radiation which is really energy, right yea.
• 44:05
  Speaker 1: So in the first moments of the universe that we
• 44:07
  Speaker 1: can really talk about we have all these buzzing quantum
• 44:10
  Speaker 1: fields with massless particles flying everywhere. The whole universe was radiation.
• 44:14
  Speaker 1: Then the Higgs field broke that symmetry between electromagnetism and
• 44:18
  Speaker 1: the weak force, made the W and the Z massive
• 44:21
  Speaker 1: and also made a bunch of other particles massive, and
• 44:23
  Speaker 1: then you have matter, and then the electron has mass.
• 44:26
  Speaker 1: You know, the corks have mass, and so that happened
• 44:29
  Speaker 1: very early on in the universe. But still most of
• 44:32
  Speaker 1: the energy in the universe was in terms of radiation
• 44:35
  Speaker 1: photons and other massless particles, meaning like it was in particles,
• 44:39
  Speaker 1: but it wasn't. It was in particles moving at the
• 44:42
  Speaker 1: speed of light. And so the first like fifty thousand
• 44:44
  Speaker 1: years of the universe was a radiation dominated era. Most
• 44:48
  Speaker 1: of the energy in the universe was in terms of
• 44:51
  Speaker 1: massless speed of light particles for the first fifty thousand years,
• 44:55
  Speaker 1: which sounds like a lot in human years, but in
• 44:59
  Speaker 1: the terms of the age of the universe, it's like
• 45:01
  Speaker 1: it's like just the first blink. Yeah, exactly, it's just
• 45:04
  Speaker 1: like a blip. Like if you ruled for fifty years,
• 45:07
  Speaker 1: that sounds pretty impressive, But if the universe is fourteen
• 45:09
  Speaker 1: billion years, then it's almost forgettable, all right. So then
• 45:13
  Speaker 1: at first it was all radiation and then what happened?
• 45:16
  Speaker 1: When did it change? Things are expanding and things are
• 45:18
  Speaker 1: cooling down, and that expansion affects matter and radiation differently
• 45:22
  Speaker 1: because as the universe expands, matter gets dilute. Right, the
• 45:25
  Speaker 1: same amount of matter exists, we have more volume, so
• 45:28
  Speaker 1: the density of matter drops. That makes sense, But radiation
• 45:32
  Speaker 1: is effected in another way. As space expands, radiation gets dilute.
• 45:36
  Speaker 1: It also gets red shifted. Like if you have a
• 45:39
  Speaker 1: photon in space and that space expands, it doesn't just
• 45:42
  Speaker 1: make the photon have fewer neighbors, It makes the photon
• 45:45
  Speaker 1: have a longer wavelength, which means less energy. So this
• 45:49
  Speaker 1: red shifting of radiation means that radiation loses energy faster
• 45:54
  Speaker 1: than matter does as the universe expands. Whoa interesting, It's
• 45:58
  Speaker 1: like it slows down light. But you can't slow down light,
• 46:01
  Speaker 1: but it just it makes it kind of less energetic. Yeah,
• 46:04
  Speaker 1: it steals away energy from light and we know that happens.
• 46:08
  Speaker 1: We see it all the time. Like the cosmic background
• 46:11
  Speaker 1: radiation was generated actually really high energies like three thousand
• 46:15
  Speaker 1: degrees kelvin. We see it now like three degrees kelvin
• 46:18
  Speaker 1: really long wavelengths because the universe has expanded and red
• 46:21
  Speaker 1: shifted all of that, and so radiation sort of lost
• 46:24
  Speaker 1: out after about fifty thousand years, and then for a
• 46:26
  Speaker 1: long time the universe was matter dominated. Most of the
• 46:29
  Speaker 1: energy in the universe was in the form of matter,
• 46:33
  Speaker 1: and a lot of that came because matter kind of
• 46:36
  Speaker 1: transformed from that early energy, right, like things, things kind
• 46:40
  Speaker 1: of clumped together and then they became matter. Yeah, the
• 46:43
  Speaker 1: Higgs boson gave math to a lot of those particles
• 46:46
  Speaker 1: and shifted them from the radiation category into the matter
• 46:49
  Speaker 1: category because now they had mass. And so then there
• 46:52
  Speaker 1: was this huge universe filled with particles, you know, electrons
• 46:56
  Speaker 1: and protons, and stars were formed and galaxies were formed,
• 46:59
  Speaker 1: and I was most of the energy budget of the
• 47:01
  Speaker 1: universe for billions of years was in terms of stuff,
• 47:05
  Speaker 1: mostly dark matter actually, but in terms of like things
• 47:07
  Speaker 1: we would think of today as stuff. It was the
• 47:10
  Speaker 1: stuff dominated era of the universe. WHOA, well, you just
• 47:13
  Speaker 1: blew my mind a little bit here, uh, either in
• 47:16
  Speaker 1: the dark matter here as a surprise twist here, so
• 47:19
  Speaker 1: like we know where dark matter came from, is that
• 47:21
  Speaker 1: what you're saying, Like, we traced the history of dark matter,
• 47:23
  Speaker 1: we know that dark matter was made at the same
• 47:25
  Speaker 1: time as all those other particles. When the energy in
• 47:27
  Speaker 1: the early universe coalesced into the different fields, electrons, and quirks.
• 47:31
  Speaker 1: That happened equally across all of the fields. And so
• 47:35
  Speaker 1: if dark matter is a particle and it's described by
• 47:38
  Speaker 1: a quantum field, then it was also made in the
• 47:40
  Speaker 1: early universe and it's been around since then. We're pretty
• 47:43
  Speaker 1: sure about that because it's changed the way the universe
• 47:46
  Speaker 1: has evolved. Like the reason we have stars and galaxies
• 47:49
  Speaker 1: is because of the gravity of dark matter early on
• 47:52
  Speaker 1: in the universe. So it had to have been around
• 47:54
  Speaker 1: for a long time. So when you say that the
• 47:57
  Speaker 1: universe became matter dominated, really you mean dark matter are dominated,
• 48:00
  Speaker 1: because there's like, even since the beginning of time and
• 48:04
  Speaker 1: or those early moments, there's been you know, five times
• 48:07
  Speaker 1: more dark matter than regular matter. Yeah, although the ratio
• 48:10
  Speaker 1: between dark matter and regular matter does change through the
• 48:13
  Speaker 1: history of the universe, we think there was even more
• 48:15
  Speaker 1: dark matter early on and some of it converted into
• 48:17
  Speaker 1: normal matter. That's a whole other podcast episode. We talked
• 48:20
  Speaker 1: about the whimp miracle ones about how we think dark
• 48:23
  Speaker 1: matter converted into normal matter. But yes, there's been dark
• 48:26
  Speaker 1: matter since the very beginning. Well, and so when really
• 48:30
  Speaker 1: in this period of matter domination, really you're saying it's
• 48:33
  Speaker 1: dark matter domination. Dark matter ruled for about nine billion
• 48:37
  Speaker 1: years long lived dark matter, but then something happened, the
• 48:41
  Speaker 1: dark energy revolution. Yes, dark energy took over. I remember
• 48:45
  Speaker 1: that the universe is expanding, and so as the universe
• 48:48
  Speaker 1: gets bigger and bigger, every new chunk of space that's
• 48:51
  Speaker 1: created comes with its own dark energy. So, unlike matter
• 48:55
  Speaker 1: and radiation, which get more and more dilute as space expands,
• 48:59
  Speaker 1: dark energy doesn't get diluted because a new chunk of
• 49:02
  Speaker 1: space comes with its own fresh dark matter. So as
• 49:05
  Speaker 1: the universe expands, dark energy starts to climb, and eventually,
• 49:09
  Speaker 1: at some point it crosses over and there's more dark
• 49:12
  Speaker 1: energy in the universe than there is energy in the
• 49:15
  Speaker 1: dark matter. And that happened about four or five billion
• 49:17
  Speaker 1: years ago. I see, yeah, And we're still in that period, right,
• 49:20
  Speaker 1: We're still in the dark energy dynasty. We're still in
• 49:23
  Speaker 1: that period, and this period is gonna last for a
• 49:25
  Speaker 1: long long time. Maybe forever, because once dark energy is dominant,
• 49:28
  Speaker 1: it accelerates the expansion of the universe, which makes more
• 49:31
  Speaker 1: dark energy more rapidly. And so now dark energy is
• 49:34
  Speaker 1: like completely dominant sev of the energy of the universe,
• 49:38
  Speaker 1: and the future suggests it's going to get higher and higher,
• 49:41
  Speaker 1: and it might even expand the universe to almost nothingness
• 49:44
  Speaker 1: right into my dad expanded into that there's nothing left. Yeah.
• 49:48
  Speaker 1: Although remember, dark energy is something we observe, we see
• 49:51
  Speaker 1: it happening. We have these ideas about how it works,
• 49:53
  Speaker 1: but we're really not very confident in it, which makes
• 49:55
  Speaker 1: it very difficult to make solid predictions for the future
• 49:58
  Speaker 1: of dark energy. You could turn out the dark energy
• 50:01
  Speaker 1: is much more complicated than we imagine. It has some
• 50:03
  Speaker 1: weird oscillations in it, for example, and maybe it's going
• 50:06
  Speaker 1: to turn around and cause a big crunch. We really
• 50:08
  Speaker 1: just can't say for sure because we don't understand it
• 50:10
  Speaker 1: like at all. But I guess we go back to
• 50:13
  Speaker 1: Jews question. He kind of just wanted to know which
• 50:15
  Speaker 1: came first, matter or energy. I think what you're saying
• 50:18
  Speaker 1: is that the picture is kind of complicated. It's not
• 50:19
  Speaker 1: just kind of about the sequence of things it's you know,
• 50:22
  Speaker 1: two physicists. It's kind of like which is more dominant,
• 50:25
  Speaker 1: and that that question has changed over the Big Bang
• 50:28
  Speaker 1: and the history of the universe. It's a really fascinating
• 50:31
  Speaker 1: history and nuanced and one that we've only really picked
• 50:34
  Speaker 1: apart in the last couple of decades. So we're just
• 50:37
  Speaker 1: at the very beginning of understanding the whole history of
• 50:40
  Speaker 1: the universe in terms of its energy budget, how it formed,
• 50:42
  Speaker 1: and how that evolved. N see. But I guess to
• 50:45
  Speaker 1: answer the question the question, the answer is that energy
• 50:47
  Speaker 1: came first, that's kind of for sure you sort of
• 50:50
  Speaker 1: have high confidence in. But in terms of what came second,
• 50:53
  Speaker 1: and third and four, that's been changing and it's a
• 50:55
  Speaker 1: more complex picture. And can we described the early moments
• 50:59
  Speaker 1: of the universe in turn energy? That is an open question. Yeah,
• 51:02
  Speaker 1: math otherians, I think people who ate math. That's a
• 51:06
  Speaker 1: question for people to chew on. I'm sure we'll have
• 51:08
  Speaker 1: a very filling answer. All right. Well, thank you Jeels
• 51:10
  Speaker 1: for that great question, and thank you to everyone who
• 51:13
  Speaker 1: sent in their questions. We really enjoy answering them on
• 51:16
  Speaker 1: the podcast. We absolutely do. We love your messages with
• 51:19
  Speaker 1: or with out questions, so please don't be shy if
• 51:22
  Speaker 1: it's something you've been thinking about, don't hesitate right to us.
• 51:24
  Speaker 1: Do questions at Daniel and Jorne dot com. Yeah, we
• 51:27
  Speaker 1: look forward to your awesome questions. Until then, keep being
• 51:31
  Speaker 1: curious about the universe. Come up with questions and look
• 51:34
  Speaker 1: at the things you're on you and think about what
• 51:36
  Speaker 1: might have come first for a second or third, or
• 51:38
  Speaker 1: whether or not you can get a PhD. Of a
• 51:41
  Speaker 1: PhD because science is just people asking questions and that
• 51:46
  Speaker 1: includes you. We hope you enjoyed that. Thanks for joining us,
• 51:49
  Speaker 1: See you next time. Thanks for listening, and remember that
• 52:00
  Speaker 1: Anniel and Jorge Explain the Universe is a production of
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