Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions 40: Ways our Universe could end us

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Listener Questions 40: Ways our Universe could end us · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Ang orgey. Does learning more about the universe make you
• 0:12
  Speaker 1: feel more or less safe?
• 0:14
  Speaker 2: I think it makes me feel small and insignificant, which
• 0:17
  Speaker 2: I guess is less.
• 0:18
  Speaker 1: Safe me too. The forces out there are just so
• 0:21
  Speaker 1: crazy and powerful. It's like it would take nothing to
• 0:25
  Speaker 1: squish us and wipe us out of existence.
• 0:27
  Speaker 2: But I hear there's a silver lining.
• 0:29
  Speaker 1: Oh yeah, what's that?
• 0:30
  Speaker 2: You know, as science progresses, maybe we figure out ways
• 0:33
  Speaker 2: to protect ourselves.
• 0:34
  Speaker 1: Hmmm. That sounds like a job for the engineers, not
• 0:37
  Speaker 1: the scientists.
• 0:38
  Speaker 2: Yeah, that's right. These scientists learn how we might die,
• 0:41
  Speaker 2: and engineers save us.
• 0:43
  Speaker 1: I'm totally happy with that division of labor.
• 0:45
  Speaker 2: Are you saying that engineers are superheroes?
• 0:49
  Speaker 1: That's no problem for me. I mean I hate wearing spandex.
• 0:52
  Speaker 2: Awesome, I have my cape ready.
• 1:09
  Speaker 1: Hi.
• 1:09
  Speaker 2: I am Poorhem, a cartoonist and the creator of PhD comics.
• 1:12
  Speaker 1: Hi, I'm Daniel. I'm a particle physicist and a professor
• 1:15
  Speaker 1: at UC Irvine, and science is my superpower.
• 1:18
  Speaker 2: The way you're not a superhero, you're a super villain
• 1:22
  Speaker 2: almost kind of like you're trying to figure out how
• 1:25
  Speaker 2: everyone might die.
• 1:26
  Speaker 1: Yeah, but I'm not shooting laser beams out of my
• 1:28
  Speaker 1: eyeballs and actually killing people. There's a distinction there.
• 1:31
  Speaker 2: What are you plotting? Are you plotting how to do it? Though?
• 1:36
  Speaker 1: I mean, if someone offered to make my eyeballs in
• 1:38
  Speaker 1: the laser beams, I would seriously consider it. I guess yeah.
• 1:41
  Speaker 2: I would make cooking easier, right, starting a fire while
• 1:44
  Speaker 2: when you're camping, also easier.
• 1:46
  Speaker 1: Doing the dishes, you know, frying that crusty stuff off
• 1:48
  Speaker 1: the bottom of pants, no need to soak it anymore.
• 1:51
  Speaker 2: That's right. Super villains have it easy.
• 1:53
  Speaker 1: But I do think it's incredible that we have this
• 1:55
  Speaker 1: power to understand the universe and unravel its true nature,
• 1:59
  Speaker 1: even if that does sometimes reveal great danger.
• 2:03
  Speaker 2: Although we always say that everyone is a physicist, which
• 2:05
  Speaker 2: technically means everybody has that superpower, which maybe makes it
• 2:09
  Speaker 2: not a superpower, just makes it a skill.
• 2:12
  Speaker 1: Is that like Superman on his planet Krypton, is not
• 2:15
  Speaker 1: really super at all, even if it's a planet of Superman.
• 2:17
  Speaker 2: Oh Man, Daniel, We've had this conversation. Everyone in Superman's
• 2:21
  Speaker 2: planet doesn't have powers because of the sun.
• 2:24
  Speaker 1: Oh, that's right, that's right. But if all of them
• 2:26
  Speaker 1: came to Earth, would they all then be superheroes. Is
• 2:29
  Speaker 1: there a limit to the number of superheroes you could have?
• 2:31
  Speaker 2: They would be super compared to us, So technically, yes,
• 2:34
  Speaker 2: they would be super. This is all a very philosophical conversation.
• 2:37
  Speaker 2: What is super?
• 2:39
  Speaker 1: Well, then we're all superheroes compared to like cats and dogs.
• 2:42
  Speaker 1: I can't do any.
• 2:43
  Speaker 2: Science, yes, I imagine. So yeah, to your dog, you
• 2:46
  Speaker 2: probably are a superhero. I mean you give it food,
• 2:49
  Speaker 2: magic food that just appears every day, twice a day.
• 2:52
  Speaker 1: And I don't even have to wear a cape.
• 2:53
  Speaker 2: And you also pick up their poop. I mean that's like,
• 2:58
  Speaker 2: that's like the best kind of superhero. But anyways, welcome
• 3:00
  Speaker 2: to our podcast Daniel and Jorge Explain the Universe, a
• 3:03
  Speaker 2: production of Our Heart Radio.
• 3:05
  Speaker 1: In which we dig into the deepest questions of the
• 3:07
  Speaker 1: nature of the universe, such as who is picking up
• 3:10
  Speaker 1: daniels dogs poop? And what's inside a black hole? And
• 3:13
  Speaker 1: can we use one question to solve the other one?
• 3:16
  Speaker 2: That's right, although I'm guessing that the answer to the
• 3:19
  Speaker 2: first question who picks up daniels dogs poop is Daniel.
• 3:23
  Speaker 2: I mean, it is your dog, it is.
• 3:25
  Speaker 1: My dog, and I'm very conscientious about it.
• 3:27
  Speaker 2: But yeah, it is an amazing universe, full of interesting
• 3:30
  Speaker 2: and crazy phenomena and mysteries and things for us to
• 3:33
  Speaker 2: discover and figure out with our puny, little human brains.
• 3:37
  Speaker 1: And many times when we explore the universe, we discover
• 3:39
  Speaker 1: fascinating facts about the way that it works. Sometimes we
• 3:43
  Speaker 1: can even put those facts to work to improve our lives.
• 3:45
  Speaker 1: Maybe one day someone will invent a black hole power
• 3:49
  Speaker 1: to dog poop picker upper. But sometimes we discover that
• 3:52
  Speaker 1: the universe is crazy and powerful and dangerous, that our
• 3:56
  Speaker 1: lives are a little bit more precarious and fragile than
• 3:59
  Speaker 1: we ever imagine.
• 4:00
  Speaker 2: Yeah, I guess if you think about it, we're just tiny,
• 4:02
  Speaker 2: little squishy beings living in a little thin layer of
• 4:06
  Speaker 2: air on a giant rock, hurling through space, barely not
• 4:11
  Speaker 2: falling into a giant ball of fire called the Sun.
• 4:13
  Speaker 1: Living right on the edge between being burned up and
• 4:16
  Speaker 1: being frozen to death. We are riding that knife edge
• 4:20
  Speaker 1: into infinity.
• 4:21
  Speaker 2: Yeah, it sort of makes you appreciate how precious life is, right,
• 4:24
  Speaker 2: or the fact that we're here to talk about the universe.
• 4:26
  Speaker 1: And how amazing that it's gone on for so long,
• 4:29
  Speaker 1: that the Earth has been habitable for billions of years,
• 4:32
  Speaker 1: even under vastly changing conditions. Over all that time, it's
• 4:37
  Speaker 1: been possible for these little squishy things to make more
• 4:40
  Speaker 1: squishy things.
• 4:41
  Speaker 2: Yeah, and I guess it also makes you think about
• 4:42
  Speaker 2: how precarious our existence is, and what are all the
• 4:46
  Speaker 2: things out there in the universe that could maybe end
• 4:48
  Speaker 2: our existence?
• 4:49
  Speaker 1: And even if there are crazy dangerous things out there
• 4:51
  Speaker 1: in the universe, I still want to know what they are,
• 4:54
  Speaker 1: not just because I have a deep curiosity for understanding
• 4:57
  Speaker 1: the nature of the universe, but because I'm hopefu that
• 5:00
  Speaker 1: if we can characterize what's going on out there in
• 5:02
  Speaker 1: the universe, eventually the engineers will save us.
• 5:05
  Speaker 2: Yeah. I guess that's the only way you might say
• 5:07
  Speaker 2: yourselves is if you know what's coming for you right
• 5:09
  Speaker 2: then you maybe we'll be able to do something about
• 5:12
  Speaker 2: it exactly.
• 5:13
  Speaker 1: That is why we track all the asteroids in the
• 5:16
  Speaker 1: Solar System and try to keep a handle on where
• 5:18
  Speaker 1: the comments are so that we can see one coming
• 5:21
  Speaker 1: with enough time to maybe divert it. That is why
• 5:24
  Speaker 1: we try to understand the nature of space and time
• 5:27
  Speaker 1: so that if a black hole does approach our Solar system,
• 5:29
  Speaker 1: and we'll have some ideas for how maybe to handle it.
• 5:33
  Speaker 2: Yeah, and it all starts with questions. And it's not
• 5:35
  Speaker 2: just scientists who have questions, it's everybody. Everybody has questions
• 5:39
  Speaker 2: about what's out there, what might affect them, what it
• 5:42
  Speaker 2: might change the way you live out there in the universe.
• 5:45
  Speaker 2: Everybody has questions.
• 5:46
  Speaker 1: That's right, and we love hearing your questions. If you
• 5:49
  Speaker 1: have thoughts and questions about the nature of the universe
• 5:52
  Speaker 1: and its future and how we might live in crazy
• 5:55
  Speaker 1: future times or strange corners of the universe, please don't
• 5:58
  Speaker 1: hesitate to write to us answer all of our questions.
• 6:01
  Speaker 1: Just email us at questions at Danielandjorge dot com.
• 6:05
  Speaker 2: So do they. On the podcast, we'll be tackling listener
• 6:12
  Speaker 2: questions number forty ways the universe could kill you. Addition,
• 6:19
  Speaker 2: I just.
• 6:20
  Speaker 1: Happen to notice when I was putting these together that
• 6:22
  Speaker 1: all of today's questions have something to do with very
• 6:25
  Speaker 1: powerful forces that could extinguish humanity.
• 6:28
  Speaker 2: Isn't that every physics question ever? I mean, is there
• 6:33
  Speaker 2: physics questions about something that would not totally annihilate humanity?
• 6:38
  Speaker 1: Sometimes it's just about everyday objects. Remember we had people
• 6:40
  Speaker 1: asking about like why does my truck look blue? And
• 6:43
  Speaker 1: how does the sun bleach my clothing and stuff like that?
• 6:46
  Speaker 1: Though I suppose there are cancer risks.
• 6:48
  Speaker 2: There, yes, radiation and chemicals. I mean maybe the more
• 6:54
  Speaker 2: you know, the more afraid it makes you.
• 6:56
  Speaker 1: I think it's something like a rorshark test. You know,
• 6:58
  Speaker 1: the way you look at the universe. Do you see
• 7:00
  Speaker 1: it as dangerous and crazy or do you see it
• 7:03
  Speaker 1: as fragile but still wonderful and lovingly supportive of our existence?
• 7:08
  Speaker 2: I see, like, is the universe half dangerous or half safe? Like,
• 7:12
  Speaker 2: if you have a fifty percent chance of surviving, is
• 7:14
  Speaker 2: that a good thing or a bad thing?
• 7:15
  Speaker 1: Yeah? Is the universe half trying to kill you or
• 7:17
  Speaker 1: half trying to save you? Or both?
• 7:19
  Speaker 2: I guess it depends on what it's like for dogs
• 7:22
  Speaker 2: and cats, and if it's better worse than us.
• 7:24
  Speaker 1: I think my dog, at least is a pretty good life.
• 7:26
  Speaker 2: But it is a pretty interesting topic. I guess people
• 7:29
  Speaker 2: are curious about what's out there and how it might,
• 7:32
  Speaker 2: you know, change our existence, and what can suddenly happen
• 7:35
  Speaker 2: to change our existence.
• 7:37
  Speaker 1: That's right, and so we're very excited to answer today's
• 7:39
  Speaker 1: questions all about the nature of space and time and
• 7:43
  Speaker 1: the whole universe and storms and dramatic supernova.
• 7:47
  Speaker 2: Yeah, we have three awesome questions here, and so let's
• 7:49
  Speaker 2: jump right in with the first question from Steve.
• 7:52
  Speaker 3: Hello, Daniel n Johe my name is Steve, and I
• 7:55
  Speaker 3: have a question about dark energy. You've mentioned on your
• 7:57
  Speaker 3: podcast previously that since we don't really you understand what
• 8:01
  Speaker 3: drives dark energy, it may be possible that the current
• 8:04
  Speaker 3: rate of expansion could at some point in the future
• 8:06
  Speaker 3: slow down and maybe even reverse, so that space starts
• 8:09
  Speaker 3: contracting rather than expanding. If this scenario did happen, My
• 8:14
  Speaker 3: question is, how would be first to take this?
• 8:16
  Speaker 2: Hmm, interesting question. I think Steve is saying that we
• 8:19
  Speaker 2: know that right now the universe is expanding, and it's
• 8:23
  Speaker 2: expanding faster and faster every day. But could that change,
• 8:27
  Speaker 2: Could somehow the universe stop expanding faster and faster and
• 8:31
  Speaker 2: maybe even start shrinking, In which case, when and how
• 8:35
  Speaker 2: would we even notice that that's?
• 8:37
  Speaker 1: Right? Could it be happening right now? And how could
• 8:40
  Speaker 1: we tell? Steve wants to know whether he should sell
• 8:44
  Speaker 1: his bitcoin or not.
• 8:46
  Speaker 2: Or real estate? Right? Should we buy more planets because
• 8:49
  Speaker 2: the universe is shrinking and real estate is going to
• 8:51
  Speaker 2: be a premium in the future or not. If the
• 8:55
  Speaker 2: universe is just going to keep growing, it's going to
• 8:57
  Speaker 2: be worth less and less.
• 9:00
  Speaker 1: This is a really pretty dark question because I don't
• 9:02
  Speaker 1: think there's anything the engineers could do to save you.
• 9:04
  Speaker 1: I mean, if the universe decides it's going to turn
• 9:06
  Speaker 1: around and crunch back to a super dense state, it's
• 9:09
  Speaker 1: pretty hard to imagine anybody surviving that.
• 9:12
  Speaker 2: It is a dark question also because it involves dark energy.
• 9:17
  Speaker 1: It does involve dark energy, and one of our favorite
• 9:20
  Speaker 1: topics the expansion of the universe and our almost total
• 9:24
  Speaker 1: lack of understanding for how it works, which makes it
• 9:26
  Speaker 1: pretty hard to predict what's going to happen in the future.
• 9:29
  Speaker 2: All right, well, let's dig into the answer to this question, Daniel.
• 9:33
  Speaker 2: I guess, first of all, how do we measure that
• 9:34
  Speaker 2: the universe is expanding?
• 9:36
  Speaker 1: Right? So Steve makes a good point, which is that
• 9:38
  Speaker 1: we are measuring the current rate of expansion, and then
• 9:40
  Speaker 1: we're extrapolating into the future and we're wondering about whether
• 9:44
  Speaker 1: that's going to change, and wondering about how we're going
• 9:46
  Speaker 1: to know that. So, yeah, let's think about how we
• 9:48
  Speaker 1: actually measure the expansion of the universe. And so what
• 9:50
  Speaker 1: we mean when we say the expansion of the universe
• 9:53
  Speaker 1: is we mean the increasing distances between galaxies. So we
• 9:57
  Speaker 1: look at our galaxy, and we look at other galleyalaxies,
• 10:01
  Speaker 1: and the best way to measure it, in principle would
• 10:03
  Speaker 1: be to pick a galaxy, measure our distance from it
• 10:06
  Speaker 1: and our speed relative to it, and then come back
• 10:08
  Speaker 1: a billion years later and say, Okay, where's that galaxy
• 10:12
  Speaker 1: now and how fast is it going. We can't do
• 10:14
  Speaker 1: that because it would take a billion years, and so
• 10:16
  Speaker 1: instead we do something different, which is that we look
• 10:19
  Speaker 1: further back in time for other galaxies and we say, well,
• 10:22
  Speaker 1: galaxies at a certain distance, which is a certain distance
• 10:25
  Speaker 1: back in time because of the propagation of light are
• 10:29
  Speaker 1: moving away from us at some velocity. And galaxies that
• 10:31
  Speaker 1: are further away, which is further back in time, back
• 10:34
  Speaker 1: in the history of the universe, how fast are they going?
• 10:37
  Speaker 1: So we can sort of read back the expansion of
• 10:40
  Speaker 1: the universe the velocity of galaxies relative to us versus distance,
• 10:44
  Speaker 1: which is also reading it versus time. Right.
• 10:47
  Speaker 2: But I guess the basics of it is that we're
• 10:49
  Speaker 2: measuring how fast galaxies are moving away from us. They'll
• 10:52
  Speaker 2: look like they're moving away from us, and we attribute
• 10:55
  Speaker 2: that to the expansion of the universe. And then you
• 10:56
  Speaker 2: want to check whether, like that that speed that the
• 10:59
  Speaker 2: galaxies are moved away from us, whether it's faster now
• 11:02
  Speaker 2: than it used to be, or whether it's lower than
• 11:04
  Speaker 2: it used to be, right exactly.
• 11:05
  Speaker 1: And to draw those conclusions, you need two pieces of
• 11:08
  Speaker 1: information per a galaxy. One is you have to know
• 11:10
  Speaker 1: how far away is it, so you basically know how
• 11:13
  Speaker 1: far back in time are we looking, and you have
• 11:16
  Speaker 1: to measure its velocity, how fast is it going relative
• 11:19
  Speaker 1: to us?
• 11:20
  Speaker 3: You know.
• 11:20
  Speaker 1: Something to understand also is that when you look out
• 11:22
  Speaker 1: into the sky, everything is moving away from us, except
• 11:26
  Speaker 1: for Andromeda, which is gravitationally dominated and moving towards us.
• 11:30
  Speaker 1: The overall picture is that everything is moving away from us.
• 11:33
  Speaker 1: And this is something that Hubble first noticed like one
• 11:35
  Speaker 1: hundred years ago, that if you look out into the sky,
• 11:38
  Speaker 1: everything is essentially red shifted because the light that comes
• 11:42
  Speaker 1: from these objects, its frequency is shifted towards the red
• 11:45
  Speaker 1: side of the spectrum. And that's how we measure the
• 11:48
  Speaker 1: velocity of these things. We look at the light from
• 11:50
  Speaker 1: a distant galaxy, we see how much it's shifted from
• 11:52
  Speaker 1: the light it should be sending us, and we use
• 11:55
  Speaker 1: that shift to measure its relative velocity.
• 11:57
  Speaker 2: Right, Because if it's moving away from us, light it
• 12:00
  Speaker 2: senses gets a little bit stretched out into the red spectrum, right,
• 12:04
  Speaker 2: And if something is moving towards us, the light gets
• 12:06
  Speaker 2: get a little bit compressed as it moves towards us
• 12:10
  Speaker 2: into the blue spectrum.
• 12:11
  Speaker 1: Right.
• 12:12
  Speaker 2: So the reder the light looks, the faster it's moving
• 12:15
  Speaker 2: away from.
• 12:16
  Speaker 1: Us, exactly. And there's two different ways to think about that.
• 12:19
  Speaker 1: One is that these galaxies have velocity relative to us,
• 12:22
  Speaker 1: and things that are in motion relative to us, their
• 12:24
  Speaker 1: light will be shifted, so it's called the Doppler shift.
• 12:26
  Speaker 1: The same way that like a police siren sounds different
• 12:29
  Speaker 1: as it passes you, because when it approaches you, its
• 12:32
  Speaker 1: sound waves are blue shifted to higher frequency, and when
• 12:35
  Speaker 1: it passes you, its sound waves are red shifted to
• 12:37
  Speaker 1: lower frequency. You can do the same sort of thinking
• 12:40
  Speaker 1: about the light from these galaxies. That's not one hundred
• 12:43
  Speaker 1: percent really the right way to think about it, because
• 12:46
  Speaker 1: these galaxies are so far away and it gives you
• 12:49
  Speaker 1: velocities greater than the speed of light. The way cosmologists
• 12:52
  Speaker 1: think about it instead is that space is expanding between
• 12:55
  Speaker 1: us and those galaxies, and so instead what's happening to
• 12:58
  Speaker 1: the light is that it's getting stretched out out by
• 13:00
  Speaker 1: space expanding, So the wavelengths get longer as the light
• 13:04
  Speaker 1: travels through space, and so that's why we'd see it
• 13:07
  Speaker 1: red shifted. So it's two different ways to think about
• 13:09
  Speaker 1: it that end up giving you exactly the same prediction.
• 13:12
  Speaker 1: Either you're measuring the expansion of space or you're measuring
• 13:15
  Speaker 1: the velocity of those galaxies relative to us.
• 13:19
  Speaker 2: It's the stretching of space itself that is changing the
• 13:23
  Speaker 2: color of the light.
• 13:24
  Speaker 1: Yeah, that's the way cosmologists think about it, because they
• 13:27
  Speaker 1: think about each galaxy as having like its own little
• 13:29
  Speaker 1: inertial frame. You could think about physics happening in those
• 13:32
  Speaker 1: galaxies and then between them space is expanding, and that's
• 13:35
  Speaker 1: why the light gets red shifted. And that avoids anything
• 13:38
  Speaker 1: being like faster than the speed of light because you
• 13:40
  Speaker 1: can't really compare velocities in one frame to velocities in
• 13:43
  Speaker 1: another frame. In general relativity, it gets really hairy.
• 13:46
  Speaker 2: All right. So then you said that we can look
• 13:48
  Speaker 2: back in history, in the history of the universe by
• 13:50
  Speaker 2: looking at galaxies that are further and further away from us,
• 13:53
  Speaker 2: And what we'd notice is that galaxies that are really
• 13:57
  Speaker 2: old move at a different rate away from for most
• 14:00
  Speaker 2: in galaxies that are younger.
• 14:02
  Speaker 1: Yeah, exactly, we can look at the velocity versus time,
• 14:06
  Speaker 1: and from that we can see how the velocity is
• 14:08
  Speaker 1: changing versus time, and so basically we're seeing whether the
• 14:12
  Speaker 1: universe's expansion is accelerating, speeding up, or whether it's decelerating,
• 14:17
  Speaker 1: whether it's slowing down. So we can see like the
• 14:20
  Speaker 1: history of the expansion velocity of the universe by looking
• 14:24
  Speaker 1: further and further back in time. Nearby galaxies are very recent,
• 14:28
  Speaker 1: they tell us about the expansion rate. Now, the very
• 14:30
  Speaker 1: very far away galaxies, the light from them we get
• 14:33
  Speaker 1: is very old. It's very out of date. But it's
• 14:36
  Speaker 1: sort of like looking at the fossil record. It's seeing
• 14:38
  Speaker 1: what was happening in the universe a long time ago.
• 14:41
  Speaker 1: So we can see the acceleration or deceleration history of
• 14:44
  Speaker 1: the universe.
• 14:45
  Speaker 2: Now, the fossils also turn red the older they get,
• 14:48
  Speaker 2: or is that why Like when you go to a
• 14:50
  Speaker 2: museum on the bones are brown? Where am I totally
• 14:54
  Speaker 2: misinforming our public.
• 14:55
  Speaker 1: Here. You got to get a paleontologist on here to
• 14:58
  Speaker 1: answer that question.
• 15:00
  Speaker 2: We need a paleophysicist.
• 15:02
  Speaker 1: Paleophysicist wow, a phrase I don't think I've ever heard before.
• 15:06
  Speaker 1: And who is picking up dinosaur poops? Really? Nobody was
• 15:09
  Speaker 1: cleaning up.
• 15:10
  Speaker 2: After the rest? Yeah, maybe it was a dinosaur. Physicists.
• 15:15
  Speaker 1: Paleophysicists should have been picking up those paleo poops. But
• 15:18
  Speaker 1: one thing I think is super fascinating and not really
• 15:21
  Speaker 1: widely enough appreciated, is that the universe has not always
• 15:24
  Speaker 1: been accelerating. Like, the universe has always been expanding, but
• 15:27
  Speaker 1: it hasn't always been accelerating, right.
• 15:30
  Speaker 2: There's been like periods when the universe was getting bigger
• 15:33
  Speaker 2: at a bigger rate or a slower rate.
• 15:35
  Speaker 1: Right Exactly. The sort of brief version of it is
• 15:37
  Speaker 1: that you have this very very super rapid inflation, very
• 15:41
  Speaker 1: early universe that we don't understand at all, but gives
• 15:44
  Speaker 1: you this huge universe with hot, dense plasma.
• 15:47
  Speaker 2: Does what we call the Big Bang? Right, sort of,
• 15:49
  Speaker 2: we're like right after the Big Bang.
• 15:51
  Speaker 1: So there's a bit of a disconnect in the terminology here.
• 15:54
  Speaker 1: What most people think of as the Big Bang is
• 15:56
  Speaker 1: that inflation that really rapid expansion very early on. What
• 16:00
  Speaker 1: scientists call the Big Bang is actually what happened after that.
• 16:04
  Speaker 1: Once you start from a very hot, dense place and
• 16:07
  Speaker 1: then you evolve that forwards in time. That's what we
• 16:10
  Speaker 1: mean when we say the Big Bang. We don't know
• 16:12
  Speaker 1: how we got that original very hot and dense state.
• 16:14
  Speaker 1: Maybe it was inflation, maybe it was something else. We
• 16:16
  Speaker 1: really just don't know. Big Bang starts from sort of
• 16:18
  Speaker 1: the Plank era, when the universe already existed and was
• 16:21
  Speaker 1: super hot and dense, and we evolve it forward in time.
• 16:24
  Speaker 1: That's sort of what we mean by the Big Bang.
• 16:26
  Speaker 1: It's sort of different from the popular conception of the
• 16:28
  Speaker 1: Big Bang.
• 16:29
  Speaker 2: Okay, but do you say there was an initial period
• 16:31
  Speaker 2: where the universe was expanding super fast?
• 16:33
  Speaker 1: Yeah, So we think probably inflation is this very rapid
• 16:36
  Speaker 1: expansion from quantum primordial soup to some very hot, dense state.
• 16:41
  Speaker 1: Then general relativity takes over and gravity and things cool
• 16:44
  Speaker 1: and expand, and we end up with the universe we
• 16:47
  Speaker 1: have today. Between the very hot and dense state and
• 16:49
  Speaker 1: where we are today. The universe has expanded a lot,
• 16:52
  Speaker 1: but it wasn't always accelerating. It was always expanding, but
• 16:56
  Speaker 1: for the first seven or eight billion years or so,
• 16:59
  Speaker 1: that expand was slowing down. But either there was enough
• 17:02
  Speaker 1: matter and energy in the universe to start pulling stuff
• 17:05
  Speaker 1: back together. Gravity was working hard to pull stuff back
• 17:08
  Speaker 1: together because of all that mass has gravity yanking on it.
• 17:11
  Speaker 1: But around eight billion years after the universe started, something changed.
• 17:15
  Speaker 1: Dark energy took over. This expansion of the universe slipped
• 17:19
  Speaker 1: from being decelerating to being accelerating. The expansion used to
• 17:22
  Speaker 1: be sort of slowing down, but then it turned over
• 17:24
  Speaker 1: and it started accelerating. So the last six or so
• 17:28
  Speaker 1: billion years of the universe we've had an accelerating expansion
• 17:31
  Speaker 1: of the universe. It's been going faster and faster.
• 17:34
  Speaker 2: It's like the universe hit the accelerator button or pedal.
• 17:38
  Speaker 1: Yeah, And it all comes down to the nature of
• 17:40
  Speaker 1: dark energy. Like as the universe expands, matter gets more dilute,
• 17:44
  Speaker 1: it gets more thinned out right, the same amount of matter,
• 17:47
  Speaker 1: and you have more space, and so things get more dilute.
• 17:49
  Speaker 1: But dark energy, we don't think it's like that. Dark
• 17:51
  Speaker 1: energy is a constant in space, and so as the
• 17:54
  Speaker 1: universe expands, you get more space, you get more dark energy.
• 17:58
  Speaker 1: So dark energy increases in its fraction of the universe
• 18:02
  Speaker 1: because everything else is getting more and more dilute, and
• 18:04
  Speaker 1: so eventually it takes over because as the universe expands,
• 18:07
  Speaker 1: it starts to win and it drives the expansion, and
• 18:10
  Speaker 1: so eventually it just takes over, and it's zooms so
• 18:12
  Speaker 1: far ahead that nobody can catch up to it. But
• 18:15
  Speaker 1: if you look back at the history of the universe
• 18:16
  Speaker 1: and you look at these diagrams and the expansion, you'll
• 18:19
  Speaker 1: notice that there was a time when the universe was
• 18:21
  Speaker 1: decelerating a little bit and before it started to zoom off.
• 18:24
  Speaker 3: Hmm.
• 18:25
  Speaker 1: Interesting.
• 18:25
  Speaker 2: Yeah, We've often talked about how dark energy the exceluration
• 18:29
  Speaker 2: of the universe changed, but it's I think what I'm
• 18:31
  Speaker 2: getting is that it like nothing really changed, Like dark
• 18:34
  Speaker 2: energy didn't suddenly turn on or some fundamental parameter of
• 18:38
  Speaker 2: the universe suddenly flipped. It's more like the density of
• 18:41
  Speaker 2: the universe got so sparse at some point that dark
• 18:45
  Speaker 2: energy just became more significant. Because dark energy, its power
• 18:48
  Speaker 2: is sort of proportional to how much space.
• 18:50
  Speaker 1: There is matter and energy is power gravitational is proportional
• 18:54
  Speaker 1: to its density, which drops as space gets bigger, and
• 18:57
  Speaker 1: that doesn't happen for dark energy. So you're right, the
• 18:59
  Speaker 1: rules didn't change, and what we think of as the
• 19:01
  Speaker 1: amount of dark energy in the universe didn't change. It's
• 19:04
  Speaker 1: just that things got so cold and dilute that eventually
• 19:07
  Speaker 1: dark energy sort of wins the tug of war.
• 19:09
  Speaker 2: But I wonder, like, if the universe had started with
• 19:12
  Speaker 2: more stuff, like more density of stuff. Is there a
• 19:15
  Speaker 2: universe in which thinks they're so dense that dark energy
• 19:18
  Speaker 2: always loses and things always compress.
• 19:21
  Speaker 1: Yeah, it's possible to have a closed universe like that
• 19:24
  Speaker 1: universe where you start with enough stuff that dark energy
• 19:27
  Speaker 1: doesn't win. Absolutely. You can start with different initial conditions
• 19:29
  Speaker 1: and you might end up with different outcome. Absolutely.
• 19:33
  Speaker 2: All right. Well, so thee's question is, what if that
• 19:36
  Speaker 2: acceleration of the universe slows down and even reverses, like
• 19:39
  Speaker 2: the universe starts to get smaller, there's less space every day.
• 19:43
  Speaker 2: Could we detect that and when would we detect that? Right,
• 19:46
  Speaker 2: that's a good question.
• 19:48
  Speaker 1: A super good question, and motivated by the fact that
• 19:50
  Speaker 1: everything we've said about dark energy so far is kind
• 19:53
  Speaker 1: of a guess, like we do not understand what dark
• 19:56
  Speaker 1: energy is. We have no like real theory for it
• 19:58
  Speaker 1: what we've talked about. So if our dark energy is
• 20:01
  Speaker 1: this constant in space and time, that's just really like
• 20:04
  Speaker 1: a hack. We just like put a number into the
• 20:06
  Speaker 1: equations and said, here's the number you got to put
• 20:08
  Speaker 1: in to make the equations work. We don't know where
• 20:10
  Speaker 1: that number comes from. We don't know why that number
• 20:13
  Speaker 1: would be constant. We just like use the number because
• 20:16
  Speaker 1: that's the simplest description. And the point is that that
• 20:18
  Speaker 1: could change. And what if in the future it does,
• 20:20
  Speaker 1: and it changes to another value, and it changes to
• 20:23
  Speaker 1: a smaller value, goes away, so that gravity then does
• 20:26
  Speaker 1: win and the universe does take over, or if it
• 20:29
  Speaker 1: changes in such a way that it works in the
• 20:30
  Speaker 1: opposite direction to compress the universe. Basically, because we don't
• 20:34
  Speaker 1: know what's going on, we can't make any predictions about
• 20:36
  Speaker 1: what's going to happen in the future. And so Save's
• 20:38
  Speaker 1: question is great. It's like, how would we observe a change,
• 20:41
  Speaker 1: How would we notice that things deviate from this simple prediction?
• 20:45
  Speaker 1: And it would be hard. The first clues we would
• 20:47
  Speaker 1: have would be for nearby stuff, right, stuff that's really
• 20:51
  Speaker 1: really far away. We're not going to get messages from
• 20:53
  Speaker 1: that for a long time. But closer by stuff, nearby
• 20:57
  Speaker 1: galaxies and galaxy clusters, those are the ones that are
• 20:59
  Speaker 1: telling us about the recent history of the universe, but
• 21:03
  Speaker 1: how things are expanding right now or at least in
• 21:05
  Speaker 1: the very recent past. So if we watch very carefully
• 21:08
  Speaker 1: the closer stuff, that's where we could see like a
• 21:10
  Speaker 1: change in the slope, like if things are accelerating less
• 21:13
  Speaker 1: or more, or if it's even started to decelerate.
• 21:16
  Speaker 2: Oh, I think you're saying that, Like, if the universe
• 21:19
  Speaker 2: starts to decelerate, right's expand slower, it's going to happen
• 21:23
  Speaker 2: all throughout the universe at the same time. And so
• 21:26
  Speaker 2: it's going to happen now, and it's going to happen
• 21:28
  Speaker 2: to the galaxies that are really really far away. So
• 21:31
  Speaker 2: if it all happens at the same time, then the
• 21:34
  Speaker 2: freshest news we would get up of it would be
• 21:36
  Speaker 2: from the nearby stuff.
• 21:37
  Speaker 1: Yeah, and that's also an assumption, right there could be
• 21:39
  Speaker 1: like weird bubbles. Maybe it doesn't happen everywhere in the universe,
• 21:42
  Speaker 1: But the simplest model is, like, let's assume that something
• 21:45
  Speaker 1: changes in the whole parameter of the universe everywhere at once,
• 21:48
  Speaker 1: and so we wouldn't notice it from really far away
• 21:51
  Speaker 1: galaxies very quickly. We'd notice it from nearby galaxies. As
• 21:54
  Speaker 1: you say, that's the freshest news. And so we'd have
• 21:56
  Speaker 1: to notice a change in the relative velocities of nearby
• 22:00
  Speaker 1: galaxies that their velocity away from us is decreasing instead
• 22:04
  Speaker 1: of increasing, Like if things nearby start to blue shift
• 22:07
  Speaker 1: instead of red shift, we'd be like, WHOA, that's weird.
• 22:10
  Speaker 2: Right, But I guess if you're assuming that it all
• 22:11
  Speaker 2: happens at the same time, wouldn't it already have happened
• 22:15
  Speaker 2: to stuff that's really far away.
• 22:17
  Speaker 1: If it's happening all at the same time, then it
• 22:18
  Speaker 1: happens also to stuff that's really far away. We wouldn't
• 22:21
  Speaker 1: see any evidence of it for a long time. Like
• 22:23
  Speaker 1: we can't see right now what's happening for stuff really
• 22:26
  Speaker 1: really far away, we won't see that for a long
• 22:28
  Speaker 1: long time because it's so far away.
• 22:31
  Speaker 2: So that's good. We would know right away if the
• 22:33
  Speaker 2: universe was slowing down.
• 22:35
  Speaker 1: Yeah, that's true, although the nearest galaxies are even not
• 22:37
  Speaker 1: that nearby, and the closest galaxies are dominated by gravity
• 22:41
  Speaker 1: like Andromeda in the Milky Way, are actually approaching each
• 22:44
  Speaker 1: other because of their relative gravity. So what you'd have
• 22:47
  Speaker 1: to do is look far enough away that you're looking
• 22:49
  Speaker 1: at stuff where dark energy is really dominant. That's like
• 22:52
  Speaker 1: between galaxy clusters, so it wouldn't even be that nearby.
• 22:56
  Speaker 1: So now we're talking about like tens or hundreds of
• 22:59
  Speaker 1: millions of light years away these galaxies, which means if
• 23:02
  Speaker 1: the universe starts to turn around and compress, we wouldn't
• 23:05
  Speaker 1: know for tens or hundreds of millions of years.
• 23:08
  Speaker 2: Right, But I guess there's some comfort to know that
• 23:10
  Speaker 2: we're looking at galaxies that are, you know, thirteen billion
• 23:14
  Speaker 2: years old, and so far it doesn't look like the
• 23:18
  Speaker 2: universe is compressing, right, So like, why would it suddenly change?
• 23:22
  Speaker 1: Now, Yeah, we have no reason to suspect that it will,
• 23:25
  Speaker 1: but we also don't understand what's going on really at all.
• 23:28
  Speaker 1: So you're right, the simplest model is to just extractly
• 23:31
  Speaker 1: continued accelerating expansion, So don't worry about this if you're
• 23:35
  Speaker 1: an anxious person. But the truth is that we don't
• 23:37
  Speaker 1: really have a reason to believe that, and so the
• 23:40
  Speaker 1: universe has surprised us many times in the past. And
• 23:43
  Speaker 1: remember this whole idea of accelerating expansion was also a surprise.
• 23:47
  Speaker 1: Nobody expected that at all, so there probably are more
• 23:50
  Speaker 1: surprises in store.
• 23:52
  Speaker 2: I think what you're saying is that engineers could say
• 23:55
  Speaker 2: was in the future. We don't know yet.
• 23:58
  Speaker 4: We should keep funding engineers. Yes, I totally agree, that's right.
• 24:01
  Speaker 4: Keep us around please. All right, Well, I think that
• 24:03
  Speaker 4: answers Steve's question. How would we first detected, Well, we
• 24:06
  Speaker 4: would detect it in the galaxies that are closest to us.
• 24:09
  Speaker 4: If there is sort of a universe wide shift in
• 24:12
  Speaker 4: how things are expanding, we would know right away from
• 24:15
  Speaker 4: where if the things around us are expanding faster, or
• 24:17
  Speaker 4: if they're starting to creep in a little bit more
• 24:20
  Speaker 4: each day, then we would know. All right, let's get
• 24:22
  Speaker 4: to our other two questions. We have an awesome question
• 24:25
  Speaker 4: about supernovas, or I guess kind of a deadly question
• 24:28
  Speaker 4: about supernovas, and about danger storms in our solar system.
• 24:32
  Speaker 2: Let's get to those. But first, let's take a quick break.
• 24:47
  Speaker 2: All right, we are answering listener questions, and I guess
• 24:50
  Speaker 2: these are very worried listener questions. Our listeners are worried
• 24:55
  Speaker 2: about how the universe might end human existence.
• 24:58
  Speaker 1: Or they're just in awe the crazy power out there
• 25:01
  Speaker 1: in astronomical and after physical objects.
• 25:04
  Speaker 2: You're shocked and odd. All right? Our next question comes
• 25:08
  Speaker 2: from christof and it's about supernova's. Dear Daniel, I have
• 25:12
  Speaker 2: always wondered what would happen to the Earth if there
• 25:14
  Speaker 2: was a super and nova nearby?
• 25:16
  Speaker 1: Thanks?
• 25:17
  Speaker 2: We would all die? Done? Next question?
• 25:20
  Speaker 1: Oh, let's give him a little bit of hope.
• 25:21
  Speaker 2: Come on, that's right. Yes, it depends on which side
• 25:26
  Speaker 2: of the Earth you're in. Maybe hopefully it's like nighttime
• 25:30
  Speaker 2: or you're sleeping when it happens.
• 25:32
  Speaker 1: That's only if the supernova is brief enough to only
• 25:35
  Speaker 1: last during somebody else's night.
• 25:37
  Speaker 2: Mmmm A, right, let's dig into it. I guess the
• 25:40
  Speaker 2: question is what would happen even supernova if a star
• 25:42
  Speaker 2: explodes nearby us? Would we have a chance of surviving?
• 25:47
  Speaker 3: Or?
• 25:47
  Speaker 2: I guess also, how likely is that to happen to us?
• 25:50
  Speaker 1: Yes? So to understand the amazing, incredible power of a supernova,
• 25:55
  Speaker 1: you have to understand what we're talking about here. What
• 25:57
  Speaker 1: is the supernova? Where does its energy come from? And
• 26:00
  Speaker 1: a supernova is essentially the end point of really massive stars.
• 26:05
  Speaker 1: They burn their hydrogen to make helium. They burn their
• 26:07
  Speaker 1: helium to make heavier stuff. They burn carbon, they burn oxygen,
• 26:10
  Speaker 1: they burn nitrogen. Eventually they get really really heavy. They
• 26:14
  Speaker 1: have accumulated all this really heavy metal in their core,
• 26:17
  Speaker 1: and gravity gets so powerful inside these stars that it
• 26:20
  Speaker 1: can no longer be resisted by the pressure of that fusion.
• 26:24
  Speaker 1: And all that energy flying out has been puffing up
• 26:27
  Speaker 1: the star keeping it from collapsing. So you get this
• 26:30
  Speaker 1: million or billion year long struggle between gravity trying to
• 26:33
  Speaker 1: compress the star and fusion resisting it. But eventually gravity
• 26:36
  Speaker 1: is going to win that battle, and you get this
• 26:39
  Speaker 1: incredible compression of the star, this collapse of the star
• 26:42
  Speaker 1: we call it a core collapse, which leads to very
• 26:45
  Speaker 1: very high temperatures inside the star, which triggers this brief
• 26:48
  Speaker 1: moment of super intense fusion, which then explodes the star.
• 26:52
  Speaker 1: So you get this gravitational collapse followed by this very
• 26:55
  Speaker 1: dramatic explosion. And in that explosion, the supernova gives off
• 26:59
  Speaker 1: soul much energy that it can outshine the entire galaxy
• 27:03
  Speaker 1: that it's in. Right, a single supernova can be as
• 27:06
  Speaker 1: bright or brighter than like one hundred billion stars in
• 27:10
  Speaker 1: the galaxy that it's in.
• 27:11
  Speaker 2: Yeah, it's a big explosion.
• 27:13
  Speaker 1: It's a big explosion.
• 27:14
  Speaker 2: And it's basically it's sort of like if a building collapses,
• 27:17
  Speaker 2: but the building is full of dynamite, kind of right, Like,
• 27:20
  Speaker 2: it collapses and then the wind it crunches down together.
• 27:24
  Speaker 2: Things get exciting and the explode and then everything flies out.
• 27:27
  Speaker 1: Yeah, it's actually a pretty good model for how hydrogen
• 27:29
  Speaker 1: bombs work. Hydrogen bombs are fusion bombs, but the conditions
• 27:34
  Speaker 1: for fusion are created by a fission bomb, which implodes
• 27:38
  Speaker 1: the fusion fuel. So you get this fission bomb which
• 27:41
  Speaker 1: blows up and then squeezes the fuel for fusion, which
• 27:44
  Speaker 1: then triggers the more dramatic fusion bomb. And that's basically
• 27:48
  Speaker 1: what's going on inside of supernova, except the fuel pellet
• 27:51
  Speaker 1: is like the size of a star, and so that's
• 27:53
  Speaker 1: what we call a type two supernova. There's also another
• 27:56
  Speaker 1: kind which are even brighter, even more dangerous and more
• 28:00
  Speaker 1: deadly to life on Earth, which is a type one.
• 28:03
  Speaker 1: That's the kind of star that originally wasn't going to
• 28:05
  Speaker 1: go supernova. It burned and accumulated these hot metals at
• 28:09
  Speaker 1: its core, but not enough so that gravity would take
• 28:12
  Speaker 1: over and actually collapse until some other source of fuel
• 28:16
  Speaker 1: comes by, some like red giant in a binary star
• 28:20
  Speaker 1: system with this white dwarf, and the white dwarf steals
• 28:22
  Speaker 1: a little bit more fuel, which gets it heavy enough
• 28:25
  Speaker 1: for gravity to overcome this threshold and then trigger a collapse.
• 28:29
  Speaker 1: That's a type one supernova, and they can be like
• 28:31
  Speaker 1: ten times as bright as a type two supernova.
• 28:34
  Speaker 2: M that's interesting, I guess the question is why is that?
• 28:37
  Speaker 2: Why is it brighter and more explosive if it's sort
• 28:41
  Speaker 2: of like the same amount of stuff being exploded.
• 28:43
  Speaker 1: So we don't really understand very well exactly what's going
• 28:47
  Speaker 1: on inside supernova. So this is sort of an area
• 28:49
  Speaker 1: of current research. People speculate that, like the amount of
• 28:52
  Speaker 1: coalbalt inside these things might be enough to trigger more
• 28:56
  Speaker 1: dramatic reactions it, or at least more energy, but it's
• 28:59
  Speaker 1: really sort of a area of fuzzy understanding. So far,
• 29:01
  Speaker 1: we don't even understand exactly when a star will go supernova.
• 29:04
  Speaker 1: It's the exact thing that triggers this collapse. It's not
• 29:08
  Speaker 1: something that we understand very well yet. So this is
• 29:10
  Speaker 1: something we're still trying to figure out. A lot of
• 29:12
  Speaker 1: this stuff is just descriptive, Like we see these kind
• 29:15
  Speaker 1: of things in the universe, and we so describe these
• 29:17
  Speaker 1: one way and we describe these another way. We don't
• 29:20
  Speaker 1: always understand the mechanisms and the underlying science.
• 29:23
  Speaker 2: I guess maybe a follow question is like how do
• 29:25
  Speaker 2: we know that they're different? I mean, I imagine we
• 29:28
  Speaker 2: saw some things blow up in the sky and we
• 29:29
  Speaker 2: saw somewhere them are bigger and smaller than others. How
• 29:33
  Speaker 2: do we know like, oh, this is a totally different
• 29:35
  Speaker 2: kind of explosion.
• 29:36
  Speaker 1: Yeah, it comes down to categorizing. We are like looking
• 29:38
  Speaker 1: at these things and we're tracing their light curves, and
• 29:40
  Speaker 1: then we're looking back through our records to find the progenitor,
• 29:43
  Speaker 1: like what was the thing that led to this? Was
• 29:46
  Speaker 1: it a big red star or was it a white dwarf?
• 29:49
  Speaker 1: And we don't know what's going to go supernova? So
• 29:51
  Speaker 1: you can't just like watch one and see it happen.
• 29:54
  Speaker 1: You have to go backwards. You see, oh we saw supernova.
• 29:56
  Speaker 1: Now let's go back and see what used to be
• 29:58
  Speaker 1: there in the sky. And so if it was a
• 30:01
  Speaker 1: red giant, then you're going to call it a core collapse.
• 30:04
  Speaker 1: If it was a white dwarf, and there was a
• 30:05
  Speaker 1: red giant nearby that it was stealing matter from. You're
• 30:08
  Speaker 1: going to call that a type one supernova.
• 30:10
  Speaker 2: And then if it's really particular about every little detail
• 30:13
  Speaker 2: of the explosion, then it's a Type A supernova.
• 30:17
  Speaker 1: If it just got to be the biggest supernova in
• 30:19
  Speaker 1: the galaxy, no matter what, then yeah, exactly.
• 30:22
  Speaker 2: The very competitive. If it's a super dupernova.
• 30:25
  Speaker 1: It's a tiger supernova exactly.
• 30:27
  Speaker 2: All right, Well, let's get to Christof's question, which is
• 30:29
  Speaker 2: what would happen if one of these stars, either a
• 30:33
  Speaker 2: red giant or white dwarf, it explodes near us? What
• 30:36
  Speaker 2: would happen to Earth? Like, First of all, what are
• 30:39
  Speaker 2: the chances of that happening?
• 30:40
  Speaker 1: It's very unlikely because supernova, first of all, are very rare,
• 30:44
  Speaker 1: Like we think that maybe one in every few million
• 30:47
  Speaker 1: stars will go supernova just because massive stars starts big
• 30:51
  Speaker 1: enough to have this happen are pretty rare. Most of
• 30:54
  Speaker 1: the stars in the universe are colder and smaller than
• 30:56
  Speaker 1: stars that will go supernova. They're even mostly colder and
• 30:59
  Speaker 1: small more than our star. So most of these stars
• 31:02
  Speaker 1: are red dwarfs, and they will end up making white
• 31:05
  Speaker 1: dwarfs and they will not go supernova. In fact, they're
• 31:08
  Speaker 1: so rare that we haven't even seen a supernova in
• 31:10
  Speaker 1: our galaxy in four hundred years.
• 31:14
  Speaker 2: They're that rare, so they're not likely to happen. But
• 31:16
  Speaker 2: I don't think that's why it keeps people up. I
• 31:19
  Speaker 2: guess maybe let's think about it, like, what's the closest
• 31:21
  Speaker 2: star to us, and what's the likelihood that it will
• 31:24
  Speaker 2: go supernova?
• 31:25
  Speaker 1: Yeah, so the closest star to us is Proximist Centari,
• 31:28
  Speaker 1: and it's a pretty low mass star. It's much more
• 31:30
  Speaker 1: typical than our star. It's like twelve percent of the
• 31:33
  Speaker 1: mass of the Sun. So that thing is definitely not
• 31:36
  Speaker 1: going to go supernova.
• 31:37
  Speaker 2: Right, Like a star needs to be a certain size
• 31:40
  Speaker 2: for it to go even think about going supernova, and
• 31:42
  Speaker 2: like our Sun and Proximus Centari are not they'll qualify
• 31:46
  Speaker 2: for supernova's status.
• 31:47
  Speaker 1: To really even have any chance to go supernova, you
• 31:50
  Speaker 1: need to have like eight to ten times the mass
• 31:52
  Speaker 1: of the Sun. I remember, the Sun is already an
• 31:54
  Speaker 1: unusually massive star, and so ten times the mass of
• 31:58
  Speaker 1: the Sun is even less likely. The more mass of
• 32:01
  Speaker 1: the star, the much less common they are. There are
• 32:04
  Speaker 1: some sort of nearby stars. For example, there's a star
• 32:07
  Speaker 1: named Speaker, which is eighty parsecs away, that's like two
• 32:12
  Speaker 1: hundred and fifty light years and its mass is a
• 32:14
  Speaker 1: little uncertain, but you know, order of magnitude about ten
• 32:16
  Speaker 1: times the mass of the Sun, and so that's a candidate,
• 32:20
  Speaker 1: you know, but it's two hundred and fifty light years away.
• 32:23
  Speaker 2: Right. There's some sort of list out there right of
• 32:26
  Speaker 2: like of the stars that we can see that are
• 32:28
  Speaker 2: closest to us, which of these stars are big enough
• 32:31
  Speaker 2: to maybe go supernova. There's like a list out there, right.
• 32:34
  Speaker 1: There is a list exactly, and so Speaker is one
• 32:36
  Speaker 1: of them. Another one is Beetlejuice. Right, Beetlejuice is like
• 32:40
  Speaker 1: six hundred light years away, but is a pretty massive star.
• 32:43
  Speaker 1: It's like maybe up to twenty times the mass of
• 32:45
  Speaker 1: the Sun. And so these things are candidates. And again,
• 32:48
  Speaker 1: because we don't know exactly what triggers the supernova, like
• 32:52
  Speaker 1: what are the conditions to make this happen, we can't
• 32:54
  Speaker 1: look at Beetlejuice and be like, oh, this one is
• 32:56
  Speaker 1: ten years to supernova, or this one is ten million
• 32:59
  Speaker 1: years to supernova. But all of these things are pretty
• 33:02
  Speaker 1: far away. So you don't have to be too worried
• 33:04
  Speaker 1: about it.
• 33:05
  Speaker 2: Right, they're far away, but it maybe depends on the
• 33:07
  Speaker 2: size of the explosion, Like if something is super duper massive,
• 33:11
  Speaker 2: could that explosion affect us? Or is the distance going
• 33:14
  Speaker 2: to keep us safe?
• 33:15
  Speaker 1: So really the danger zone is something like twenty five
• 33:18
  Speaker 1: light years. Anything like twenty five light years away or
• 33:21
  Speaker 1: closer is going to do some significant damage to the Earth.
• 33:24
  Speaker 1: Anything further away than twenty five or fifty light years
• 33:27
  Speaker 1: is so far away that things are not going to
• 33:29
  Speaker 1: be so dramatic. Remember that all the radiation that comes
• 33:32
  Speaker 1: out of a supernova and all the particles and all
• 33:34
  Speaker 1: the energy drops very quickly as the distance gets larger,
• 33:38
  Speaker 1: because there's this one over distance squared rule in physics.
• 33:42
  Speaker 1: So if you are ten times further away, then the
• 33:44
  Speaker 1: amount of radiation is one over one hundred, and if
• 33:48
  Speaker 1: you're a thousand times further away, then the radiation drops
• 33:51
  Speaker 1: by a million. So every time the distance doubles, the
• 33:53
  Speaker 1: danger drops by a factor of four.
• 33:55
  Speaker 2: All right, so that means we're safe. Right, Like the
• 33:57
  Speaker 2: nearest star to us that could even goes supernova is
• 34:02
  Speaker 2: two hundred and fifty light years away, so we're good, right, maybe.
• 34:06
  Speaker 1: I mean there is this other star called I K. Pagassi.
• 34:08
  Speaker 1: It's about one hundred and fifty light years away, and
• 34:11
  Speaker 1: it's actually kind of small, but they think it's a
• 34:14
  Speaker 1: candidate to be a Type one A supernova because they
• 34:17
  Speaker 1: think it's probably gonna end up as a white dwarf,
• 34:19
  Speaker 1: and there is a red super giant nearby that it
• 34:21
  Speaker 1: could draw. So it's like a candidate to be a
• 34:24
  Speaker 1: Type one A supernova. And those are the most dangerous ones, right,
• 34:27
  Speaker 1: those are the ten times as bright ones.
• 34:29
  Speaker 2: Yeah, that's what I meant earlier. It sort of depends
• 34:31
  Speaker 2: on how big the explosion. So is a Type one
• 34:33
  Speaker 2: A explosion one hundred and fifty light years away from
• 34:36
  Speaker 2: us safe or would that totally burn us to a crisp.
• 34:40
  Speaker 1: Well, let's do the math. One hundred and fifty light
• 34:42
  Speaker 1: years away, it's like six times as far away as
• 34:44
  Speaker 1: the danger zone we said of like twenty five light years,
• 34:48
  Speaker 1: and so to be as dangerous at one hundred and
• 34:51
  Speaker 1: fifty light years away as another supernova is a twenty
• 34:53
  Speaker 1: five light years away. Since it's six times as far,
• 34:56
  Speaker 1: it would have to be like thirty six times as powerful,
• 35:00
  Speaker 1: only ten times as powerful then we'll be all right.
• 35:03
  Speaker 2: Okay, so that's good news.
• 35:04
  Speaker 1: Then that is good news.
• 35:06
  Speaker 2: Exactly, we're safe.
• 35:07
  Speaker 1: We're safe. But you know, a lot of it depends on
• 35:10
  Speaker 1: the uncertain physics of supernovas, or we just don't really
• 35:13
  Speaker 1: know which stars are going to go supernova or not,
• 35:16
  Speaker 1: so we could always be surprised.
• 35:17
  Speaker 2: You mean, like if we're totally wrong about this limit
• 35:21
  Speaker 2: for star, Like if we're wrong and our star could
• 35:23
  Speaker 2: certainly go supernova, is that even a possibilities? I think
• 35:26
  Speaker 2: that's what you're saying, right, Like, what if we're wrong,
• 35:28
  Speaker 2: what if like any star can go supernova? Or are
• 35:30
  Speaker 2: we pretty sure it's not going to go supernova.
• 35:32
  Speaker 1: We're pretty sure our star is not going to go supernova.
• 35:35
  Speaker 1: I'm just saying, don't take financial advice based on the
• 35:37
  Speaker 1: uncertain physics of supernovas.
• 35:41
  Speaker 2: Don't take financial advice from physicists in any circumstance that's right,
• 35:45
  Speaker 2: super nova or not exactly.
• 35:47
  Speaker 1: That's why we have the whole crash in two thousand
• 35:49
  Speaker 1: and eight. Too many physicists working on Wall Street.
• 35:54
  Speaker 2: Because there were too distracted looking at stars and not
• 35:56
  Speaker 2: paying attention to the economy.
• 35:59
  Speaker 1: Because they were buildings, numerical models that didn't make any sense.
• 36:01
  Speaker 2: Because clearly they don't care about money if they went
• 36:03
  Speaker 2: into a career in physics.
• 36:07
  Speaker 1: But if there was a supernova nearby, it is interesting
• 36:10
  Speaker 1: to think about exactly what the danger is. In one sense,
• 36:13
  Speaker 1: we're fortunate because most of the energy of a supernova
• 36:16
  Speaker 1: is actually put out in the form of neutrinos, Like
• 36:18
  Speaker 1: ninety nine percent of the crazy energy of a supernova
• 36:22
  Speaker 1: comes out in the form of neutrinos, which the universe
• 36:24
  Speaker 1: is mostly transparent to, so it's not actually dangerous. A
• 36:28
  Speaker 1: huge flux of neutrinos could pass right through you. You wouldn't
• 36:31
  Speaker 1: even notice it's happening. Right now, the Sun puts out
• 36:33
  Speaker 1: lots of neutrinos, you don't even notice. So it's like
• 36:36
  Speaker 1: that one percent of the energy of the supernova which
• 36:38
  Speaker 1: comes at as like very high energy photons gamma rays,
• 36:42
  Speaker 1: that could potentially damage us.
• 36:44
  Speaker 2: So it would be bad news.
• 36:45
  Speaker 1: It would be bad news. Like if it's high enough
• 36:48
  Speaker 1: intensity that actually makes it down to the surface, that
• 36:51
  Speaker 1: gets through the ozone layer in our atmosphere, which is
• 36:53
  Speaker 1: mostly opaque to these very high energy photons, then they
• 36:56
  Speaker 1: would just directly fry you, right, and it would fry
• 36:58
  Speaker 1: the Earth. The supernovas they are very short lived, but
• 37:02
  Speaker 1: you know we're talking about like days, weeks, months, So
• 37:06
  Speaker 1: even if you're on the other side of the Earth,
• 37:08
  Speaker 1: eventually the Earth is going to rotate and you're going
• 37:10
  Speaker 1: to be exposed. So unless the supernova is super short lived,
• 37:14
  Speaker 1: it's gonna fry both sides of the Earth. That's pretty unlikely.
• 37:17
  Speaker 1: It'd have to be super close to like literally actually
• 37:19
  Speaker 1: fry the Earth to a crisp More realistic is if
• 37:22
  Speaker 1: the supernova's close enough to o bathe us in high
• 37:24
  Speaker 1: energy radiation, but the atmosphere absorbs that. Even that would
• 37:28
  Speaker 1: be pretty dangerous because they would basically deplete our ozone layer.
• 37:31
  Speaker 1: It would fry all the oxygen and nitrogen the atmosphere
• 37:34
  Speaker 1: into other oxides and basically strip us up protection, exposing
• 37:38
  Speaker 1: us to UV radiation from the Sun, which would basically
• 37:42
  Speaker 1: kill all the planks in the oceans, which would undermine
• 37:45
  Speaker 1: the ecosystem, and things would be bad.
• 37:48
  Speaker 2: Things would be bad.
• 37:49
  Speaker 1: Things would be bad.
• 37:50
  Speaker 2: Well, I think that answer is Christo's question directly, Like
• 37:52
  Speaker 2: he asked, what would happen if there's a supernova nearby?
• 37:55
  Speaker 2: And the answer is bad. Things would happen, we would
• 37:58
  Speaker 2: get fried or ozone would get fried. It would be
• 38:02
  Speaker 2: not good. But the bigger answer is that it's not
• 38:05
  Speaker 2: likely to happen. Like, as far as we know, there
• 38:08
  Speaker 2: are no stars nearras enough that might go supernova to
• 38:12
  Speaker 2: really harm us.
• 38:13
  Speaker 1: That's right. So for the near future we're pretty safe.
• 38:15
  Speaker 1: Remember that the stars were nearby change as the galaxy
• 38:18
  Speaker 1: is rotating and we move up and down through the
• 38:20
  Speaker 1: galactic disk, And so this is sort of like an
• 38:22
  Speaker 1: answer for right now or the next few thousand years.
• 38:25
  Speaker 1: You want to project forward to like hundreds of millions
• 38:28
  Speaker 1: of years, then things might change and other stars might
• 38:31
  Speaker 1: get closer to us that are more dangerous. They estimate
• 38:34
  Speaker 1: when they look back that maybe twenty supernovas have happened
• 38:37
  Speaker 1: within a thousand light years of Earth in the last
• 38:39
  Speaker 1: ten million years. But remember a thousand light years is
• 38:42
  Speaker 1: pretty far away. That's well out of the danger zone.
• 38:46
  Speaker 2: But don't we sort of know, like all the stars
• 38:49
  Speaker 2: our neighborhood, like how it's going to change over the
• 38:51
  Speaker 2: next you know, maybe several hundred million years. Can we
• 38:54
  Speaker 2: do that math?
• 38:55
  Speaker 1: We can do that math in some cases, but measuring
• 38:57
  Speaker 1: these stellar velocities can be challenging. We have these awesome
• 39:00
  Speaker 1: new satellites, a Gaya satellite, for example, which is cataloging
• 39:03
  Speaker 1: the exact location of these stars and tracking them, and
• 39:06
  Speaker 1: so we're getting better and better at modeling these things.
• 39:08
  Speaker 1: But it's kind of chaotic, right, stars pull and tug
• 39:11
  Speaker 1: on each other. You have a very high number of objects.
• 39:14
  Speaker 1: We can't really even solve equations for three objects, and
• 39:17
  Speaker 1: we're talking about like one hundreds or thousands or millions
• 39:20
  Speaker 1: of objects, So there can be chaotic predictions. You can
• 39:23
  Speaker 1: never really be sure what's going to happen deep into
• 39:26
  Speaker 1: the future.
• 39:27
  Speaker 2: All right, So Christoph, the answer is bad things might happen,
• 39:30
  Speaker 2: but you don't have to worry about that, but maybe
• 39:33
  Speaker 2: check back again in one hundred million years, just to
• 39:35
  Speaker 2: double check.
• 39:36
  Speaker 1: Keep making those retirement deposits.
• 39:38
  Speaker 2: Though, I think he's good for now. All right, Well,
• 39:41
  Speaker 2: let's get to our last question of the day, and
• 39:43
  Speaker 2: this one is about storms in our solar system. We'll
• 39:47
  Speaker 2: get into that, but first let's take another quick break.
• 40:02
  Speaker 2: All right. We're answering listener questions here today about the
• 40:06
  Speaker 2: ways that the universe could put an end to human
• 40:10
  Speaker 2: existence perhaps, and so our last question comes from Jane
• 40:14
  Speaker 2: who is in fifth grade.
• 40:16
  Speaker 3: Hi, I'm Jane.
• 40:18
  Speaker 2: I'm in fifth grade and we're learning about our solar system,
• 40:22
  Speaker 2: and I would like to know what is the strongest
• 40:25
  Speaker 2: storm in our solar system. Awesome question from Jane. Thank
• 40:28
  Speaker 2: you Jane for asking that question. I wonder if she's
• 40:31
  Speaker 2: asking so whether she knows to bring an umbrella to
• 40:34
  Speaker 2: school the next day.
• 40:36
  Speaker 1: Or maybe she's planning a trip and she wants to
• 40:38
  Speaker 1: know if she should visit Venus or Mars or Jupiter because.
• 40:42
  Speaker 2: She wants to see the storm or avoid the storm.
• 40:45
  Speaker 2: She sounds like a very curious person.
• 40:46
  Speaker 1: She does sound like it. Yeah, exactly, Let's send Jane
• 40:49
  Speaker 1: on our next trip to visit the Sun.
• 40:52
  Speaker 2: Give her a lead umbrella just in case. I guess
• 40:55
  Speaker 2: her question is that like actual storms, like weather storms
• 40:58
  Speaker 2: that happen not just on Earth, they happen in other planets, right,
• 41:01
  Speaker 2: other planets half atmospheres with gases and things like that,
• 41:05
  Speaker 2: and clouds and weather. And so her question, I think
• 41:09
  Speaker 2: is like, out of all the planets in the Solar System,
• 41:11
  Speaker 2: who has the biggest storm that we've seen?
• 41:13
  Speaker 1: Yeah, because there's this tendency to imagine that things out
• 41:16
  Speaker 1: there in the universe are sort of like they are
• 41:18
  Speaker 1: here on Earth. But as you look around the Solar System,
• 41:21
  Speaker 1: you discover, wow, Earth is pretty different, right. We have
• 41:24
  Speaker 1: liquid water on the surface, we have clouds, we have
• 41:27
  Speaker 1: very different kind of situation. And the storms we have
• 41:29
  Speaker 1: here on Earth are actually not very representative of what's
• 41:32
  Speaker 1: going on in the rest of the Solar System. It's
• 41:34
  Speaker 1: actually quite nice and calm here on Earth compared to
• 41:38
  Speaker 1: the stormy Solar system we live in.
• 41:40
  Speaker 2: Yeah, so that's the recap of all the storms in
• 41:42
  Speaker 2: the Solar system, starting with I guess the Sun, right,
• 41:45
  Speaker 2: the Sun has storms.
• 41:46
  Speaker 1: The Sun has really big storms. Right. It's not just
• 41:49
  Speaker 1: a ball of plasma. It's like throbbing and pulsating, and
• 41:53
  Speaker 1: there's these tubes of plasma controlled by magnetic fields that
• 41:56
  Speaker 1: we don't even really understand. And occasionally big loops of
• 42:00
  Speaker 1: plasma are ejected from the Sun and travel towards the Earth.
• 42:04
  Speaker 1: These are called coronal mass ejections, and when they happen,
• 42:07
  Speaker 1: they're very dramatic, like these loops of plasma can be
• 42:10
  Speaker 1: bigger than the entire Earth. And so some of the
• 42:13
  Speaker 1: biggest storms in the Solar System are in the Sun itself.
• 42:18
  Speaker 2: I guess maybe let's take a quick step back here,
• 42:20
  Speaker 2: and what do you define as a storm, Like what
• 42:23
  Speaker 2: counts as a storm and what is just the irregular
• 42:25
  Speaker 2: things moving around.
• 42:26
  Speaker 1: Yeah, it's a good question. I guess I would call
• 42:28
  Speaker 1: a storm sort of an unusual high energy like high
• 42:32
  Speaker 1: speed or high velocity event, right, Like, that's what we
• 42:35
  Speaker 1: think about on Earth. There's wind every day, there's a
• 42:37
  Speaker 1: storm when the wind is sort of like unusually high,
• 42:40
  Speaker 1: or there's unusual amount of rain.
• 42:43
  Speaker 2: Okay, so like when things get exciting in the atmosphere
• 42:46
  Speaker 2: or something.
• 42:47
  Speaker 1: Exactly exciting or dangerous depending on your attitude. And so
• 42:51
  Speaker 1: basically we're thinking about like unusual events like tales of distributions.
• 42:55
  Speaker 1: And it's even fun to think about like the strongest
• 42:57
  Speaker 1: storms here on Earth. The strongest typhoon on Earth or
• 43:01
  Speaker 1: equivalently hurricane depending on which ocean you're in, was in
• 43:04
  Speaker 1: nineteen and seventy nine. It's called Typhoon Tip and this
• 43:09
  Speaker 1: lasted for weeks, and it was one thousand miles wide.
• 43:13
  Speaker 1: It's like big enough to cover like half of the
• 43:16
  Speaker 1: United States, though he was actually in the Pacific.
• 43:20
  Speaker 2: So this is a weather event here on Earth that
• 43:22
  Speaker 2: was one thousand miles wide. And here on Earth, I
• 43:25
  Speaker 2: guess storms happened because you know, there's air currents moving around,
• 43:28
  Speaker 2: because the air heats up from the sun and moves
• 43:31
  Speaker 2: into the cold sides. And I guess sometimes in all
• 43:34
  Speaker 2: of this air moving, sometimes you get like these pockets
• 43:37
  Speaker 2: of things where things get intense. That's kind of what
• 43:40
  Speaker 2: a storm is on Earth.
• 43:41
  Speaker 1: Exactly, and they get spinning because of the Coriolis force,
• 43:44
  Speaker 1: which is why these storms spin differently in the Northern
• 43:47
  Speaker 1: Hemisphere and the Southern hemisphere. You know, it's a myth
• 43:50
  Speaker 1: that toilets flush differently in Australia than they do in
• 43:53
  Speaker 1: the US, for example, But it's not a myth that
• 43:56
  Speaker 1: storms spin differently in the northern and southern hemispheres.
• 43:59
  Speaker 2: How do you know it's a myth? You have you
• 44:00
  Speaker 2: flushed every toilet in Australia to make that statement.
• 44:05
  Speaker 1: I have not gone on a toilet flushing tour of Australia.
• 44:07
  Speaker 1: That's still on my to do list. But I've relied
• 44:09
  Speaker 1: on listeners who've written in who can verify this for us.
• 44:12
  Speaker 2: But it is true that it affects like if you
• 44:14
  Speaker 2: drain a giant waiting pool, it is going to affect
• 44:16
  Speaker 2: how the water swirls. Right, maybe, just like in toilets
• 44:21
  Speaker 2: is too small.
• 44:23
  Speaker 1: If you have a hurricane sized toilet, then yes, that
• 44:25
  Speaker 1: will definitely affect you. I'm not exactly sure what the
• 44:28
  Speaker 1: minimum sized toilet has to be to see this effect.
• 44:31
  Speaker 2: Sounds like an experiment of physicist should do.
• 44:33
  Speaker 1: I'm going to go ride a grand proposal after we're
• 44:35
  Speaker 1: done here, all.
• 44:35
  Speaker 2: Right, So then on Earth, that's the biggest storm and
• 44:38
  Speaker 2: in recorded history, one thousand miles wide a couple of
• 44:41
  Speaker 2: decades ago.
• 44:42
  Speaker 1: Lasted for weeks and had winds up to like six
• 44:45
  Speaker 1: hundred kilometers per hour, which is pretty dramatic. And then
• 44:47
  Speaker 1: of course there are storms on our neighboring planets. Venus
• 44:51
  Speaker 1: has storms, and in general the weather on Venus is
• 44:53
  Speaker 1: generally pretty terrible. It's like very high air pressure, very
• 44:57
  Speaker 1: strong winds, sulfuric acid rain, lightning storms driven by volcanic eruptions.
• 45:03
  Speaker 2: And it's super hot in Venus too, right, And it's.
• 45:05
  Speaker 1: Super hot exactly, is the reason that when we talk
• 45:08
  Speaker 1: about colonizing Venus, we think about like creating floating cities
• 45:12
  Speaker 1: above the cloud layers. But there are also some really
• 45:15
  Speaker 1: cool storms on Venus at its poles, like the pioneer
• 45:19
  Speaker 1: Venus spacecraft in nineteen seventy nine saw this really incredible
• 45:23
  Speaker 1: hurricane on Venus's north pole that had two eyes to it.
• 45:28
  Speaker 1: The storms on Earth usually have one core, right, there's
• 45:31
  Speaker 1: an eye at the center and it's a big swirl,
• 45:33
  Speaker 1: but this one on the north pole of Venus has
• 45:36
  Speaker 1: two eyes. Whoa.
• 45:38
  Speaker 2: It sounds like somebody flushed two toilets at the same
• 45:40
  Speaker 2: time in the north pole of Venus.
• 45:42
  Speaker 1: And then they went back to Venus in two thousand
• 45:44
  Speaker 1: and six and the Venus Express saw what looked like
• 45:47
  Speaker 1: a double vortex at the south pole. As a scientist
• 45:50
  Speaker 1: where like, whoa, maybe these crazy double hurricanes on Venus
• 45:55
  Speaker 1: are stable and permanent, But as they watched, they saw
• 45:57
  Speaker 1: that it sort of shifted and morphed and didn't really survive.
• 46:01
  Speaker 2: It didn't become a viral video. This is going WHOA
• 46:05
  Speaker 2: double storm.
• 46:07
  Speaker 1: But it's interesting because Venus has these like very high
• 46:10
  Speaker 1: wind speeds, and the weather changes a lot from the
• 46:13
  Speaker 1: poles to the equator, where the winds, for example, vary
• 46:17
  Speaker 1: greatly with altitude. The windspeeds can vary by like a
• 46:19
  Speaker 1: factor of two. Anyway, it's really crazy weather on Venus,
• 46:22
  Speaker 1: as well, all.
• 46:23
  Speaker 2: Right, well, what's there in the next planet on the
• 46:25
  Speaker 2: list of Mars. Does Mars get storms?
• 46:28
  Speaker 1: Mars does get storms.
• 46:29
  Speaker 2: Mars has a very sparse atmosphere, right, yeah, and so.
• 46:32
  Speaker 1: They can look very dramatic, but they're not actually that powerful.
• 46:36
  Speaker 1: Like there are maybe once per decade or so a
• 46:39
  Speaker 1: dust storm that can engulf like the entire planet for
• 46:43
  Speaker 1: a whole month. That's pretty dramatic. And people who saw
• 46:46
  Speaker 1: the movie The Martian will have noticed like, ooh wow,
• 46:48
  Speaker 1: these storms are dangerous and they can knock stuff over.
• 46:51
  Speaker 1: But as you say, Mars does not have a very
• 46:53
  Speaker 1: dense atmosphere. It's like one percent as dense as the
• 46:56
  Speaker 1: Earth's atmosphere, and so like you couldn't really fly a
• 46:59
  Speaker 1: kite on very easily. Or the helicopter that they recently
• 47:03
  Speaker 1: landed on Mars was really amazing that he could even
• 47:05
  Speaker 1: fly because the air is so sparse, So even the
• 47:08
  Speaker 1: wind in like the largest dust storm on Mars could
• 47:12
  Speaker 1: not really tip over or rip apart like major mechanical equipment,
• 47:16
  Speaker 1: not the way storms here on Earth do.
• 47:17
  Speaker 2: But isn't it the case that scientists think Mars had
• 47:21
  Speaker 2: an atmosphere and past or maybe Mars did have bigger
• 47:23
  Speaker 2: storms before.
• 47:24
  Speaker 1: Yeah, Mars probably lost its atmosphere because of solar winds
• 47:27
  Speaker 1: and the lack of a magnetic field. And also it's
• 47:29
  Speaker 1: just lower mass and so it's not as good as
• 47:31
  Speaker 1: holding onto its particles. So in its past it may
• 47:34
  Speaker 1: have had more dramatic storms. These days, they look dramatic,
• 47:38
  Speaker 1: but they're not actually very intense.
• 47:40
  Speaker 2: All right, let's get to some of the bigger planets.
• 47:42
  Speaker 2: What about Jupiter.
• 47:43
  Speaker 1: Jupiter has, of course the famous Great Red Spot. This
• 47:46
  Speaker 1: is a huge storm, a few times the size of
• 47:49
  Speaker 1: the Earth, right, so, like we're talking mind boggling all
• 47:52
  Speaker 1: sizes here, though again it's small compared to Jupiter, which
• 47:56
  Speaker 1: is just much much bigger than the Earth. The Great
• 47:58
  Speaker 1: Red Spot goes around Jupiter six earth days and it's
• 48:01
  Speaker 1: like a couple hundred miles deep, and it's really impressive
• 48:05
  Speaker 1: because it's lasted a long time. Like we've been watching
• 48:07
  Speaker 1: this storm on Jupiter since Galileo, basically since the sixteen hundreds,
• 48:12
  Speaker 1: and so it's hundreds of years old, which makes it
• 48:15
  Speaker 1: incredibly stable.
• 48:16
  Speaker 2: Mmm. Yeah, and it's shrinking too, right, like it's been
• 48:20
  Speaker 2: getting smaller.
• 48:21
  Speaker 1: Yeah, it is stable in that it's like lasted a
• 48:23
  Speaker 1: long time, but in the last forty years or so,
• 48:26
  Speaker 1: we noticed that it has been getting smaller. Now it's
• 48:29
  Speaker 1: like maybe just one and a half times the size
• 48:31
  Speaker 1: of the Earth. And you know, not something we understand
• 48:34
  Speaker 1: very well. These chaotic things turbulence and vortices are very
• 48:37
  Speaker 1: difficult to model and very difficult to understand. But it's
• 48:40
  Speaker 1: still a huge.
• 48:41
  Speaker 2: Storm, right, and we don't know why it's red, right,
• 48:45
  Speaker 2: Like we don't know for sure.
• 48:46
  Speaker 1: Yeah, that's right, And we did a whole episode about
• 48:48
  Speaker 1: the Great Red Spots to dig into that. If you
• 48:50
  Speaker 1: want to learn more about that crazy storm.
• 48:52
  Speaker 2: M all right, how about Saturn.
• 48:55
  Speaker 1: Saturn is super cool because it has really weird storms
• 48:59
  Speaker 1: on the pole like Venus does, remember with its double hurricane,
• 49:02
  Speaker 1: except Saturn has this six sided storm on its poles.
• 49:07
  Speaker 1: It's a hexagon. It's like thirty thousand kilometers widen, like
• 49:10
  Speaker 1: one hundred kilometers deep, first discovered nineteen eighty one by
• 49:14
  Speaker 1: Voyager and then when Cassini flew by took really beautiful
• 49:18
  Speaker 1: pictures of it, and now they think it's probably like
• 49:21
  Speaker 1: a complex set of vortices and different layers of clouds,
• 49:24
  Speaker 1: but it creates this incredible hexagon effect, which looks really weird.
• 49:28
  Speaker 2: It's almost like it's wearing a hat.
• 49:30
  Speaker 1: Yeah, exactly, all right, yeah, i'mu coo right, yeah, But
• 49:33
  Speaker 1: it's sort of a stable feature of Saturn, we think.
• 49:36
  Speaker 1: On the other hand, Saturn also has unusual features, like
• 49:40
  Speaker 1: it has these storms which crop up like every twenty
• 49:42
  Speaker 1: or thirty years, and sometimes they can encircle the entire planet.
• 49:47
  Speaker 1: So there was one in December of twenty ten that
• 49:49
  Speaker 1: was like ten times the size of the Earth, so
• 49:52
  Speaker 1: like much bigger than even the Great Red Spot and
• 49:55
  Speaker 1: lasted for like ten months.
• 49:57
  Speaker 2: Whoa, it's a big store. And how fast we're the
• 50:00
  Speaker 2: winds moving.
• 50:01
  Speaker 1: The winds in that storm we think move around one
• 50:02
  Speaker 1: hundred kilometers per hour, So pretty dramatic stuff, right. What
• 50:06
  Speaker 1: about Neptune, Well, the strongest winds in the Solar System
• 50:10
  Speaker 1: might be on Neptune, so maybe the biggest storm it
• 50:13
  Speaker 1: was that one on Saturn, but the most powerful winds
• 50:16
  Speaker 1: are probably on Neptune. So in Neptune, we saw this
• 50:19
  Speaker 1: great dark spot in nineteen eighty nine, this huge spot
• 50:23
  Speaker 1: on Neptune, which they now think are methane ice clouds
• 50:27
  Speaker 1: which are forming crystals probably about the size of one
• 50:30
  Speaker 1: Earth this storm had wind speeds of two thousand kilometers
• 50:34
  Speaker 1: per hour.
• 50:34
  Speaker 2: Two thousand kilometers per hour. That's super fast. Is that
• 50:40
  Speaker 2: faster than the speed of sound here on Earth?
• 50:42
  Speaker 1: Yeah? The speed of sound here on Earth is about
• 50:45
  Speaker 1: twelve hundred kilometers per hour.
• 50:47
  Speaker 2: Whoa, So this was a supersonic storm.
• 50:52
  Speaker 1: That's pretty awesome. Although the speed of sound depends a
• 50:55
  Speaker 1: lot on the density and the temperature and all sorts
• 50:57
  Speaker 1: of stuff, So I don't know what the speed of
• 50:59
  Speaker 1: sound is in those methane ice clouds, but yeah, it's
• 51:02
  Speaker 1: faster than the speed of sound in air on Earth.
• 51:06
  Speaker 1: So that's pretty incredible.
• 51:07
  Speaker 2: And it's also the most powerful storm because it's made
• 51:09
  Speaker 2: out of methane, which means it smells like farts.
• 51:14
  Speaker 1: And that's why we're glad it's on Neptune and not
• 51:16
  Speaker 1: on Urinous.
• 51:19
  Speaker 2: He who storm smelt it? I guess.
• 51:24
  Speaker 1: I'm just glad there are no supersonic farts here on Earth.
• 51:26
  Speaker 2: Yeah, or supersonic storms or farts that'd be even worse.
• 51:32
  Speaker 2: All right. So maybe to answer Jamee's question, those would
• 51:35
  Speaker 2: be maybe the candidates we would put up as the
• 51:37
  Speaker 2: strongest storms in our solar system. There's the one at
• 51:40
  Speaker 2: the top of Saturn which looks like a hexagon, which
• 51:42
  Speaker 2: is thirty thousand kilometers wide, which is like ten times
• 51:46
  Speaker 2: the diameter of Earth or something like that.
• 51:48
  Speaker 1: Mm hmm.
• 51:49
  Speaker 2: And then there's the storm we saw on Neptune about
• 51:52
  Speaker 2: thirty years ago that had two thousand kilometers per hour winds.
• 51:56
  Speaker 1: I don't know if you want to study those or
• 51:58
  Speaker 1: avoid those, but either way, some boots in a raincoat.
• 52:01
  Speaker 2: But I guess the Neptune one is gone now.
• 52:03
  Speaker 1: Right when we looked at it again in nineteen ninety
• 52:05
  Speaker 1: four with Hubble, they didn't see it and it has
• 52:08
  Speaker 1: not come back.
• 52:09
  Speaker 2: So maybe the most awesome storm right now is Saturn
• 52:11
  Speaker 2: until we see something else which can happen. Because all
• 52:14
  Speaker 2: of these things are happening right now and they can
• 52:16
  Speaker 2: change at any moment.
• 52:17
  Speaker 1: That's right, And these aren't complex effects. Remember, we can't
• 52:20
  Speaker 1: even predict the weather on Earth very well, and so
• 52:23
  Speaker 1: when it comes to the weather on Neptune, we are
• 52:25
  Speaker 1: all left guessing.
• 52:26
  Speaker 2: All right, Well, thank you Jane for your question. I
• 52:28
  Speaker 2: guess she's maybe asking because, like if we go to
• 52:31
  Speaker 2: another planet, we want to avoid these storms, right because
• 52:34
  Speaker 2: they can also end.
• 52:35
  Speaker 1: Us exactly, Or maybe she's just in awe of the
• 52:39
  Speaker 1: incredible conditions out there in the rest of the Solar System,
• 52:41
  Speaker 1: and grateful that we don't have such crazy storms here and.
• 52:44
  Speaker 2: That we can look at them from a distance. All right, Well,
• 52:47
  Speaker 2: that's all of our questions for today. Thank you to
• 52:49
  Speaker 2: everyone who's sent in their questions and hopefully we answered
• 52:53
  Speaker 2: them a little bit.
• 52:54
  Speaker 1: And I hope we give you confidence that whatever the
• 52:56
  Speaker 1: scientists uncover about the crazy natures of the universe, eventually
• 52:59
  Speaker 1: and hear and we'll save us.
• 53:01
  Speaker 2: That's right, a super engineer.
• 53:03
  Speaker 1: They're all superheroes in my book.
• 53:04
  Speaker 2: All Right, Well, we hope you enjoyed that. Thanks for
• 53:07
  Speaker 2: joining us, See you next time.
• 53:16
  Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain
• 53:19
  Speaker 1: the Universe is a production of iHeartRadio. For more podcasts
• 53:23
  Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
• 53:28
  Speaker 1: you listen to your favorite shows.