Latest / Daniel and Kelly’s Extraordinary Universe / Can the Earth survive when the Sun expands?

Transcript

Can the Earth survive when the Sun expands? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Kelly, I've been thinking about something you said to me.
0:12
Speaker 1: Oh okay, what did I say? Well, when you moved
0:15
Speaker 1: to the Science Farm awhile ago, you said that I
0:17
Speaker 1: was welcome to come visit. But then last episode you
0:20
Speaker 1: officially retracted that invitation. Well, yeah I did because you
0:25
Speaker 1: said you were going to tell my kids that shooting
0:27
Speaker 1: stars might kill them. So I think I was justified.
0:30
Speaker 1: All right, Well, then it's now my official goal to
0:33
Speaker 1: earn back an invitation. Okay, but like it's not a
0:36
Speaker 1: super high bar. Just don't give my kids nightmares. Well
0:40
Speaker 1: do your kids want to hear about how the sun
0:41
Speaker 1: is going to explode one day? So you know, I'm
0:44
Speaker 1: thinking that maybe you should just wait until they grow
0:47
Speaker 1: up and move away, and then you can come visit,
0:50
Speaker 1: assuming they move away before the sun explodes, I hope. So.
0:57
Speaker 1: As much as we love our kids, we do want
0:59
Speaker 1: them to move away eventually, eventually. Yes, Hi, I'm Daniel.
1:18
Speaker 1: I'm a particle physicist and a professor at U C Irvine,
1:21
Speaker 1: and I don't like scaring children, but I do like
1:24
Speaker 1: telling them the truth. I'm Kelly Wayner Smith um an
1:30
Speaker 1: edgeunt professor at Rice University, and I prefer lying to them.
1:35
Speaker 1: What you lie to your kids. What if they ask
1:37
Speaker 1: you a science question you don't know the answer, you
1:39
Speaker 1: just make one up. No, in that case, I tell
1:41
Speaker 1: them the truth. That's important, you know. But one of
1:44
Speaker 1: them does still believe in Santa And now we'll not
1:46
Speaker 1: be listening to this episode. What if they ask you
1:51
Speaker 1: a science question that has a scary answer, It depends
1:54
Speaker 1: on it if I think they can handle it or not.
1:56
Speaker 1: And it depends on what I want to go to
1:58
Speaker 1: bed that night, because I might be up late doing
2:00
Speaker 1: the explaining. There's lots of things to consider. Well, then
2:03
Speaker 1: let's hope they don't ask you about when the sun
2:05
Speaker 1: is gonna But welcome to the podcast Daniel and Jorge
2:08
Speaker 1: Explain the Universe, in which we try to teach you
2:11
Speaker 1: everything about the universe, scary or not, the things that
2:15
Speaker 1: will keep you up at night, worried about whether you
2:18
Speaker 1: will survive, and the things that make you feel like
2:20
Speaker 1: the universe is a comfortable, cozy places all set up
2:24
Speaker 1: for you to have a good time. We talk about
2:26
Speaker 1: black holes, we talk about quirks. We talk about the
2:28
Speaker 1: future of the human race and whether it has a
2:31
Speaker 1: future or not. Dark stuff, My friend and co host
2:36
Speaker 1: Jorge can't be here today, so we are joined by
2:38
Speaker 1: Kelly Weener Smith, who is trying to teach you things
2:41
Speaker 1: without scaring your children. I feel like maybe I need
2:44
Speaker 1: to defend that decision, but I'm just gonna let it go.
2:47
Speaker 1: Sometimes kids don't need to be scared. You get to
2:49
Speaker 1: spend your whole adulthood being scared about stuff. You know
2:52
Speaker 1: you're right, And the thing I love about the universe
2:54
Speaker 1: is that it doesn't really care about our feelings. It's
2:57
Speaker 1: just crazy. It's just bonkers. It's just doing its thing,
3:01
Speaker 1: whether that means it's threatening to tear you apart and
3:03
Speaker 1: blow you away, or whether it's created this wonderful environment
3:07
Speaker 1: for you to relax in and sip your market riata
3:09
Speaker 1: while you listen to a podcast. The universe doesn't care
3:12
Speaker 1: either way. You know, it's really good that you went
3:14
Speaker 1: into physics and not like psychiatry or something. And how
3:18
Speaker 1: how are your kids turning out? My kids so far
3:21
Speaker 1: are not sociopaths, you know, but hey, we need to
3:24
Speaker 1: collect more data. No, my strategy has always been to
3:27
Speaker 1: answer their questions honestly, though I will admit if their
3:31
Speaker 1: questions bring up something awkward or uncomfortable or maybe age inappropriate.
3:35
Speaker 1: I'll try to deflect the question once or twice, but
3:38
Speaker 1: if they really insist, if they drill in for an answer,
3:40
Speaker 1: I'm giving it to them. Well, you know, we should
3:42
Speaker 1: both be trying to collect more systematic data, and we'll
3:45
Speaker 1: see if you were kids or my kids handle the
3:47
Speaker 1: future better. I see whose kids grew up weirder, like
3:51
Speaker 1: the children of a physicist or the children of a
3:54
Speaker 1: cartoonist and parasitologist. I don't know. Both sets have stiff
3:58
Speaker 1: odds overcoming their parents are doing to them, I think exactly.
4:02
Speaker 1: And it's a weird universe out there, and one that
4:06
Speaker 1: sort of defines the context of our lives. The more
4:08
Speaker 1: we learn about how the universe works and how our
4:11
Speaker 1: neighborhood has been put together, the more we understand how
4:14
Speaker 1: fragile our existence on this rock is. That's right, you know.
4:17
Speaker 1: The more we talk, the more I'm wondering if maybe
4:19
Speaker 1: you should be lying to me. Also, forget the kids.
4:23
Speaker 1: I'm not sure I can handle this, but alright, alright,
4:25
Speaker 1: let's see how I do today. All right, If this
4:27
Speaker 1: podcast keeps you, feel free to call me at two
4:29
Speaker 1: am and I'll tell you even scarier things about the universe.
4:33
Speaker 1: I'll pass. Thanks, you're like an anti friend. Well, something
4:38
Speaker 1: I think that people should be more worried about and
4:41
Speaker 1: more scared of is sort of the context of our
4:44
Speaker 1: situation here. You know. I think a lot of people
4:46
Speaker 1: think about the solar system as something old, something that's
4:50
Speaker 1: been there for a long time, like a mountain that's
4:52
Speaker 1: survived millions and millions of years. But the truth is
4:55
Speaker 1: that the solar system is actually a very chaotic and
4:58
Speaker 1: dynamic place. It hasn't a we've looked the way that
5:01
Speaker 1: it does today, and it will not always look the
5:03
Speaker 1: way that it does today. And in the future. Is
5:05
Speaker 1: it going to be less nice to us than it
5:07
Speaker 1: is right now? Because last time we talked to you
5:09
Speaker 1: told me that shooting stars were trying to kill us.
5:12
Speaker 1: It gets worse, I don't know about worse. It's going
5:15
Speaker 1: to get different, for sure, sort of in the science
5:18
Speaker 1: fiction movie plot twists sort of a way. I mean,
5:20
Speaker 1: I think there's something that people don't appreciate, which is
5:22
Speaker 1: that our solar system hasn't even existed for the whole
5:26
Speaker 1: length of the universe. The universe is like fourteen billion
5:30
Speaker 1: years old. Our solar systems only four and a half billion,
5:33
Speaker 1: which means the first nine billion years our Sun didn't
5:37
Speaker 1: even exist, Like there was nothing like our Solar system.
5:41
Speaker 1: So we're relative newcomers in the universe. We're not even
5:45
Speaker 1: middle aged, and we might just be here for a blip.
5:49
Speaker 1: And as you and I have talked about on the
5:50
Speaker 1: podcast a couple of times, the Solar system itself has
5:53
Speaker 1: seen a lot of transformations. People think that maybe Jupiter
5:57
Speaker 1: was formed closer to the Sun, or maybe it formed
5:59
Speaker 1: far out and then migrated in and then migrated back
6:02
Speaker 1: out the outer Solar system, ejecting some other planets along
6:06
Speaker 1: the way. Our Solar system might have had other planets
6:08
Speaker 1: which are now lost to us, like siblings that were
6:11
Speaker 1: rejected by our parents. But surely when the Sun realizes
6:15
Speaker 1: that humans are on the Earth, the whole Solar system
6:17
Speaker 1: is going to start behaving for us. Right. I don't
6:21
Speaker 1: think the Sun cares at all about us, and I
6:24
Speaker 1: think it's amazing that we have sort of evolved on
6:26
Speaker 1: this rock under these conditions which have been fairly stable
6:31
Speaker 1: over the last few billion years. But we're also very
6:34
Speaker 1: dependent on those conditions. If they change even just a
6:37
Speaker 1: little bit, then life on Earth could be very, very different.
6:41
Speaker 1: When is that going to happen? Do we know? It
6:43
Speaker 1: turns out that the conditions are constantly changing. The Sun
6:47
Speaker 1: is getting brighter and brighter every year. Originally for us,
6:50
Speaker 1: it's pretty slow, but as we think deep, deep into
6:53
Speaker 1: the future of humanity, conditions could change a lot over
6:56
Speaker 1: millions or billions of years. And I hope at least
7:00
Speaker 1: that our children and our children's children and our children's
7:02
Speaker 1: children's children's children's children are around in billions or billions
7:06
Speaker 1: of years to scare each other with crazy stories about
7:08
Speaker 1: the future. Me too, but probably they're gonna have to
7:12
Speaker 1: be pretty clever to stick around for that long. They
7:15
Speaker 1: are going to have to be pretty clever if we
7:17
Speaker 1: want to outlast our cosmic conditions, if we want a
7:20
Speaker 1: society that lasts for millions or billions of years, then
7:23
Speaker 1: the clock is ticking. We're going to have to figure
7:26
Speaker 1: this out before our conditions changed. I mean, we've only
7:29
Speaker 1: ever lived here on Earth under these circumstances, so we're
7:33
Speaker 1: gonna have to do some pretty clever engineering if we're
7:36
Speaker 1: going to figure out how to live in the future
7:39
Speaker 1: of our own solar system. Well, I sure hope we're
7:41
Speaker 1: smart to figure that out. It might depend on how
7:43
Speaker 1: long we have to figure it out. But I'm keeping
7:45
Speaker 1: my fingers crossed exactly, And that's precisely what we'll be
7:48
Speaker 1: talking about today. So on the podcast, we'll be asking
7:52
Speaker 1: the question can the Earth survive when the sun expands?
8:04
Speaker 1: How do you feel, Kelly about this sort of apocalyptic
8:06
Speaker 1: scenarios we've been imagining recently on the podcast, asteroid impacts,
8:11
Speaker 1: nuclear disasters. Yeah, well, you know, I gotta say I'm
8:14
Speaker 1: starting to have this feeling of anxiety when our monthly
8:17
Speaker 1: time to record together comes, you know, to what extent
8:20
Speaker 1: is my conversation with Daniel going to amp up the
8:23
Speaker 1: existential dread in my life? So here we go again
8:26
Speaker 1: for another roller coaster ride. Well, that's one way to
8:29
Speaker 1: look at it. The other way to look at it
8:31
Speaker 1: is like, what is physics going to do to save us? Right?
8:34
Speaker 1: We are constantly thinking about the deep future of humanity
8:37
Speaker 1: and wondering what we have to do today to make
8:40
Speaker 1: sure that we are prepared for those eventualities, to make
8:43
Speaker 1: sure that those humans living many many years from now
8:46
Speaker 1: can build on our work and survive. Yeah, I suppose
8:50
Speaker 1: I should be. I should be thanking the physicists for
8:52
Speaker 1: figuring out these problems way ahead of time, so we
8:55
Speaker 1: have a long lead time to try to do something
8:57
Speaker 1: about it. Exactly. The thing to really be scared about
9:00
Speaker 1: are the things business haven't yet figured out that we'll
9:03
Speaker 1: probably kill us all m This is why we need
9:05
Speaker 1: more money for the sciences, exactly. It's always the unknown
9:08
Speaker 1: unknowns that'd kill you that, right, I mean you well,
9:12
Speaker 1: you know, we we've also talked about how the nonns
9:15
Speaker 1: will kill you. So it sounds like there's a lot
9:16
Speaker 1: of things that can kill you. There are a lot
9:18
Speaker 1: of things that can kill you, but there are also
9:20
Speaker 1: a lot of things we can do, I think, to
9:22
Speaker 1: our physicist and engineers to maybe save our tissues. It's
9:29
Speaker 1: been a long time since I've heard the wood tushies.
9:32
Speaker 1: Is that what you said? That tusses? Yeah, I'm trying
9:34
Speaker 1: to be family friendly here. I'm hoping if kids are
9:36
Speaker 1: listening to the podcast, you know that we're not scarring
9:39
Speaker 1: them in multiple ways. We're just scaring them about extinction
9:41
Speaker 1: of humanity. Right, So we talk about death, but no
9:44
Speaker 1: foul words for hyenees. Got it. Hey, we're Americans were
9:48
Speaker 1: totally inconsistent about these things. Yeah, I'm not sure you
9:51
Speaker 1: understand your audience perfectly, but that's all right. Let's move forward.
9:56
Speaker 1: So today we're wondering how humanity will survive and whether
9:59
Speaker 1: we can preserve the Earth as a place for humanity
10:02
Speaker 1: to live on as the Sun's condition changes, as the
10:06
Speaker 1: Sun goes through its evolution to a larger and large
10:09
Speaker 1: or star and eventually collapses into a white dwarf. And
10:13
Speaker 1: as usual, I was wondering whether people are aware of
10:16
Speaker 1: this issue and whether they had thought about plans humanity
10:19
Speaker 1: might have to survive it. And so as usual, I
10:23
Speaker 1: called on our list of volunteers to answer random and
10:26
Speaker 1: difficult physics questions without any opportunity to do any research
10:29
Speaker 1: for googling. So if that sounds like a lot of
10:32
Speaker 1: fun to you, please don't be shy. We'd love if
10:34
Speaker 1: you've participated in the future. Just right to me. Two
10:37
Speaker 1: questions at Daniel and Jorge dot com. So let's hear
10:41
Speaker 1: what they had to say. I think it would probably
10:43
Speaker 1: survive um because it wouldn't necessarily change how the orbit
10:48
Speaker 1: is functioning. If the it's just kind of generally swallowed up.
10:52
Speaker 1: So would it survive well, not as a grain water
10:58
Speaker 1: filled planet. It maybe as a roasted lump of rock
11:05
Speaker 1: that Earth like an object, probably will survive like a rock,
11:10
Speaker 1: but no formal life probably would survive. Hopefully, by then
11:17
Speaker 1: we can develop the technology to move the Sun whenever
11:23
Speaker 1: we want, whenever it's good for it and for us,
11:29
Speaker 1: probably to a different solar system. So everybody go, study, study, study, study.
11:37
Speaker 1: We need to do something with the Sun. As far
11:39
Speaker 1: as I know, the Sun will eventually become a red giant,
11:45
Speaker 1: and I heard that when the Sun will expands, its
11:51
Speaker 1: diameter will encompass the current orbit of the Earth. So
11:56
Speaker 1: it doesn't seem to be any salvation for us unless
12:02
Speaker 1: we build some massive rocket boosters and steer the Earth
12:08
Speaker 1: away from from the expanding Sun. But maybe we will
12:13
Speaker 1: have blown ourselves up by then. I think it all
12:16
Speaker 1: depends on the ratio of the temperature loss to the
12:19
Speaker 1: size increase. I know red giants are cooler um, but
12:23
Speaker 1: I don't know if there is a set ratio in
12:27
Speaker 1: terms of the growth of the um Sun compared to
12:30
Speaker 1: the heat loss. So I think if it ends up
12:34
Speaker 1: being perfect, I mean, we can have a climate similar
12:37
Speaker 1: to what we're having now, where yeah, the Sun is closer,
12:40
Speaker 1: but it's given off less heat. Yeah, but we need
12:42
Speaker 1: some pretty big technology, you know. I think the person
12:45
Speaker 1: who said but we'll have blown ourselves up by then,
12:48
Speaker 1: so we don't need to worry has been listening to
12:51
Speaker 1: too much of your podcast. Maybe, but why is that
12:55
Speaker 1: something not to worry about, Like don't worry about the
12:58
Speaker 1: sun exploding, worry about us blowing ourselves up instead, or
13:01
Speaker 1: just like fatalistic, like, look, we're all gonna die anyway,
13:04
Speaker 1: so don't even worry about anything. Oh, I could see
13:07
Speaker 1: it either way, though. I think they have a point
13:09
Speaker 1: that there's a lot of things we should worry about
13:11
Speaker 1: maybe first, but I you know, I suppose we can
13:14
Speaker 1: divide and conquer. There's enough humans to address all these
13:17
Speaker 1: problems exactly. And I like that some people are hopeful,
13:20
Speaker 1: you know, that we'll have some good technology that maybe
13:23
Speaker 1: we'll figure it out. Yeah. I like that you have
13:25
Speaker 1: You've got a mix of optimists pessimists, and you know,
13:28
Speaker 1: maybe one of them is a realist thrown in there.
13:31
Speaker 1: So I guess we'll just have to see. So how
13:33
Speaker 1: about you give us a little bit more information on
13:35
Speaker 1: what the problem is and like how long we've got
13:38
Speaker 1: to solve it. Yeah, that's a great idea, Like people
13:41
Speaker 1: might be wondering, why won't the Sun just sit there
13:44
Speaker 1: burning forever? Right, It's always looked the same to you.
13:48
Speaker 1: It hasn't changed a lot over the ten fifty years
13:51
Speaker 1: that you've been alive and looking up at it. Why
13:54
Speaker 1: is it suddenly going to change? The answer is that
13:56
Speaker 1: the Sun is really a delicate balancing act. Like what's
14:00
Speaker 1: going on inside the sun? Why is it possible for
14:03
Speaker 1: you to get warmed by this ball of plasma that's
14:06
Speaker 1: ninety million miles away. Well, inside the Sun, there's incredible
14:10
Speaker 1: gravitational pressure. Gravity is pulling on all the molecules of
14:14
Speaker 1: the Sun, all that hydrogen, a little bit of helium
14:16
Speaker 1: and other stuff, and squeezing it down, and in doing so,
14:20
Speaker 1: it creates the conditions for fusion. Fusion squeezes two protons together,
14:24
Speaker 1: for example, the nuclei of hydrogen atoms. Those protons don't
14:28
Speaker 1: typically like to get together because they're both positively charged.
14:31
Speaker 1: But if it's enough gravitational pressure, they get squeezed together,
14:34
Speaker 1: and all of a sudden, boom, they fused together and
14:37
Speaker 1: you get helium. It's actually a little bit more complicated.
14:39
Speaker 1: Sometimes you have four protons involved, you get two helium atoms.
14:43
Speaker 1: But the upshot is that you make heavier elements out
14:46
Speaker 1: of lighter elements, and you also get energy in return,
14:49
Speaker 1: and that energy keeps the Sun from collapsing, right, Like,
14:53
Speaker 1: why doesn't the Sun just run away into a black hole?
14:55
Speaker 1: Because that energy from fusion is providing like a back pressure.
14:58
Speaker 1: So the Sun itself is in this balancing act as
15:01
Speaker 1: this tug of war between two dramatic forces in the universe,
15:05
Speaker 1: fusion pushing out and gravity pulling in. And so this
15:09
Speaker 1: is a fairly efficient way of doing things, isn't it.
15:12
Speaker 1: And that's why we're trying to make fusion power work
15:15
Speaker 1: on Earth, Like, so, what is it going to take
15:17
Speaker 1: a long time to burn up because of that? Or
15:19
Speaker 1: am I sort of not understanding? Yeah, fusion is very
15:21
Speaker 1: efficient and very clean and very nice, and if we
15:24
Speaker 1: could make that happen here on Earth, we would love to.
15:27
Speaker 1: There's a bunch of efforts to try to make that happen.
15:29
Speaker 1: Magnetized fusion we could create like a little mini star
15:33
Speaker 1: inside a magnetic bottle. And then there's laser fusion, where
15:36
Speaker 1: use zapp pellets with really high intensity lasers and hope
15:39
Speaker 1: that they implode and fuse so far, we haven't gotten
15:42
Speaker 1: any of those things working because these conditions are hard
15:45
Speaker 1: to establish. The Sun is doing a pretty good job
15:47
Speaker 1: of it, and it's steadily turning hydrogen into helium, but
15:50
Speaker 1: it's a really big ball of hydrogen, and so it's
15:53
Speaker 1: gonna take a long long time. The lifetime of a
15:56
Speaker 1: star depends a little bit on how much mass it has.
16:00
Speaker 1: The more massive it is, the hotter it is at
16:02
Speaker 1: the core, and the faster fusion happens. The smaller it is,
16:05
Speaker 1: the cooler it is at the core, and the slower
16:07
Speaker 1: fusion happens. So like a really really big star, like
16:10
Speaker 1: some of the earliest stars in the universe that were
16:12
Speaker 1: like three hundred times the mass of the Sun, might
16:14
Speaker 1: just burn for millions of years, and a really small
16:17
Speaker 1: star might burn for billions and billions or even trillions
16:21
Speaker 1: of years. Whoa, and so so where are we on
16:23
Speaker 1: that that spectrum? How long do we get to burn?
16:26
Speaker 1: So we think that our son is going to burn
16:28
Speaker 1: for about ten billion years total. So this is sort
16:31
Speaker 1: of like a light bulb. You know, you put it
16:32
Speaker 1: in the ceiling, you know it's gonna burn for weeks
16:34
Speaker 1: or months or years, depending on the kind that you have.
16:37
Speaker 1: Our sun is like a ten billion year light bulb,
16:40
Speaker 1: and we're about five billion years in, which means we've
16:44
Speaker 1: got about five billion more years of the Sun successfully
16:47
Speaker 1: balancing fusion and gravity. You know, the light bulbs in
16:50
Speaker 1: our house never last as long as they're supposed to,
16:52
Speaker 1: So I hope the physicists are doing a better job
16:55
Speaker 1: than the people who give the light bulb ratings. But okay,
16:59
Speaker 1: so we're about of the way there. That's that's a
17:02
Speaker 1: little bit scary. It is a little bit scary, right.
17:04
Speaker 1: It makes you feel like, oh my gosh, we're halfway done.
17:07
Speaker 1: What have we done with ourselves so far? Right? What
17:09
Speaker 1: if we accomplished? You know, I mean, we build the
17:13
Speaker 1: Golden gate Bridge and all some buildings, and we discovered
17:15
Speaker 1: a lot of the secrets of the universe. But there's
17:18
Speaker 1: so much left to do and not that much time.
17:20
Speaker 1: And one of the issues is that the next five
17:22
Speaker 1: billion years are not going to be exactly like the
17:25
Speaker 1: last five billion. It's not like a light bulb that
17:27
Speaker 1: just burns nicely and then one day it pops and
17:30
Speaker 1: goes out. The Sun is going to change steadily over
17:33
Speaker 1: the next few billion years. Oh so, like, how how
17:35
Speaker 1: long do we have to solve the problem or to
17:37
Speaker 1: like figure out what we're gonna do. Not the full
17:40
Speaker 1: four billion, maybe more like a billion years. One of
17:43
Speaker 1: the issues is that as the Sun burns, it makes
17:46
Speaker 1: more helium, and the helium is heavier than the hydrogen,
17:49
Speaker 1: so it sinks to the core of the Sun. This
17:52
Speaker 1: makes the core of the Sun more dense, which means
17:54
Speaker 1: more gravity and increases the temperature, which makes the Sun hotter.
17:58
Speaker 1: So the Sun is getting hotter Italy. Every hundred million years,
18:02
Speaker 1: the Sun gets about one percent brighter. You might think, well,
18:05
Speaker 1: one percent, what's the big deal? One percent can make
18:07
Speaker 1: a big difference in the overall energy deposited on the
18:10
Speaker 1: Earth and totally change our climate. And that compounds every
18:14
Speaker 1: hundred million years. It's one percent brighter, So like in
18:16
Speaker 1: a billion or two billion years, we think the surface
18:19
Speaker 1: of the Earth will be at a hundred C. That's
18:22
Speaker 1: like the boiling point of water. Oh my gosh, Okay,
18:25
Speaker 1: so we need we need to find a solution way
18:27
Speaker 1: before that. Is it just going to be hotter or
18:30
Speaker 1: is this I feel like I remember pictures of the
18:32
Speaker 1: Sun expanding while this happens, Or is I guess that's
18:35
Speaker 1: part of the whole process. So the Sun is like
18:38
Speaker 1: seven hundred thousand kilometers in radius, right, which seems pretty big,
18:42
Speaker 1: But as time goes on, it's going to expand to
18:45
Speaker 1: about two hundred times that radius. So the outer edges
18:50
Speaker 1: of the Sun are going to get pushed out by
18:51
Speaker 1: all this extra fusion energy. And that's about one au right,
18:55
Speaker 1: that's right about where the Earth orbits. Oh my gosh,
18:59
Speaker 1: So it's gonna oil or oceans off, and then it's
19:02
Speaker 1: going to engulf like all of the Earth. It sort
19:05
Speaker 1: of seems like it in a naive calculation. The radius
19:08
Speaker 1: of the Sun is now the same as the radius
19:10
Speaker 1: of the Earth's orbit, so we'll be like flying through
19:13
Speaker 1: the outer layers of the Sun. But it's actually a
19:16
Speaker 1: tiny bit more complicated than that, because as it gets larger,
19:20
Speaker 1: it also loses mass, Like some of its mass just
19:22
Speaker 1: gets blown out past the Solar system. So the Sun
19:26
Speaker 1: will lose some of this mass, right, Like the final
19:29
Speaker 1: white dwarf that's left over in the end doesn't have
19:31
Speaker 1: all the mass of the Sun. Some of it's been
19:33
Speaker 1: lost by getting blown out. So that means that as
19:35
Speaker 1: the Sun expands, it's gravity actually weakens a little bit,
19:39
Speaker 1: and so it's tug on the Earth weakens a little bit,
19:42
Speaker 1: so the Earth will actually drift out naturally to a
19:45
Speaker 1: larger radius. It's orbit will get enlarged because the Sun's
19:48
Speaker 1: gravity is getting weaker. So for a moment, I had
19:50
Speaker 1: this little glimmer of hope, thinking, like, you know, the
19:52
Speaker 1: Earth is going to move away, and maybe we'll move
19:54
Speaker 1: away fast enough that the oceans aren't going to burn up.
19:57
Speaker 1: But you, being you, you're gonna go ahead and squash
20:01
Speaker 1: that right and and tell me that even if the
20:03
Speaker 1: Earth keeps a little bit ahead of the Sun, we're
20:06
Speaker 1: still all going to be dead, right, because it's still
20:07
Speaker 1: going to boil off our oceans. Well, Kelly, I mean,
20:10
Speaker 1: do you want the truth or do you want to
20:12
Speaker 1: feel good about the universe? You can't always get both.
20:15
Speaker 1: Obviously I want to feel good about the but but
20:19
Speaker 1: you're going to give me the truth. So people have
20:21
Speaker 1: done some studies to try to understand what's going to
20:23
Speaker 1: happen here. It turns out that the sun expansion outpaces
20:26
Speaker 1: the sun losing mass, and so even though the Earth
20:29
Speaker 1: would start to drift out to a higher radius, it's
20:32
Speaker 1: going to get caught by the outer surfaces of the
20:34
Speaker 1: Sun before it can do that. And one of the
20:37
Speaker 1: issues is that once you are skimming over the surface
20:40
Speaker 1: of the Sun, you're not really in a simple orbit
20:43
Speaker 1: anymore because now there's drag. Right, You're like flying through
20:46
Speaker 1: plasma of the Sun that slows you down. In our
20:49
Speaker 1: current orbit, we don't really hit very much, right, and
20:51
Speaker 1: we don't lose a lot of kinetic energy as we
20:53
Speaker 1: go around. But this is gonna be like flying through
20:55
Speaker 1: the outer surfaces of the Sun, sort of like a
20:58
Speaker 1: spaceship experiencing drag. It flies in too low an orbit,
21:01
Speaker 1: it gets pulled down into the planet. So even a
21:04
Speaker 1: tiny little bit of getting engulfed by the Sun means
21:07
Speaker 1: the Earth eventually just plummets directly into the Sun. I
21:10
Speaker 1: shouldn't have asked, how is that for sleeping at night?
21:13
Speaker 1: Exactly all right, So now the Earth has been absorbed
21:21
Speaker 1: by the Sun. What happens after that? The Sun is
21:23
Speaker 1: non as red giant phase, it's very bright as a
21:26
Speaker 1: huge radius, and now it moves to the next stage,
21:29
Speaker 1: which is that it begins to fuse helium. So mostly
21:32
Speaker 1: at the core we have hydrogen that's fusing into helium.
21:36
Speaker 1: But if the Sun has enough mass, and Ours does.
21:38
Speaker 1: Eventually it will reach a temperature where helium itself can
21:41
Speaker 1: get fused into heavier stuff. Now, if we have an
21:44
Speaker 1: even more massive star tens or hundreds of times the
21:47
Speaker 1: mass of the Sun, this could go into the next
21:50
Speaker 1: stage where helium then fuses into something else, which then
21:52
Speaker 1: fuses into something else, and you get elements all the
21:54
Speaker 1: way up there, like iron in the heaviest of stars.
21:57
Speaker 1: Ours isn't big enough to do that. We can only
22:00
Speaker 1: achieve helium fusion. But when that happens, it's really awesome
22:03
Speaker 1: because the whole stage just lasts for a few seconds.
22:06
Speaker 1: It's like we fuse hydrogen for billions of years, accumulating
22:10
Speaker 1: all this helium ash, and then once the helium is
22:13
Speaker 1: ready to fuse, we burn through that in just a
22:15
Speaker 1: few seconds, creating this incredible helium flash. Oh my gosh.
22:19
Speaker 1: Is this where galactic cosmic radiation comes from in bigger
22:23
Speaker 1: stars where they make iron ions and then shoot them
22:26
Speaker 1: out or is that a different process? I think that's
22:28
Speaker 1: a different process. This helium flash turns out to me
22:31
Speaker 1: entirely internal to the star because the star is opaque
22:35
Speaker 1: to this radiation. So even though it releases like as
22:38
Speaker 1: much light as the entire Milky Way, like as much
22:41
Speaker 1: as billions of stars. It's all internally absorbed, so you
22:43
Speaker 1: can't actually see it from the outside. But it's very
22:46
Speaker 1: cool this helium flash which just last for seconds. I
22:49
Speaker 1: love the discrepancy there, and like how long we burn hydrogen,
22:52
Speaker 1: how long we burn helium? And in other stars where
22:55
Speaker 1: you continue, then these cycles get shorter and shorter, and
22:58
Speaker 1: so you're like fusing iron for a very very small
23:01
Speaker 1: amount of time before the star starts to go out.
23:03
Speaker 1: That is incredible. Yeah, and it's really fascinating. Okay, so
23:06
Speaker 1: we've we've lost the Earth, but there are proposals for
23:09
Speaker 1: going to other places. So I want to know is
23:13
Speaker 1: anything in the Solar System going to be left when
23:15
Speaker 1: this is done? The Solar System will probably be totally unrecognizable.
23:19
Speaker 1: I mean, remember that the Sun's weakening gravity also has
23:22
Speaker 1: impacts on other planets, right, So Jupiter and Saturn, for example,
23:26
Speaker 1: will get much larger orbits because the Sun's gravity it
23:30
Speaker 1: gets weaker as it loses a little bit of its mass,
23:33
Speaker 1: and this is going to create a lot of chaos
23:34
Speaker 1: for the Solar System. Anytime Jupiter does anything, it creates chaos,
23:38
Speaker 1: and now you're moving Jupiter and Saturn like two entirely
23:41
Speaker 1: new orbits. Probably they will eject all the other planets
23:45
Speaker 1: in the Solar System, bye by Neptune, by by Uranus,
23:48
Speaker 1: bye by Pluto, whether or not you call it a planet,
23:51
Speaker 1: they're all probably gone. And why it's always Jupiter. Jupiter
23:55
Speaker 1: is the big bully of the Solar System. And in
23:57
Speaker 1: some of these simulations I've seen, we're basically left with
24:00
Speaker 1: Jupiter right as the only planet now. And then after
24:03
Speaker 1: the Sun is done expanding, then it collapses into a
24:06
Speaker 1: white dwarf, and that's what's left behind. You have this
24:09
Speaker 1: hot lob of glowing helium fusion products. You have some helium,
24:12
Speaker 1: some carbon maybe, and that's all that's left. And the
24:15
Speaker 1: outer layers that were the red giant I'll get blown out.
24:19
Speaker 1: And so you have like Jupiter, solo planet orbiting this
24:22
Speaker 1: hot lump of helium and carbon. Does it just keep
24:25
Speaker 1: glowing for eternity? Does does something else happen to it
24:27
Speaker 1: after that? So it's not fusing anymore, but it's still
24:30
Speaker 1: really really hot. So I think about what happens to
24:33
Speaker 1: like a lump of hot stuff in space. It's glowing
24:36
Speaker 1: which means it's losing energy, so it's cooling down, but
24:39
Speaker 1: it happens really slowly. So scientists think that a white dwarf, eventually,
24:43
Speaker 1: after trillions of years, will cool down so it's not
24:47
Speaker 1: glowing anymore, and they call that a black dwarf. But
24:50
Speaker 1: our universe isn't old enough to have any black dwarfs
24:53
Speaker 1: in it. So we have a bunch of white dwarves,
24:55
Speaker 1: but none of them have cooled yet because our universe
24:57
Speaker 1: is still so young on that time, do we have
25:00
Speaker 1: an estimate for when we might find the first black dwarf?
25:04
Speaker 1: Trillions of years. These things can stay hot in space
25:07
Speaker 1: for a long long time. Remember, in space, it is
25:10
Speaker 1: actually harder to lose your energy, to lose your heat
25:13
Speaker 1: than it is here on Earth because there is no air.
25:16
Speaker 1: All you can do is radiated away. There's no like
25:18
Speaker 1: wind to come and cool you down. Got it. Okay, Well,
25:22
Speaker 1: now you have made it so it will be tough
25:24
Speaker 1: for me to sleep at night. But we still have
25:26
Speaker 1: some time left on this podcast, and so after this break,
25:30
Speaker 1: I'm going to ask you to tell me if there's
25:32
Speaker 1: any prospects for survival. Okay, we're back from the break.
25:49
Speaker 1: What kind of options do we have for being proactive
25:51
Speaker 1: about this problem? Because you know, if I was going
25:53
Speaker 1: to tell my kids about a problem, I'd want to
25:55
Speaker 1: make sure I had some strategies I can tell them
25:57
Speaker 1: about so they felt like they had so control over
26:00
Speaker 1: the situation. Yeah, there are a lot of clever people
26:03
Speaker 1: thinking deeply about these problems, and I think it's super
26:06
Speaker 1: fun to think about problems that you don't need to
26:08
Speaker 1: solve for millions or billions of years, because you know,
26:10
Speaker 1: the technology is going to be different in a million
26:13
Speaker 1: years and people will have better ideas. But that only
26:16
Speaker 1: happens if we start thinking about it now, right, we
26:19
Speaker 1: have to begin those explorations. You start with the bad ideas,
26:22
Speaker 1: and those generate the good ideas. That's sort of like
26:25
Speaker 1: the way my research happens. A student comes into my
26:27
Speaker 1: office and we sort of brainstorm bad ideas until one
26:30
Speaker 1: of them turns into a good idea. So it's important
26:32
Speaker 1: that we dig into this stuff now, and the ideas
26:35
Speaker 1: are sort of categorized by like what time scale we're
26:38
Speaker 1: talking about, you know, before, for example, the sun actually
26:41
Speaker 1: grows to have the radius of the orbit of the Earth,
26:45
Speaker 1: we still have to worry about things getting hotter right
26:47
Speaker 1: like before five billion years from now when we risk
26:50
Speaker 1: being engulfed, we still need to survive somehow without our
26:54
Speaker 1: oceans boiling. You know, it almost seems like we should
26:57
Speaker 1: start worrying about what your planet does when it gets hotter,
26:59
Speaker 1: like you know now anyway, Yeah, that's right. We have
27:03
Speaker 1: other reasons to worry about how to keep the Earth cool,
27:06
Speaker 1: like how do you build a planet wide cooling system?
27:08
Speaker 1: And so this is something people are thinking about, and
27:10
Speaker 1: it's something you could actually get started on, like tomorrow.
27:14
Speaker 1: Some of these strategies, like geo engineering, involves spraying things
27:19
Speaker 1: into the atmosphere to reflect more of the Sun's light. Basically,
27:23
Speaker 1: even though the Sun is going to get hotter and brighter,
27:26
Speaker 1: we just want less of that energy to fall on
27:28
Speaker 1: the Earth and we should be okay. These kinds of
27:31
Speaker 1: proposals always make me a little nervous because I feel
27:33
Speaker 1: like we still don't understand what causes climate. And if
27:37
Speaker 1: you do something like you know, spraying particles are blocking
27:40
Speaker 1: part of the sun, there's just as good a chance
27:43
Speaker 1: that you're going to mess something up. But here's hoping
27:45
Speaker 1: we figure this all out soon. So what kind of
27:48
Speaker 1: stuff are we thinking of trying to spray up there.
27:50
Speaker 1: It's definitely a Rube Goldberg device, right. We have no
27:53
Speaker 1: idea how these things are working, and we're like, huh,
27:55
Speaker 1: let's just add another gear over here and see what happens.
27:57
Speaker 1: One thing that people are thinking about is sulfur. Sulfur
28:01
Speaker 1: is very reflective and not that expensive, and we have
28:04
Speaker 1: a lot of it. So if you just like spread
28:06
Speaker 1: a bunch of sulfur into the upper atmosphere, that would
28:09
Speaker 1: effectively reflect a lot of the light that is hitting
28:13
Speaker 1: the earth and cool it down. This is something people
28:16
Speaker 1: are thinking about, like for climate change today, and what
28:18
Speaker 1: we're talking about today on the podcast is effectively climate
28:21
Speaker 1: change writ large the sun getting much much brighter and
28:24
Speaker 1: a lot more energy. So the same kinds of solutions
28:27
Speaker 1: are being considered, but this would have a lot of
28:30
Speaker 1: weird effects on the climate on the Earth, and would
28:32
Speaker 1: they stay where we put them? They would not necessarily
28:34
Speaker 1: stay where we put them, and there are currents up
28:37
Speaker 1: there right. Also, these things would eventually drift back down,
28:39
Speaker 1: so we need to continuously pump sulfur into the atmosphere
28:43
Speaker 1: to replace it. And it would also change a lot
28:45
Speaker 1: what it's like to be on the Earth. If we
28:47
Speaker 1: had this like diffuse shield, it would bounce the Sun's
28:50
Speaker 1: light around a lot, so you wouldn't necessarily like see
28:53
Speaker 1: a sun in the sky. It's like the whole sky
28:56
Speaker 1: would go from being blue with like a yellow sun
28:58
Speaker 1: in it just being like white glow. This honestly isn't
29:02
Speaker 1: sounding like a great idea to me so far. It's
29:05
Speaker 1: sort of like, you know on a cloudy day, how
29:07
Speaker 1: it can feel bright even though you can't see the sun.
29:10
Speaker 1: It would be a very different experience of being a human.
29:13
Speaker 1: And the other issue is that it wouldn't have a
29:15
Speaker 1: constant effect everywhere on the Earth. It would change the climate.
29:18
Speaker 1: Parts of the Earth would get hotter and other parts
29:20
Speaker 1: would get colder. So even though on average you might
29:22
Speaker 1: keep the same temperature, the tropics would be cooler and
29:25
Speaker 1: the high latitudes would be a little bit warmer. And
29:27
Speaker 1: that would have all sorts of crazy effects like flooding
29:30
Speaker 1: certain areas, making other areas drier. And I'm pretty sure
29:34
Speaker 1: that you know, different countries would have different opinions about
29:36
Speaker 1: like who gets a drought this year? Yeah, well, I mean,
29:39
Speaker 1: I suppose it's it's all better than the oceans boiling,
29:42
Speaker 1: But it doesn't sound ideal, and hopefully by then we're
29:45
Speaker 1: all getting along really well. So well refugees are fleeing
29:48
Speaker 1: around the planets, they'll be welcomed with open arms. Yeah.
29:51
Speaker 1: I don't have a lot of hope for us coming
29:53
Speaker 1: up with communal compromises to these big decisions. So, but
29:56
Speaker 1: you know, this is the kind of strategy people are
29:58
Speaker 1: thinking about for sort of short term geo engineering of
30:02
Speaker 1: preventing the Earth from getting toasted. All right, so that
30:05
Speaker 1: messing with our atmosphere is one method which sounds a
30:09
Speaker 1: little scary. Can we stop the Sun before it gets
30:12
Speaker 1: to our atmosphere? Yeah, some people are thinking about like
30:15
Speaker 1: building massive space mirrors to reflect the light. Right, so
30:19
Speaker 1: instead of geo engineering, like, let's have massive space engineering projects.
30:23
Speaker 1: And the idea is that all you need to do
30:25
Speaker 1: is counteract, Like currently two percent of the energy that
30:29
Speaker 1: comes to the Earth would solve our global warming problem.
30:33
Speaker 1: And then in the future you need more and more
30:35
Speaker 1: to protect ourselves from the growing sun. But you know,
30:37
Speaker 1: there are attractive places to put this in space. You've
30:40
Speaker 1: probably heard of the L two lagrange point, which is
30:43
Speaker 1: a gravitationally stable place where the James Web space telescope
30:47
Speaker 1: is it's like along the line between the Sun and
30:50
Speaker 1: the Earth. For example, it keeps the Earth between it
30:52
Speaker 1: and the Sun. So it's a stable place where the
30:55
Speaker 1: James Webb could stay in the shadow of the Earth.
30:57
Speaker 1: There's another one, the l one lagrange point, is between
31:01
Speaker 1: the Earth and the Sun and it's also stable, so
31:04
Speaker 1: you put something there and it will remain between the
31:07
Speaker 1: Earth and the Sun. So you could build like a
31:08
Speaker 1: shield and put it at the l one point and
31:11
Speaker 1: the Earth has like a little parasol. How cute and charming,
31:16
Speaker 1: But it would probably have to be huge. It sounds
31:18
Speaker 1: like a tough engineering problem. But we've got like a
31:20
Speaker 1: billion years. How how big would it need to be.
31:22
Speaker 1: The l One point is four times the distance from
31:25
Speaker 1: the Earth to the Moon, so it's pretty far away
31:28
Speaker 1: and that makes it a challenge, right because the further
31:31
Speaker 1: away it is from the Earth, the bigger it has
31:33
Speaker 1: to be. And imagine like a shield at the Earth.
31:36
Speaker 1: You could be the size of the Earth and totally
31:38
Speaker 1: block the Sun. But as that shield gets closer and
31:40
Speaker 1: closer to the Sun, it needs to get bigger and
31:43
Speaker 1: bigger to effectively shield the Earth. Like an earth size
31:46
Speaker 1: shield at the Sun would basically do nothing. So the
31:49
Speaker 1: l one point is four times the Earth Moon distance.
31:52
Speaker 1: So you need a shield that's like a million square kilometers,
31:56
Speaker 1: have to be basically as big as the Moon. And
31:59
Speaker 1: do you have to worry about like, you know, so
32:01
Speaker 1: there's stuff shooting around in space, you know, running into
32:05
Speaker 1: stuff and causing problems. Do you have to worry I
32:07
Speaker 1: guess you'd have to worry about it poking a hole
32:09
Speaker 1: or something big enough hitting it and moving it out
32:11
Speaker 1: of orbits or is there nothing big enough that could
32:13
Speaker 1: move something four times the moon? No, there is definitely
32:16
Speaker 1: something big enough, and that's the Sun. Like you build
32:18
Speaker 1: a big shield that is that wide, it's basically a
32:20
Speaker 1: solar sale and it'll just fly away, right, And so
32:23
Speaker 1: you have to worry about this somehow, right, Like if
32:26
Speaker 1: it's reflective, then it's going to get pushed away by
32:29
Speaker 1: the Sun, even if it's just like black, and then
32:32
Speaker 1: it's going to absorb all that energy. It's going to
32:34
Speaker 1: get overheated and it's still going to absorb all that momentum.
32:37
Speaker 1: And so people have really worried about how to design
32:39
Speaker 1: this thing. And there's a guy, Roger Angel, who has
32:42
Speaker 1: this idea instead of like a big sheets like make
32:45
Speaker 1: it a screen, and so instead of absorbing the light
32:48
Speaker 1: or reflecting the light, it's like just bend the light.
32:51
Speaker 1: So it's like a huge lens, but built out of
32:54
Speaker 1: these little rings, each of which deflects light away from
32:58
Speaker 1: the earth, so it doesn't get any momentum pressure or
33:00
Speaker 1: it just sort of like bends some of the light
33:02
Speaker 1: out of our path. That's pretty cool. And what would
33:04
Speaker 1: this change the amount of light that the whole Earth
33:07
Speaker 1: gets or would this be like, you know, the southern
33:09
Speaker 1: hemisphere gets as much light, Like is it going to
33:13
Speaker 1: be evenly distributed? That's a great question. Probably wouldn't be.
33:16
Speaker 1: I think you'd probably get most deflection at the center,
33:19
Speaker 1: and other places would get some of the light that
33:21
Speaker 1: would have gone to the equator we go to higher
33:23
Speaker 1: latitudes for example. That's a good question. But even this
33:26
Speaker 1: would still need to be really big, Like initial designs
33:30
Speaker 1: for this kind of shield would require twenty million tons
33:34
Speaker 1: of mass. Oh my gosh, I mean that's going to
33:37
Speaker 1: be incredibly expensive, but I guess all the world's governments
33:40
Speaker 1: would probably pitch in. Hopefully, Elon Musk and his generations
33:45
Speaker 1: of descendants have driven the cost down to like a
33:47
Speaker 1: penny per pound or something by that point, I don't know.
33:50
Speaker 1: There are ideas about building this thing on the moon
33:53
Speaker 1: and then launching it from there, but you know, we're
33:56
Speaker 1: talking about an incredible space industry, and you know, we
33:59
Speaker 1: are far far away from being able to build anything
34:02
Speaker 1: on the moon. Even getting people to the Moon right
34:04
Speaker 1: now is challenging for us. Another idea I read about,
34:07
Speaker 1: which is really cool, is to develop a new kind
34:09
Speaker 1: of launch technology, magnetic launch, when you basically have like
34:13
Speaker 1: an aluminum tube and a magnetic field rises up the
34:17
Speaker 1: tube and pushes a piece of metal up into space.
34:20
Speaker 1: It's sort of like a maglev version of a train,
34:22
Speaker 1: but vertical. So first you'd process the aluminum out of
34:25
Speaker 1: the regulars and then you'd shoot it. He's in one
34:28
Speaker 1: of these canons. Yeah, but this is technology that's like
34:31
Speaker 1: very speculative. People have like worked on the theory of it,
34:34
Speaker 1: but nobody's ever built one of these things before. But
34:36
Speaker 1: you know, this is like, how could we solve this one?
34:38
Speaker 1: Are the biggest problems involved? You know, this is passing
34:41
Speaker 1: it off to the engineers. Were like, in theory, if
34:43
Speaker 1: we put a shield in l one, that might work.
34:46
Speaker 1: Let's let the engineers figure out how to build it.
34:48
Speaker 1: So you said that L one is stable, Is it
34:50
Speaker 1: perfectly stable? Like if you put those rings there, are
34:53
Speaker 1: they really going to stay there forever? They are not. Unfortunately,
34:57
Speaker 1: these places are quasi stable, right. Stay Able technically means
35:01
Speaker 1: you get pushed away from it a little bit, then
35:02
Speaker 1: the force naturally restores you to the original location, whereas
35:06
Speaker 1: unstable at the opposite unstable means that as soon as
35:09
Speaker 1: you deviate from it a tiny little bit, then you
35:11
Speaker 1: get further away. Like a pencil balancing on its tip
35:14
Speaker 1: is unstable. It could balance there if a state exactly vertical,
35:18
Speaker 1: as soon as it leans over a little bit, then
35:20
Speaker 1: the game is over. So these things are quasi stable,
35:23
Speaker 1: which means some deviations get pushed back and some deviations
35:26
Speaker 1: don't get pushed back, and eventually we'll lose them all,
35:30
Speaker 1: so we'll need to continuously be shooting up new elements
35:33
Speaker 1: of it. And the good news is you don't just
35:35
Speaker 1: need like one big piece. It's okay to have like
35:38
Speaker 1: two thousand or two million small little lenses that each
35:42
Speaker 1: blur the sun's light a little bit, so it's okay
35:45
Speaker 1: to continuously lose them and then build more, but it
35:48
Speaker 1: means a continuing expense. Let's make sure we don't mess
35:50
Speaker 1: up those lenses and then all end up like ants
35:53
Speaker 1: under some kids, magnifying less. Al Right, So any of
35:57
Speaker 1: these methods that we've just talked about are just buying
36:00
Speaker 1: us time. So this is to try to reduce the
36:03
Speaker 1: temperature increase as the Sun is getting closer, but the
36:06
Speaker 1: Earth is still going to get engulfed. So we need
36:09
Speaker 1: some way to outrun the Sun, some bigger solutions. So
36:12
Speaker 1: we're gonna need something else. What are some of these
36:14
Speaker 1: longer term solutions. Yeah, you're right. Eventually we want to
36:18
Speaker 1: move the Earth somehow in order to avoid it getting
36:21
Speaker 1: engulfed and dropping into the Sun. And you know, this
36:24
Speaker 1: is a really fun idea, and it appears a lot
36:27
Speaker 1: of times in science fiction, which means a lot of
36:29
Speaker 1: people have thought about it. You know, science fiction authors
36:31
Speaker 1: really do contribute to these problems by thinking through the details.
36:35
Speaker 1: And here we really benefit from the fact that the
36:38
Speaker 1: Sun's intensity, the amount of light you get falls very
36:41
Speaker 1: quickly as you get further away. Right, it's not like
36:44
Speaker 1: twice as far away you get half the sunlight. Twice
36:46
Speaker 1: as far away you get a quarter of the sunlight.
36:49
Speaker 1: And so if you want to remove like one percent
36:51
Speaker 1: of the Sun's intensity of its lubidosity, you only need
36:54
Speaker 1: to move the Earth half a percent further away. And
36:57
Speaker 1: if you increase the radius less than ten percent, you
37:00
Speaker 1: like twenty or more reduction in the Sun's light. So
37:03
Speaker 1: the universe is against us, but for once, math and
37:06
Speaker 1: physics are kind of on our side exactly. Then the
37:11
Speaker 1: question is how do you get the Earth into another orbit? Right?
37:15
Speaker 1: This is complicated. The Earth is a big mass with
37:17
Speaker 1: a lot of kinetic energy. Moving it is not going
37:20
Speaker 1: to be something that you can do easily. So people
37:23
Speaker 1: have thought of a few different scenarios here. One of
37:25
Speaker 1: my favorites is to use a gravitational slingshot. Like you
37:30
Speaker 1: know how sometimes we send satellites around Jupiter to whizz
37:34
Speaker 1: around and change their direction or even change their speed. Well,
37:37
Speaker 1: that actually changes the flight path of Jupiter, right, It
37:41
Speaker 1: steals a little bit of energy from Jupiter. So the
37:43
Speaker 1: idea is to do sort of the opposite is to
37:46
Speaker 1: send a big asteroid near the Earth, send it around
37:50
Speaker 1: the Earth to sort of like push the Earth out right,
37:52
Speaker 1: to like change the orbit of the Earth. I can't
37:55
Speaker 1: imagine how that could go wrong. Tell that to your kids.
38:00
Speaker 1: I'm sure they'll believe it. Well. In this case, people
38:03
Speaker 1: have thought about an asteroid like a hundred kilometers y
38:06
Speaker 1: something weighing like ten to the nine, And if you
38:10
Speaker 1: have it like counterbalancing around the Earth, it could slowly
38:13
Speaker 1: get pulled out and use Jupiter's gravity a little bit also,
38:16
Speaker 1: and you get the Earth out to a larger radius.
38:18
Speaker 1: And of course you need a whole different set of
38:21
Speaker 1: physicists trying to figure out how you go about moving
38:23
Speaker 1: an asteroid carefully. But that sounds like a fun problem
38:26
Speaker 1: to solve. And I'm pretty sure that sixty two miles
38:28
Speaker 1: is more than an extinction level event. If you mess
38:31
Speaker 1: it up right, it is exactly. So that's danger number
38:34
Speaker 1: one is oops, you killed everybody. Danger number two is
38:37
Speaker 1: you miscalculated, and now the Earth doesn't have a larger radius.
38:40
Speaker 1: It's got no radius. It's just getting ejected from the
38:43
Speaker 1: Solar System and it's now flying free in dark dark space.
38:47
Speaker 1: That's failure mode number two, neither of which you can
38:50
Speaker 1: recover from. It's not like oops, let's try again or
38:53
Speaker 1: something right. These are one time only mistakes. Yeah, we
38:56
Speaker 1: should be investing in science more. But there's a cleverness
38:59
Speaker 1: I like that because instead of moving the Earth now
39:02
Speaker 1: you just have to move a hundred kilometer asteroid, which
39:05
Speaker 1: seems easier I guess than moving the entire Earth. But
39:09
Speaker 1: some folks are working on that, you know, they say,
39:11
Speaker 1: how could we actually move the whole earth further out?
39:14
Speaker 1: Like could you build engines like rocket engines and put
39:18
Speaker 1: them on the south pole and fire them up and
39:21
Speaker 1: like treat the whole earth as a spaceship move it
39:24
Speaker 1: out to a larger radius. Well, I guess that you
39:28
Speaker 1: also have to be pretty careful about not not messing up.
39:31
Speaker 1: How much of an increase in radius are we talking. Well,
39:33
Speaker 1: if you increase the radius by like four or something
39:35
Speaker 1: per cent, then the energy you receive drops by like
39:38
Speaker 1: ten percent. And you know, as the Sun gets larger
39:41
Speaker 1: and larger over the next few billion years, we could
39:43
Speaker 1: just like keep moving the Earth. One way to think
39:46
Speaker 1: about it is that right now the Earth is in
39:49
Speaker 1: the habitable region, right we have just about the right
39:51
Speaker 1: amount of energy falling on the surface so that we
39:53
Speaker 1: can survive. But as the Sun gets brighter and bigger,
39:57
Speaker 1: the habitable zone changes, and so we could just sort
39:59
Speaker 1: of cruise the Earth gradually, so we always stay in
40:03
Speaker 1: the sweet spot. And if global warming hasn't killed us
40:06
Speaker 1: by then, the amount of fossil fuels we're going to
40:08
Speaker 1: have to burn to move the entire planet will probably
40:11
Speaker 1: finish the job. Well, you know, people have talked about
40:14
Speaker 1: using like a solar array, building one that's like ten
40:17
Speaker 1: to the fifteen square meters, which captures a tiny fraction
40:21
Speaker 1: of the Sun's energy, but that's ten times the surface
40:25
Speaker 1: area of the Earth. And remember we talked about space
40:28
Speaker 1: based solar power and you were pretty skeptical that we
40:30
Speaker 1: could even like power Australia's refrigerators using space based technology.
40:35
Speaker 1: Now we're talking about building a space based solar power
40:38
Speaker 1: network that's ten times the surface area of the Earth,
40:41
Speaker 1: and so that seems a little ambitious. Well, you know,
40:44
Speaker 1: we've got some time. Are we just moving away or
40:47
Speaker 1: at some point are we moving back in again? Like,
40:49
Speaker 1: do we need to be able to go in both
40:50
Speaker 1: directions long term? We do, absolutely, because what happens in
40:54
Speaker 1: the very far future is that we just have that
40:55
Speaker 1: white dwarf, right, and then we need to get pretty
40:58
Speaker 1: close because the white dwarf is not going to be
41:00
Speaker 1: that hot and there are habitable regions around white dwarfs.
41:03
Speaker 1: In fact, astronomers found white dwarfs with planets before. In fact,
41:08
Speaker 1: recently they found one it's called w D ten fifty
41:11
Speaker 1: four to to six, that they think has a planet
41:14
Speaker 1: in its habitable zone where the surface of it could
41:17
Speaker 1: have like liquid water. So technically it is possible to
41:21
Speaker 1: have a planet in orbit around a white dwarf. But
41:24
Speaker 1: the plan would then be to have the Earth go
41:27
Speaker 1: further out as the Sun expands, and then when the
41:29
Speaker 1: Sun collapses again, to move the Earth back into the
41:32
Speaker 1: now shrinking habitable zone. So I really like my schedule,
41:37
Speaker 1: and I make three year plans and five year plans,
41:40
Speaker 1: and I'm feeling like, if we're changing how far the
41:42
Speaker 1: Earth is from the Sun, we're probably changing how long
41:45
Speaker 1: a year is, and that's really going to mess up
41:48
Speaker 1: my scheduling. Is this going to be a problem. This
41:51
Speaker 1: is gonna be a big problem. Absolutely. For example, we
41:54
Speaker 1: move the orbit of the Earth out by five percent
41:56
Speaker 1: or something, the year is going to be fifteen percent
41:59
Speaker 1: longer because our orbital speed is going to be slower.
42:02
Speaker 1: Remember that the further away you are from the Sun,
42:04
Speaker 1: the less the Sun pulls on you. And so the
42:06
Speaker 1: slower you need to be going to be in orbit.
42:09
Speaker 1: And so for example, in some of these scenarios, the
42:12
Speaker 1: year is now four hundred and eighteen days. That's when
42:15
Speaker 1: we're out at the larger radius, and then we bring
42:17
Speaker 1: the Earth back in the year could be very short, right,
42:20
Speaker 1: it could be several weeks long. So you could be
42:22
Speaker 1: having birthdays like all the time. Oh nice, Although I
42:25
Speaker 1: don't necessarily want to feel like I'm aging too much quicker.
42:29
Speaker 1: I think I prefer the four hundred and eighteen day version.
42:32
Speaker 1: I'll get much more done every year. I don't know.
42:33
Speaker 1: Then you could, like, you know, live to the year
42:35
Speaker 1: six hundred or something. Right, we could all have biblical ages.
42:41
Speaker 1: That sounds great. We should bring back biblical names too.
42:44
Speaker 1: They were more epic, although not more epic than waiters.
42:47
Speaker 1: And I just want to comment that there's an idea
42:49
Speaker 1: in a popular science fiction story called The Wandering Earth
42:52
Speaker 1: where people move the Earth out of the Solar system.
42:55
Speaker 1: They give up on the Sun entirely, and they're like,
42:57
Speaker 1: let's just move to a different star, and there they
43:00
Speaker 1: build these enormous engines, these plasma thrusters that pushed the
43:03
Speaker 1: Earth like out of the Solar System to another planet,
43:06
Speaker 1: like treat the whole Earth as a spaceship. And these
43:09
Speaker 1: are crazy, these plasma engines they build. I read an
43:12
Speaker 1: interview with a guy at JPL who works on these
43:15
Speaker 1: kind of thrusters, and he was skeptical because he said
43:17
Speaker 1: that it would require of the mass of the Earth
43:21
Speaker 1: to be used as fuel. So I think that would
43:23
Speaker 1: have some serious drawbacks. Yeah, I think maybe the math
43:26
Speaker 1: on that one is not in our favor. So you
43:29
Speaker 1: you told me that after we get to the point
43:31
Speaker 1: where the Earth has been enveloped, everything's gonna go crazy,
43:35
Speaker 1: and like, who knows what's going to survive, but probably
43:38
Speaker 1: Jupiter is gonna survive. So rather than trying to do
43:42
Speaker 1: these engineering solutions, which seemed like if you don't get perfect,
43:46
Speaker 1: there's a big chance you're going to fail, and we've
43:48
Speaker 1: never tried anything like this before, maybe we should just
43:51
Speaker 1: move to Jupiter. But that's not an option. Are Jupiter's
43:55
Speaker 1: moons still going to be around? Well, you know, it's
43:58
Speaker 1: a good idea because Jupiter is likely to stay in
44:01
Speaker 1: the habitable zone. Like in the new Sun, the habital
44:04
Speaker 1: zone will probably include Jupiter, So it's not a terrible idea.
44:07
Speaker 1: And you know, I know somebody who's writing a book
44:09
Speaker 1: on space settlements, and so I should ask you, for example,
44:13
Speaker 1: like could we build floating colonies in the clouds of
44:16
Speaker 1: Jupiter or could we settle on Io and use the
44:18
Speaker 1: like underground oceans and the underground tectonics to extract the energy?
44:23
Speaker 1: What do you think about all that? Well, so we
44:25
Speaker 1: are focusing on more near term, which we think is
44:28
Speaker 1: going to focus on the Moon or Mars or rotating
44:32
Speaker 1: space stations. So I haven't thought too much about the
44:35
Speaker 1: moons of Jupiter. There are some that have like nicer
44:39
Speaker 1: ish conditions, and couldn't you have some of the stuff
44:42
Speaker 1: that life needs. But at the end of the day,
44:45
Speaker 1: they don't seem so nice. But maybe they'll seem nice
44:47
Speaker 1: when we're in the habitable zone billions of years from now.
44:50
Speaker 1: What do you think I'm imagining you designing a pamphlet
44:53
Speaker 1: for people to move to these colonies and you call
44:55
Speaker 1: it nice ish better than death moons of Jupiter. I
45:01
Speaker 1: think it's pretty unlikely. And I think it comes back
45:03
Speaker 1: to something you often say, which is that people think
45:05
Speaker 1: about colonization, but they always assume that the Earth is
45:08
Speaker 1: going to be there as the core of the infrastructure. Like, yeah,
45:11
Speaker 1: maybe we could send people to Mars next year, but
45:14
Speaker 1: they're not going to be self sustaining for a long
45:16
Speaker 1: time to rely on shipments from Earth and technology from
45:20
Speaker 1: Earth for a long time. So it'd be hard to
45:22
Speaker 1: imagine sending up colonies on Io or something and having
45:25
Speaker 1: them be self sustaining in a way that could support
45:27
Speaker 1: like billions of people. So I think that scenario is
45:31
Speaker 1: like maybe dozens, hundreds thousands of people survive, but not
45:36
Speaker 1: the whole human race. I think most people are gonna
45:38
Speaker 1: lose out if we have to move to the moons
45:39
Speaker 1: of Jupiter. I think the space settlement advocates would tell
45:42
Speaker 1: you that that's why we need to start now working
45:45
Speaker 1: on these technologies. And also, if you can build rotating
45:48
Speaker 1: space stations, those are more movable, so you build those
45:51
Speaker 1: out of the stuff in the asteroids, and then that's
45:53
Speaker 1: easier to move closer or away from the Sun, depending
45:56
Speaker 1: on you know where the best places that at any
45:59
Speaker 1: particular moment, that'll be much easier than moving the entire Earth. Yeah,
46:02
Speaker 1: I agree, let's start building. Well. To me, you that
46:07
Speaker 1: still brings a whole new set of problems about what
46:09
Speaker 1: we'll be able to peacefully move out into space or
46:12
Speaker 1: what we kill ourselves before any of this becomes a problem.
46:14
Speaker 1: But you know, some people believe more in humans than
46:17
Speaker 1: I do, so so we'll see. So we have mostly
46:20
Speaker 1: been talking about trying to get away from the Sun
46:23
Speaker 1: as it expands. Next, we're gonna have to figure out
46:27
Speaker 1: how to survive when the Sun becomes a white dwarf.
46:30
Speaker 1: But let's chat about that after the break. Okay, So
46:46
Speaker 1: let's imagine that somehow humanity has managed to avoid having
46:50
Speaker 1: our oceans boiled off, We've managed to outrun the sun.
46:54
Speaker 1: What comes next the Sun becomes a white dwarf, and
46:57
Speaker 1: how do we eke out in existence then? So it
47:00
Speaker 1: would be cool if we were around to see the
47:02
Speaker 1: helium flash of the Sun, or send probes in there
47:05
Speaker 1: or something. It would be pretty awesome to study that.
47:07
Speaker 1: After that that, basically the Sun collapses. It's sort of
47:09
Speaker 1: like a mini supernova. You have this shock wave which
47:13
Speaker 1: blows out a lot of the layers of the Sun
47:15
Speaker 1: and then you're left with just this core, this hot
47:18
Speaker 1: lump of stuff, the white dwarf. So, as we talked
47:20
Speaker 1: about a little bit earlier, we need to then somehow
47:23
Speaker 1: move the Earth or our colonies or whatever we're living
47:26
Speaker 1: in closer, because it's gonna be a lot colder. If
47:29
Speaker 1: you're out in Jupiter's radius right now and the Sun
47:32
Speaker 1: becomes a white dwarf, you're gonna get almost no energy.
47:35
Speaker 1: So if you want to grow your space salads, for example,
47:38
Speaker 1: then you're gonna have to move everything much closer in.
47:41
Speaker 1: And the other technology is basically the same. You know,
47:43
Speaker 1: find another asteroid to gravitationally slingshot yourself closer to the Sun,
47:48
Speaker 1: or turn that rocket engine around that you build and
47:51
Speaker 1: pointed the other way and just fly the Earth towards
47:54
Speaker 1: the Sun. Though that seems pretty terrifying to me. Yeah,
47:57
Speaker 1: you gotta hope you don't overshoot, but you could fee
48:00
Speaker 1: ably get enough heat and sunlight if you managed to
48:03
Speaker 1: get close enough, You definitely could write. White dwarves are
48:06
Speaker 1: pretty hot. They do give off a lot of light.
48:09
Speaker 1: I mean there are regions near a white dwarf that
48:11
Speaker 1: are too hot for us to survive, which means that
48:14
Speaker 1: there is a habitable zone there. Right, You couldn't get
48:16
Speaker 1: just the right distance from a white dwarf, It is possible.
48:19
Speaker 1: The good news is white dwarfs last for a long,
48:22
Speaker 1: long time, right, trillions of years, and so that could
48:26
Speaker 1: be a pretty good long term scenario. All right, I'm
48:29
Speaker 1: like in this, but it also sounds like there's that
48:31
Speaker 1: complicated phase where we're sort of needing to do a
48:34
Speaker 1: lot of moving and we're hoping that all of that
48:36
Speaker 1: doesn't destroy the climate on Earth. Maybe at some point
48:40
Speaker 1: we should just like try a whole different system and
48:44
Speaker 1: move to a move near a different star. What do
48:46
Speaker 1: we need to do to make that happen? I think
48:48
Speaker 1: you're right, And if we're thinking very long term, then
48:50
Speaker 1: we have to think about other options and other stars. Currently,
48:54
Speaker 1: getting to another star is very tricky, right, We're talking
48:57
Speaker 1: about building like generation ships that move less than the
49:01
Speaker 1: speed of light to take tens or hundreds of years
49:04
Speaker 1: to get to proximate centauri. And they're still like, what
49:08
Speaker 1: fraction of the human race can you really fit onto ships?
49:11
Speaker 1: Thousands of people maybe millions of people? You have a
49:13
Speaker 1: lottery where like one in a thousand people gets to
49:16
Speaker 1: go and everybody else like stays behind to die. Sounds
49:20
Speaker 1: pretty sad. It's bleak. It's bleak, exactly. I think if
49:24
Speaker 1: we're talking about technology and millions and billions of years.
49:27
Speaker 1: Then we get to think about things that are theoretically
49:29
Speaker 1: allowed right now, but we haven't figured out how to
49:31
Speaker 1: do things we like to talk about in this podcast
49:34
Speaker 1: a lot like wormholes and warp drives. These are things
49:38
Speaker 1: that we think are allowed, that the physics of them
49:41
Speaker 1: says it's possible that we don't have a recipe for
49:43
Speaker 1: how to build a warp driver, how to construct or
49:46
Speaker 1: even find a wormhole, or to know if they're even traversible.
49:49
Speaker 1: But you know, fund basic physics for another thousand years
49:53
Speaker 1: and we'll probably figure a lot of that out. So
49:55
Speaker 1: you know, if we're talking about deep future and speculation,
49:58
Speaker 1: then physics could open a lot of in doors for
50:00
Speaker 1: how to get two other stars without actually having a
50:03
Speaker 1: fly there on a big fat ship. But I used
50:06
Speaker 1: to really like watching Doctor Who, and I'm pretty sure
50:08
Speaker 1: that on Doctor Who there was a point where time
50:11
Speaker 1: ends and at some point you're going to have the
50:14
Speaker 1: death of all stars, And so is there anything we
50:17
Speaker 1: can do? Can we make it until then? And then
50:20
Speaker 1: what happens? Right, if we're thinking about the really deep future,
50:23
Speaker 1: like all of the stars are burning and most of
50:26
Speaker 1: them have burned out, then we do think the universe
50:28
Speaker 1: will get darker, right Like, most of the university is
50:31
Speaker 1: hydrogen and that will continue to burn stars. But at
50:34
Speaker 1: some point the universe stops making stars, right Like, in
50:37
Speaker 1: order for stars to form, the gas that coalesces that
50:41
Speaker 1: builds a solar system has to be kind of cold,
50:43
Speaker 1: needs to be able to collapse. It can't be too hot.
50:46
Speaker 1: And we don't really understand, but we see that in
50:48
Speaker 1: galaxies when they get to a certain age, they just
50:50
Speaker 1: stop making stars. This is called quenching, and so we
50:54
Speaker 1: don't really understand it, but we do suspect that the
50:56
Speaker 1: universe is past its prime. In Star Make game, that like,
51:00
Speaker 1: the rate of new stars being formed is dropping. So
51:03
Speaker 1: as you say, that suggests that in the far far
51:06
Speaker 1: future we may not have any more stars. And some
51:09
Speaker 1: people imagine that what will be left with is just
51:12
Speaker 1: a bunch of black holes, right that used to be
51:14
Speaker 1: the centers of galaxies that have now swallowed up all
51:17
Speaker 1: those stars. And then dark energy is going to push
51:19
Speaker 1: those black holes apart. Remember that the universe is expanding,
51:23
Speaker 1: and that expansion is accelerating, and so the deep deep
51:26
Speaker 1: future is a bunch of black holes that are super
51:29
Speaker 1: duper far apart from each other, and no light in
51:31
Speaker 1: the universe at all. You know what, I want my
51:34
Speaker 1: kids to stay home living with us for a really
51:36
Speaker 1: long time so that you never come visit me either.
51:41
Speaker 1: But you know, there are possible ways to survive that future.
51:44
Speaker 1: We talked to the podcast recently about how to take
51:46
Speaker 1: energy from black holes. Black holes have this region around
51:50
Speaker 1: them called the ergosphere, which is ergo means work right,
51:54
Speaker 1: or ergs like an energy And turns out you can
51:56
Speaker 1: drop stuff into the ergo spheres outside the event horizon,
52:00
Speaker 1: so it'll come back to you and it will come
52:01
Speaker 1: back with more energy. So you can like drop rocks
52:05
Speaker 1: near a black hole and they'll whizz around and come
52:07
Speaker 1: back with more energy. So you can extract energy from
52:10
Speaker 1: black holes and use that to power you know, your
52:12
Speaker 1: underground salad farm or whatever you need to survive in
52:16
Speaker 1: the deep deep future. All right now, I want them
52:18
Speaker 1: to move out again. But you know, we're talking about
52:22
Speaker 1: something like a hundred trillion years from now, and the
52:25
Speaker 1: error bars on that are huge because it's always very
52:28
Speaker 1: difficult to predict far far in the future, and also
52:30
Speaker 1: because we just don't know what dark energy is going
52:33
Speaker 1: to do. Remember that we see the universe expanding We
52:36
Speaker 1: know that expansion is accelerating, but we don't understand it,
52:39
Speaker 1: which means that we can't accurately predict what it's going
52:41
Speaker 1: to do. So any speculation about the far far future
52:44
Speaker 1: comes with a huge galaxy sized asterisk and job security physicists.
52:51
Speaker 1: But you know, I think the lesson to take home
52:53
Speaker 1: is that while the future of our neighborhood is dynamic
52:57
Speaker 1: and changing and it won't always be the way that
52:59
Speaker 1: it is today, it's going to be different, and we
53:02
Speaker 1: have clever ways to maybe survive that human ingenuity might
53:06
Speaker 1: allow us to persist millions, billions, even trillions of years
53:10
Speaker 1: into the future. You know, human beings have done pretty
53:12
Speaker 1: amazing things that the fact that we have rovers going
53:15
Speaker 1: around studying Mars makes me optimistic about humanity in general.
53:19
Speaker 1: So I'm keeping my fingers crossed. We haven't died out yet, right,
53:22
Speaker 1: If you're listening to this podcast, that means that humans
53:25
Speaker 1: have still survived. Is that not hopeful enough for your Kelly?
53:32
Speaker 1: That's as hopeful as we can get on this show.
53:35
Speaker 1: So that's that's fine, alright. So remember that our time
53:38
Speaker 1: here on Earth is precious, and that the Earth's time
53:40
Speaker 1: around the Sun is also precious and short lived. And
53:44
Speaker 1: on this podcast, we're all hopeful that you folks out there,
53:48
Speaker 1: those young people thinking about signs and wanting to become
53:50
Speaker 1: business or engineers, will come up with the solutions to
53:53
Speaker 1: save us all. Otherwise we die. And somehow I became
53:58
Speaker 1: the optimist in this episode. So thanks for tuning in, everybody,
54:03
Speaker 1: and thank you Kelly very much for joining us, Thanks
54:05
Speaker 1: for having me. Have a nice week, everyone, alright, tune
54:08
Speaker 1: in next time. Thanks for listening, and remember that Daniel
54:18
Speaker 1: and Jorge explained. The Universe is a production of I
54:21
Speaker 1: Heart Radio. For more podcast For my heart Radio, visit
54:24
Speaker 1: the I heart Radio app, Apple Podcasts, or wherever you
54:28
Speaker 1: listen to your favorite shows.