WEBVTT - Can we engineer the sun? 0:00:07.800 --> 0:00:10.959 Are we at the mercy of our cosmic fates or 0:00:11.000 --> 0:00:15.480 are we masters of our domain. We've been lucky so far, 0:00:15.840 --> 0:00:18.680 living on this tiny spinning rock at just the right 0:00:18.760 --> 0:00:22.720 distance from an enormous ball of plasma. It keeps us 0:00:22.800 --> 0:00:26.760 warm but not too warm, and it's been stable enough 0:00:26.760 --> 0:00:29.680 to give us time to evolve, to develop technology in 0:00:29.760 --> 0:00:34.919 science and understand our fragile place in the universe. And 0:00:35.040 --> 0:00:38.280 is there also time for us to intervene in the 0:00:38.360 --> 0:00:43.000 Sun's eventual demise? Can we develop the technology and massive 0:00:43.040 --> 0:00:47.080 engineering capacity to keep the Sun from going red giant 0:00:47.159 --> 0:00:51.320 and frying the whole planet? That's the cosmic question we're 0:00:51.320 --> 0:00:57.640 tackling today. Welcome to Daniel and Kelly's extraordinarily engineered Universe. 0:01:10.959 --> 0:01:14.640 Hello, I'm Kelly Windersmith. I study parasites and space, and 0:01:14.680 --> 0:01:17.560 I'm looking forward to putting on my skeptical face today. 0:01:18.280 --> 0:01:21.640 Hi. I'm Daniel. I'm a particle physicist, and I'm going 0:01:21.680 --> 0:01:25.600 to be optimistic about our ability to preserve the future 0:01:25.640 --> 0:01:26.800 of humanity today. 0:01:27.200 --> 0:01:28.640 Ah, why are you going to make me sound like 0:01:28.760 --> 0:01:30.039 such a wet blanket? 0:01:30.880 --> 0:01:33.720 Because you love it, Kelly, you love it. 0:01:33.720 --> 0:01:37.959 It's the most comfortable feeling for me. I guess all right, 0:01:37.959 --> 0:01:42.119 So let's start with another amazing engineering project for our 0:01:42.160 --> 0:01:46.720 intro question here, So do you think we should terraform Mars? 0:01:47.840 --> 0:01:50.080 Wow, that feels like a trap to me. 0:01:53.160 --> 0:01:55.560 You brought up this amazing geo engineering. 0:01:56.320 --> 0:01:58.200 That's true. No, you're right. Compared to what we're talking 0:01:58.240 --> 0:02:02.160 about today, terraforming Mars is like just a warm up exercise. 0:02:02.440 --> 0:02:03.000 There you go. 0:02:03.240 --> 0:02:06.200 I think that we should first figure out if Mars 0:02:06.280 --> 0:02:08.880 has life on it before we go in and muck 0:02:08.960 --> 0:02:11.680 it up with our kind of life. Because wouldn't it 0:02:11.720 --> 0:02:15.960 be incredible to discover Martian life that evolved independently, that 0:02:16.120 --> 0:02:19.760 started from nothing independently, or if it weirdly has like 0:02:19.800 --> 0:02:21.840 something in common with Earth life, so we could have 0:02:21.880 --> 0:02:24.880 some sort of like mini pan spermia. I feel like 0:02:24.919 --> 0:02:28.120 the scientific consequences would be amazing and be ashamed to 0:02:28.200 --> 0:02:30.880 muck that all up by just dropping a million people 0:02:30.919 --> 0:02:34.560 on Mars too soon. But that's a pretty extensive project. 0:02:34.639 --> 0:02:38.040 Once we're done with that, though, then yeah, I think 0:02:38.240 --> 0:02:40.720 if we have the capacity and the resources and we've 0:02:40.720 --> 0:02:43.119 thought it through, then I do think it's a reasonable 0:02:43.160 --> 0:02:46.640 place to extend humanity. What do you think where am 0:02:46.639 --> 0:02:47.000 I wrong. 0:02:47.240 --> 0:02:48.720 Oh, I don't think you're wrong in any of the 0:02:48.800 --> 0:02:51.680 things that you just said. I guess I'm more thinking 0:02:51.720 --> 0:02:55.000 about how we would go about terraforming Mars. One of 0:02:55.040 --> 0:02:57.760 the things that surprised me when A City on Mars 0:02:57.800 --> 0:03:02.360 came out, which available in paperback now, was that the 0:03:02.480 --> 0:03:06.680 geology community felt like we hadn't spent enough time talking 0:03:06.720 --> 0:03:10.040 about how Mars is a like unique geological treasure and 0:03:10.080 --> 0:03:12.280 we shouldn't be going out there and mucking it. 0:03:12.280 --> 0:03:15.880 Up from a scientific perspective, like answering geological questions. 0:03:16.160 --> 0:03:17.720 I think that was part of it, but I think 0:03:17.760 --> 0:03:20.320 there was also a bit of a thread of a like, well, 0:03:20.320 --> 0:03:22.560 we've messed up a lot of stuff about our planet. 0:03:22.639 --> 0:03:25.440 We shouldn't let people go out and mess up another planet. 0:03:25.919 --> 0:03:29.040 And you know, I see their point, and I particularly 0:03:29.080 --> 0:03:32.440 see their point when you hear about terraforming arguments that 0:03:32.480 --> 0:03:35.760 go something along the lines of let's dump a bunch 0:03:35.760 --> 0:03:39.080 of nuclear weapons on the poles at Mars to release 0:03:39.120 --> 0:03:42.200 a bunch of water vapor, which will then create a 0:03:42.240 --> 0:03:44.440 greenhouse effect and will warm up the planet and will 0:03:44.440 --> 0:03:46.800 create an atmosphere that would be more hospitable to human life. 0:03:46.840 --> 0:03:49.520 Blah blah, blah. I think I'm not super excited about 0:03:49.560 --> 0:03:51.800 dropping nuclear weapons on Mars, is what I'm saying. 0:03:51.640 --> 0:03:53.520 Especially because to get n FCO two to warm with 0:03:53.520 --> 0:03:55.960 the planet, you'll create an atmosphere which is toxic to 0:03:56.120 --> 0:03:59.000 humans anyway, And so like, yeah, there's a lot of 0:03:59.080 --> 0:04:01.760 challenges there, And so I guess my answer is like 0:04:01.800 --> 0:04:04.680 assuming we can solve a lot of these really big 0:04:04.720 --> 0:04:07.880 engineering challenges, because in today's episode, we're going to think 0:04:08.040 --> 0:04:12.640 really big and really broad about like mega engineering, engineering 0:04:12.840 --> 0:04:17.720 that would impress visiting aliens. That's what we're talking about today. WHOA. 0:04:17.760 --> 0:04:19.960 Well, I guess if you're an alien civilization that made 0:04:20.000 --> 0:04:21.560 it all the way to Earth, you maybe wouldn't be 0:04:21.560 --> 0:04:24.120 impressed with what we've done. But I am personally impressed 0:04:24.160 --> 0:04:26.880 with the extent to which we have molded the planet 0:04:27.040 --> 0:04:28.200 to meet our needs. 0:04:28.480 --> 0:04:31.000 But anyway, there are lots of moments of awe. You know, 0:04:31.040 --> 0:04:33.240 every time I like drive across the Golden gate Bridge, 0:04:33.240 --> 0:04:36.360 I'm like, Wow, humans built this and it's still here 0:04:36.400 --> 0:04:40.360 like decades later. It's pretty impressive. Or every skyscraper, or 0:04:40.400 --> 0:04:45.080 frankly the COVID vaccine, I'm like, wow, we can do Yeah. 0:04:45.920 --> 0:04:48.359 So yeah, humanity has done a lot of impressive stuff, 0:04:48.360 --> 0:04:50.440 but it's just the beginning, you know. The kinds of 0:04:50.480 --> 0:04:53.640 things that we might do, the challenges we might take on, 0:04:53.680 --> 0:04:57.359 the solutions we might engineer, really are almost limitless. 0:04:57.600 --> 0:04:59.840 We are only getting started, which is why we need 0:04:59.880 --> 0:05:02.960 to make sure that our species persists for a very 0:05:02.960 --> 0:05:04.800 long time. So today we're gonna be talking about how 0:05:04.839 --> 0:05:08.000 we can engineer the Sun to keep our species going 0:05:08.120 --> 0:05:09.000 for much longer. 0:05:09.240 --> 0:05:13.040 That's right, because one of Mars terraforming proponents is always 0:05:13.040 --> 0:05:15.440 saying that Earth is going to get fried in a 0:05:15.480 --> 0:05:18.599 few billion years anyway, when the Sun expands and goes 0:05:18.680 --> 0:05:21.240 red giant, and so not only do we need to 0:05:21.360 --> 0:05:23.920 have outposts on Mars, but we got to get interstellar. 0:05:24.400 --> 0:05:27.040 And so today we're gonna talking about exactly that scenario. 0:05:27.560 --> 0:05:31.040 Is it possible to engineer the Sun using a technique 0:05:31.080 --> 0:05:35.719 called starlifting to prolong our time in the habitable zone? So, 0:05:35.880 --> 0:05:37.960 as usual, I went out there to ask our audience 0:05:38.000 --> 0:05:41.839 if they knew something about starlifting. Here's what they had 0:05:41.880 --> 0:05:42.280 to say. 0:05:42.880 --> 0:05:45.520 What is starlifting is that when you go to the 0:05:45.560 --> 0:05:48.680 gym and you see someone famous and you pick them up. No, 0:05:49.400 --> 0:05:52.800 that can't be it. Maybe it's something to do when 0:05:52.800 --> 0:05:56.279 a star's about to go supernova and the core is 0:05:56.320 --> 0:06:00.240 starting to burn carbon and getting into iron. Maybe the 0:06:00.320 --> 0:06:04.160 layers start to lift off and that's starlifting. I have 0:06:04.279 --> 0:06:04.919 no idea. 0:06:05.560 --> 0:06:08.039 Well, that is that new show that is airing on 0:06:08.240 --> 0:06:13.239 NBC at seven o'clock on Thursday nights where big movie 0:06:13.279 --> 0:06:18.599 stars compete in weightlifting competition, and it's intense and I'm ready. 0:06:18.640 --> 0:06:20.560 I'm really looking forward to seeing it. 0:06:21.160 --> 0:06:26.799 I have not heard of starlifting, but a star lift 0:06:27.240 --> 0:06:28.760 sounds like it could be a fun. Right at the 0:06:28.760 --> 0:06:29.520 amusement park. 0:06:30.040 --> 0:06:32.719 Amazing answers as always, and if you want to contribute 0:06:32.760 --> 0:06:36.000 your amazing answers, write us at questions at Daniel and 0:06:36.080 --> 0:06:38.000 Kelly dot org and we'll add you to the list 0:06:38.040 --> 0:06:41.000 of folks who get these questions ahead of time. I 0:06:41.040 --> 0:06:43.000 love the when you go to the gym and see 0:06:43.000 --> 0:06:47.040 someone famous response. I live in Charlottesville, Virginia, and I 0:06:47.120 --> 0:06:51.479 heard that Dwayne the Rock Johnson also lives in Charlottesville. 0:06:51.480 --> 0:06:53.880 And sometimes if you go to the gym, what you 0:06:53.960 --> 0:06:54.840 will see the Rock. 0:06:55.160 --> 0:06:57.760 How often has that happened to you, Kelly, Oh. 0:06:57.720 --> 0:07:00.320 Zero times, zero times. I don't think you go to 0:07:00.360 --> 0:07:03.120 the YMCA. It probably goes to a better gym than 0:07:03.160 --> 0:07:05.039 I go to. But you know, another good reason to 0:07:05.080 --> 0:07:06.200 work out. I guess why. 0:07:06.120 --> 0:07:07.680 Doesn't he live in La. I thought he would be 0:07:07.720 --> 0:07:08.520 in La Dude. 0:07:08.600 --> 0:07:11.320 I think that he's probably part time La, part time 0:07:11.520 --> 0:07:14.080 the better coast, you know, like you're in You're in 0:07:14.160 --> 0:07:16.520 California when you have to be, but in Virginia when 0:07:16.560 --> 0:07:18.360 you have a choice, that sort of thing. 0:07:18.680 --> 0:07:22.120 Virginia is for lovers of Virginia. So there you go. 0:07:22.720 --> 0:07:26.120 Oh oh, Virginia is for everyone. 0:07:26.040 --> 0:07:28.920 All right. So starlifting is an engineering technique to solve 0:07:28.920 --> 0:07:31.960 a very particular problem. So before we get into the solution, 0:07:32.120 --> 0:07:34.480 I thought it'd be helpful to introduce what is the 0:07:34.520 --> 0:07:35.480 problem we're solving. 0:07:35.600 --> 0:07:38.480 Anyway, that's right, and fortunately for me, I won't get 0:07:38.480 --> 0:07:41.880 too mired in existential dread because the timeline here is 0:07:42.000 --> 0:07:44.680 way off in the future. But let's go ahead. Tell 0:07:44.720 --> 0:07:46.880 us about the future of the sun. Why won't the 0:07:46.920 --> 0:07:47.840 sun last forever? 0:07:48.200 --> 0:07:50.960 The sun won't last forever because it's in frankly, a 0:07:51.000 --> 0:07:54.240 delicate balance. It's amazing to me that stars last as 0:07:54.280 --> 0:07:57.600 long as they do. I mean, there's this incredible balancing 0:07:57.640 --> 0:08:00.560 act between gravity, which is pulling the star together and 0:08:00.640 --> 0:08:04.240 trying to collapse it down, and fusion, which is creating 0:08:04.320 --> 0:08:07.440 heat and energy and pushing the star out. And these 0:08:07.480 --> 0:08:10.640 two forces, which are fundamentally very very different, right, Fusion 0:08:10.720 --> 0:08:14.040 uses the quantum mechanical strong nuclear force. Gravity, of course, 0:08:14.400 --> 0:08:17.440 uses the curvature of space. We don't even know how 0:08:17.480 --> 0:08:22.440 to unify these things. Conceptionally they're very different pillars of physics. 0:08:22.440 --> 0:08:25.440 But here they come together and they dance together nicely 0:08:25.520 --> 0:08:28.960 for billions and billions of years. Right in the heart 0:08:29.000 --> 0:08:32.120 of the star, you have incredible pressure and temperature, and 0:08:32.160 --> 0:08:36.160 so hydrogen gets squeezed together to form helium, which releases heat. 0:08:36.320 --> 0:08:40.080 When light elements fuse together, you release heat, and when 0:08:40.120 --> 0:08:44.400 heavy elements break apart, that's fission that also releases heat. 0:08:44.520 --> 0:08:46.280 So in the heart of a star, it's sort of 0:08:46.320 --> 0:08:51.400 like a constantly exploding nuclear bomb that's generating all of 0:08:51.440 --> 0:08:54.000 this energy to prevent the star from collapsing. 0:08:54.559 --> 0:08:57.120 I think that's where your beautiful dance metaphor kind of 0:08:57.120 --> 0:09:00.640 falls apart, and I don't usually think of beautiful dance involving 0:09:01.160 --> 0:09:03.120 explosions of nuclear type. 0:09:03.200 --> 0:09:06.040 Well, that's why it's so incredible imagine a constantly exploding 0:09:06.120 --> 0:09:09.600 nuclear bomb that you're keeping in a gravitational bubble, right, 0:09:09.640 --> 0:09:11.520 and if you compress it too much, it's going to 0:09:11.559 --> 0:09:13.040 go out, it's going to turn into a black hole. 0:09:13.080 --> 0:09:14.960 If you don't compress it enough, it's going to blow 0:09:15.000 --> 0:09:19.360 itself apart. And so it's really amazing. And the outcome 0:09:19.400 --> 0:09:22.720 for these stars depends almost entirely on how much mass 0:09:22.760 --> 0:09:25.480 you have, Like if you don't have a lot of mass, 0:09:25.480 --> 0:09:27.720 you end up with a red dwarf, a smaller star, 0:09:28.080 --> 0:09:31.240 and the heart of it is lower temperature and lower pressure, 0:09:31.559 --> 0:09:33.720 and so the rate of fusion is lower, and so 0:09:33.800 --> 0:09:36.200 these stars are dimmer and cooler, which is why they're 0:09:36.200 --> 0:09:38.960 called red dwarfs. Or a much bigger stars like a 0:09:39.000 --> 0:09:42.000 blue giant, and these are hotter at their core, and 0:09:42.000 --> 0:09:44.800 they fuse a lot faster, and the peak of their 0:09:44.840 --> 0:09:47.000 glow is at a higher frequency, which is why they're 0:09:47.000 --> 0:09:51.240 called blue giants. But those stars, the bigger, more massive stars, 0:09:51.480 --> 0:09:54.200 fusion happens much more rapidly, and so they burn through 0:09:54.240 --> 0:09:57.520 their fuel. So this is this really tight relationship between 0:09:57.520 --> 0:09:59.920 the mass of the star and how long it's to 0:10:00.040 --> 0:10:03.319 expected to live. Smaller stars are cooler, and they can 0:10:03.360 --> 0:10:07.040 burn for billions, maybe even trillions of years. Red dwarfs 0:10:07.120 --> 0:10:11.320 are very very long lasting, whereas bigger stars don't burn 0:10:11.360 --> 0:10:14.199 for very long because they burn so hot and so fast. 0:10:14.800 --> 0:10:17.080 Like if you look at a population of stars, you 0:10:17.120 --> 0:10:20.199 can tell how old the population is by how many 0:10:20.240 --> 0:10:22.680 big blue stars there are. It's got a bunch of 0:10:22.679 --> 0:10:24.680 big blue stars, you know, it's got to be pretty young, 0:10:24.720 --> 0:10:27.760 because they don't last very long. As galaxies aid, they 0:10:27.800 --> 0:10:30.560 turn redder and redder because all the blue stars burn out. 0:10:31.360 --> 0:10:34.080 And where is our Sun on the gradient from any 0:10:34.120 --> 0:10:35.760 bitty stars to big stars. 0:10:36.240 --> 0:10:37.880 Our star is not one of the biggest stars in 0:10:37.920 --> 0:10:40.720 the universe. The limit is around three hundred times the 0:10:40.760 --> 0:10:42.960 mass of the Sun. A star bigger than that will 0:10:42.960 --> 0:10:47.120 have fusion so terrifyingly powerful it'll tear itself apart and 0:10:47.120 --> 0:10:50.280 it'll become smaller. But our star is bigger than the 0:10:50.320 --> 0:10:53.520 average star. So the most common star is a red 0:10:53.600 --> 0:10:56.720 dwarf that's like the median star in the universe. Our 0:10:56.760 --> 0:10:58.720 star is bigger than that, so it's a bigger, hotter 0:10:58.800 --> 0:11:01.240 star than it's typical, and its lifetime is expected to 0:11:01.240 --> 0:11:04.640 be about ten billion years, and we're halfway through that. 0:11:04.679 --> 0:11:06.680 So we've got another five billion years. 0:11:06.880 --> 0:11:09.160 Oh man, what do you think of midlife crisis looks like? 0:11:09.160 --> 0:11:09.680 For a Sun? 0:11:12.679 --> 0:11:16.040 It's talking to all the other stars. It's wondering, like, hey, 0:11:16.040 --> 0:11:18.400 do I have the right number of planets? It should 0:11:18.400 --> 0:11:23.040 I have accomplished more by this point. Have I dealt 0:11:23.040 --> 0:11:25.320 with that nacking infection on my third planet? You know? 0:11:25.360 --> 0:11:27.760 I really should snuff that out? Oh gosh before it 0:11:27.800 --> 0:11:28.320 takes over. 0:11:28.520 --> 0:11:30.320 No, no, let us go, Let us go. We're gonna 0:11:30.320 --> 0:11:33.480 save you in the long run, baby, we'll see, or 0:11:33.480 --> 0:11:36.000 at least we're gonna tinker with you. Okay, So we're 0:11:36.000 --> 0:11:36.679 halfway through. 0:11:36.880 --> 0:11:40.040 We're halfway through, and the future, the second half of 0:11:40.120 --> 0:11:41.800 the Sun's life is going to be quite different from 0:11:41.840 --> 0:11:44.520 the first half. What's going to happen is that as 0:11:44.600 --> 0:11:48.319 fusion progresses, it forms helium, and that helium is heavier 0:11:48.360 --> 0:11:51.760 than hydrogen, so it sinks to the core. So instead 0:11:51.760 --> 0:11:54.319 of just being like basically a huge ball of hydrogen, 0:11:54.520 --> 0:11:56.960 you're gonna get a helium core. Like the ash from 0:11:56.960 --> 0:12:00.200 the fusion sinks and goes to the core. But our 0:12:00.320 --> 0:12:03.320 star is not hot enough to fuse that helium, like 0:12:03.400 --> 0:12:06.440 if it was hotter and denser. You could fuse helium together, 0:12:06.679 --> 0:12:09.520 three them together to get carbon, but we can't do that. 0:12:09.840 --> 0:12:11.840 Our star is just not hot enough, so the helium 0:12:11.880 --> 0:12:15.160 is sort of inert and it blocks fusion from happening. 0:12:15.440 --> 0:12:18.439 But before that, because it's denser, it increases the temperature 0:12:18.440 --> 0:12:20.640 at the core of the star, which makes the Sun hotter. 0:12:21.120 --> 0:12:24.080 So our sun is gradually getting hotter and hotter as 0:12:24.120 --> 0:12:27.200 its core gets denser and denser because of the helium 0:12:27.200 --> 0:12:30.440 that sinks there. Roughly every one hundred million years, the 0:12:30.520 --> 0:12:32.600 Sun gets one percent brighter. 0:12:32.840 --> 0:12:35.040 So I guess it. It's the same with this is 0:12:35.040 --> 0:12:37.400 gonna be one of the things that like ends are 0:12:37.520 --> 0:12:41.160 species that's not funny. Helium's supposed to be funny. 0:12:41.559 --> 0:12:43.360 I know, if it makes you sound like a chipmugget 0:12:43.360 --> 0:12:45.600 should be funny. But also chipmunks can be quite deadly, 0:12:45.679 --> 0:12:47.400 you know. Yeah, they could take over the whole planet. 0:12:47.520 --> 0:12:49.120 They carry the bubonic platey. 0:12:49.160 --> 0:12:52.240 You go, well do yeah in New Mexico actually home 0:12:52.320 --> 0:12:53.959 with the flea land of the plague, we call it 0:12:56.160 --> 0:12:59.520 all right, there's some New Mexico pride for you. So, yeah, 0:12:59.520 --> 0:13:02.000 the sun is gradually getting brighter, and in a few 0:13:02.040 --> 0:13:05.160 billion years, the Sun will be forty percent brighter. This 0:13:05.280 --> 0:13:07.000 is why people say like the Sun is going to 0:13:07.040 --> 0:13:09.920 boil off the oceans, because in a couple of billion years, 0:13:09.920 --> 0:13:12.360 the global average temperature is going to rise to one 0:13:12.440 --> 0:13:16.760 hundred degrees sea, right where the oceans will boil. And 0:13:16.840 --> 0:13:19.200 so this is just a natural progression of the Sun. 0:13:19.240 --> 0:13:21.199 It's gonna get brighter and brighter and brighter. The Sun 0:13:21.240 --> 0:13:23.800 itself is not getting that much hotter, but it is 0:13:23.840 --> 0:13:27.360 getting brighter, and the outer layers are going to grow 0:13:27.840 --> 0:13:31.720 because as the core accumulates helium, then fusion moves further 0:13:31.800 --> 0:13:35.760 out right, you can't have fusion at the ash helium core, 0:13:36.000 --> 0:13:38.160 so you start getting fusion in the outer layers and 0:13:38.200 --> 0:13:40.480 that puffs up the Sun and that's what makes it 0:13:40.480 --> 0:13:43.160 become a red giant and does just puff it up 0:13:43.200 --> 0:13:45.080 a little bit. We're talking about the radius of the 0:13:45.080 --> 0:13:48.679 Sun growing from its current radius to two hundred times 0:13:48.840 --> 0:13:49.920 its current radius. 0:13:50.040 --> 0:13:52.880 Okay, so I'm starting to feel the existential dread bubble up. 0:13:52.960 --> 0:13:55.440 I didn't think this was going to happen. But we 0:13:55.480 --> 0:13:57.920 only have one to two billion years even though Earth 0:13:58.000 --> 0:14:00.880 is middle aged before our oceans boil. But I'm betting 0:14:00.880 --> 0:14:03.320 that we all die long before the oceans boil, because 0:14:03.360 --> 0:14:05.160 it takes a lot of hate to get the oceans 0:14:05.200 --> 0:14:05.600 to boil. 0:14:05.880 --> 0:14:08.040 You mean me and you? Are you talking about? Like 0:14:08.080 --> 0:14:08.880 me and you and all of. 0:14:08.800 --> 0:14:12.240 Our descendants, it would be our descendants at that point. Yeah, 0:14:12.240 --> 0:14:14.839 So how long before Earth becomes uninhabitable? 0:14:14.960 --> 0:14:16.920 Yeah, that's a great question. That's just a few hundred 0:14:16.960 --> 0:14:19.760 million years, right, because the temperature on the surface of 0:14:19.760 --> 0:14:23.920 one hundred sea is intolerable obvious there, Right, It's a 0:14:23.960 --> 0:14:27.040 pretty good approximation that every hundred million years you get 0:14:27.080 --> 0:14:30.560 one percent brighter. It's roughly linear, and so yeah, it's 0:14:30.600 --> 0:14:32.320 going to be a few hundred million years. It's going 0:14:32.400 --> 0:14:35.080 to be much hotter than it is now. Definitely, we're 0:14:35.080 --> 0:14:38.120 talking climate change for sure. So this is something we're 0:14:38.120 --> 0:14:40.880 going to have to adapt to well before the oceans 0:14:40.920 --> 0:14:44.000 boil or the outer layers of the Sun consume the Earth. 0:14:44.160 --> 0:14:45.840 All right, we've got time to figure this out. But 0:14:46.120 --> 0:14:49.560 I'm still not loving it. Not cool sun. 0:14:50.000 --> 0:14:52.080 And so the crucial things to understand there for our 0:14:52.160 --> 0:14:55.880 later conversation is what's driving the Sun to get hotter 0:14:56.160 --> 0:14:58.600 and to get bigger, and that's the mass of the Sun. Right, 0:14:58.680 --> 0:15:01.800 If the sun were smaller, then it wouldn't do this 0:15:01.920 --> 0:15:04.760 as quickly. It would burn a lot lot longer, right, 0:15:04.800 --> 0:15:07.160 because the core would be cooler, and it wouldn't fuse 0:15:07.200 --> 0:15:09.520 as fast, and it wouldn't accumulate as much helium, and 0:15:09.560 --> 0:15:12.080 it wouldn't push the layers out, and it wouldn't get 0:15:12.080 --> 0:15:15.240 hotter and brighter. And so that's the thing that's driving 0:15:15.280 --> 0:15:18.600 the Sun to basically vanish our habitable zone. 0:15:18.840 --> 0:15:21.520 All right. So mostly I care about what happens to me, 0:15:21.680 --> 0:15:23.560 and I'm going to die before the Earth. Well, my 0:15:23.640 --> 0:15:26.600 ancestors will die before the Earth gets consumed by the Sun. 0:15:26.680 --> 0:15:28.400 But let's say I still care about the Earth even 0:15:28.400 --> 0:15:30.720 when there's no humans there anymore. Is it going to 0:15:30.880 --> 0:15:34.160 actually get engulfed by the Sun like swallowed up? 0:15:34.360 --> 0:15:36.280 Yeah, this is something you hear in pops eye all 0:15:36.320 --> 0:15:38.880 the time, and it's not clear because there's a lot 0:15:38.920 --> 0:15:41.840 of small effects here that could change the answer. So, 0:15:41.920 --> 0:15:45.280 for example, as the Sun in its last little bit 0:15:45.840 --> 0:15:48.480 is blowing out and its redias is really growing rapidly, 0:15:48.520 --> 0:15:52.240 it's also losing some mass because it's puffing out so much, 0:15:52.280 --> 0:15:54.720 it doesn't contain all that A lot of this plasma 0:15:54.800 --> 0:15:57.840 just shoots off into space, and because it loses mass, 0:15:57.880 --> 0:16:01.120 it loses gravity, and so the Sun's pull on the 0:16:01.160 --> 0:16:04.040 Earth gets weaker. So the Earth's orbit is going to 0:16:04.120 --> 0:16:07.760 drift further out, and so rather than just staying at 0:16:07.800 --> 0:16:10.120 the same place, it's going to drift out as the 0:16:10.120 --> 0:16:13.200 Sun grows and loses some of its mass. And so 0:16:13.240 --> 0:16:15.200 people have done modeling to answer the question, are we 0:16:15.280 --> 0:16:17.720 going to escape the outer layers of the Sun. It's 0:16:17.760 --> 0:16:20.520 sort of a silly question because like it doesn't really 0:16:20.600 --> 0:16:22.880 matter if you're in the Sun or right next to 0:16:22.920 --> 0:16:26.440 the Sun, like neither way can you survive. But you know, 0:16:26.680 --> 0:16:30.320 just from a sort of like academic question, it's fascinating. 0:16:31.040 --> 0:16:33.160 You don't want to be even like a little bit engulfed. 0:16:33.440 --> 0:16:35.480 But it looks like the Earth might just sort of 0:16:35.480 --> 0:16:39.120 like skip over the outer atmosphere of the Sun, the 0:16:39.240 --> 0:16:42.240 radius of its orbit growing with the radius of the Sun. 0:16:42.480 --> 0:16:46.520 Could we keep ourselves in good shape by just sort 0:16:46.560 --> 0:16:50.080 of like nudging Earth farther away and closer to state 0:16:50.160 --> 0:16:53.440 exactly the right temperature throughout this whole process. 0:16:53.680 --> 0:16:55.680 You could try to do that to move further out, 0:16:56.160 --> 0:16:57.960 And you know, you want to stay far enough away 0:16:58.000 --> 0:17:00.400 from the Sun for sure, not just because it's going 0:17:00.440 --> 0:17:03.200 to be hot, but because if you are anywhere near 0:17:03.280 --> 0:17:05.359 the atmosphere of the Sun, then you're going to be 0:17:05.440 --> 0:17:08.680 losing kinetic energy because you're flying through the atmosphere, there's 0:17:08.680 --> 0:17:11.680 gonna be friction. You're gonna fall into the Sun. Bad bad. 0:17:12.040 --> 0:17:14.600 But anyway, if you've wanted to engineer just the Earth, 0:17:14.680 --> 0:17:17.000 the simpler thing is to move the Earth's orbit. There 0:17:17.000 --> 0:17:19.200 are things you could do to like build a huge 0:17:19.240 --> 0:17:22.560 planet rocket to move the Earth out this kind of stuff, 0:17:23.080 --> 0:17:25.080 but it's a bit of a crap shot because the 0:17:25.080 --> 0:17:27.840 whole Solar system is going to be very chaotic. Like 0:17:28.160 --> 0:17:30.880 when you lose mass of the Sun, you're also weakening 0:17:30.920 --> 0:17:33.680 the Sun's grip on Jupiter. Jubiter is going to drift 0:17:33.680 --> 0:17:36.040 further out, it's going to interact with Saturn. That's going 0:17:36.119 --> 0:17:38.480 to be a chaotic mess. And the chances that we 0:17:38.480 --> 0:17:42.400 can like predict that and navigate through Jupiter and Saturn 0:17:42.800 --> 0:17:44.920 like having a big argument and cluttering up the whole 0:17:45.080 --> 0:17:48.600 Solar system very unlikely. We think that that happened in 0:17:48.640 --> 0:17:51.520 the past, that Jupiter and Saturn went into the inner 0:17:51.560 --> 0:17:54.760 Solar System and then back out again and maybe ejected 0:17:54.760 --> 0:17:57.600 another gas giant from the Solar System, So there could 0:17:57.600 --> 0:18:00.760 be like a lost sibling planet out there and frozen 0:18:00.760 --> 0:18:05.679 in space, feeling rejected, having been literally rejected. And so 0:18:05.720 --> 0:18:07.800 the Solar System is going to get very chaotic if 0:18:07.800 --> 0:18:09.840 we let the Sun do this. And I think it'd 0:18:09.880 --> 0:18:12.520 be pretty hard not just to move the planet, but 0:18:12.560 --> 0:18:14.080 to figure out how to move it and how to 0:18:14.119 --> 0:18:16.119 protect it against Jupiter's craziness. 0:18:16.359 --> 0:18:20.160 I wish I had felt more optimistic during our episodes 0:18:20.160 --> 0:18:23.640 on interstellar Travel. I think I'd like to just skip 0:18:23.680 --> 0:18:26.159 all of this, just leave town. What all of this 0:18:26.240 --> 0:18:28.840 problem starts? All right, So let's take a break, and 0:18:28.880 --> 0:18:30.919 when we get back, let's talk about how we can 0:18:31.000 --> 0:18:34.359 engineer the Sun so we can avoid this situation altogether. 0:18:54.240 --> 0:18:57.040 All Right, we're back. Daniel has scared the pants off 0:18:57.080 --> 0:18:59.560 of all of us. We're going to burn up where 0:18:59.600 --> 0:19:01.359 we're going to fall into the Sun, but we're probably 0:19:01.359 --> 0:19:03.439 not going to actually fall into the Sun. We're just 0:19:03.440 --> 0:19:06.200 going to be in its hot atmosphere layers. Anyway, we're dead. 0:19:07.359 --> 0:19:10.160 So Daniel, how do we avoid this whole we die 0:19:10.240 --> 0:19:11.160 in billions of years. 0:19:11.160 --> 0:19:15.680 Thing we turn to the engineers and we ask them, hey, 0:19:15.760 --> 0:19:19.480 can you solve this problem. We think we understand enough 0:19:19.520 --> 0:19:21.920 of the physics of the Sun to figure out when 0:19:22.040 --> 0:19:24.719 it's going to grow and get hotter, and so in 0:19:24.800 --> 0:19:28.000 principle we should be able to engineer a solution. And 0:19:28.040 --> 0:19:30.120 there was a paper in the eighties by a guy 0:19:30.200 --> 0:19:34.680 named David Criswell coined this phrase star lifting to imagine 0:19:34.680 --> 0:19:36.800 that maybe we could prevent the Sun from getting so 0:19:36.840 --> 0:19:39.719 big and so hot by making it more like longer 0:19:39.840 --> 0:19:43.840 lasting stars, by making it smaller. That's why it's called 0:19:43.920 --> 0:19:47.840 star lifting. It's like take stuff off of the Sun. Essentially, 0:19:47.840 --> 0:19:49.600 could we go in and take a big scoop off 0:19:49.600 --> 0:19:52.120 of the Sun. And this is a little bit delicate 0:19:52.160 --> 0:19:54.520 because you don't want to turn the Sun like into 0:19:54.560 --> 0:19:57.199 a red dwarf. A red dwarf is cooler, and then 0:19:57.240 --> 0:20:00.040 the Earth wouldn't be in the habitable zone anymore. I 0:20:00.040 --> 0:20:01.960 want to do is scoop off just enough to keep 0:20:02.000 --> 0:20:04.119 the Sun from getting too big and too hot, so 0:20:04.160 --> 0:20:08.000 it sort of like maintains the same temperature throughout its 0:20:08.040 --> 0:20:12.160 lifetime and lasts a lot longer. Removing some mass would 0:20:12.200 --> 0:20:15.520