WEBVTT - Could we spot an alien nuclear blast? 0:00:09.000 --> 0:00:11.080 Hey, Daniel, what do you think will happen the day 0:00:11.200 --> 0:00:15.000 we discover alien life? Oh? I'm imagining like a huge 0:00:15.240 --> 0:00:18.800 worldwide celebration. Oh yeah, and you think it'll be good news. Yeah, 0:00:18.920 --> 0:00:22.280 I think we'll learn something very deep and important about 0:00:22.320 --> 0:00:25.319 the nature of life and the universe and everything. But 0:00:25.400 --> 0:00:27.400 what if it's not good news? What do you considered 0:00:27.800 --> 0:00:31.840 darker possibilities about alien life? Like if they're not friendly 0:00:31.840 --> 0:00:34.479 to humans they show up in space and zappaus, Well, 0:00:34.479 --> 0:00:36.639 they could be friendly to humans. You know, they might 0:00:36.640 --> 0:00:38.839 find us delicious. I guess that depends on which kind 0:00:38.840 --> 0:00:41.760 of humans they find delicious. We probably all taste the same, 0:00:41.880 --> 0:00:47.000 you know, like chicken. Maybe chickens taste like humans. I'm 0:00:47.040 --> 0:00:49.239 sure there are people in this world who know the 0:00:49.360 --> 0:00:52.040 answer to that question. What if we find out about 0:00:52.080 --> 0:00:55.480 aliens because of some giant space battle they're having with themselves. 0:00:55.640 --> 0:00:58.080 Oh well, that sounds pretty exciting. In that case, I'd 0:00:58.160 --> 0:01:01.480 like to reserve a front row seat. Well really, Oh 0:01:01.640 --> 0:01:04.160 you do that, I'll be running away in the other direction, 0:01:05.160 --> 0:01:22.920 and I'll be popping the popcorn. Hi, am Orham and 0:01:23.000 --> 0:01:26.160 cartoonists and the creator of PhD comments. Hi, I'm Daniel 0:01:26.200 --> 0:01:29.360 I'm a particle physicist and a professor at UC Irvine, 0:01:29.560 --> 0:01:32.520 and I don't wish any aliens to die, but I 0:01:32.600 --> 0:01:35.600 do want to see a giant alien space battle. Wait, 0:01:35.640 --> 0:01:37.679 so how would they have a battle but without any 0:01:37.680 --> 0:01:41.119 even dying. Isn't just like a virtual battle or they're 0:01:41.160 --> 0:01:43.600 like plane laser tag? What are you talking about here? 0:01:43.959 --> 0:01:45.880 I mean it's like a wortal battle. Are they having 0:01:45.920 --> 0:01:48.919 a wortal battle? Maybe they've evolved to a higher plane 0:01:48.920 --> 0:01:51.880 of combat exactly. No, it's tension within me. As much 0:01:51.920 --> 0:01:54.240 as I would like to see alien space battles, I 0:01:54.280 --> 0:01:56.760 also don't want any aliens out there to die. But 0:01:56.800 --> 0:01:59.280 you know some of our favorite stories are about alien 0:01:59.320 --> 0:02:01.600 space battles. Isn't that what Star Wars is all about. 0:02:02.280 --> 0:02:04.920 Star Wars is about aliens. That's what you told me. 0:02:04.920 --> 0:02:08.079 It's in another galaxy, far far away, right, they're all aliens. 0:02:08.480 --> 0:02:12.120 Maybe we're the aliens in the Star Wars universe. Well, 0:02:12.120 --> 0:02:15.000 we're not capable of putting on giant space battles yet. Also, 0:02:15.040 --> 0:02:17.040 people don't die in Star Wars. They just come back 0:02:17.080 --> 0:02:21.359 as ghosts, Jedi ghosts more powerful than you could even imagine, 0:02:21.480 --> 0:02:23.000 Or do you the Emperor did they just keep bringing 0:02:23.000 --> 0:02:25.639 you back for all the movies. Don't the Stormtrooper die though, 0:02:25.720 --> 0:02:28.160 or do they also come back as Jedi ghosts. I 0:02:28.200 --> 0:02:30.440 guess it's not clear. You know, they get zapped with 0:02:30.480 --> 0:02:32.519 their little armor and they just fall down. Maybe they're 0:02:32.560 --> 0:02:34.280 just taking a nap. There you go. I'd like a 0:02:34.320 --> 0:02:37.680 giant alien space battle where the losers just take a nap. Yeah, 0:02:37.760 --> 0:02:41.359 I want to see that movie. Star naps were Welcome 0:02:41.360 --> 0:02:43.920 to our podcast Daniel and Jorge Explain the Universe, a 0:02:44.000 --> 0:02:47.079 production of iHeartRadio, in which we try to zap your 0:02:47.160 --> 0:02:50.960 brain with all sorts of incredible information about the universe. 0:02:51.120 --> 0:02:54.600 We know that everything out there is amazing and mysterious 0:02:54.760 --> 0:02:58.760 and confusing, but we hope to help you understand what 0:02:58.960 --> 0:03:02.400 little of it human entity has managed to decode. And 0:03:02.440 --> 0:03:04.960 we hope that one day aliens come and give us 0:03:05.000 --> 0:03:07.440 a little bit more information about what's going on out 0:03:07.440 --> 0:03:10.960 there in the universe, if indeed they do exist. That's right, 0:03:11.000 --> 0:03:14.160 because it is a pretty incredible universe, and we do 0:03:14.240 --> 0:03:17.800 battle every day here with the mysteries of it, and 0:03:17.840 --> 0:03:20.440 we go to war with our ignorance about how it 0:03:20.440 --> 0:03:23.000 works and what's going on in the universe. We're trying 0:03:23.000 --> 0:03:25.920 to drop a knowledge bomb on everybody's ignorance. That's right. 0:03:26.200 --> 0:03:28.320 You can think of us as a laser gun of 0:03:28.360 --> 0:03:33.680 amazing facts zapping people's brains. There's that warm, fuzzy feeling 0:03:33.720 --> 0:03:36.840 you get when you understand something about the universe. But 0:03:36.880 --> 0:03:39.560 there's also lots of things that we still don't understand 0:03:39.560 --> 0:03:43.040 about the universe, things that give you that gnawing feeling 0:03:43.080 --> 0:03:47.000 of desperate curiosity, that desire to just know what's going 0:03:47.120 --> 0:03:49.720 on out there. There's some of the deepest questions in 0:03:49.840 --> 0:03:53.920 human existence which have answers, which are facts about the 0:03:54.000 --> 0:03:57.920 universe which maybe one day people will know. How frustrating 0:03:58.000 --> 0:04:00.360 is it to live in the era of dark to 0:04:00.520 --> 0:04:03.240 not know the answers to basic questions like are we 0:04:03.320 --> 0:04:06.839 alone in the universe? Yeah? What bigger question can there 0:04:06.880 --> 0:04:10.240 be about the existence of humans than the question of 0:04:10.280 --> 0:04:14.720 whether we are the only living thing or intelligent thing 0:04:14.920 --> 0:04:18.320 living and existing in this universe? And we wonder about it, 0:04:18.400 --> 0:04:21.120 we speculate about it, but we have a very very 0:04:21.240 --> 0:04:25.320 deep lack of information about it. The universe is vast, 0:04:25.480 --> 0:04:27.800 and from our tiny little rock we have done a 0:04:27.839 --> 0:04:31.600 pretty good job of exploring a tiny, little corner of it. 0:04:31.680 --> 0:04:34.520 We have telescopes to tell us about nearby star systems 0:04:34.520 --> 0:04:37.800 and compeer further and deeper into the universe, but we've 0:04:37.839 --> 0:04:42.120 only begun recently to identify other planets and other places 0:04:42.120 --> 0:04:46.760 in the universe where life might spring independently from Earth. Yeah, 0:04:46.839 --> 0:04:48.680 we know that here in our Solar systems there aren't 0:04:48.680 --> 0:04:50.839 on at the signs of life, and so we know 0:04:50.920 --> 0:04:52.960 that if there is alien life out there, it has 0:04:53.000 --> 0:04:55.560 to be kind of far away. Right, how close is 0:04:55.600 --> 0:04:58.200 the nearest planet to us light years away? The nearest 0:04:58.200 --> 0:05:00.800 planet to me is about zero meters away. It's right 0:05:00.839 --> 0:05:03.200 here under my feet. There are other places in the 0:05:03.240 --> 0:05:06.480 Solar System people think there might be life, like under 0:05:06.520 --> 0:05:09.760 the frozen crust of Europa. So there are still exciting 0:05:09.800 --> 0:05:13.080 places in our backyard. But you're right, other Solar systems 0:05:13.120 --> 0:05:17.720 are frustratingly far away, several light years. The closest identified 0:05:17.760 --> 0:05:21.800 exoplanets around Proxima Centauri, which happens to be their closest star, 0:05:22.200 --> 0:05:24.919 just under four light years away. And what that tells 0:05:24.960 --> 0:05:28.000 us is that there are planets everywhere in the galaxy 0:05:28.120 --> 0:05:31.239 and in the universe. We now think that almost every 0:05:31.279 --> 0:05:33.799 star out there has planets around it, and a huge 0:05:33.839 --> 0:05:37.960 fraction of them have even earthlike planets, maybe around this size, 0:05:38.040 --> 0:05:41.160 maybe around this kind of surface temperature, maybe even with 0:05:41.279 --> 0:05:44.320 liquid water on their surface. And so with so many 0:05:44.400 --> 0:05:46.960 places that life could be out there in the universe, 0:05:47.279 --> 0:05:51.520 sometimes we wonder, why haven't we found it already. Yeah, 0:05:51.560 --> 0:05:54.479 it's a very big question, one that would kind of 0:05:54.480 --> 0:05:57.720 determine our place in the universe. Because if the answer 0:05:57.839 --> 0:06:00.200 is that there isn't life out there, that is that 0:06:00.520 --> 0:06:04.000 humans are pretty special right in the entire universe. Imagine 0:06:04.000 --> 0:06:05.919 what it'd be like to know that we're the only 0:06:05.920 --> 0:06:08.680 intelligence species in such a big place. Yeah, it would 0:06:08.680 --> 0:06:11.000 make you feel special. It'll also make you feel kind 0:06:11.040 --> 0:06:14.760 of lonely being the only intelligent life in the entire universe. 0:06:14.760 --> 0:06:17.880 It's kind of a lot of responsibility also, like we're 0:06:17.920 --> 0:06:20.240 the only ones out there doing anythinking. We're the only 0:06:20.240 --> 0:06:22.600 ones trying to figure out this huge puzzle about the 0:06:22.680 --> 0:06:25.239 nature of the universe, trying to crack the cosmic mystery 0:06:25.360 --> 0:06:28.880 of how all these quantum particles weave themselves together into 0:06:29.000 --> 0:06:32.080 this experience. I prefer to imagine that there's lots of 0:06:32.080 --> 0:06:34.760 other civilizations out there, and maybe they've even solved some 0:06:34.800 --> 0:06:38.120 of these questions and have the answers waiting for us. 0:06:38.560 --> 0:06:41.000 But we don't know. And we've been looking out in 0:06:41.080 --> 0:06:45.359 the cosmos and listening for signals from aliens, hoping that 0:06:45.400 --> 0:06:48.320 they are as excited as we are to meet their neighbors, 0:06:48.320 --> 0:06:51.480 and sending us messages which we might capture in radio 0:06:51.520 --> 0:06:55.520 waves or other electromagnetic signals. Of course, so far we've 0:06:55.560 --> 0:06:58.640 heard nothing conclusive. Wait, so you want aliens to exist 0:06:58.800 --> 0:07:01.039 just to take some of the pressure off of your job. 0:07:01.240 --> 0:07:05.000 Is that kind of what you're you're talking about? You know, 0:07:05.040 --> 0:07:08.920 I'm very strongly believe in funding basic research and expanding science, 0:07:09.000 --> 0:07:11.840 and that goes beyond the limits of our species. I 0:07:11.880 --> 0:07:15.280 think science should be funded here on Earth and everywhere 0:07:15.400 --> 0:07:18.960 in the universe, and I hope that budget aliens out 0:07:18.960 --> 0:07:22.239 there are, you know, giving a healthy dose of funding 0:07:22.320 --> 0:07:26.200 to those science aliens out there struggling to understand the 0:07:26.320 --> 0:07:29.080 nature of the universe, burned by the same curiosity that 0:07:29.120 --> 0:07:31.680 we have. Or maybe they don't. Maybe they just don't 0:07:31.680 --> 0:07:33.320 care about the nature of the universe and they're not 0:07:33.360 --> 0:07:36.080 even doing science. I feel like you're like little kid 0:07:36.120 --> 0:07:38.520 in class who's looking at his test or her tests 0:07:38.520 --> 0:07:40.360 and going like, I have no idea what's going on, 0:07:40.840 --> 0:07:43.480 and you're sort of like looking around to see if 0:07:43.480 --> 0:07:46.400 anyone else knows the answers. Yes, I definitely want to 0:07:46.480 --> 0:07:49.560 cheat off of alien physicists. I would love to get 0:07:49.640 --> 0:07:52.080 like an alien physics textbook and then win like a 0:07:52.080 --> 0:07:55.600 whole string of Nobel prizes here on Earth just by 0:07:55.680 --> 0:07:58.960 copying their ideas. Yes, I will completely admit that is 0:07:59.000 --> 0:08:02.240 my fantasy. Really, So wait, you would get the secrets 0:08:02.240 --> 0:08:04.080 from the alien I'm just trying to figure this scenario. 0:08:04.360 --> 0:08:06.560 Let's work through it. You would get the secrets from 0:08:06.560 --> 0:08:08.920 the aliens, but you wouldn't tell anyone that aliens exist, 0:08:09.400 --> 0:08:11.800 and you would use that knowledge for your own personal game. 0:08:12.080 --> 0:08:17.320 That sounds fantastic. Yes, remind me not to tell you 0:08:17.360 --> 0:08:20.320 any secrets. Then, If you are holding a Nobel prize 0:08:20.320 --> 0:08:23.280 winning secret, please do share it with me. I would 0:08:23.320 --> 0:08:25.040 love to hear it. You would be the last person 0:08:25.080 --> 0:08:28.560 I would share with, obviously. I hope you would share 0:08:28.560 --> 0:08:30.800 it with all of humanity, Like if somebody gave me 0:08:30.920 --> 0:08:32.719 secrets from aliens, I would share it with all of 0:08:32.800 --> 0:08:36.360 humanity absolutely, But the aliens themselves would be the biggest secrets. 0:08:36.400 --> 0:08:39.440 I just said it's the biggest question in human existence. No, 0:08:39.520 --> 0:08:41.560 you're right, And of course, if aliens do come or 0:08:41.559 --> 0:08:44.920 communicate with us, probably physicists wouldn't be at the front 0:08:44.920 --> 0:08:47.439 of the line of people who get to chat with them, right, 0:08:47.480 --> 0:08:51.240 probably would send like engineers or doctors, or politicians or 0:08:51.320 --> 0:08:55.400 linguists or mathematicians or philosophers before the physicists even get 0:08:55.440 --> 0:08:57.720 their shot. I think I would send the physicists first 0:08:57.840 --> 0:09:00.960 for sure. Yeah, because you know what, if they're hungry, 0:09:02.760 --> 0:09:04.960 we got to test the waters here. So you don't 0:09:04.960 --> 0:09:06.720 want me to learn the secrets from the aliens, but 0:09:06.760 --> 0:09:08.880 you do want me to be there first. I mean, 0:09:09.160 --> 0:09:11.560 there's two sides to that coin. Well, I want you 0:09:11.600 --> 0:09:13.360 to learn the secrets, but I want you to share 0:09:13.400 --> 0:09:17.280 the secrets verybody. I will share the secrets with you 0:09:17.559 --> 0:09:20.360 and the Nobel Committee. And if their secret is what 0:09:20.400 --> 0:09:23.360 their stomachs look like, well, you know you can't share it, 0:09:23.400 --> 0:09:26.640 but at least we would know. Just like going inside 0:09:26.640 --> 0:09:29.240 a black hole, you learn some deep secrets about the universe, 0:09:29.320 --> 0:09:31.680 but only you can know them. But it's interesting you 0:09:31.720 --> 0:09:34.400 talk about some of the ways that people usually think 0:09:34.440 --> 0:09:37.480 that we're gonna meet aliens or know about aliens, which 0:09:37.520 --> 0:09:39.520 is getting signals from them. I mean that's sort of 0:09:39.520 --> 0:09:42.240 like one way we can learn about them. I guess 0:09:42.280 --> 0:09:44.600 another way is to go to another planet and see 0:09:44.600 --> 0:09:47.200 them too, right, Yeah, And this is a really common 0:09:47.240 --> 0:09:50.040 thing in science. When you have no idea how hard 0:09:50.200 --> 0:09:53.600 a problem is, you start with the easiest things, like 0:09:53.840 --> 0:09:56.719 maybe the universe is filled with aliens and they're all 0:09:56.720 --> 0:09:59.200 sending messages and we just haven't been listening, and as 0:09:59.200 --> 0:10:03.280 soon as we turn on our electronic ears and use 0:10:03.400 --> 0:10:06.640 our radio satellites to tune in, maybe we could instantly 0:10:06.679 --> 0:10:10.120 tap into the galactic internet and hear all those conversations. 0:10:10.200 --> 0:10:12.480 There's some scenario in which it would have been easy, 0:10:12.720 --> 0:10:14.880 and as soon as we started listening, we discovered it. 0:10:15.120 --> 0:10:17.600 So it makes sense to first do the easy thing 0:10:17.679 --> 0:10:20.680 and see if alien messages our feeling space. Of course, 0:10:20.720 --> 0:10:23.320 we've been listening and we haven't heard anything, and so 0:10:23.440 --> 0:10:26.160 people are starting to try to be creative and think about, like, well, 0:10:26.160 --> 0:10:28.800 what are other ways we could hear from aliens, or 0:10:28.960 --> 0:10:31.480 what are other ways we could detect their existence? As 0:10:31.480 --> 0:10:34.199 you say, maybe we could go to those planets and 0:10:34.320 --> 0:10:37.560 discover them. Right. That's limited, of course, by our ability 0:10:37.600 --> 0:10:40.560 to travel from star to star. These stars are so 0:10:40.760 --> 0:10:43.560 far away and the speed of light is such a 0:10:43.559 --> 0:10:46.760 stubborn limitation. But until we develop a warp drives or 0:10:46.840 --> 0:10:50.240 practical wormholes, it's not realistic to think that we could 0:10:50.240 --> 0:10:54.160 explore a significant fraction of the galaxy. Yeah, Like, what 0:10:54.200 --> 0:10:56.120 would it take, I guess to send a probe to 0:10:56.400 --> 0:10:59.600 Alpha Centauri? Right, it's four light years away. That's like 0:11:00.040 --> 0:11:02.280 zillions of miles away. Right now, it seems kind of 0:11:02.320 --> 0:11:05.480 impossible because I think the furthest we've send a probe 0:11:05.559 --> 0:11:08.679 right now is just barely outside this Solar system, right, 0:11:08.679 --> 0:11:11.319 and it took like thirty years, yes, exactly, the most 0:11:11.360 --> 0:11:15.160 distant object send by humanity. Some of these old Voyager 0:11:15.200 --> 0:11:18.520 and Pioneer probes are not very far outside the Solar system, 0:11:18.800 --> 0:11:21.160 so it would take a long time for anything to 0:11:21.200 --> 0:11:23.280 get anywhere. But you know, if you were thinking about 0:11:23.320 --> 0:11:25.760 it on long time scales, it's not going to take 0:11:25.800 --> 0:11:28.920 like millions of years. We're talking like thousands or tens 0:11:28.920 --> 0:11:30.920 of thousands of years. And if you send a few 0:11:31.000 --> 0:11:35.080 probes to other planets, and if those probes are very clever, 0:11:35.280 --> 0:11:39.280 they're like AI driven self replicating probes, so they can 0:11:39.640 --> 0:11:42.560 land on some distant moon, they can find materials on 0:11:42.600 --> 0:11:45.400 those moons to make more of themselves, and then they 0:11:45.400 --> 0:11:48.320 can send those probes out, and those probes make more 0:11:48.360 --> 0:11:51.040 of themselves, and those make more of themselves. It's not 0:11:51.120 --> 0:11:56.080 impossible to imagine rapidly exploring the entire galaxy, where by 0:11:56.160 --> 0:11:58.360 rapid we mean on the time scale of like fifty 0:11:58.400 --> 0:12:01.199 to one hundred thousand years. So that's a really interesting 0:12:01.280 --> 0:12:04.800 argument because it suggests that with technology not super far 0:12:04.840 --> 0:12:08.960 in our future, some other civilization could have explored the 0:12:08.960 --> 0:12:12.160 whole galaxy with self replicating probes. And then you have 0:12:12.200 --> 0:12:15.199 to ask, like, well, why haven't we been visited by 0:12:15.240 --> 0:12:18.120 such a probe yet? Are there no other advanced civilizations 0:12:18.160 --> 0:12:20.840 out there who have this idea? Yeah, we address this 0:12:20.960 --> 0:12:23.520 question and this whole scenario in our book. Frequently asked 0:12:23.559 --> 0:12:25.680 questions about the universe. That was one of the chapters, 0:12:25.760 --> 0:12:29.400 right like why haven't we seen aliens? And maybe we 0:12:29.440 --> 0:12:33.040 can do that with these self repulating robots, which would 0:12:33.080 --> 0:12:37.160 litter the universe in no time exactly. And one basic 0:12:37.200 --> 0:12:40.760 assumptions a lot of these scenarios make is that aliens 0:12:41.000 --> 0:12:43.640 want us to find them, or that they are trying 0:12:43.679 --> 0:12:46.120 to talk to us, or they are curious about the 0:12:46.160 --> 0:12:49.000 rest of the universe as well, so they're sending messages 0:12:49.000 --> 0:12:52.679 out or they're sending probes out there explorational the same 0:12:52.720 --> 0:12:54.920 way that we are. But of course we don't know 0:12:55.000 --> 0:12:58.280 what alien psychology is like, and what does aliens want, 0:12:58.400 --> 0:13:01.160 or even what it means to want something as an alien. 0:13:01.320 --> 0:13:03.559 So these days a lot of people are imagining other 0:13:03.640 --> 0:13:08.000 ways to detect aliens when they're not trying to be detected. 0:13:08.360 --> 0:13:11.200 Are there things the aliens can do imprints they leave 0:13:11.280 --> 0:13:14.640 on the universe that aren't intended for us to discover them, 0:13:14.679 --> 0:13:17.679 but might allow us to spot them anyway. So today 0:13:17.679 --> 0:13:25.079 on the program, we'll be asking the question could we 0:13:25.200 --> 0:13:30.079 detect alien nuclear explosions? I imagine you're saying these are 0:13:30.120 --> 0:13:35.959 like accidental nuclear explosions or on purpose nuclear explosions, either one, right, 0:13:36.040 --> 0:13:38.680 we don't discriminate. We just like to know the aliens 0:13:38.720 --> 0:13:44.160 are there, and whatever they do in their normal civilization extrapolasition, 0:13:44.600 --> 0:13:47.440 we'd like to see if we could detect it. Maybe 0:13:47.480 --> 0:13:49.840 they're just doing testing like we're doing, or maybe they 0:13:49.960 --> 0:13:55.160 have some globe spanning nuclear annihilation. The question is, could 0:13:55.240 --> 0:13:58.600 we see it right, If aliens are blowing up nuclear bombs, 0:13:58.720 --> 0:14:01.240 is it possible for us to spot that? Yeah, because 0:14:01.280 --> 0:14:03.400 as you mentioned, you know, one scenario is that they're 0:14:03.559 --> 0:14:07.679 sending out signals on purpose, either to talk to us 0:14:07.679 --> 0:14:11.600 directly or just like that's their TV, maybe their broadcast TV. 0:14:11.920 --> 0:14:14.200 But I think we talked in an earlier episode about 0:14:14.280 --> 0:14:17.040 how like for us to detect the signal from an alien, 0:14:17.120 --> 0:14:20.320 it would have to be like a pretty focus beam, right, 0:14:20.320 --> 0:14:22.240 like the like the club we're just listening to their 0:14:22.280 --> 0:14:24.880 TV broadcast is pretty low, that's right. If you're just 0:14:24.960 --> 0:14:28.240 sending signals in every direction, then you pay a really 0:14:28.360 --> 0:14:32.000 big price because those signals get weaker with distance, and 0:14:32.000 --> 0:14:35.280 they get weaker with distance squared. So when signals go 0:14:35.640 --> 0:14:38.480 twice as far, they're four times as week, When they 0:14:38.520 --> 0:14:41.080 go ten times as far, they're one hundred times as week. 0:14:41.440 --> 0:14:45.680 That makes it really really hard to detect non focus signals. 0:14:46.280 --> 0:14:49.000 And if we wanted to detect signals that we could 0:14:49.040 --> 0:14:52.400 generate using technology that we have, we would not be 0:14:52.520 --> 0:14:55.400 able to spot signals of the kinds we can generate 0:14:55.520 --> 0:14:58.320 using our own technology from planets that are more than 0:14:58.400 --> 0:15:01.920 like one light year away. If however, they're like beaming 0:15:02.000 --> 0:15:05.280 us messages, they're shooting laser beams in our direction. Then 0:15:05.280 --> 0:15:07.680 the math works differently and we could get messages from 0:15:07.720 --> 0:15:10.000 further away, But then they'd have to know we were 0:15:10.120 --> 0:15:13.320 here and try to send us messages on purpose, which 0:15:13.320 --> 0:15:16.360 seems less likely. I think here today we're exploring a 0:15:16.400 --> 0:15:18.880 different scenario, which is like, what if they're doing something 0:15:19.320 --> 0:15:23.360 without trying by accident maybe or through some sort of event, 0:15:23.640 --> 0:15:26.360 and then that's what we see, and that's how we 0:15:26.400 --> 0:15:28.440 know that there are aliens exactly. And people have been 0:15:28.480 --> 0:15:30.560 thinking about this and wondering like, well, what's the most 0:15:30.720 --> 0:15:34.480 visible thing that you can do, not just broadcasting Rick 0:15:34.480 --> 0:15:37.920 and Morty episodes into the cosmos? All right, Sometimes our 0:15:37.960 --> 0:15:42.480 civilization does things which generate very bright flashes of radiation, 0:15:42.520 --> 0:15:45.680 and hey, what's brighter than a nuclear explosion? But what 0:15:45.720 --> 0:15:47.800 if there's a kid in that alien planet pointing a 0:15:47.880 --> 0:15:55.120 laser partner directly Ow my eye? Ow alien burnt my eye? Yeah, 0:15:55.120 --> 0:15:56.960 I know, that's why you should be careful you knock 0:15:57.000 --> 0:15:59.320 about this guy. So then the scenario here is that 0:15:59.480 --> 0:16:03.200 somehow this alien civilization out there is exploding nuclear their 0:16:03.200 --> 0:16:08.080 own nuclear bombs, either by accident, or some testing or something. 0:16:08.160 --> 0:16:10.080 Maybe they have their own nuclear war, and so the 0:16:10.160 --> 0:16:14.440 question is like, could we see those nuclear explosions exactly? 0:16:14.600 --> 0:16:16.680 All right? Well, as usual, we were wondering how many 0:16:16.680 --> 0:16:21.200 people out there had the interesting curiosity to ask this 0:16:21.320 --> 0:16:24.120 question about alien life and how we could detect them. So, 0:16:24.120 --> 0:16:26.120 as usual, Daniel went out there. Did you go to 0:16:26.200 --> 0:16:28.360 the internet or are you? Are you going on campus? 0:16:28.360 --> 0:16:31.720 Now these are still Internet based questions. I felt a 0:16:31.760 --> 0:16:34.800 little bit weird walking around campus asking people about aliens 0:16:34.840 --> 0:16:38.240 and nuclear bombs. That's never stopped you before. I thought 0:16:38.240 --> 0:16:42.000 it might get reported to the UCI police. Yeah, you 0:16:42.040 --> 0:16:45.200 have tenure. They're not gonna fire you. Anyways, usually have 0:16:45.280 --> 0:16:48.680 to do worst things. So thanks very much to our 0:16:48.760 --> 0:16:52.640 internet volunteers who responded with enthusiasm to this question. If 0:16:52.680 --> 0:16:54.800 you would like to play this part in future episodes, 0:16:54.840 --> 0:16:57.760 please write to me to questions at Daniel and Jorge 0:16:57.760 --> 0:17:00.400 dot com. We can do it all over email. It's fast, 0:17:00.520 --> 0:17:03.320 it's easy, it's fun to think about it for a second. 0:17:03.320 --> 0:17:08.240 Do you think we could detect alien nuclear explosions? Here's 0:17:08.280 --> 0:17:10.720 what people have to say. Yes, So it depends whether 0:17:10.760 --> 0:17:14.679 the detonation happened on Earth or a planet from Solar 0:17:14.680 --> 0:17:18.040 System or somewhere far away. In any of these cases, 0:17:18.080 --> 0:17:20.800 I think we might be able to detect. Considering that 0:17:21.240 --> 0:17:23.920 why decaying of the matter and the amount of radiation 0:17:23.960 --> 0:17:26.600 that is being exposed out of that location on Earth, 0:17:26.800 --> 0:17:29.760 we might be able to analyze whether it's man made 0:17:30.280 --> 0:17:33.960 or alien, and if it is happening on some other planet. 0:17:34.160 --> 0:17:38.280 Considering the amount of information that we have already gained 0:17:38.280 --> 0:17:41.679 with the telescopes in place, we will be able to 0:17:41.720 --> 0:17:44.080 do it. That's what I believe. By now, we have 0:17:44.119 --> 0:17:47.639 satellites now that can detect detonations on Earth. I don't 0:17:47.640 --> 0:17:51.800 think it would work at interstellar distances, especially considering that 0:17:51.800 --> 0:17:55.359 there's so many sources of radiation in space, you know, 0:17:55.440 --> 0:17:59.000 from stars to gamma ray burst everything in between. So no, 0:17:59.440 --> 0:18:02.320 I don't think we could. Well, I guess so. I 0:18:02.359 --> 0:18:05.439 guess it would depend on how good the detector was 0:18:05.480 --> 0:18:08.520 and how far away it was away from you. If 0:18:08.560 --> 0:18:11.159 there was set off over your head, you might be 0:18:11.200 --> 0:18:14.399 able to detect it pretty soon. I feel like we 0:18:14.560 --> 0:18:19.000 probably could detect alien nuclear detonations if there was like 0:18:19.160 --> 0:18:24.080 enough radiation to reach far enough, But other than that, 0:18:24.480 --> 0:18:27.240 I don't really think we could all right. Some people 0:18:27.280 --> 0:18:30.560 said yes, some people said no, some people said maybe yeah. 0:18:30.560 --> 0:18:32.760 I think they really put their finger on the issue, 0:18:32.880 --> 0:18:36.320 which is that nobody knows, not even us. It's all 0:18:36.359 --> 0:18:40.240 about brightness and distance. You know, what's the faintest radiation 0:18:40.359 --> 0:18:42.439 we could pick up? And how close would these bombs 0:18:42.480 --> 0:18:44.640 have to be for us to spot them. I feel 0:18:44.680 --> 0:18:48.160 like you're missing one important factor, which is how big 0:18:48.200 --> 0:18:50.280 are these bombs? That's a huge unknown. You're right, and 0:18:50.320 --> 0:18:52.040 we'll get into it in a minute. And the only 0:18:52.080 --> 0:18:55.000 standard we have is like how big are our bombs? 0:18:55.400 --> 0:18:59.360 So we can imagine whether we could detect nuclear explosions 0:18:59.400 --> 0:19:03.040 of the size we could make if aliens also did them. 0:19:03.040 --> 0:19:04.880 All right, we'll dig into it, but I guess first 0:19:04.920 --> 0:19:07.640 let's start with the basics, Like Daniel, what happens during 0:19:07.680 --> 0:19:10.760 a nuclear explosion? Besides the explosion part of it. Yeah, 0:19:10.800 --> 0:19:13.600 to understand whether we could see a nuclear explosion on 0:19:13.640 --> 0:19:16.520 another planet, you have to think about what the signals are, 0:19:16.880 --> 0:19:19.800 like what signals does a nuclear explosion generate? And we 0:19:19.840 --> 0:19:22.480 had a whole episode about how nuclear bombs work where 0:19:22.680 --> 0:19:24.840 we went to a lot of detail, but not enough 0:19:24.920 --> 0:19:28.639 detail for you to build a nuclear bomb. Hopefully but 0:19:28.960 --> 0:19:32.679 human nuclear weapons at least are either fission weapons or 0:19:32.840 --> 0:19:36.720 fusion weapons triggered by fission. And remember that the basic 0:19:36.800 --> 0:19:41.080 processes here fission involved breaking up of a heavy nucleus 0:19:41.080 --> 0:19:44.480 like plutonium or uranium, which then shoots off a bunch 0:19:44.480 --> 0:19:48.040 of neutrons and rams into other nuclei, which breaks them 0:19:48.040 --> 0:19:50.720 apart and sets off a chain reaction where you very 0:19:50.880 --> 0:19:54.440 rapidly are releasing energy. And the fusion bomb is similar 0:19:54.640 --> 0:19:58.080 except it uses a fission bomb to compress a bunch 0:19:58.080 --> 0:20:02.360 of fusion fuel that it fuses, and in both scenarios 0:20:02.400 --> 0:20:05.240 the key thing is releasing a huge amount of energy 0:20:05.520 --> 0:20:08.840 very very quickly, but not just energy, right, You're releasing 0:20:08.920 --> 0:20:12.040 energy but also a lot of radiation. Yeah, maybe step 0:20:12.080 --> 0:20:15.000 us through like what's actually being released, Like when you 0:20:15.080 --> 0:20:19.159 fuse things together they click together, to nuclear click together, 0:20:19.280 --> 0:20:25.200 and then what actually gets released like light or particles 0:20:25.440 --> 0:20:29.399 or Yeah, so fusion produces high energy photons. It also 0:20:29.520 --> 0:20:35.200 produces neutrons and electrons and neutrinos. Right, so all these 0:20:35.280 --> 0:20:37.959 kinds of things are produced and then much just produced, 0:20:38.000 --> 0:20:42.160 but they're like they're produced, but then they're flying really fast. Yes, 0:20:42.359 --> 0:20:44.879 they're produced, and they're carrying a lot of energy is 0:20:45.000 --> 0:20:47.359 what you actually see from the bomb from like a 0:20:47.400 --> 0:20:50.720 certain distance. Depends on how that energy is absorbed or 0:20:50.840 --> 0:20:53.320 not absorbed. So, for example, a lot of the energy 0:20:53.600 --> 0:20:57.399 gets dumped into the matters immediately surrounding the bomb, right, 0:20:57.440 --> 0:20:59.800 and so it's absorbed very very rapidly by the st 0:21:00.119 --> 0:21:03.280 around the bomb, which expands that matter and creates a 0:21:03.280 --> 0:21:06.680 shock wave. I mean like the bomb casing or like whatever, 0:21:07.520 --> 0:21:09.080 if it's on the ground, that that's what it's going 0:21:09.160 --> 0:21:12.199 to push out. Yeah, I mean whatever material is around 0:21:12.200 --> 0:21:14.760 the bomb, like the air or the water or the ground, 0:21:15.320 --> 0:21:18.000 and you get very different scenarios if you have an 0:21:18.000 --> 0:21:22.320 in air explosion or underground explosion or just above the water. 0:21:22.520 --> 0:21:25.480 But the material that surrounds the bomb is inundated with 0:21:25.560 --> 0:21:27.480 a huge amount of energy, a lot of it from 0:21:27.520 --> 0:21:30.240 gamma rays, and a lot of that gets rapidly absorbed 0:21:30.280 --> 0:21:32.639