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Could we spot an alien nuclear blast? · Daniel and Kelly’s Extraordinary Universe

• 0:09
  Speaker 1: Hey, Daniel, what do you think will happen the day
• 0:11
  Speaker 1: we discover alien life? Oh? I'm imagining like a huge
• 0:15
  Speaker 1: worldwide celebration. Oh yeah, and you think it'll be good news. Yeah,
• 0:18
  Speaker 1: I think we'll learn something very deep and important about
• 0:22
  Speaker 1: the nature of life and the universe and everything. But
• 0:25
  Speaker 1: what if it's not good news? What do you considered
• 0:27
  Speaker 1: darker possibilities about alien life? Like if they're not friendly
• 0:31
  Speaker 1: to humans they show up in space and zappaus, Well,
• 0:34
  Speaker 1: they could be friendly to humans. You know, they might
• 0:36
  Speaker 1: find us delicious. I guess that depends on which kind
• 0:38
  Speaker 1: of humans they find delicious. We probably all taste the same,
• 0:41
  Speaker 1: you know, like chicken. Maybe chickens taste like humans. I'm
• 0:47
  Speaker 1: sure there are people in this world who know the
• 0:49
  Speaker 1: answer to that question. What if we find out about
• 0:52
  Speaker 1: aliens because of some giant space battle they're having with themselves.
• 0:55
  Speaker 1: Oh well, that sounds pretty exciting. In that case, I'd
• 0:58
  Speaker 1: like to reserve a front row seat. Well really, Oh
• 1:01
  Speaker 1: you do that, I'll be running away in the other direction,
• 1:05
  Speaker 1: and I'll be popping the popcorn. Hi, am Orham and
• 1:23
  Speaker 1: cartoonists and the creator of PhD comments. Hi, I'm Daniel
• 1:26
  Speaker 1: I'm a particle physicist and a professor at UC Irvine,
• 1:29
  Speaker 1: and I don't wish any aliens to die, but I
• 1:32
  Speaker 1: do want to see a giant alien space battle. Wait,
• 1:35
  Speaker 1: so how would they have a battle but without any
• 1:37
  Speaker 1: even dying. Isn't just like a virtual battle or they're
• 1:41
  Speaker 1: like plane laser tag? What are you talking about here?
• 1:43
  Speaker 1: I mean it's like a wortal battle. Are they having
• 1:45
  Speaker 1: a wortal battle? Maybe they've evolved to a higher plane
• 1:48
  Speaker 1: of combat exactly. No, it's tension within me. As much
• 1:51
  Speaker 1: as I would like to see alien space battles, I
• 1:54
  Speaker 1: also don't want any aliens out there to die. But
• 1:56
  Speaker 1: you know some of our favorite stories are about alien
• 1:59
  Speaker 1: space battles. Isn't that what Star Wars is all about.
• 2:02
  Speaker 1: Star Wars is about aliens. That's what you told me.
• 2:04
  Speaker 1: It's in another galaxy, far far away, right, they're all aliens.
• 2:08
  Speaker 1: Maybe we're the aliens in the Star Wars universe. Well,
• 2:12
  Speaker 1: we're not capable of putting on giant space battles yet. Also,
• 2:15
  Speaker 1: people don't die in Star Wars. They just come back
• 2:17
  Speaker 1: as ghosts, Jedi ghosts more powerful than you could even imagine,
• 2:21
  Speaker 1: Or do you the Emperor did they just keep bringing
• 2:23
  Speaker 1: you back for all the movies. Don't the Stormtrooper die though,
• 2:25
  Speaker 1: or do they also come back as Jedi ghosts. I
• 2:28
  Speaker 1: guess it's not clear. You know, they get zapped with
• 2:30
  Speaker 1: their little armor and they just fall down. Maybe they're
• 2:32
  Speaker 1: just taking a nap. There you go. I'd like a
• 2:34
  Speaker 1: giant alien space battle where the losers just take a nap. Yeah,
• 2:37
  Speaker 1: I want to see that movie. Star naps were Welcome
• 2:41
  Speaker 1: to our podcast Daniel and Jorge Explain the Universe, a
• 2:44
  Speaker 1: production of iHeartRadio, in which we try to zap your
• 2:47
  Speaker 1: brain with all sorts of incredible information about the universe.
• 2:51
  Speaker 1: We know that everything out there is amazing and mysterious
• 2:54
  Speaker 1: and confusing, but we hope to help you understand what
• 2:58
  Speaker 1: little of it human entity has managed to decode. And
• 3:02
  Speaker 1: we hope that one day aliens come and give us
• 3:05
  Speaker 1: a little bit more information about what's going on out
• 3:07
  Speaker 1: there in the universe, if indeed they do exist. That's right,
• 3:11
  Speaker 1: because it is a pretty incredible universe, and we do
• 3:14
  Speaker 1: battle every day here with the mysteries of it, and
• 3:17
  Speaker 1: we go to war with our ignorance about how it
• 3:20
  Speaker 1: works and what's going on in the universe. We're trying
• 3:23
  Speaker 1: to drop a knowledge bomb on everybody's ignorance. That's right.
• 3:26
  Speaker 1: You can think of us as a laser gun of
• 3:28
  Speaker 1: amazing facts zapping people's brains. There's that warm, fuzzy feeling
• 3:33
  Speaker 1: you get when you understand something about the universe. But
• 3:36
  Speaker 1: there's also lots of things that we still don't understand
• 3:39
  Speaker 1: about the universe, things that give you that gnawing feeling
• 3:43
  Speaker 1: of desperate curiosity, that desire to just know what's going
• 3:47
  Speaker 1: on out there. There's some of the deepest questions in
• 3:49
  Speaker 1: human existence which have answers, which are facts about the
• 3:54
  Speaker 1: universe which maybe one day people will know. How frustrating
• 3:58
  Speaker 1: is it to live in the era of dark to
• 4:00
  Speaker 1: not know the answers to basic questions like are we
• 4:03
  Speaker 1: alone in the universe? Yeah? What bigger question can there
• 4:06
  Speaker 1: be about the existence of humans than the question of
• 4:10
  Speaker 1: whether we are the only living thing or intelligent thing
• 4:14
  Speaker 1: living and existing in this universe? And we wonder about it,
• 4:18
  Speaker 1: we speculate about it, but we have a very very
• 4:21
  Speaker 1: deep lack of information about it. The universe is vast,
• 4:25
  Speaker 1: and from our tiny little rock we have done a
• 4:27
  Speaker 1: pretty good job of exploring a tiny, little corner of it.
• 4:31
  Speaker 1: We have telescopes to tell us about nearby star systems
• 4:34
  Speaker 1: and compeer further and deeper into the universe, but we've
• 4:37
  Speaker 1: only begun recently to identify other planets and other places
• 4:42
  Speaker 1: in the universe where life might spring independently from Earth. Yeah,
• 4:46
  Speaker 1: we know that here in our Solar systems there aren't
• 4:48
  Speaker 1: on at the signs of life, and so we know
• 4:50
  Speaker 1: that if there is alien life out there, it has
• 4:53
  Speaker 1: to be kind of far away. Right, how close is
• 4:55
  Speaker 1: the nearest planet to us light years away? The nearest
• 4:58
  Speaker 1: planet to me is about zero meters away. It's right
• 5:00
  Speaker 1: here under my feet. There are other places in the
• 5:03
  Speaker 1: Solar System people think there might be life, like under
• 5:06
  Speaker 1: the frozen crust of Europa. So there are still exciting
• 5:09
  Speaker 1: places in our backyard. But you're right, other Solar systems
• 5:13
  Speaker 1: are frustratingly far away, several light years. The closest identified
• 5:17
  Speaker 1: exoplanets around Proxima Centauri, which happens to be their closest star,
• 5:22
  Speaker 1: just under four light years away. And what that tells
• 5:24
  Speaker 1: us is that there are planets everywhere in the galaxy
• 5:28
  Speaker 1: and in the universe. We now think that almost every
• 5:31
  Speaker 1: star out there has planets around it, and a huge
• 5:33
  Speaker 1: fraction of them have even earthlike planets, maybe around this size,
• 5:38
  Speaker 1: maybe around this kind of surface temperature, maybe even with
• 5:41
  Speaker 1: liquid water on their surface. And so with so many
• 5:44
  Speaker 1: places that life could be out there in the universe,
• 5:47
  Speaker 1: sometimes we wonder, why haven't we found it already. Yeah,
• 5:51
  Speaker 1: it's a very big question, one that would kind of
• 5:54
  Speaker 1: determine our place in the universe. Because if the answer
• 5:57
  Speaker 1: is that there isn't life out there, that is that
• 6:00
  Speaker 1: humans are pretty special right in the entire universe. Imagine
• 6:04
  Speaker 1: what it'd be like to know that we're the only
• 6:05
  Speaker 1: intelligence species in such a big place. Yeah, it would
• 6:08
  Speaker 1: make you feel special. It'll also make you feel kind
• 6:11
  Speaker 1: of lonely being the only intelligent life in the entire universe.
• 6:14
  Speaker 1: It's kind of a lot of responsibility also, like we're
• 6:17
  Speaker 1: the only ones out there doing anythinking. We're the only
• 6:20
  Speaker 1: ones trying to figure out this huge puzzle about the
• 6:22
  Speaker 1: nature of the universe, trying to crack the cosmic mystery
• 6:25
  Speaker 1: of how all these quantum particles weave themselves together into
• 6:29
  Speaker 1: this experience. I prefer to imagine that there's lots of
• 6:32
  Speaker 1: other civilizations out there, and maybe they've even solved some
• 6:34
  Speaker 1: of these questions and have the answers waiting for us.
• 6:38
  Speaker 1: But we don't know. And we've been looking out in
• 6:41
  Speaker 1: the cosmos and listening for signals from aliens, hoping that
• 6:45
  Speaker 1: they are as excited as we are to meet their neighbors,
• 6:48
  Speaker 1: and sending us messages which we might capture in radio
• 6:51
  Speaker 1: waves or other electromagnetic signals. Of course, so far we've
• 6:55
  Speaker 1: heard nothing conclusive. Wait, so you want aliens to exist
• 6:58
  Speaker 1: just to take some of the pressure off of your job.
• 7:01
  Speaker 1: Is that kind of what you're you're talking about? You know,
• 7:05
  Speaker 1: I'm very strongly believe in funding basic research and expanding science,
• 7:09
  Speaker 1: and that goes beyond the limits of our species. I
• 7:11
  Speaker 1: think science should be funded here on Earth and everywhere
• 7:15
  Speaker 1: in the universe, and I hope that budget aliens out
• 7:18
  Speaker 1: there are, you know, giving a healthy dose of funding
• 7:22
  Speaker 1: to those science aliens out there struggling to understand the
• 7:26
  Speaker 1: nature of the universe, burned by the same curiosity that
• 7:29
  Speaker 1: we have. Or maybe they don't. Maybe they just don't
• 7:31
  Speaker 1: care about the nature of the universe and they're not
• 7:33
  Speaker 1: even doing science. I feel like you're like little kid
• 7:36
  Speaker 1: in class who's looking at his test or her tests
• 7:38
  Speaker 1: and going like, I have no idea what's going on,
• 7:40
  Speaker 1: and you're sort of like looking around to see if
• 7:43
  Speaker 1: anyone else knows the answers. Yes, I definitely want to
• 7:46
  Speaker 1: cheat off of alien physicists. I would love to get
• 7:49
  Speaker 1: like an alien physics textbook and then win like a
• 7:52
  Speaker 1: whole string of Nobel prizes here on Earth just by
• 7:55
  Speaker 1: copying their ideas. Yes, I will completely admit that is
• 7:59
  Speaker 1: my fantasy. Really, So wait, you would get the secrets
• 8:02
  Speaker 1: from the alien I'm just trying to figure this scenario.
• 8:04
  Speaker 1: Let's work through it. You would get the secrets from
• 8:06
  Speaker 1: the aliens, but you wouldn't tell anyone that aliens exist,
• 8:09
  Speaker 1: and you would use that knowledge for your own personal game.
• 8:12
  Speaker 1: That sounds fantastic. Yes, remind me not to tell you
• 8:17
  Speaker 1: any secrets. Then, If you are holding a Nobel prize
• 8:20
  Speaker 1: winning secret, please do share it with me. I would
• 8:23
  Speaker 1: love to hear it. You would be the last person
• 8:25
  Speaker 1: I would share with, obviously. I hope you would share
• 8:28
  Speaker 1: it with all of humanity, Like if somebody gave me
• 8:30
  Speaker 1: secrets from aliens, I would share it with all of
• 8:32
  Speaker 1: humanity absolutely, But the aliens themselves would be the biggest secrets.
• 8:36
  Speaker 1: I just said it's the biggest question in human existence. No,
• 8:39
  Speaker 1: you're right, And of course, if aliens do come or
• 8:41
  Speaker 1: communicate with us, probably physicists wouldn't be at the front
• 8:44
  Speaker 1: of the line of people who get to chat with them, right,
• 8:47
  Speaker 1: probably would send like engineers or doctors, or politicians or
• 8:51
  Speaker 1: linguists or mathematicians or philosophers before the physicists even get
• 8:55
  Speaker 1: their shot. I think I would send the physicists first
• 8:57
  Speaker 1: for sure. Yeah, because you know what, if they're hungry,
• 9:02
  Speaker 1: we got to test the waters here. So you don't
• 9:04
  Speaker 1: want me to learn the secrets from the aliens, but
• 9:06
  Speaker 1: you do want me to be there first. I mean,
• 9:09
  Speaker 1: there's two sides to that coin. Well, I want you
• 9:11
  Speaker 1: to learn the secrets, but I want you to share
• 9:13
  Speaker 1: the secrets verybody. I will share the secrets with you
• 9:17
  Speaker 1: and the Nobel Committee. And if their secret is what
• 9:20
  Speaker 1: their stomachs look like, well, you know you can't share it,
• 9:23
  Speaker 1: but at least we would know. Just like going inside
• 9:26
  Speaker 1: a black hole, you learn some deep secrets about the universe,
• 9:29
  Speaker 1: but only you can know them. But it's interesting you
• 9:31
  Speaker 1: talk about some of the ways that people usually think
• 9:34
  Speaker 1: that we're gonna meet aliens or know about aliens, which
• 9:37
  Speaker 1: is getting signals from them. I mean that's sort of
• 9:39
  Speaker 1: like one way we can learn about them. I guess
• 9:42
  Speaker 1: another way is to go to another planet and see
• 9:44
  Speaker 1: them too, right, Yeah, And this is a really common
• 9:47
  Speaker 1: thing in science. When you have no idea how hard
• 9:50
  Speaker 1: a problem is, you start with the easiest things, like
• 9:53
  Speaker 1: maybe the universe is filled with aliens and they're all
• 9:56
  Speaker 1: sending messages and we just haven't been listening, and as
• 9:59
  Speaker 1: soon as we turn on our electronic ears and use
• 10:03
  Speaker 1: our radio satellites to tune in, maybe we could instantly
• 10:06
  Speaker 1: tap into the galactic internet and hear all those conversations.
• 10:10
  Speaker 1: There's some scenario in which it would have been easy,
• 10:12
  Speaker 1: and as soon as we started listening, we discovered it.
• 10:15
  Speaker 1: So it makes sense to first do the easy thing
• 10:17
  Speaker 1: and see if alien messages our feeling space. Of course,
• 10:20
  Speaker 1: we've been listening and we haven't heard anything, and so
• 10:23
  Speaker 1: people are starting to try to be creative and think about, like, well,
• 10:26
  Speaker 1: what are other ways we could hear from aliens, or
• 10:28
  Speaker 1: what are other ways we could detect their existence? As
• 10:31
  Speaker 1: you say, maybe we could go to those planets and
• 10:34
  Speaker 1: discover them. Right. That's limited, of course, by our ability
• 10:37
  Speaker 1: to travel from star to star. These stars are so
• 10:40
  Speaker 1: far away and the speed of light is such a
• 10:43
  Speaker 1: stubborn limitation. But until we develop a warp drives or
• 10:46
  Speaker 1: practical wormholes, it's not realistic to think that we could
• 10:50
  Speaker 1: explore a significant fraction of the galaxy. Yeah, Like, what
• 10:54
  Speaker 1: would it take, I guess to send a probe to
• 10:56
  Speaker 1: Alpha Centauri? Right, it's four light years away. That's like
• 11:00
  Speaker 1: zillions of miles away. Right now, it seems kind of
• 11:02
  Speaker 1: impossible because I think the furthest we've send a probe
• 11:05
  Speaker 1: right now is just barely outside this Solar system, right,
• 11:08
  Speaker 1: and it took like thirty years, yes, exactly, the most
• 11:11
  Speaker 1: distant object send by humanity. Some of these old Voyager
• 11:15
  Speaker 1: and Pioneer probes are not very far outside the Solar system,
• 11:18
  Speaker 1: so it would take a long time for anything to
• 11:21
  Speaker 1: get anywhere. But you know, if you were thinking about
• 11:23
  Speaker 1: it on long time scales, it's not going to take
• 11:25
  Speaker 1: like millions of years. We're talking like thousands or tens
• 11:28
  Speaker 1: of thousands of years. And if you send a few
• 11:31
  Speaker 1: probes to other planets, and if those probes are very clever,
• 11:35
  Speaker 1: they're like AI driven self replicating probes, so they can
• 11:39
  Speaker 1: land on some distant moon, they can find materials on
• 11:42
  Speaker 1: those moons to make more of themselves, and then they
• 11:45
  Speaker 1: can send those probes out, and those probes make more
• 11:48
  Speaker 1: of themselves, and those make more of themselves. It's not
• 11:51
  Speaker 1: impossible to imagine rapidly exploring the entire galaxy, where by
• 11:56
  Speaker 1: rapid we mean on the time scale of like fifty
• 11:58
  Speaker 1: to one hundred thousand years. So that's a really interesting
• 12:01
  Speaker 1: argument because it suggests that with technology not super far
• 12:04
  Speaker 1: in our future, some other civilization could have explored the
• 12:08
  Speaker 1: whole galaxy with self replicating probes. And then you have
• 12:12
  Speaker 1: to ask, like, well, why haven't we been visited by
• 12:15
  Speaker 1: such a probe yet? Are there no other advanced civilizations
• 12:18
  Speaker 1: out there who have this idea? Yeah, we address this
• 12:20
  Speaker 1: question and this whole scenario in our book. Frequently asked
• 12:23
  Speaker 1: questions about the universe. That was one of the chapters,
• 12:25
  Speaker 1: right like why haven't we seen aliens? And maybe we
• 12:29
  Speaker 1: can do that with these self repulating robots, which would
• 12:33
  Speaker 1: litter the universe in no time exactly. And one basic
• 12:37
  Speaker 1: assumptions a lot of these scenarios make is that aliens
• 12:41
  Speaker 1: want us to find them, or that they are trying
• 12:43
  Speaker 1: to talk to us, or they are curious about the
• 12:46
  Speaker 1: rest of the universe as well, so they're sending messages
• 12:49
  Speaker 1: out or they're sending probes out there explorational the same
• 12:52
  Speaker 1: way that we are. But of course we don't know
• 12:55
  Speaker 1: what alien psychology is like, and what does aliens want,
• 12:58
  Speaker 1: or even what it means to want something as an alien.
• 13:01
  Speaker 1: So these days a lot of people are imagining other
• 13:03
  Speaker 1: ways to detect aliens when they're not trying to be detected.
• 13:08
  Speaker 1: Are there things the aliens can do imprints they leave
• 13:11
  Speaker 1: on the universe that aren't intended for us to discover them,
• 13:14
  Speaker 1: but might allow us to spot them anyway. So today
• 13:17
  Speaker 1: on the program, we'll be asking the question could we
• 13:25
  Speaker 1: detect alien nuclear explosions? I imagine you're saying these are
• 13:30
  Speaker 1: like accidental nuclear explosions or on purpose nuclear explosions, either one, right,
• 13:36
  Speaker 1: we don't discriminate. We just like to know the aliens
• 13:38
  Speaker 1: are there, and whatever they do in their normal civilization extrapolasition,
• 13:44
  Speaker 1: we'd like to see if we could detect it. Maybe
• 13:47
  Speaker 1: they're just doing testing like we're doing, or maybe they
• 13:49
  Speaker 1: have some globe spanning nuclear annihilation. The question is, could
• 13:55
  Speaker 1: we see it right, If aliens are blowing up nuclear bombs,
• 13:58
  Speaker 1: is it possible for us to spot that? Yeah, because
• 14:01
  Speaker 1: as you mentioned, you know, one scenario is that they're
• 14:03
  Speaker 1: sending out signals on purpose, either to talk to us
• 14:07
  Speaker 1: directly or just like that's their TV, maybe their broadcast TV.
• 14:11
  Speaker 1: But I think we talked in an earlier episode about
• 14:14
  Speaker 1: how like for us to detect the signal from an alien,
• 14:17
  Speaker 1: it would have to be like a pretty focus beam, right,
• 14:20
  Speaker 1: like the like the club we're just listening to their
• 14:22
  Speaker 1: TV broadcast is pretty low, that's right. If you're just
• 14:24
  Speaker 1: sending signals in every direction, then you pay a really
• 14:28
  Speaker 1: big price because those signals get weaker with distance, and
• 14:32
  Speaker 1: they get weaker with distance squared. So when signals go
• 14:35
  Speaker 1: twice as far, they're four times as week, When they
• 14:38
  Speaker 1: go ten times as far, they're one hundred times as week.
• 14:41
  Speaker 1: That makes it really really hard to detect non focus signals.
• 14:46
  Speaker 1: And if we wanted to detect signals that we could
• 14:49
  Speaker 1: generate using technology that we have, we would not be
• 14:52
  Speaker 1: able to spot signals of the kinds we can generate
• 14:55
  Speaker 1: using our own technology from planets that are more than
• 14:58
  Speaker 1: like one light year away. If however, they're like beaming
• 15:02
  Speaker 1: us messages, they're shooting laser beams in our direction. Then
• 15:05
  Speaker 1: the math works differently and we could get messages from
• 15:07
  Speaker 1: further away, But then they'd have to know we were
• 15:10
  Speaker 1: here and try to send us messages on purpose, which
• 15:13
  Speaker 1: seems less likely. I think here today we're exploring a
• 15:16
  Speaker 1: different scenario, which is like, what if they're doing something
• 15:19
  Speaker 1: without trying by accident maybe or through some sort of event,
• 15:23
  Speaker 1: and then that's what we see, and that's how we
• 15:26
  Speaker 1: know that there are aliens exactly. And people have been
• 15:28
  Speaker 1: thinking about this and wondering like, well, what's the most
• 15:30
  Speaker 1: visible thing that you can do, not just broadcasting Rick
• 15:34
  Speaker 1: and Morty episodes into the cosmos? All right, Sometimes our
• 15:37
  Speaker 1: civilization does things which generate very bright flashes of radiation,
• 15:42
  Speaker 1: and hey, what's brighter than a nuclear explosion? But what
• 15:45
  Speaker 1: if there's a kid in that alien planet pointing a
• 15:47
  Speaker 1: laser partner directly Ow my eye? Ow alien burnt my eye? Yeah,
• 15:55
  Speaker 1: I know, that's why you should be careful you knock
• 15:57
  Speaker 1: about this guy. So then the scenario here is that
• 15:59
  Speaker 1: somehow this alien civilization out there is exploding nuclear their
• 16:03
  Speaker 1: own nuclear bombs, either by accident, or some testing or something.
• 16:08
  Speaker 1: Maybe they have their own nuclear war, and so the
• 16:10
  Speaker 1: question is like, could we see those nuclear explosions exactly?
• 16:14
  Speaker 1: All right? Well, as usual, we were wondering how many
• 16:16
  Speaker 1: people out there had the interesting curiosity to ask this
• 16:21
  Speaker 1: question about alien life and how we could detect them. So,
• 16:24
  Speaker 1: as usual, Daniel went out there. Did you go to
• 16:26
  Speaker 1: the internet or are you? Are you going on campus?
• 16:28
  Speaker 1: Now these are still Internet based questions. I felt a
• 16:31
  Speaker 1: little bit weird walking around campus asking people about aliens
• 16:34
  Speaker 1: and nuclear bombs. That's never stopped you before. I thought
• 16:38
  Speaker 1: it might get reported to the UCI police. Yeah, you
• 16:42
  Speaker 1: have tenure. They're not gonna fire you. Anyways, usually have
• 16:45
  Speaker 1: to do worst things. So thanks very much to our
• 16:48
  Speaker 1: internet volunteers who responded with enthusiasm to this question. If
• 16:52
  Speaker 1: you would like to play this part in future episodes,
• 16:54
  Speaker 1: please write to me to questions at Daniel and Jorge
• 16:57
  Speaker 1: dot com. We can do it all over email. It's fast,
• 17:00
  Speaker 1: it's easy, it's fun to think about it for a second.
• 17:03
  Speaker 1: Do you think we could detect alien nuclear explosions? Here's
• 17:08
  Speaker 1: what people have to say. Yes, So it depends whether
• 17:10
  Speaker 1: the detonation happened on Earth or a planet from Solar
• 17:14
  Speaker 1: System or somewhere far away. In any of these cases,
• 17:18
  Speaker 1: I think we might be able to detect. Considering that
• 17:21
  Speaker 1: why decaying of the matter and the amount of radiation
• 17:23
  Speaker 1: that is being exposed out of that location on Earth,
• 17:26
  Speaker 1: we might be able to analyze whether it's man made
• 17:30
  Speaker 1: or alien, and if it is happening on some other planet.
• 17:34
  Speaker 1: Considering the amount of information that we have already gained
• 17:38
  Speaker 1: with the telescopes in place, we will be able to
• 17:41
  Speaker 1: do it. That's what I believe. By now, we have
• 17:44
  Speaker 1: satellites now that can detect detonations on Earth. I don't
• 17:47
  Speaker 1: think it would work at interstellar distances, especially considering that
• 17:51
  Speaker 1: there's so many sources of radiation in space, you know,
• 17:55
  Speaker 1: from stars to gamma ray burst everything in between. So no,
• 17:59
  Speaker 1: I don't think we could. Well, I guess so. I
• 18:02
  Speaker 1: guess it would depend on how good the detector was
• 18:05
  Speaker 1: and how far away it was away from you. If
• 18:08
  Speaker 1: there was set off over your head, you might be
• 18:11
  Speaker 1: able to detect it pretty soon. I feel like we
• 18:14
  Speaker 1: probably could detect alien nuclear detonations if there was like
• 18:19
  Speaker 1: enough radiation to reach far enough, But other than that,
• 18:24
  Speaker 1: I don't really think we could all right. Some people
• 18:27
  Speaker 1: said yes, some people said no, some people said maybe yeah.
• 18:30
  Speaker 1: I think they really put their finger on the issue,
• 18:32
  Speaker 1: which is that nobody knows, not even us. It's all
• 18:36
  Speaker 1: about brightness and distance. You know, what's the faintest radiation
• 18:40
  Speaker 1: we could pick up? And how close would these bombs
• 18:42
  Speaker 1: have to be for us to spot them. I feel
• 18:44
  Speaker 1: like you're missing one important factor, which is how big
• 18:48
  Speaker 1: are these bombs? That's a huge unknown. You're right, and
• 18:50
  Speaker 1: we'll get into it in a minute. And the only
• 18:52
  Speaker 1: standard we have is like how big are our bombs?
• 18:55
  Speaker 1: So we can imagine whether we could detect nuclear explosions
• 18:59
  Speaker 1: of the size we could make if aliens also did them.
• 19:03
  Speaker 1: All right, we'll dig into it, but I guess first
• 19:04
  Speaker 1: let's start with the basics, Like Daniel, what happens during
• 19:07
  Speaker 1: a nuclear explosion? Besides the explosion part of it. Yeah,
• 19:10
  Speaker 1: to understand whether we could see a nuclear explosion on
• 19:13
  Speaker 1: another planet, you have to think about what the signals are,
• 19:16
  Speaker 1: like what signals does a nuclear explosion generate? And we
• 19:19
  Speaker 1: had a whole episode about how nuclear bombs work where
• 19:22
  Speaker 1: we went to a lot of detail, but not enough
• 19:24
  Speaker 1: detail for you to build a nuclear bomb. Hopefully but
• 19:28
  Speaker 1: human nuclear weapons at least are either fission weapons or
• 19:32
  Speaker 1: fusion weapons triggered by fission. And remember that the basic
• 19:36
  Speaker 1: processes here fission involved breaking up of a heavy nucleus
• 19:41
  Speaker 1: like plutonium or uranium, which then shoots off a bunch
• 19:44
  Speaker 1: of neutrons and rams into other nuclei, which breaks them
• 19:48
  Speaker 1: apart and sets off a chain reaction where you very
• 19:50
  Speaker 1: rapidly are releasing energy. And the fusion bomb is similar
• 19:54
  Speaker 1: except it uses a fission bomb to compress a bunch
• 19:58
  Speaker 1: of fusion fuel that it fuses, and in both scenarios
• 20:02
  Speaker 1: the key thing is releasing a huge amount of energy
• 20:05
  Speaker 1: very very quickly, but not just energy, right, You're releasing
• 20:08
  Speaker 1: energy but also a lot of radiation. Yeah, maybe step
• 20:12
  Speaker 1: us through like what's actually being released, Like when you
• 20:15
  Speaker 1: fuse things together they click together, to nuclear click together,
• 20:19
  Speaker 1: and then what actually gets released like light or particles
• 20:25
  Speaker 1: or Yeah, so fusion produces high energy photons. It also
• 20:29
  Speaker 1: produces neutrons and electrons and neutrinos. Right, so all these
• 20:35
  Speaker 1: kinds of things are produced and then much just produced,
• 20:38
  Speaker 1: but they're like they're produced, but then they're flying really fast. Yes,
• 20:42
  Speaker 1: they're produced, and they're carrying a lot of energy is
• 20:45
  Speaker 1: what you actually see from the bomb from like a
• 20:47
  Speaker 1: certain distance. Depends on how that energy is absorbed or
• 20:50
  Speaker 1: not absorbed. So, for example, a lot of the energy
• 20:53
  Speaker 1: gets dumped into the matters immediately surrounding the bomb, right,
• 20:57
  Speaker 1: and so it's absorbed very very rapidly by the st
• 21:00
  Speaker 1: around the bomb, which expands that matter and creates a
• 21:03
  Speaker 1: shock wave. I mean like the bomb casing or like whatever,
• 21:07
  Speaker 1: if it's on the ground, that that's what it's going
• 21:09
  Speaker 1: to push out. Yeah, I mean whatever material is around
• 21:12
  Speaker 1: the bomb, like the air or the water or the ground,
• 21:15
  Speaker 1: and you get very different scenarios if you have an
• 21:18
  Speaker 1: in air explosion or underground explosion or just above the water.
• 21:22
  Speaker 1: But the material that surrounds the bomb is inundated with
• 21:25
  Speaker 1: a huge amount of energy, a lot of it from
• 21:27
  Speaker 1: gamma rays, and a lot of that gets rapidly absorbed
• 21:30
  Speaker 1: and that material gets heated up to like tens of
• 21:32
  Speaker 1: millions of degrees and then you get this shockwave. So
• 21:36
  Speaker 1: in the end, on average, and it depends on exactly
• 21:38
  Speaker 1: what you've surrounded the bomb with, about half of the
• 21:41
  Speaker 1: energy of a nuclear bomb go these shockwaves, these expanding
• 21:45
  Speaker 1: waves of matter basically sound waves through matter that carry
• 21:50
  Speaker 1: away a lot of this energy, doesn't It depend on
• 21:52
  Speaker 1: what's around the bomb. Like if you explode it in water,
• 21:55
  Speaker 1: all of it's going to go into the water, But
• 21:57
  Speaker 1: if you put it in air, you know there's maybe
• 21:59
  Speaker 1: a chance for that energy to go out further. Even
• 22:02
  Speaker 1: in air, a lot of that energy is absorbed by
• 22:04
  Speaker 1: the air and you get shock waves. So yes, it
• 22:06
  Speaker 1: definitely does depend on the kind of material surrounded. Like
• 22:10
  Speaker 1: if you blow it up underground, it's absorbed differently than
• 22:13
  Speaker 1: if you blow it up in the air. But you know,
• 22:15
  Speaker 1: since we're just dealing with like approximate numbers here, roughly
• 22:18
  Speaker 1: on average, over all those circumstances, about half of the
• 22:21
  Speaker 1: energy gets dumped into shock waves and then like another
• 22:25
  Speaker 1: forty percent of the energy comes out in what we
• 22:28
  Speaker 1: call thermal radiation, basically photons to which the atmosphere is
• 22:32
  Speaker 1: transparent visible light, infrared light, UV light, things that are
• 22:36
  Speaker 1: not immediately absorbed by the surrounding material which conduct fly
• 22:39
  Speaker 1: out through that material because that material is transparent to
• 22:44
  Speaker 1: this kind of radiation. Why is it transparent. Is it
• 22:47
  Speaker 1: because it just doesn't absorb because of quantum effects, or
• 22:50
  Speaker 1: is it just that it's so like air is so
• 22:53
  Speaker 1: thin that it just doesn't hit enough air molecules. Yeah,
• 22:55
  Speaker 1: air is transparent to visible light, right, we know that
• 22:58
  Speaker 1: because we can see the sun through the air. Why
• 23:01
  Speaker 1: is the air transparent to visible light, You're right, is
• 23:03
  Speaker 1: quantum effects. You have certain gases under certain conditions, and
• 23:07
  Speaker 1: they either like to absorb photons of various frequencies or
• 23:10
  Speaker 1: they don't. These air molecules can't just absorb a photon
• 23:13
  Speaker 1: of an arbitrary frequency. They have to have like a
• 23:16
  Speaker 1: quantum state that their electron can jump up into, or
• 23:20
  Speaker 1: like a new rotation that they can do. So atoms
• 23:22
  Speaker 1: can only absorb certain frequencies of light, and the other
• 23:26
  Speaker 1: frequencies pass right through. So air is mostly transparent to
• 23:30
  Speaker 1: visible light and also infrared light. It's less transparent in
• 23:33
  Speaker 1: the UV, which is one reason why we have like
• 23:36
  Speaker 1: UV space telescopes above the atmosphere. But you know a
• 23:39
  Speaker 1: lot of energy is dumped out and so some of
• 23:42
  Speaker 1: these very high energy UV light does survive passing through
• 23:47
  Speaker 1: the atmosphere. If you're near a nuclear bomb, so you
• 23:49
  Speaker 1: have like fifty percent of it roughly in the shock wave,
• 23:52
  Speaker 1: like another forty percent in thermal radiation these photons that
• 23:57
  Speaker 1: don't get absorbed, and then another ten percent in other
• 24:00
  Speaker 1: particles like neutrons or very high energy photons we call
• 24:04
  Speaker 1: gamma rays or electrons. Is it sort of like lightning
• 24:07
  Speaker 1: and thunder? Like you will see the flash of a
• 24:10
  Speaker 1: nuclear bomb before you actually get hit by the shockwave. Yeah,
• 24:14
  Speaker 1: it's really cool. You actually see two flashes of a
• 24:17
  Speaker 1: nuclear bomb. You see the first flash because the visible
• 24:21
  Speaker 1: light reaches you before the shockwave. But at some point
• 24:23
  Speaker 1: the shock wave passes the fireball because the shockwave is
• 24:27
  Speaker 1: making the material more dense, which acts to obscure the fireball.
• 24:32
  Speaker 1: So the shockwave itself is opaque to the kind of
• 24:35
  Speaker 1: light being generated by the nuclear bomb. So then for
• 24:38
  Speaker 1: a moment you can't see the fireball, but then it
• 24:41
  Speaker 1: dissipates and you can see it again. So it's like
• 24:43
  Speaker 1: you see fireball and then you see the shock wave,
• 24:46
  Speaker 1: and then you see the fireball. So it's sort of
• 24:47
  Speaker 1: like lightning and then thunder and then a second flash
• 24:50
  Speaker 1: of lightning. Whoa, I mean, assuming you survived the first
• 24:54
  Speaker 1: event to get to see the other two. Yeah, So
• 24:57
  Speaker 1: this is a very characteristic signature of nuclear bombs. This
• 25:00
  Speaker 1: double peak of gamma radiation over several milliseconds. Well, it's
• 25:05
  Speaker 1: definitely an event and nuclear explosion. And so the question
• 25:08
  Speaker 1: is if aliens exploded nuclear bombs in their planets, could
• 25:13
  Speaker 1: we see them from here. Let's dig into that question
• 25:16
  Speaker 1: and what we should be looking for if we're looking
• 25:18
  Speaker 1: for those kinds of signals. First, let's take a quick break.
• 25:36
  Speaker 1: All right, we are spending today imagining aliens blowing themselves up.
• 25:41
  Speaker 1: We're not hoping they blow themselves up, but if they do,
• 25:44
  Speaker 1: we hope to see it. We're not hoping they blow
• 25:47
  Speaker 1: themselves up, but if they do, it would be nice.
• 25:49
  Speaker 1: Is that what you say? Is that? What are you saying?
• 25:52
  Speaker 1: I mean, I don't aliens living in obscurity forever, or
• 25:56
  Speaker 1: aliens killing themselves about then we find out about them.
• 26:00
  Speaker 1: I mean, it would also be kind of sad to
• 26:01
  Speaker 1: discover aliens only to discover they had all killed themselves,
• 26:06
  Speaker 1: that they were the last ones. Yeah, that would be
• 26:08
  Speaker 1: that would be pretty tragic. Yeah, that would be a bummer. Well,
• 26:11
  Speaker 1: we've talked about what a nuclear explosion is and what
• 26:14
  Speaker 1: happens to it. So you said about half of the
• 26:16
  Speaker 1: energy is really just pushing the stuff around it so
• 26:19
  Speaker 1: I imagine that won't get very far. Maybe forty percent
• 26:22
  Speaker 1: of it goes into just light, basically invisible light or
• 26:26
  Speaker 1: light you'd be light, And about ten percent of it
• 26:29
  Speaker 1: goes into shooting out basically radiation, right, like charged particles. Yeah,
• 26:35
  Speaker 1: not just charged particles, but neutrons, gamma rays, and also electrons. Well,
• 26:39
  Speaker 1: gamma rays are light, right, Gamma rays are very high
• 26:42
  Speaker 1: energy photons, Yeah, even more high energy than X rays
• 26:45
  Speaker 1: or UV. These are all ionizing radiation. They all have
• 26:48
  Speaker 1: the capacity to knock electrons off of materials. And because
• 26:52
  Speaker 1: they're ionizing and electrons themselves have charge, they can also
• 26:56
  Speaker 1: generate an electro magnetic pulse. This is a common feature
• 27:00
  Speaker 1: a lot of movies nuclear weapons knocking out electronics because
• 27:04
  Speaker 1: of a very high energy pulse of electromagnetic radiation. Oh interesting,
• 27:08
  Speaker 1: it's not just that it's like a giant magnet. It's
• 27:11
  Speaker 1: like it's actually shooting out little magnets. Yeah, exactly. And
• 27:15
  Speaker 1: so all those gamma rays and all those electrons can
• 27:17
  Speaker 1: damage a lot of electronics. So if you have electronics
• 27:20
  Speaker 1: near a nuclear weapons blast, then you will feel it.
• 27:23
  Speaker 1: They could get knocked offline. They don't shoot protons explosions
• 27:26
  Speaker 1: or neutrinos. They do generate a lot of neutrinos. He
• 27:29
  Speaker 1: has absolutely fusion and fission both generate neutrinos, but not
• 27:33
  Speaker 1: so many protons. Mostly neutrons and neutrinos and electrons. What
• 27:36
  Speaker 1: about later rays and sound effects like in Star Wars?
• 27:40
  Speaker 1: They don't go pupupu as far as I've seen. It's
• 27:43
  Speaker 1: not in the literature. But the sounds of thousands of
• 27:47
  Speaker 1: souls being snuffed at the same time, Oh, that's sad.
• 27:51
  Speaker 1: I don't know if they create a great disturbance in
• 27:52
  Speaker 1: the force. We don't have detectors that can measure the
• 27:55
  Speaker 1: force yet, so I'm not sure about that, not yet
• 27:57
  Speaker 1: at least, although I have a good acronym for them.
• 28:00
  Speaker 1: They should be a named Jedi, right, And how does
• 28:05
  Speaker 1: that work? Just the Electron Detection Institute sounds good? Are
• 28:11
  Speaker 1: you setting that up with some funding? Are you going
• 28:13
  Speaker 1: to endow the Jedi Institute? Maybe I have already, I'm
• 28:16
  Speaker 1: just not telling you. No. That's extra frustrating. But you know,
• 28:20
  Speaker 1: there are a lot of scientists here on Earth that
• 28:23
  Speaker 1: are developed very sensitive technology for a studying nuclear weapons,
• 28:27
  Speaker 1: both because we want to understand what happens when they
• 28:30
  Speaker 1: blow up, because we have done tests and we want
• 28:32
  Speaker 1: to understand whether our nuclear weapons are working and are
• 28:35
  Speaker 1: still working and are surviving the test of time as
• 28:38
  Speaker 1: they sit in our stockpiles. But also because we wanted
• 28:41
  Speaker 1: to detect if other countries are blowing up their nuclear bombs.
• 28:45
  Speaker 1: So there's been a lot of investment in detection of
• 28:48
  Speaker 1: nuclear weapons activity, you mean, like here on Earth. Like
• 28:51
  Speaker 1: if you wanted to detect whether a nuclear bomb exploded
• 28:54
  Speaker 1: here on Earth, not in an alien planet, we have
• 28:57
  Speaker 1: techniques here on Earth to do that because I guess
• 28:59
  Speaker 1: if someone explodes a nuther bomb on the other side
• 29:02
  Speaker 1: of the world, in the middle of the ocean, you
• 29:03
  Speaker 1: may not necessarily know what happened, right, And if you're
• 29:07
  Speaker 1: a big country in a cold war or not, you
• 29:10
  Speaker 1: might want to know if your enemies are exploding bombs
• 29:13
  Speaker 1: or testing them, that's right, and you might not want
• 29:15
  Speaker 1: the other country to know that you're doing it. So,
• 29:17
  Speaker 1: like secret testing of nuclear weapons was a big industry
• 29:20
  Speaker 1: and a sort of an arms race of hiding nuclear
• 29:23
  Speaker 1: bomb detonations and nuclear weapons detections. I grew up in
• 29:27
  Speaker 1: Los Almos, which was certainly a nerve center for this
• 29:29
  Speaker 1: kind of stuff. My mom actually worked on a nuclear
• 29:32
  Speaker 1: non proliferation technology when she was at Los Almos, trying
• 29:35
  Speaker 1: to detect if people are blowing up nuclear bombs and
• 29:38
  Speaker 1: all this kind of stuff. So we have a lot
• 29:40
  Speaker 1: of ways to try to figure out if someone has
• 29:42
  Speaker 1: blown up a nuclear bomb here on Earth. Yeah, it
• 29:44
  Speaker 1: sounds like you would want to know. And it's kind
• 29:46
  Speaker 1: of interesting that we test nuclear bombs right Like, first
• 29:49
  Speaker 1: of all, I guess you have to test them right
• 29:51
  Speaker 1: now or the wise do not even know they work.
• 29:52
  Speaker 1: But it's amazing to me that we have tested nuclear
• 29:55
  Speaker 1: bombs here in the US, right in the desert back
• 29:57
  Speaker 1: in the fifties and sixties that there was all they did. Yeah,
• 30:00
  Speaker 1: they have done above ground tests here in the US.
• 30:02
  Speaker 1: You know, Alamagordo was the first site in New Mexico
• 30:05
  Speaker 1: and they tested them on a bunch of islands, which
• 30:07
  Speaker 1: was terrible and like totally obliterated them. And then there
• 30:10
  Speaker 1: was an atmosphereic test ban treaty, so you couldn't test
• 30:13
  Speaker 1: the nuclear weapons in the atmosphere anymore, which is good,
• 30:16
  Speaker 1: and they moved the testing underground. So in the United States,
• 30:19
  Speaker 1: for example, there's the Nevada underground test site where they
• 30:22
  Speaker 1: blow these weapons up underground. But there hasn't been any
• 30:24
  Speaker 1: recent testing. There's a Comprehensive Test Band treaty now and
• 30:28
  Speaker 1: so instead people now do simulations. They try to understand
• 30:32
  Speaker 1: what would happen in the event of a nuclear explosion,
• 30:35
  Speaker 1: or try to model what's happening to the nuclear weapons
• 30:38
  Speaker 1: we have now, are they going to survive? The whole
• 30:40
  Speaker 1: big industry called stockpile stewardship to try to make sure
• 30:43
  Speaker 1: that our nuclear weapons would still work if we fired them. Interesting,
• 30:47
  Speaker 1: So it's a treaty. So like with Russian other countries,
• 30:50
  Speaker 1: we have a handshake agreement that you can't test. Basically,
• 30:53
  Speaker 1: you can't test nuclear weapons anymore. Yeah, there's a Comprehensive
• 30:56
  Speaker 1: Nuclear Test Band Treaty signed in nineteen ninety six. And
• 31:00
  Speaker 1: you know, these treatings are always complicated because some nations
• 31:03
  Speaker 1: don't ratify them. They're signed by presidents and then their
• 31:06
  Speaker 1: local parliaments don't agree to them. But yeah, it's been
• 31:08
  Speaker 1: a long time since there was sort of a public
• 31:10
  Speaker 1: test of a nuclear weapon out in the open, all right.
• 31:13
  Speaker 1: So if someone did test the weapon or use one
• 31:16
  Speaker 1: here on earth, how can we detect them? So we
• 31:18
  Speaker 1: have a few ways to try to spot this. Number
• 31:20
  Speaker 1: one is seismic. If you do test underground, then it's
• 31:23
  Speaker 1: going to shake the earth and the earth will ring
• 31:26
  Speaker 1: like a bell. Shock waves will pass all the way
• 31:28
  Speaker 1: around the Earth, and you can detect them in other
• 31:31
  Speaker 1: places the same way we can put detectors in California
• 31:34
  Speaker 1: that can spot earthquakes in Japan or in other parts
• 31:37
  Speaker 1: of the world. You can detect large seismic events all
• 31:41
  Speaker 1: over the world. Right because I guess the shock waves
• 31:44
  Speaker 1: of these earthquakes or nuclear explosions, they kind of go
• 31:46
  Speaker 1: through the rock of the Earth, right, even though it's
• 31:49
  Speaker 1: like lava and molten it'll still kind of propagate sound
• 31:52
  Speaker 1: waves lava sound waves. Imagine the Earth is just like
• 31:56
  Speaker 1: a ball of metal and you ring it with a hammer,
• 31:58
  Speaker 1: then those sound chock waves are going to bounce all
• 32:00
  Speaker 1: around inside it. And this is actually really cool for
• 32:03
  Speaker 1: studying the interior of the Earth. You ring the earth
• 32:07
  Speaker 1: and how those shockwaves move through the earth tells you
• 32:09
  Speaker 1: about what's inside of it. And like the boundary layers,
• 32:12
  Speaker 1: that's actually given us a lot of clues about what's
• 32:14
  Speaker 1: inside the earth. Is watching the impact of earthquakes sending
• 32:18
  Speaker 1: shockwaves through the earth. It can be hard, however, to
• 32:21
  Speaker 1: tell the difference between an earthquake and a smaller nuclear
• 32:24
  Speaker 1: weapons explosion, and they try to do a lot these
• 32:27
  Speaker 1: days to hide the nuclear weapons explosions by having like
• 32:29
  Speaker 1: dampers materials which will absorb a lot of this energy
• 32:33
  Speaker 1: instead of properly getting it into the earth. And one
• 32:35
  Speaker 1: thing that they've done to try to distinguish between earthquakes
• 32:38
  Speaker 1: and nuclear bombs is to listen to it, to take
• 32:41
  Speaker 1: the data and translate it into an audio file. And
• 32:44
  Speaker 1: it turns out the human brains are pretty good at
• 32:47
  Speaker 1: distinguishing the sound of an earthquake versus the sound of
• 32:51
  Speaker 1: a nuclear bomb going off. Okay, so sound waves through
• 32:55
  Speaker 1: the earth is one way we can detect them here
• 32:57
  Speaker 1: on Earth. What are some of the other ways? Other
• 32:59
  Speaker 1: ways are through the air and through the water. So
• 33:02
  Speaker 1: if you, for example, blowing up underwater, then you create
• 33:06
  Speaker 1: hydroacoustic signals. It's just like shock waves through the earth,
• 33:10
  Speaker 1: but instead now you're make sways through the water, and
• 33:12
  Speaker 1: water is very good at transmitting sound. Right. The speed
• 33:15
  Speaker 1: of sound through water is faster than it is through air,
• 33:18
  Speaker 1: and so sound travels pretty far. All the way across
• 33:20
  Speaker 1: the globe, which is one reason why they think that
• 33:23
  Speaker 1: like whales can talk to each other from different parts
• 33:25
  Speaker 1: of the planet. You know, they think whales in Japan
• 33:28
  Speaker 1: might be able to hear the songs of whales off
• 33:30
  Speaker 1: of Alaska, this kind of stuff. And so in the
• 33:33
  Speaker 1: same way, if you blow up a nuclear bomb anywhere
• 33:35
  Speaker 1: neither its not even just in the water, then the
• 33:37
  Speaker 1: seismic waves will propagate through the ocean. And we have
• 33:40
  Speaker 1: a lot of listening stations underwater to try to listen
• 33:43
  Speaker 1: for all sorts of activity, but including nuclear explosions. Is
• 33:47
  Speaker 1: that allowed? Can you test nuclear weapons in the water?
• 33:50
  Speaker 1: Definitely not allowed, but has been done in the past, right,
• 33:54
  Speaker 1: all right, how else you can also look more directly
• 33:56
  Speaker 1: for the radioactivity, right if you do blow up a
• 33:59
  Speaker 1: nuclear bomb, and there's a lot of radiation emitted and
• 34:01
  Speaker 1: radioactive elements. So one thing we do is we try
• 34:04
  Speaker 1: to sample by airplane. You know, you have airplanes flying
• 34:07
  Speaker 1: all around the world, and they're sampling for unusual radioactive isotopes,
• 34:11
  Speaker 1: some of which are indicative of nuclear explosions. Even if
• 34:15
  Speaker 1: you like test it underground, a little bit of these
• 34:17
  Speaker 1: radioactive isotopes will eventually leak. It's not always easy to
• 34:21
  Speaker 1: tell where the nuclear bomb explosion happened using these techniques,
• 34:25
  Speaker 1: because it depends on how it's carried by the wind
• 34:27
  Speaker 1: and the weather and how recently it happened. But you
• 34:30
  Speaker 1: can sort of tell that one maybe did happen if
• 34:33
  Speaker 1: you pick up a signal of these particular fingerprints of
• 34:35
  Speaker 1: a nuclear bomb through their radioactive isotopes. So that's happening
• 34:39
  Speaker 1: right now. Like there are aeroplanes out there up there
• 34:43
  Speaker 1: basically sweeping the earth like a like a roombay. Exactly.
• 34:47
  Speaker 1: I don't know the details because they're not public because
• 34:49
  Speaker 1: like the US doesn't want Russia, for example, to know
• 34:52
  Speaker 1: exactly how it's monitoring it, because then Russia will know
• 34:55
  Speaker 1: how best to evade it. So it's a whole game
• 34:57
  Speaker 1: of secrecy. But absolutely I'm sure that the Russians and
• 35:01
  Speaker 1: the Americans are both monitoring the atmosphere in high altitude
• 35:04
  Speaker 1: planes to try to detect whether the other side is
• 35:07
  Speaker 1: cheating on the Test band treaty. We're also basically looking
• 35:10
  Speaker 1: for these explosions, right like if you can have satellites
• 35:12
  Speaker 1: maybe with camera strain at the Earth looking waiting for
• 35:15
  Speaker 1: these flashes of light, absolutely, and that's one of the
• 35:17
  Speaker 1: most powerful ways we can see these and one of
• 35:20
  Speaker 1: the ways that might apply to alien detonations, which is
• 35:23
  Speaker 1: just look with satellites, right, we have pictures basically the
• 35:26
  Speaker 1: entire surface of the Earth, and we can look for
• 35:28
  Speaker 1: high energy sources of gamma rays and X rays, which
• 35:31
  Speaker 1: are unusual and you don't expect to produce these things
• 35:34
  Speaker 1: in lots of different ways. And so if you see
• 35:36
  Speaker 1: one of these signals, flashes of gamma rays, especially the
• 35:39
  Speaker 1: double peak signature, then you have a very strong smoking
• 35:42
  Speaker 1: gun signature of a nuclear detonation. But what if you
• 35:45
  Speaker 1: detonated underground, like deep underground would be with the X
• 35:48
  Speaker 1: rays and gamma rays still make it through all those
• 35:50
  Speaker 1: layers of rock. It depends a lot on the shielding, right,
• 35:53
  Speaker 1: and sometimes they try to shield it with heavier metals
• 35:55
  Speaker 1: or they go deep deep underground. X rays can penetrate
• 35:58
  Speaker 1: a lot of material. Rays tend to be more ionizing,
• 36:01
  Speaker 1: so they do end up getting absorbed, but it depends
• 36:04
  Speaker 1: a lot on the depth. All right, Well, that's how
• 36:06
  Speaker 1: you can tell if someone exploded something here on Earth.
• 36:09
  Speaker 1: But what about the question of aliens exploding things in
• 36:12
  Speaker 1: their planets? Could we detect alien explosions or an alien
• 36:17
  Speaker 1: nuclear war. So if aliens have the same kind of
• 36:20
  Speaker 1: technology that we have, meaning they're blowing up bombs similar
• 36:23
  Speaker 1: to the ones we have, then we can look for
• 36:24
  Speaker 1: the same signatures from their planets that we would look
• 36:27
  Speaker 1: for on Earth. Obviously, we can't look for seismic activity
• 36:31
  Speaker 1: or hydroacoustic activity, and we can't sample their atmosphere directly.
• 36:36
  Speaker 1: The best way to do it would be to look
• 36:37
  Speaker 1: for these gamma ray flashes. And of course we already
• 36:41
  Speaker 1: have telescopes that are scanning the sky looking for gamma
• 36:44
  Speaker 1: rays because lots of non alien sources of gamma rays
• 36:48
  Speaker 1: are very interesting to us, and there's even a huge
• 36:51
  Speaker 1: fun physics mystery about gamma ray flashes. These things are
• 36:55
  Speaker 1: called gamma ray bursts that come from all over the sky.
• 36:59
  Speaker 1: We don't really understand them. They last for like sometimes
• 37:01
  Speaker 1: a few seconds, sometimes like thirty seconds. We think they
• 37:05
  Speaker 1: might be due to the collapse of supermassive stars, but
• 37:09
  Speaker 1: they generate very bright flashes of gamma rays that are
• 37:12
  Speaker 1: sort of similar to what you might expect from a
• 37:15
  Speaker 1: nuclear detonation. M I think you're sort of painting the
• 37:19
  Speaker 1: scenario where We're basically looking at the sky right with
• 37:23
  Speaker 1: giant antennas that can detect gamma rays. And if we
• 37:27
  Speaker 1: somehow are pointing to a particular planet or star and
• 37:29
  Speaker 1: we see a big flash or a signal, then that
• 37:32
  Speaker 1: could be the sign that the amiens blew themselves up.
• 37:34
  Speaker 1: It could be the sign. As one of the members
• 37:36
  Speaker 1: of Listener Panel pointed out, it might be hard to distinguish. Right.
• 37:40
  Speaker 1: On one hand, it's cool that supermassive stars collapse and
• 37:43
  Speaker 1: give off gamma ray bursts. On the other hand, it's
• 37:46
  Speaker 1: a bit of a bomber because it makes it harder
• 37:48
  Speaker 1: to distinguish between alien nuclear bomb gamma ray bursts and
• 37:52
  Speaker 1: just natural sources of gamma ray bursts. But I guess
• 37:55
  Speaker 1: if it was a super massive star collapsing, wouldn't we
• 37:59
  Speaker 1: also see other signs that go along with it that
• 38:01
  Speaker 1: wouldn't go along with a nuclear explosion. It could be,
• 38:05
  Speaker 1: And one thing we're doing is to try to study
• 38:07
  Speaker 1: these gamma ray bursts in more detail and see whether
• 38:10
  Speaker 1: they come along with other signs like flashes of neutrinos
• 38:13
  Speaker 1: or other things we can see in the optical To
• 38:16
  Speaker 1: try to figure these things out. We don't always have
• 38:18
  Speaker 1: a lot of warning, right, We don't know when it's
• 38:20
  Speaker 1: going to happen. We just see like, oh wow, that
• 38:21
  Speaker 1: was a big flash of gamma rays from this spot
• 38:24
  Speaker 1: in the sky. You don't always have time to train
• 38:26
  Speaker 1: other telescopes on that spot to get sort of multi
• 38:29
  Speaker 1: channel data, and they do look kind of similar. In fact,
• 38:33
  Speaker 1: when we first discovered gamma ray bursts, scientists thought that
• 38:36
  Speaker 1: what they were seeing were gamma rays from earthbound detonations
• 38:40
  Speaker 1: of nuclear weapons. They thought they had just picked up
• 38:43
  Speaker 1: the Russian explosions because I would explain the signal too, Yeah,
• 38:48
  Speaker 1: because that would have explained the signal. Now, gamma ray
• 38:51
  Speaker 1: bursts come from really really incredibly powerful events. These things
• 38:55
  Speaker 1: release enormous amounts of energy, so we can see gamma
• 38:58
  Speaker 1: ray bursts from all across the universe. We've seen them
• 39:01
  Speaker 1: from really really far away, like millions and millions, almost
• 39:04
  Speaker 1: a billion light years away, because they are so powerful.
• 39:08
  Speaker 1: Some of these things released like ten to the forty
• 39:11
  Speaker 1: four jewels of energy just in the gamma rays, and
• 39:15
  Speaker 1: so they're very bright, very powerful. We can see these
• 39:18
  Speaker 1: things from very very far away. Our nuclear bombs are
• 39:21
  Speaker 1: not nearly as powerful as these other natural sources of
• 39:24
  Speaker 1: gamma rays, so they would be relatively dim in comparison.
• 39:28
  Speaker 1: You mean if there was an alien looking at us
• 39:30
  Speaker 1: for these gamma ray bursts, Yeah, exactly. If aliens were
• 39:33
  Speaker 1: watching our nuclear explosions and they had technology similar to hours,
• 39:37
  Speaker 1: they would not be able to see our explosions from
• 39:40
  Speaker 1: very very far away because our explosions are not that
• 39:43
  Speaker 1: bright compared to gamma ray bursts. Well, sort of depends
• 39:46
  Speaker 1: on how many nukes we detonate at the same time.
• 39:49
  Speaker 1: It does. But if you imagine, like a doomsday scenario,
• 39:52
  Speaker 1: you take all of our nuclear weapons, you set them
• 39:54
  Speaker 1: all off at the same time, you can calculate, like
• 39:57
  Speaker 1: how much energy in gamma ray bursts would be emitted.
• 40:00
  Speaker 1: It's only like ten to the nineteen jewels, Like obviously cataclysmic,
• 40:05
  Speaker 1: terrible scenario, enough energy to devastate civilization on Earth. But
• 40:09
  Speaker 1: compared to gamma ray bursts, which are ten to the
• 40:11
  Speaker 1: forty four jewels, we're talking about ten to the twenty
• 40:14
  Speaker 1: five times less powerful than a gamma ray burst, So
• 40:18
  Speaker 1: they're relatively dim compared to these other astrophysical sources. It's
• 40:22
  Speaker 1: twenty five orders of magnitude weaker, but I guess you're saying, like,
• 40:27
  Speaker 1: if we do see a gamma ray burst and we're
• 40:30
  Speaker 1: not sure if it's an alien or a star collapsing,
• 40:33
  Speaker 1: I mean that would mean that this alien civilization blew
• 40:36
  Speaker 1: up twenty five orders of magnude, many more bombs than
• 40:40
  Speaker 1: we did. We're a bomb that was twenty five orders
• 40:43
  Speaker 1: of magnitude bigger than ours. Yeah, it depends on how
• 40:45
  Speaker 1: far away they are. If they are as far away
• 40:47
  Speaker 1: as some of these really distant gamma ray bursts, then
• 40:50
  Speaker 1: you're right, they would have like much much bigger nuclear
• 40:53
  Speaker 1: arsenals than we have, like ten to twenty five times
• 40:56
  Speaker 1: as powerful, or they had or they exactly exactly kind
• 41:02
  Speaker 1: of tense. But if you're imagining an alien civilization with
• 41:04
  Speaker 1: the power of our nuclear weapons and they had some
• 41:07
  Speaker 1: sort of cataclysmic event where they blew them all up
• 41:10
  Speaker 1: at once, then you can ask how far away would
• 41:12
  Speaker 1: they be for us to detect it. Our gamma ray
• 41:14
  Speaker 1: sensors are pretty sensitive, but remember that things get much
• 41:18
  Speaker 1: dimmer as you get further away, so the sources have
• 41:21
  Speaker 1: to be very bright to be visible. For an alien
• 41:24
  Speaker 1: nuclear war at human levels to look about as bright
• 41:27
  Speaker 1: as a typical gamma ray burst, that we see it
• 41:30
  Speaker 1: could only be around eight to ten astronomical units away
• 41:35
  Speaker 1: because it wouldn't be nearly as bright as its source
• 41:38
  Speaker 1: as gamma ray bursts that are typically much further. So
• 41:41
  Speaker 1: eight to ten AU that's like the distance to Pluto.
• 41:44
  Speaker 1: Beyond that, we might still be able to pick it up,
• 41:47
  Speaker 1: but it would start getting dimmer very fast because remember
• 41:50
  Speaker 1: the next star over is much further away than Pluto.
• 41:53
  Speaker 1: So it's possible to see it in another star system,
• 41:57
  Speaker 1: but not a guarantee, and our abilities fade very quickly
• 42:00
  Speaker 1: as you consider even further star systems. So if like
• 42:04
  Speaker 1: there are aliens in Pluto and they had a nuclear
• 42:07
  Speaker 1: war and they detonated all their nuclear weapons, then we
• 42:09
  Speaker 1: would see it through the gamma ray radiation. But if
• 42:13
  Speaker 1: it happened like and in another source system, it'd be
• 42:15
  Speaker 1: way too dim, or would it, or maybe maybe just
• 42:18
  Speaker 1: need better instruments. I mean, you're not saying it's impossible,
• 42:21
  Speaker 1: or you're saying it's impossible, or that it's really hard.
• 42:23
  Speaker 1: I'm not saying it's impossible. I'm saying it's at the
• 42:25
  Speaker 1: edge of our ability currently, like we can barely pick
• 42:29
  Speaker 1: up super bright, very distant gamma ray bursts, or we
• 42:33
  Speaker 1: could pick up less bright closer gamma ray bursts. Right,
• 42:37
  Speaker 1: there's sort of a line there between distance and brightness.
• 42:40
  Speaker 1: But we could also improve our technology and make our
• 42:42
  Speaker 1: gamma ray detectors more sensitive. Then we could see dimmer
• 42:46
  Speaker 1: things that were further away, including gamma ray bursts or
• 42:48
  Speaker 1: alien technology. Is definitely not impossible. But I think you
• 42:52
  Speaker 1: said that gamma ray are only one of the things
• 42:54
  Speaker 1: that come out of a nuclear explosion. There's also like
• 42:56
  Speaker 1: the actual visible light flash tour, and that's like many
• 43:00
  Speaker 1: times bigger than the gamma ray burst. Do we see
• 43:02
  Speaker 1: a star war happening just on the visible spectrum? We
• 43:06
  Speaker 1: might be able to, but the universe is a little
• 43:08
  Speaker 1: bit less transparent to that kind of light. Gamma rays
• 43:11
  Speaker 1: are awesome because most of the universe is transparent to them,
• 43:15
  Speaker 1: but visible life, for example, is more likely to get
• 43:17
  Speaker 1: blocked by gas or dust or these kinds of things.
• 43:20
  Speaker 1: But it is possible, and we should look for multiple signatures. Right,
• 43:25
  Speaker 1: So we can look at the gamma rays, we can
• 43:27
  Speaker 1: look in the visible light. We certainly should keep an
• 43:29
  Speaker 1: eye on that. There are also other more subtle ways
• 43:32
  Speaker 1: that we might be able to detect nuclear weapons explosions
• 43:36
  Speaker 1: on other planets and to distinguish them from gamma ray bursts.
• 43:40
  Speaker 1: The point you were making earlier about telling the difference
• 43:43
  Speaker 1: between nuclear weapons and gamma rays. All right, let's get
• 43:46
  Speaker 1: into those other ways we could detect an alien nuclear
• 43:49
  Speaker 1: war and whether or not it might ever happen. But
• 43:52
  Speaker 1: first let's take another quick break. All right, So what
• 44:08
  Speaker 1: do you think is the scenaro here where aliens have
• 44:10
  Speaker 1: a nuclear war? Do you think they just disagree about something?
• 44:15
  Speaker 1: Do you think it's inevitable for all civilizations to eventually
• 44:18
  Speaker 1: snuff themselves out? I don't know. I've heard this theory,
• 44:21
  Speaker 1: you know, the great filter that the reason we haven't
• 44:24
  Speaker 1: seen aliens or been visited by their probes is that
• 44:28
  Speaker 1: technological civilizations don't tend to last very long because they
• 44:31
  Speaker 1: tend to destroy themselves through climate change or annihilation or
• 44:35
  Speaker 1: war or whatever. And that's possible, I suppose, but it
• 44:38
  Speaker 1: seems to me like a huge amount of projection. It's
• 44:41
  Speaker 1: imagining that aliens are a lot like humans, and their
• 44:44
  Speaker 1: psychology and their struggles and their sociology is a lot
• 44:47
  Speaker 1: like ours. And that's possible, But it also seems to
• 44:50
  Speaker 1: me to be possible for it to be completely different,
• 44:52
  Speaker 1: for their politics to be totally different, and they never
• 44:54
  Speaker 1: even invent nuclear weapons. So I think it's too big
• 44:58
  Speaker 1: a question without really data to speculate on. Yeah, it's
• 45:01
  Speaker 1: a big unknown, but I think it has maybe kind
• 45:03
  Speaker 1: of the basis and the idea that, you know, anything
• 45:05
  Speaker 1: that evolves evolution works by competition, right, and so basically
• 45:10
  Speaker 1: any intelligent society will most likely it kind of come
• 45:14
  Speaker 1: up like we did, being having this kind of balanced,
• 45:17
  Speaker 1: this idea of competition and killing each other but also
• 45:21
  Speaker 1: being nice to each other. Yeah. We had an astrozoologist
• 45:24
  Speaker 1: on the podcast recently who made that point. He said,
• 45:26
  Speaker 1: predation is inevitable in evolution. You will eventually have one
• 45:30
  Speaker 1: guy that wants to eat the neighboring guy. And that's
• 45:33
  Speaker 1: probably true, but it doesn't mean that it doesn't mean
• 45:36
  Speaker 1: you can't like progress past your evolutionary impulses. Right. Our
• 45:39
  Speaker 1: behavior now is quite different from the behavior in which
• 45:42
  Speaker 1: we evolve, much more complex cooperative society. So I don't
• 45:46
  Speaker 1: know that it's inevitable that you're dominated by that competitive nature,
• 45:50
  Speaker 1: but hey, let's find out hopefully, listen, let's not find
• 45:53
  Speaker 1: out the negative outcome the hard way. So you're saying
• 45:57
  Speaker 1: before that for us to see alien nuclear explosions in
• 46:00
  Speaker 1: other planets, I mean they would have to basically detonate
• 46:04
  Speaker 1: twenty five orders of Maude, many more bombs that all
• 46:07
  Speaker 1: of humanity has for us to even have a chance
• 46:10
  Speaker 1: to see it. Yes, for us to detect these bright flashes,
• 46:12
  Speaker 1: they would have to have a much more substantial arsenal
• 46:15
  Speaker 1: than we have twenty five orders of magnitude more right,
• 46:18
  Speaker 1: like bombs that could destroy you. I don't even know
• 46:22
  Speaker 1: the number for that, but twenty five orders of magnitude
• 46:24
  Speaker 1: many more planets. Yeah, sorry, I don't know if I
• 46:27
  Speaker 1: said twenty five times right, it's ten to the twenty
• 46:29
  Speaker 1: five times, So it's one with a lot of zeros
• 46:32
  Speaker 1: in front of it. Absolutely, But if they do have
• 46:34
  Speaker 1: a canterclismic nuclear war, there will also be other impacts
• 46:38
  Speaker 1: on their planet that we might be able to detect
• 46:41
  Speaker 1: even if we don't spot the gamma ray burst. And
• 46:43
  Speaker 1: these are the kind of things we might be able
• 46:45
  Speaker 1: to spot from planets in other solar systems. And number
• 46:48
  Speaker 1: one on that list is changes in their atmosphere. You mean,
• 46:53
  Speaker 1: like maybe we don't detect the explosion itself, that of
• 46:56
  Speaker 1: the nuclear war. But we can detect their nuclear winter exactly,
• 47:00
  Speaker 1: their nuclear winter. If you do have this kind of
• 47:03
  Speaker 1: event where you blow up a lot of nuclear bombs
• 47:05
  Speaker 1: in your atmosphere, it would really change your atmosphere. Number One,
• 47:09
  Speaker 1: it would very briefly make your atmosphere glow. Right, you're
• 47:13
  Speaker 1: dumping a huge amount of energy into your atmosphere. It
• 47:16
  Speaker 1: would ionize a bunch of the gases from the radiation
• 47:19
  Speaker 1: produced by a lot of the byproducts, and so the
• 47:22
  Speaker 1: atmosphere itself would glow sort of like the Northern lights.
• 47:25
  Speaker 1: Ionized air tends to emit this kind of glow. We've
• 47:28
  Speaker 1: seen it on Earth, we've seen it on Venus, we've
• 47:30
  Speaker 1: seen it on Mars. And so if you have a
• 47:32
  Speaker 1: lot of nuclear bombs, then their atmosphere would have this
• 47:36
  Speaker 1: air glow and we might be able to spot that.
• 47:38
  Speaker 1: Wait wait, wait, we could see their atmosphere glow like
• 47:41
  Speaker 1: how like with telescopes. Yeah, telescopes pointed at these planets
• 47:44
  Speaker 1: might be able to gather some information about the light
• 47:47
  Speaker 1: that's coming directly from the planet. Right, we now have
• 47:50
  Speaker 1: direct imaging of exoplanets. And if you see, for example,
• 47:55
  Speaker 1: a spike in the oxygen line, that increases the oxygen
• 47:59
  Speaker 1: rapidly by a factor of ten than our telescopes could
• 48:02
  Speaker 1: spot that. But wait, if we can see their amosphere glow,
• 48:05
  Speaker 1: surely we would see their explosions themselves, right, Like explosions
• 48:09
  Speaker 1: would be pretty flashy, right, he said, forty percent of
• 48:12
  Speaker 1: a nuclear explosions energy goes into visible light. I mean,
• 48:16
  Speaker 1: if we can see their atmospherre glow, surely we would
• 48:18
  Speaker 1: see their like a big flash before the explosion or
• 48:21
  Speaker 1: during the explosion. The explosion itself might not be bright
• 48:24
  Speaker 1: enough for us to see. It'll also be really short lived.
• 48:27
  Speaker 1: What we're talking about here is seeing a change in
• 48:29
  Speaker 1: the atmosphere chemistry, which we usually detect from how the
• 48:33
  Speaker 1: light from the planet's star passes through its atmosphere or
• 48:37
  Speaker 1: reflex off its atmosphere. So the light we get from
• 48:39
  Speaker 1: these planets is not from any source on the planet itself,
• 48:42
  Speaker 1: but from the star, which is why it's visible at all.
• 48:45
  Speaker 1: The air glow might last longer than the flash, and
• 48:48
  Speaker 1: so it might be easier to spot. But what we're
• 48:50
  Speaker 1: doing is thinking about, like what are the multiple signatures,
• 48:54
  Speaker 1: Because in the end, the story is going to be
• 48:56
  Speaker 1: that you probably can't conclude that you've seen an alien
• 49:00
  Speaker 1: an explosion based on only one of these signatures, because
• 49:02
  Speaker 1: there are other ways to mimic any one of them.
• 49:05
  Speaker 1: So to conclude you've seen alien signatures, what you're going
• 49:08
  Speaker 1: to want is multiple pieces of evidence. I see, like
• 49:12
  Speaker 1: the afterglow will last longer, so there's more likelihood that
• 49:15
  Speaker 1: will see it. But also it's sort of like more
• 49:17
  Speaker 1: of a telltale sign. If planet is glowing more than
• 49:21
  Speaker 1: it should, then you can maybe infer that there was
• 49:23
  Speaker 1: an explosion there exactly, like maybe you see a gamma
• 49:25
  Speaker 1: ray burst and you see a bright flash of light
• 49:28
  Speaker 1: from the visible light emission and you're wondering, like, well,
• 49:30
  Speaker 1: was that some sort of star collapsing or was it
• 49:33
  Speaker 1: an alien nuclear bomb? Then you can look for the
• 49:35
  Speaker 1: air glow. There are other effects in the atmosphere as well,
• 49:38
  Speaker 1: like these blasts tend to produce a lot of nitrogen
• 49:41
  Speaker 1: oxides which react with and deplete ozone, And so if
• 49:45
  Speaker 1: you're watching the atmosphere of this planet, then you're looking
• 49:48
  Speaker 1: in the UV light, you can detect changes in the
• 49:50
  Speaker 1: ozone layer. So a lot of these other signals require
• 49:53
  Speaker 1: you to be looking at one of these planets already
• 49:56
  Speaker 1: in studying its atmosphere and seeing change in its atmosphere,
• 50:01
  Speaker 1: so it increases an ionization of the gases that lead
• 50:03
  Speaker 1: to air glow or decrease in the ozone layer by
• 50:07
  Speaker 1: interaction from some of the byproducts of the blast. Or
• 50:10
  Speaker 1: if you just like see the atmosphere become opaque, Right,
• 50:14
  Speaker 1: you have a bunch of nuclear bombs go off, it's
• 50:15
  Speaker 1: going to throw up a huge amount of either vapor
• 50:18
  Speaker 1: or dust or something to make the atmosphere more opaque,
• 50:22
  Speaker 1: and that could last for years. Right, We're talking about
• 50:24
  Speaker 1: a nuclear winter. And so if you see an atmosphere
• 50:27
  Speaker 1: becomes suddenly more opaque than it was before, that tells
• 50:30
  Speaker 1: you something big happened in that atmosphere, Like if there's
• 50:34
  Speaker 1: more dust in the atmosphere, Although that could also be
• 50:36
  Speaker 1: an asteroid, right, Like if an asteroid hits planet, it
• 50:40
  Speaker 1: would also cause a big flash of light and also
• 50:43
  Speaker 1: a lot put a lot of stuff in the atmosphere, right,
• 50:46
  Speaker 1: Or would it look differently? Is it's not radioactive? Yeah,
• 50:48
  Speaker 1: an asteroid wouldn't look exactly the same as a nuclear
• 50:52
  Speaker 1: bomb because it wouldn't deplete the ozone in the same way.
• 50:54
  Speaker 1: It might not cause the same amount of air glow
• 50:56
  Speaker 1: because it wouldn't have the same sort of radioactive byproducts,
• 50:59
  Speaker 1: but a lot of the signatures would be the same.
• 51:01
  Speaker 1: It would throw up a lot of dust in the atmosphere,
• 51:03
  Speaker 1: probably make the atmosphere opaque for years as well, but
• 51:06
  Speaker 1: you probably wouldn't also get the gamma ray burst. So
• 51:09
  Speaker 1: there's lots of things out there in the universe that
• 51:11
  Speaker 1: could make signatures similar to alien nuclear total annihilation, global
• 51:16
  Speaker 1: thermonuclear war, but not all of them. So if you
• 51:19
  Speaker 1: happen to see like several of these signatures all together
• 51:23
  Speaker 1: from an exoplanet, then you could probably conclude that there
• 51:26
  Speaker 1: were aliens and they had just had a very very
• 51:28
  Speaker 1: bad day. Or maybe they were celebrating something, you know,
• 51:33
  Speaker 1: it's just how they do fireworks in that ailing culture.
• 51:36
  Speaker 1: Maybe they detected us and they were celebrating because they
• 51:39
  Speaker 1: were going to get to eat a good mule latter.
• 51:42
  Speaker 1: Or maybe they try to have some fireworks and they
• 51:44
  Speaker 1: accidentally shot the fireworks right at their nuclear arsenal and
• 51:47
  Speaker 1: set it off. I think I've seen that on TikTok.
• 51:50
  Speaker 1: All right, well, I kind of feel like we have
• 51:52
  Speaker 1: to be looking for these things though, right, like gamma rays,
• 51:55
  Speaker 1: it's not like we have a camera looking out the
• 51:57
  Speaker 1: whole universe looking for gamma ray. Gamma detectors here on
• 52:01
  Speaker 1: Earth are very specific. Likely we have to point them
• 52:03
  Speaker 1: at specific stars and stuff, right, So it seems kind
• 52:06
  Speaker 1: of unlikely that will just happen to catch another civilization
• 52:10
  Speaker 1: having their nuclear war just as we're pointing our telescope
• 52:14
  Speaker 1: at them. I yeah, exactly. I think some people were
• 52:16
  Speaker 1: hoping that this would be a very easy way, a
• 52:18
  Speaker 1: very obvious way to identify alien civilizations. But unfortunately they're
• 52:23
  Speaker 1: not as bright as you might imagine, and the universe
• 52:26
  Speaker 1: is very very large, and there are other ways to
• 52:28
  Speaker 1: create a lot of these signals, and so you have
• 52:30
  Speaker 1: to be very lucky. You'd have to be looking at
• 52:31
  Speaker 1: a planet basically when this happens, and have been looking
• 52:35
  Speaker 1: at it beforehand so you could see the changes. And
• 52:38
  Speaker 1: this is one of the big problems in detecting alien
• 52:40
  Speaker 1: civilizations is just the deep length of time. Right, Maybe
• 52:44
  Speaker 1: alien civilizations have existed and they've all killed each other
• 52:47
  Speaker 1: and those signals came to Earth, but like a few
• 52:49
  Speaker 1: hundred years ago and we missed it, right. Jill Tarter
• 52:53
  Speaker 1: is famous for saying that we've been watching for aliens
• 52:56
  Speaker 1: for a cosmically insignificant amount of time, and adding looking
• 53:00
  Speaker 1: for nuclear explosions is a good way to increase our
• 53:03
  Speaker 1: ability to see them, But it doesn't change this problem
• 53:07
  Speaker 1: that we've only been looking very very briefly, and aliens
• 53:10
  Speaker 1: could have existed and lived for millions of years and
• 53:13
  Speaker 1: died off recently and we still wouldn't have seen it. Yeah,
• 53:16
  Speaker 1: I see what you're saying. You're saying like, maybe these
• 53:17
  Speaker 1: star wars happened a long long time ago and the
• 53:20
  Speaker 1: galaxy far far away. Is that kind of what the
• 53:23
  Speaker 1: conclusion of scientists is, Yes, exactly, that's entirely possible. Which
• 53:28
  Speaker 1: I feel like I've seen that in a movie already.
• 53:31
  Speaker 1: Did somebody have that idea already? Dang it, man, every
• 53:33
  Speaker 1: time I have a good idea, it's still your Nobel
• 53:36
  Speaker 1: Prize again and my ten billion dollars in box office receipts.
• 53:41
  Speaker 1: All right, Well, I think it's still kind of interesting
• 53:43
  Speaker 1: to think about, right, It's still worth thinking about because
• 53:46
  Speaker 1: we do happen to see the city signals, right then
• 53:49
  Speaker 1: we would know a lot about not only the idea
• 53:52
  Speaker 1: that we're out there alone or not, but also like
• 53:55
  Speaker 1: what these other aliens are capable of. Yeah, and these
• 53:58
  Speaker 1: aliens could have court developed technologies that are far beyond
• 54:01
  Speaker 1: what we have and create flashes of light much much
• 54:04
  Speaker 1: brighter than the kinds of things we're imagining, and we
• 54:07
  Speaker 1: should keep our eyes open for that. I think the
• 54:09
  Speaker 1: spirit of this is just to try to be inclusive
• 54:11
  Speaker 1: about the kind of things we're looking for, to increase
• 54:13
  Speaker 1: our chances of seeing anything at all. Yeah, or I think,
• 54:17
  Speaker 1: as we talked about in other episodes, like you might
• 54:19
  Speaker 1: be limited in your imagination, right, Like maybe if you
• 54:22
  Speaker 1: imagine giant space civilizations and have bombs that are twenty
• 54:26
  Speaker 1: five orders of mine need to bigger than our bombs,
• 54:30
  Speaker 1: then we would be able to see that kind of spectacle. Yeah,
• 54:33
  Speaker 1: we talked about the Kardaship scale of civilizations. Some aliens
• 54:36
  Speaker 1: might have tapped into all of the energy output of
• 54:39
  Speaker 1: their sun and built a huge laser capable of vaporizing planets.
• 54:44
  Speaker 1: You know, I think I've seen that in the movie also,
• 54:46
  Speaker 1: but it could be real, and if they shoot that
• 54:48
  Speaker 1: laser in our direction, we might be able to see it.
• 54:51
  Speaker 1: That is exactly the plot of these Star Wars trilogies.
• 54:55
  Speaker 1: They literally suck a son into their gun and then
• 54:58
  Speaker 1: shoot it at other planets. Not something we're recommending, but
• 55:01
  Speaker 1: if it happens, we might be able to see it. Yeah,
• 55:03
  Speaker 1: and you'll be there with your popcorn, gleefully looking at
• 55:06
  Speaker 1: the extinction of thousands or billions of alien lives as
• 55:10
  Speaker 1: they melt my eyeballs. All right, well, we hope they
• 55:13
  Speaker 1: give you something to think about, and maybe think about
• 55:16
  Speaker 1: the trajectory of our own civilization, Like do we want
• 55:20
  Speaker 1: to be known to other alien species by our last moments?
• 55:24
  Speaker 1: Or should we be working harder to work things out
• 55:27
  Speaker 1: between us so that they see us for other reasons.
• 55:30
  Speaker 1: Or maybe we should take all of our nuclear bombs
• 55:32
  Speaker 1: and launch them into space and blow them up out
• 55:34
  Speaker 1: there so aliens know we're here. You mean, like a
• 55:36
  Speaker 1: dinner bell, Like ring a different dinner bell. No, like
• 55:41
  Speaker 1: an invitation to a party, right, a dinner party? Sounds
• 55:45
  Speaker 1: like maybe we should put that up for a vote
• 55:47
  Speaker 1: before we do that. All right, Well, we hope you
• 55:50
  Speaker 1: enjoyed that. Thanks for joining us, See you next time.
• 56:00
  Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain
• 56:03
  Speaker 1: the Universe is a production of iHeartRadio. For more podcasts
• 56:07
  Speaker 1: from iHeartRadio, visit the iHeartRadio, app, Apple podcasts, or wherever
• 56:12
  Speaker 1: you listen to your favorite shows.