Speaker 1: Hey, please take a second and leave us a review
Speaker 1: on Apple Podcasts, Spotify, or wherever you listen to the podcast.
Speaker 2: Thanks a lot.
Speaker 1: Hey, Welcome to Science Stuff, a production of iHeartRadio. I'm
Speaker 1: Horehea Champ and today we are looking for aliens. There
Speaker 1: are trillions upon trillions of stars out there with planets
Speaker 1: that are not too different from the one we're living on,
Speaker 1: which means it's very likely that there's other life out
Speaker 1: there in the universe, and that begs the question where
Speaker 1: are they? Why haven't we seen them, heard from them,
Speaker 1: or why haven't they come here. We're going to talk
Speaker 1: to three scientists who've worked on the search for alien
Speaker 1: life and we're going to hear whether they think it's
Speaker 1: likely we'll ever find it. So get ready to leave
Speaker 1: Earth as we cast our eyes and ears to the
Speaker 1: cosmos to answer the question where are all the aliens?
Speaker 3: Hey?
Speaker 1: Everyone, all right, I'm just gonna come out and say it.
Speaker 1: I think there are aliens out there. Now, before you
Speaker 1: think I'm some crazy conspiracy theorists, hear me out. There
Speaker 1: are one hundred billion stars in our galaxy and at
Speaker 1: least that many galaxies in the observable universe. Scientists estimate
Speaker 1: that about one in ten stars has a planet that's
Speaker 1: like Earth, rocky and toasty enough to support life as
Speaker 1: we know it. This means there are at least one
Speaker 1: six tillion or one, followed by twenty one zeros Earth
Speaker 1: like planets out there. Plus the universe is fourteen billion
Speaker 1: years old, which is a long time for lots of
Speaker 1: things to have happened. Now, if you look at life
Speaker 1: around this here on Earth, it does seem pretty special.
Speaker 1: But is it one in one sixty million. That's one
Speaker 1: followed by twenty one zeros times fourteen billion years special.
Speaker 1: I'm willing to bet that it's not, But of course
Speaker 1: we don't know yet. That is the topic of today's episode.
Speaker 1: Why don't we know? And what are we doing to
Speaker 1: find out? Now? The search for life outside of our
Speaker 1: planet can be basically split into two. One is the
Speaker 1: search for basic life, meaning are there bacteria like life
Speaker 1: forms and the moons of Jupiter or simple organisms in
Speaker 1: the atmosphere of distant planets? And two is the search
Speaker 1: for intelligent life. Are there little green beings in flying
Speaker 1: saucers or vast civilizations with advanced technology? So in today's
Speaker 1: episode we'll tackle these one at a time. First we'll
Speaker 1: talk about the search for basic life, and then we'll
Speaker 1: cover the search for intelligent life, and then at the
Speaker 1: end we'll talk to an anthropologist who specializes in how
Speaker 1: people would react if we ever did find extraterrestrial life.
Speaker 1: Would we phone home, live long and prosper or fight
Speaker 1: and not go quietly into the night? And bonus points
Speaker 1: if you get all three of those movie references. All right,
Speaker 1: let's start with the search for basic life. To guide
Speaker 1: us through this, here's my chat with Professor Chris Impi. Well,
Speaker 1: thank you, doctor imp for joining us.
Speaker 2: Yes, it's good to be with you. My name is
Speaker 2: Chris Impi. I'm a professor of astronomy at the University
Speaker 2: of Arizona.
Speaker 1: I thought maybe you could start by telling us what
Speaker 1: are some of the different ways that us humans are
Speaker 1: trying to find life outside of our planet.
Speaker 2: Sure, well, you let off with where are all the aliens?
Speaker 2: So we can maybe move back to that. But that's
Speaker 2: her reprise is a question that Enrico Fermi asked well
Speaker 2: way back in nineteen fifty, where he was saying where
Speaker 2: are they? Where are all the aliens? So I think,
Speaker 2: in practical terms, mostly we're going to be talking about
Speaker 2: looking for microbial life or basic forms of life. So
Speaker 2: there are a set of strategies and they're coming to
Speaker 2: fruition now because we didn't know who were Earth like
Speaker 2: planets or habitable planets elsewhere, and now we know all
Speaker 2: of that, so it's like game on for finding life.
Speaker 1: Okay. The first thing doctor Impy wanted to caution us
Speaker 1: on the search for basic or simple life forms is
Speaker 1: that life is neither basic nor simple.
Speaker 2: If you want a biologist to wrap you on the knuckles,
Speaker 2: just say microbes are temple. So there are the people
Speaker 2: who try and create life in the lab, you know,
Speaker 2: start to generate life from simple chemical ingredients and see
Speaker 2: if they can simulate what they think happened on the
Speaker 2: Earth four billion years ago. They haven't succeeded yet. It's
Speaker 2: a very difficult lab experiment. They point to some very
Speaker 2: difficult steps that have to be followed to go from
Speaker 2: these very simple molecules of ten or twenty atoms to
Speaker 2: the first replicating molecule to the first simple cell. And
Speaker 2: cells are not simple.
Speaker 1: Doctor imp explains. There are two general places where we
Speaker 1: are looking for signs of basic life in our own
Speaker 1: backyard here in our Solar System and also outside our
Speaker 1: Solar system and planets around other stars. Now in our
Speaker 1: Solar system, there aren't that many places besides Earth that
Speaker 1: we can imagine there being life, at least life as
Speaker 1: we think is possible. Mercury and Venus are too hot,
Speaker 1: and all the planets Saturn and beyond are cold gas planets.
Speaker 1: So the main place we've been looking is Mars.
Speaker 2: So the first place to look for life is on
Speaker 2: an in near's location that you can study in detail,
Speaker 2: you know, place we've actually sent robotic probes Mars, and
Speaker 2: so Mars is still at the epicenter of very active
Speaker 2: searches for biology. So the first Mars life experiments with
Speaker 2: the Twin Viking experiments in nineteen seventies.
Speaker 1: So they sent some not robots but sort of like
Speaker 1: little base stations to Mars.
Speaker 2: Right, Yeah, and there are remarkable missions based on nineteen
Speaker 2: sixties technology. There are far ahead of their time because
Speaker 2: they actually did do life detection at two different locations
Speaker 2: on the surface. It's remarkable stuff. Yeah, think of how
Speaker 2: primitive computing was in the mid nineteen seventies. So there
Speaker 2: were landers, so they were stationary, but they had little
Speaker 2: diggers and so they scooted soil into containers and they
Speaker 2: could add water to see if something happened, to see
Speaker 2: if they could grow something or culture something, and they
Speaker 2: did mostly return negative results.
Speaker 1: So we've been looking for life on Mars since the
Speaker 1: nineteen seventies. Then we started sending rovers.
Speaker 2: And to sum up the research from the rovers of
Speaker 2: the last thirty years, they were essentially looking for potential.
Speaker 2: They were looking for organic material, They were looking for
Speaker 2: possible evidence of life in the geochemistry of rocks without
Speaker 2: actually looking for biology itself. So that was the limitation
Speaker 2: and still is the limitation.
Speaker 1: Over the last fifty years, we've been looking for the
Speaker 1: science of life on Mars because scientists are pretty sure
Speaker 1: Mars was once a lot like Earth. There were oceans
Speaker 1: and rivers and in the atmosphere, but then it all
Speaker 1: dried up and went away. Although that doesn't mean there
Speaker 1: isn't still liquid water on Mars.
Speaker 2: There's really good indirect evidence for subsurface liquid water aquifers.
Speaker 2: It comes from a variety of sources, from radar, from
Speaker 2: various things, people who've even seen little eruptions of sulf
Speaker 2: surface water rolling down gullies. So you can absolutely have
Speaker 2: liquid water under the surface, maybe ten fifty one hundred
Speaker 2: meters kilometer down. But that opens the prospect that there
Speaker 2: is life on Mars right now, not just fossilized life.
Speaker 1: Or who knows, maybe a little Martian fish possibly.
Speaker 2: Maybe slightly bigger than microbes. Yeah, if I mean, if
Speaker 2: there are subsurface pockets of ocean or sea, they could
Speaker 2: set up an ecosystem that might be more interesting than
Speaker 2: just microbes.
Speaker 1: Yeah, possibly in seeing people speculate, all right. The other
Speaker 1: places we can look for life in our Solar system
Speaker 1: are the moons of Jupiter and Saturn.
Speaker 2: Ask how many places could there be the ingredients for life,
Speaker 2: critically including liquid water in the Solar System. The answer
Speaker 2: is probably a dozen a dozen, and all the rest
Speaker 2: are giant planets moons, which are substantial worlds in their
Speaker 2: own right. The biggest moons of the giant planets are
Speaker 2: bigger than the Moon itself and almost like mercury size.
Speaker 2: They can keep liquid water under a rocky crust.
Speaker 1: What doctor MP's saying here is that in several of
Speaker 1: the moons of Jupiter and Saturn, like Europa and Enceladus,
Speaker 1: scientists believe there are huge underwater oceans that could have
Speaker 1: life in them.
Speaker 2: So Europa is a water world. It's entirely encased in
Speaker 2: ice of probably five to ten kilometers thickness, and that
Speaker 2: overlays an ocean that could be fifty to one hundred
Speaker 2: kilometers deep. It's really substantial ocean, far more water than
Speaker 2: the Earth's oceans. So people think of Earth as the
Speaker 2: water world. That's not true. There's a couple of places
Speaker 2: in the Solar System with more water than the Earth.
Speaker 2: We're sending the Europea clipper there right now. That was
Speaker 2: a successful launch just last year. It's going to make
Speaker 2: very clever orbital measurements to look for traces of life
Speaker 2: with spectroscopy and so on. It may even splash off
Speaker 2: some icy material by sending a projectile under the surface
Speaker 2: and then sniff the particles that come out.
Speaker 1: Wow.
Speaker 2: So it's not a true life detection experiment, but it's
Speaker 2: going to learn a lot more about Europa than we
Speaker 2: ever knew before. We also have Enceladus, which is a
Speaker 2: tiny moon of Saturn where the icy geysers were found
Speaker 2: ten or fifteen years ago, and those icy jets going
Speaker 2: into space also indicate there was liquid water and sell
Speaker 2: this it's irregular, it's a potato shaped, it's not even
Speaker 2: a round object could have the ingredients for life. And
Speaker 2: then the third most compelling place is Titan, so that's
Speaker 2: the biggest moon of Saturn. Titan is fascinating because it's
Speaker 2: a big moon. It has an atmosphere as thick as
Speaker 2: the Earth's, and it's made of the same stuff nitrogen,
Speaker 2: no oxygen, but nitrogen. It has weather, It has bodies
Speaker 2: of liquid and lakes and river deltas and clouds and precipitation.
Speaker 2: It has volcanism, but it's an alien world because it's
Speaker 2: very cold, and so that liquid is not water. It's
Speaker 2: ethane and methane. So the lakes on Titan are rather
Speaker 2: strange organic brood that's not mostly water. And if you
Speaker 2: ask a biologist, should you have biology in a medium
Speaker 2: that's ethane and methane as opposed to water, they scratch
Speaker 2: their heads and say, maybe you just get fanciful with
Speaker 2: hypothetical biology. Yes, you could maybe form complex molecules in
Speaker 2: that kind of a liquid medium.
Speaker 1: So to summarize, there are lots of places right here
Speaker 1: in our solar system where there could be alien life.
Speaker 1: But the problem, according to doctor imp is there's no
Speaker 1: funding to go look Sending probes or drones to landlin
Speaker 1: titen or drill under the ice or ground in Europe
Speaker 1: or Mars is expensive, and things at NASA are not
Speaker 1: looking so good right now for science funding.
Speaker 2: So the bottom line on the Solar System is, yes,
Speaker 2: there could be life elsewhere in the Solar System, but
Speaker 2: the experiments are very difficult, the timelines are long, they're
Speaker 2: expensive experiments, and some most astronomers saying the first detection
Speaker 2: of life on Earth will come by looking at excelp.
Speaker 1: Planets, planets that are in other stars, not the Sun.
Speaker 2: Right, planets orbiting other stars, of which we found thousands now,
Speaker 2: including hundreds that are roughly Earth like.
Speaker 1: Well, but if they're so far away, how can we
Speaker 1: tell if they have life.
Speaker 2: Well, the life detection experiment is just the cutting, the
Speaker 2: very cutting, bleeding edge.
Speaker 1: All right. When we come back, we'll talk about how
Speaker 1: to look for alien life in distant planets. We'll talk
Speaker 1: to another astronomer who specializes looking for intelligent alien life
Speaker 1: out there. Don't go anywhere, we'll be right back, welcome back.
Speaker 1: All right. We're talking about the search for alien life,
Speaker 1: and we're going to get to the search for intelligent
Speaker 1: alien life but first we're going to hear from Professor
Speaker 1: Chris Impi about how we're looking for the signs of
Speaker 1: basic life and planets far away outside of our Solar system. Okay,
Speaker 1: you were saying that we can use James Webb and
Speaker 1: some ground based telescopes to possibly detect life in other planets.
Speaker 2: Right, We're not taking pictures and seeing things swimming around
Speaker 2: in a in an exo ocean, or watching you know,
Speaker 2: exo dinosaurs lumbering about on a continent on a planet
Speaker 2: one hundred light years away. None of that wonderful thing.
Speaker 2: It's going to happen. It would be great, but it's
Speaker 2: some science fiction forever. So this is what you do.
Speaker 2: The idea is it's sort of based on the Earth
Speaker 2: because the air we breathe, one part in five is oxygen,
Speaker 2: and that oxygen was put there by microbes mostly billions
Speaker 2: of years ago, and that oxygen is the telltale as
Speaker 2: for someone looking at the Earth from far away, that
Speaker 2: the Earth is a living planet, even if they couldn't
Speaker 2: see anything else.
Speaker 1: What doctor MP is saying here is that planets outside
Speaker 1: our Solar System are too far away for us to
Speaker 1: really take a picture of them. The closest planet to
Speaker 1: us out there is orbiting a star called Proxima Centauri,
Speaker 1: four point twenty five light years or twenty five trillion
Speaker 1: miles away. Not even our best telescopes can get a
Speaker 1: clear enough view of them to tell if they have
Speaker 1: life on them. So the main way we're looking for
Speaker 1: basic life in other planets is by studying their atmosphere.
Speaker 1: That we can do by looking at the light they reflect.
Speaker 1: And once your sign of life is having a lot
Speaker 1: of oxygen.
Speaker 2: Imagine the biosphere the whole life on our shuts down overnight,
Speaker 2: within a few million years, the oxygen will be gone.
Speaker 2: It would bind with rock, it would rust things, it
Speaker 2: would dissolve in the oceans, and it would disappear because
Speaker 2: it's sustained by life. So the reverse logic is that
Speaker 2: if you see oxygen in the planet, that's a good
Speaker 2: sign that there's biology on that planet. So oxygen in
Speaker 2: that way is what's called a biomarker or biosignature by astrobiologists.
Speaker 2: So methane is a biomarker too.
Speaker 1: The study of potential life in other planets is called astrobiology.
Speaker 1: Now we have been able to see faint signs of
Speaker 1: the atmosphere and far away planets. But it's such a
Speaker 1: hard problem. We haven't been able to do it in
Speaker 1: the right kind of planet.
Speaker 2: They've proved that you can sniff the atmosphere of an
Speaker 2: exoplanet and say what's in it, but they've been done
Speaker 2: for more massive planets, more like neptunes and urinous type
Speaker 2: planets gas giants, not growth like terrestrial planets. So it's
Speaker 2: just just too hard. And then the question is how
Speaker 2: can we do better? And then we have to wait
Speaker 2: for this next generation of three large telescopes all under construction.
Speaker 1: So that's where we are in the search for basic
Speaker 1: life out there in our Solar system. We need to
Speaker 1: fund better, more complicated missions to go out there and
Speaker 1: bring back samples from Mars or the Moon's Europa or
Speaker 1: Titan and beyond our Solar system. We need better telescopes
Speaker 1: just to get a whiff of the science of life
Speaker 1: in the atmosphere of distant planets. And that brings us
Speaker 1: to the search for intelligent life out there, and for
Speaker 1: that we might not need such fancy equipment because we
Speaker 1: might not need to go looking for it. It might
Speaker 1: come to us to guide us through this possibility. I
Speaker 1: reached out to Professor Jason Wright.
Speaker 3: I am Jason Right, a professor of astronomy and astrophysics
Speaker 3: at Penn State, and I'm also the director of the
Speaker 3: Penn State Extraterrestrial Intelligence Center, where we look at all
Speaker 3: aspects of the search for intelligent life in the universe.
Speaker 1: Amazing and just adult check. You're not an alien yourself?
Speaker 1: Are you not?
Speaker 3: As far as I know, Yes, yes, I'm not.
Speaker 1: I mean, oh, that would be a good plot to
Speaker 1: this if the director of the search for intelligence turned
Speaker 1: out to be an alien but he didn't know didn't
Speaker 1: know it?
Speaker 3: Right, Yeah, all right.
Speaker 1: The first thing that they're right. I wanted to clarify
Speaker 1: for us is that looking for intelligence out there in
Speaker 1: the universe is kind of the wrong way to go
Speaker 1: about it.
Speaker 3: So we use the word intelligence a little loosely. We
Speaker 3: don't mean it in a literal sense of intelligence. What
Speaker 3: we're looking for is technology because we imagine that it
Speaker 3: might be much easier to find signs of technology across
Speaker 3: the stars than signs of life.
Speaker 1: Now, why do you draw this distinction between intelligence and technology?
Speaker 1: Isn't it sort of the same? Like put in one
Speaker 1: imply the other.
Speaker 3: We try to be really careful with that word intelligence.
Speaker 3: The word intelligence gets used in a lot of ways, like,
Speaker 3: you know, if you're looking at a culture that never
Speaker 3: developed radio transmitters, are they not intelligent? You know, we
Speaker 3: don't want to equate certain kinds of technology with a
Speaker 3: much broader and squisher concept of intelligencing.
Speaker 1: What doctor Wright is saying is that what you're doing
Speaker 1: when you say you're looking for aliens, is you're really
Speaker 1: looking for signs of technology, because there could be perfectly
Speaker 1: intelligent aliens out there, but we may never see them
Speaker 1: if they don't use technology that tells us they're there.
Speaker 1: For example, Earth had intelligent life on it for thousands
Speaker 1: of years before we even invented the light bulb. Or
Speaker 1: think about whales or dolphins. They're intelligent, but an alien
Speaker 1: species far away looking at Earth might never know they're
Speaker 1: even here.
Speaker 3: In fact, there have been many proposed alternative names for
Speaker 3: this field. Freeman Dyson said it should be called the
Speaker 3: Search for Extraterrestrial Technology, which would be set tea and
Speaker 3: Jill Tarter, who looks for radio waves, said, you know,
Speaker 3: I'm not going to detect any intelligence except that that
Speaker 3: went into building a radio transmitter, which is electrical engineering.
Speaker 3: So she joked it was a search for extraterrestrial electrical engineers,
Speaker 3: which is also set easy fit. Yeah, so as long
Speaker 3: as you just say SETI, you're you're good.
Speaker 1: Okay, this is kind of a semantic argument. What you
Speaker 1: really want to know is where are the smart aliens? Well,
Speaker 1: the way that their right breaks it down is that
Speaker 1: there are really only three ways in which we'll ever
Speaker 1: have confirmation of intelligent life out there. We're not traveling
Speaker 1: to other stars anytime soon, so the only ways left
Speaker 1: are a if we see signs of their technology from here,
Speaker 1: b if they come visit us and see if they're
Speaker 1: trying to talk to us, or if we happen to
Speaker 1: catch them talking to other aliens. Now, let's be clear,
Speaker 1: none of these things have happened. We haven't noticed any
Speaker 1: alien civilizations out there. We haven't been visited by aliens
Speaker 1: as far as I know, despite what you might have heard,
Speaker 1: and we haven't received a call from an alien yet.
Speaker 3: Why is that?
Speaker 1: As I mentioned before, there are trillions of stars and
Speaker 1: plenty of time in the universe. If there are aliens
Speaker 1: out there, surely one of these things would have happened
Speaker 1: by now. And this is what's known as the Fermi paradox.
Speaker 1: So there's this idea called the Fermi paradox, and it
Speaker 1: goes like this. Enrico Fermi was a famous physicist, and
Speaker 1: in nineteen fifty, before we even started looking, they were
Speaker 1: talking about UFOs and he realized the galaxy is so
Speaker 1: old that even with just normal rockets, it would only
Speaker 1: take millions of years to get every anywhere you wanted
Speaker 1: to go in the galaxy. And since the galaxy is
Speaker 1: billions of years old, there's plenty of time for them
Speaker 1: to have gotten here by now, even without warp drive.
Speaker 1: So where is everybody? Sometimes this gets phrased as we
Speaker 1: expect them to be out there, why haven't we found
Speaker 1: them yet? That's the Fermi paradox. And I should say
Speaker 1: there have been whole papers written on why it's not
Speaker 1: really a paradox, because we haven't yet real doubt that
Speaker 1: there are no aliens. But the point is it's a
Speaker 1: big question that is puzzling. Where are all the aliens?
Speaker 1: And here doctor Wright thinks he has an answer.
Speaker 3: The whole Fermi paradox thing is badly misunderstood because it's
Speaker 3: not really a puzzle, Like, none of us doing this
Speaker 3: work are worried about it.
Speaker 1: Meaning you have an explanation for why we haven't themed
Speaker 1: or found or been visited by any aides. Yeah, okay,
Speaker 1: we're going to tackle each scenario in well we Aliens
Speaker 1: one by one, starting with why haven't any aliens come
Speaker 1: visit us? Well, let's say, and I'm asking you, why
Speaker 1: haven't we've been visited by any aliens?
Speaker 3: I would say there's a lot of reasons. So my
Speaker 3: favorite is that we're here we haven't been visited by
Speaker 3: other species, perhaps exactly because Earth has life, and so
Speaker 3: maybe they've come through the Solar system and they've seen
Speaker 3: the Earth has life, and maybe they've you know, gone, oh,
Speaker 3: that's kind of interesting. But they're just going to leave
Speaker 3: us alone and not land and invade and like try
Speaker 3: and take the place over because it's got life. That's
Speaker 3: my favorite answer.
Speaker 1: So one possibility for why aliens haven't visited us is
Speaker 1: maybe they have they just chose to leave us alone.
Speaker 1: It's sort of like if you're on a hike and
Speaker 1: you see an ant hill or you see a bear,
Speaker 1: you don't run up to the ants or the bear screaming,
Speaker 1: planting a flag where they live and try to teach
Speaker 1: them about people, you just let them be. So maybe
Speaker 1: aliens have been here, but they just moved on.
Speaker 3: Another answer is spaceflight is just really hard. It's very, very,
Speaker 3: very hard to build a machine that can last the
Speaker 3: hundreds of thousands of years or millions of years it
Speaker 3: would take to go to another star, and it's just
Speaker 3: not worth it that no species ever does it more
Speaker 3: than a couple of times tops, And so they haven't
Speaker 3: visited every single star in the galaxy because interstellar flight
Speaker 3: is just too hard and requires machines that would have
Speaker 3: to last too long.
Speaker 1: Another reason we haven't been visited by aliens is that
Speaker 1: maybe space travel is too hard. Maybe warp drives are
Speaker 1: just to fantasy, and the reality is that it takes
Speaker 1: hundreds or thousands of years to go visit other star systems,
Speaker 1: not to mention it's super expensive, so maybe going around
Speaker 1: other planets is not really worth it, or maybe even
Speaker 1: technologically possible. I mean, can you imagine making a machine
Speaker 1: that would still work after one thousand years? All Right,
Speaker 1: when we come back, we're going to hear the other
Speaker 1: possibilities for why we haven't seen any aliens, and then
Speaker 1: we're going to talk about what we're doing to find them,
Speaker 1: stay with us. We'll be right back, and we're back
Speaker 1: all right. We're asking the question where are all the aliens?
Speaker 1: And so far we've talked about looking for basic life
Speaker 1: in the universe, and now we're talking about the search
Speaker 1: for intelligent life. There are trillions of planets out there
Speaker 1: that could have intelligent life, So where is it They
Speaker 1: could have visited us? But according to astronomer and director
Speaker 1: of the Penn State Extraterrestrial Intelligence Center, Professor Jason Wright,
Speaker 1: maybe they just chose to leave us alone, or maybe
Speaker 1: we're just not worth coming all this way to meet us.
Speaker 3: Maybe it's a little romantic to imagine that they'll all
Speaker 3: leave us alone. Maybe a little two science fiction star
Speaker 3: trek prime directivity, But I don't know, seems reasonable to me.
Speaker 3: For whatever reason, they don't travel around a lot, or
Speaker 3: if they come here, they don't.
Speaker 1: Stay all right. Venix scenario for finding intelligent life out
Speaker 1: there is seeing evidence of their advanced technology from here.
Speaker 1: You could imagine seeing lights at night on an alien planet,
Speaker 1: or hearing their TV or radio chatter, or maybe seeing
Speaker 1: giant structures they build in space, like a ring world
Speaker 1: or a space elevator. But doctor Wright says, there's a
Speaker 1: simple explanation for why we haven't seen anything like that
Speaker 1: so far.
Speaker 3: We haven't seen evidence because it's very hard to find
Speaker 3: anything out there at interstellar distances. I mean, we only
Speaker 3: discovered giant planets the size of Earth thirty years ago,
Speaker 3: and at great difficulty. NASA to find more has to
Speaker 3: spend like a billion dollars on these big space observatories
Speaker 3: to find these things. They're very hard to find. To
Speaker 3: find the technology that just lives right on the surface
Speaker 3: of these planets, it's really really hard, and there's no
Speaker 3: reason to think we would have seen anything yet haven't
Speaker 3: looked enough.
Speaker 1: So the reason we haven't seen any obvious signs of
Speaker 1: alien technology out there is that, again, space is too big.
Speaker 1: The biggest image we have of other planets out there
Speaker 1: are barely a few pixels, and that's because they're so
Speaker 1: far away, and also because planets are right next to
Speaker 1: bright stars, so it's like trying to make out the
Speaker 1: picture on a coin that's right next to a lighthouse
Speaker 1: three thousand miles away. But according to doctor Wright, there
Speaker 1: are less obvious signs of alien technology we might be
Speaker 1: able to see from here.
Speaker 2: Now.
Speaker 3: There are other things that they could do. People have
Speaker 3: pointed out that, you know, we're trying to find planets
Speaker 3: and see if they might have water on their surfaces.
Speaker 3: But you know what if instead of seeing a lot
Speaker 3: of chlorophyll on the surface, we see a lot of silicon.
Speaker 3: Maybe it's covered in solar panels, right, Or maybe we're
Speaker 3: studying the atmosphere and we discover chlorofloral carbons. We do
Speaker 3: have chlorofloral carbons that are detectable in our atmosphere. So
Speaker 3: those are two techno signatures here on Earth that might
Speaker 3: be remotely detectable.
Speaker 1: So we might not be able to see alien cities
Speaker 1: because planets are too far away, but in those one
Speaker 1: or two pixel images we can get, there could be
Speaker 1: the signs of solar panels if their planet is covered
Speaker 1: in them, or there could be signs of their industrial
Speaker 1: pollution that we could tell from the light spectrum of
Speaker 1: that one or two pixels of light we do get,
Speaker 1: and our telescopes are getting better, so stay tuned for
Speaker 1: maybe finding those signals in the future. Now you might
Speaker 1: be wondering, or hey, haven't we been listening for alien
Speaker 1: radio signals for a while now? Isn't that what SETI
Speaker 1: the search for extra terrestrial intelligence is all about, well,
Speaker 1: here's the thing. There's kind of no way that we
Speaker 1: can point the radio antenna at a distant planet and
Speaker 1: potentially listen to their TV broadcasts or their radio chatter.
Speaker 1: Space is again too big, and any random signal like
Speaker 1: that gets spread out and gets too weak by the
Speaker 1: time it gets to us. Really, the only way we
Speaker 1: can here alien signals is if they're actually trying to
Speaker 1: talk to us, or at least trying to talk to
Speaker 1: someone right behind us. In that case, the scenario is
Speaker 1: that aliens know we're here, or they think we might
Speaker 1: be here, and they're pointing their antennas at us and
Speaker 1: beaming us a signal to say hi, or they might
Speaker 1: be trying to send a signal to another alien race
Speaker 1: or planet, and we just happen to be in the
Speaker 1: way of the beam of the signals. The search for
Speaker 1: signals like that have been going on for decades.
Speaker 3: There have been a few small ish searches for decades,
Speaker 3: starting in nineteen sixty. So with radio, which is the
Speaker 3: most mature search technique, we use these big radio telescopes
Speaker 3: like satellite dishes, the biggest ones you can fit a
Speaker 3: football field inside. Of and we point them at a
Speaker 3: nearby star and we just check to see if there's
Speaker 3: any radio emission coming from the star. At most frequencies,
Speaker 3: there's nothing. And if you saw that there was strong
Speaker 3: signal just at one frequency, it's gotta be aliens. It
Speaker 3: can't be anything else. And so there are billions of
Speaker 3: those channels to check.
Speaker 1: So since the nineteen sixties, scientists have been using radio
Speaker 1: antennas to look for signals that aliens might be sending
Speaker 1: our way, and they haven't found anything. But here's the
Speaker 1: thing about the search for signals from aliens. A there's
Speaker 1: a lot of sky out there to listen to, and
Speaker 1: listening with a radio telescope is like looking at the
Speaker 1: sky through a really thin straw. You can only see
Speaker 1: a tiny little patch of it one at a time.
Speaker 1: And B the US Congress really doesn't want to fund
Speaker 1: the search for alien signals. Basically, nobody wants to be
Speaker 1: seen as using taxpayer dollars to look for little green men.
Speaker 1: So scientists in this field have had to basically beg
Speaker 1: steal and borrow time on other people's radio telescopes to
Speaker 1: do their search. They might piggybag on someone's left over time,
Speaker 1: or they'll search for signals and data collected for other
Speaker 1: science projects, all of which meant that they couldn't really
Speaker 1: search very much of this guy. But recently all that
Speaker 1: has changed thanks to a couple of Silicon Valley billionaires.
Speaker 3: Now there's a project called Breakthrough Listen. Breakthrough Listen is
Speaker 3: funded by Jury and Julia Milner, who are Silicon Valley billionaires.
Speaker 3: So it's scientific philanthropy from very wealthy Silicon Valley folks. Yes,
Speaker 3: and it's working for the first time. We're searching all
Speaker 3: of the nearby stars for these kinds of radio signals,
Speaker 3: and we're searching billions of channels at once. So back
Speaker 3: in nineteen sixty they had to pick a station listen
Speaker 3: for five minutes if they were sure they hadn't recorded anything,
Speaker 3: you know, a little turn of the dial, go to
Speaker 3: the next channel, listen to that one. By the seventies
Speaker 3: they could search like twenty or one hundred of these
Speaker 3: at once, and then by the eighties they could do
Speaker 3: a million at once. Now we can search many billions
Speaker 3: of channels at once. It's not me, but the Breakthrough
Speaker 3: Listening Project has a lot of time on some of
Speaker 3: the biggest telescopes in the world. And so that's why
Speaker 3: I say in the last five years we've done more
Speaker 3: searching than we've done in the previous sixty that's amazing.
Speaker 1: And so what have they found?
Speaker 3: And so for the first time we can actually say
Speaker 3: there are not strong beacons coming from the very nearest
Speaker 3: stars at these frequencies.
Speaker 1: Yeah, they still haven't found anything, but a doctor Wright
Speaker 1: says that doesn't mean aliens don't exist or that they're
Speaker 1: not trying to talk to us. That is a common misconception.
Speaker 3: Yeah, the biggest one is we've been looking for radio
Speaker 3: waves for sixty years. Surely you know it's time to
Speaker 3: give up, or surely they're not out there, or surely
Speaker 3: we should try something else. It's true that for sixty
Speaker 3: seventy years we've been looking for radio waves, but we've
Speaker 3: barely been looking. The sky is huge, The galaxy has
Speaker 3: one hundred billion stars, and there's billions of channels to check,
Speaker 3: and we don't know when they might be transmitting it.
Speaker 3: So the fact that we've been looking so long and
Speaker 3: haven't found anything yet doesn't actually tell us if they're
Speaker 3: there or not.
Speaker 1: All Right, this has been a pretty big topic to
Speaker 1: tackle in one episode. I mean, I didn't even get
Speaker 1: to aliens shooting lasers at us to get our attention.
Speaker 1: That's another scenario scientists are seriously exploring. So if you
Speaker 1: want to hear me go a little bit deeper with
Speaker 1: an anthropologist, but what it would mean for us to
Speaker 1: find alien life, tune in on Friday when we release
Speaker 1: a bonus mini episode. We'll talk about what people think
Speaker 1: aliens might look like and whether finding out that aliens
Speaker 1: exist will make anyone freak out or live their lives
Speaker 1: any different. So come back Friday for that. But I'll
Speaker 1: end this episode with a question I asked doctor Wright,
Speaker 1: which is, if we did get a signal from aliens,
Speaker 1: what does he think it will say?
Speaker 3: If we get a signal, My guess is we'll just
Speaker 3: barely know it's there. We won't know what's in it.
Speaker 3: It's probably going to be impots possible to the code.
Speaker 3: Like we've got dolphins chattering away, and we've got these
Speaker 3: animal language experts that have been studying the chatter their
Speaker 3: whole careers, and we can't really talk to them and
Speaker 3: have a conversation for a lot of reasons.
Speaker 1: And we haven't even seen that interesting in pugging two Dolphins.
Speaker 3: Yeah, exactly.
Speaker 1: So I think that first single is going to say
Speaker 1: with this new phone.
Speaker 3: You know, it's an old idea in SETI that the
Speaker 3: first signal will get will be something we sent out.
Speaker 3: It's their way of saying hello, like they let us
Speaker 3: know that they got our radio transmissions and so they
Speaker 3: echo it back to us. But I love the idea
Speaker 3: that they're actually quite sophisticated and they'll be all into
Speaker 3: like our pop culture and needs.
Speaker 1: Interesting. But in this case it'd be like fifties or
Speaker 1: eighties pop culture.
Speaker 3: It'd be like exactly radical.
Speaker 1: Dude, Hank Ten, Thanks for joining us. See you Friday
Speaker 1: for the bonus episode, and see you next Wednesday for
Speaker 1: a new full episode. You've been listening to Science Stuff.
Speaker 1: Production of iHeartRadio written and produced by me or Hey
Speaker 1: ch Ham, edited by Rose Seguda, Executive producer Jerry Rowland,
Speaker 1: an audio engineer and mixer Chandler Mace, and you can
Speaker 1: follow me on social media. Just search for PhD Comics
Speaker 1: and the name of your favorite platform. Be sure to
Speaker 1: subscribe to Sign Stuff on the iHeartRadio app, Apple Podcasts,
Speaker 1: or wherever you get your podcasts, and please tell your Friends.
Speaker 1: We'll be back next Wednesday with another episode.