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