What kind of signals are we searching for from aliens? What are technosignatures and biosignatures? How are we looking for non-intelligent life? Is there any hope of finding life in our own solar system? I discuss these questions and more in today’s Ask a Spaceman!
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this episode of Ask a Spaceman is brought to you by my friends at better help. Better help provides easy, convenient, affordable access to online counseling and therapy. And, you know, the therapy has been an important part of my, uh, life experience is something I'm absolutely not ashamed to talk about. I wish more people used therapists and counselors to take better care of their own mental health, just like they take of their physical health. Uh, I know a lot of you turn tune into this show for Astro Thera as a word, but maybe if you're having a really tough time, you should talk to an actual professional, and so I encourage you to go to better help. They are convenient and professional. It's real therapy and counseling, and it is affordable and you can connect online. You don't have to wait in a waiting room or any of that. You just talk to someone who who cares and and knows what they're talking about. As a listener, you'll get 10% off your first month by visiting better help at better help dot com slash spaceman, and I want you to join over 1 million people who have taken charge of their mental health again.
That's better help. HE LP dot com slash spaceman Have you heard my SETI joke yet? Well, if you already have or you are not up for listening to probably the worst joke ever, just go ahead and skip forward 30 seconds a minute, five minutes. I don't know how long this is gonna take anyway. SETI The Search for Extraterrestrial Intelligence SET I Do you know why they targeted intelligence rather than just any kind of life? Like Why isn't it the search for extraterrestrial life instead of this search for extraterrestrial intelligence? Well, the truth is, if they can't find intelligent life, they're just gonna have to settle SETL search for extraterrestrial life.
I'll just I'll just stop the episode here because that's a really bad joke. But it's my only steady joke, and it's and it's terrible, but it's also the best I got. But the question of Are we alone? It's one of the greatest questions you can possibly ask. It's up there with with what is the meaning of life? Is there divinity? Are we alone? It's been speculated about for millennia, with various kinds of thinkers throughout human history wondering if we are alone in the universe. Now it's science's turn to take a crack at it. And the fundamental thing, The first thing that science came up when when we started taking this seriously or about as seriously as we can get in the mid 20th century, it is. We came up with a paradox. That's as far as we got basically, and we haven't gone gone much further. The paradox is like this. It's called Fermi's Paradox. It's attributed to Enrico Fermi, great 20th century physicist, one of the founders of quantum mechanics, particle physics, all the rest.
And he also posed this very interesting question. He said, OK, we're here. Obviously, we're alive. There's the planet Earth. There's the sun, we're in our galaxy. There should be nothing typical about this setup, because when the universe does one thing, it tends to do it a lot there. There isn't a lot of specialness or uniqueness in the universe. So we're here. That means the universe must be teeming with life, because if life happened here, it happened everywhere. So where is everybody? We see no signs of any life anywhere. Uh, but life is supposed to be common, so something has to give. Either we really are alone or life is not as common as we might think or something is a little bit special about us. We did an entire episode on the Drake equation and how it's not really much of an equation that attempts to distill this Fermi paradox and put some numbers on it on just how common life might be in the universe.
Ultimately, as we discovered when we looked at the Drake equation, is that you're just making it up, and ultimately we got nothing until we got something. We We have no idea how common life is in the universe, that that's what it comes down to. We have no idea we might be the only intelligent critters in the entire universe. There might be a billion of us. We don't know all the estimates that we have. All the estimates you might read about are entirely made up. It's impossible to say, except it's It's rare and or hard to spot, because if it were super common, if there were aliens on Proximus Centauri blasting their radios, we would have heard it by now. but we haven't. And so it It's at least somewhat rare, but there's a lot of rare things that are not obscenely invisible or or one of a kind in the universe. There are plenty of things in the universe that happen a few times. Like like think of supernova supernova happened a few times per century in a galaxy or Kan Nova.
They happen every, what, 100,000 years in a galaxy over the lifetime of the galaxy. That's like, what? 100 kila nova total? That's not too many. So maybe life is as rare as Kan Nova in the entire history of the Milky Way galaxy. There's been 100 intelligent species like OK, then, but anyway, but even me saying that I'm just making things up, making it up. If we want to find life intelligent or otherwise, we have to go looking for it because it's not immediately obviously out there. So we have to do a little bit of leg work, and the first try is to look for intelligent life. Why? Because they might might give the most evidence that they exist. Presumably intelligent life will be more rare than regular life because presumably it's harder to get up the evolutionary ladder or chain or whatever metaphor you want to use to get to intelligence than just having a little microbe swimming around in an ocean. That could be wrong. It could be. As long as you get life, you're gonna get intelligent life, whether you like it or not.
Well, again, we're just making things up. We're spitballing here. Presumably, it. I guess it's reasonable to say that intelligent life is more rare than regular life. So why should we look for intelligent life? It's because they make a lot of noise. Think of what we do here on the Earth. We cause a ruckus, especially once we invented that whole radio thing. We've been going nuts. This is the basis of SETI, the search for extraterrestrial intelligence. Long history have said here, basically, as soon as we invented radio, we realize that if we if we are sending signals into space, then somebody else might be beaming back to us, said he has never been traditionally funded, usually paid for through fan support. Patreon dot com slash PM Sutter Why? Well, because it's usually associated. Uh, they don't deserve that. he does not deserve the association with UFO S. But they got the association with UFO S that the search for intelligent critters out there is somehow connected to believing that aliens are visiting us. They didn't deserve that connection, but they also got the connection.
And so, yeah, major funders, funding agencies, the people who power science Yeah, they're not interested too much in UFO research and said he seems like UFO adjacent when I mean SETI is legit. Although I should say it can be debated to be legit science because one of the arguments against SETI is that it's not falsifiable like in science. We like to make testable hypotheses. And then if you don't succeed, if you get what's called a null result, if you get nothing, you're supposed to discard the hypothesis and move on. But how many null observations does it take to prove that we're all alone in the universe? How many decades of no alien signals or communications does it take before you say, You know what I you know, folks, I think we're all alone. Let's pack it away. We're gonna work on something else. I really think we're all alone in the universe. How many does it take? Does it take 50 years? 500 years? 5000 years? Uh, have All you do is say life is more and more and more and more rare.
At what point do you just stop other fields of science? At least good fields of science will say, You know what? We we haven't found anything, So I suppose this is a bad idea, and we should just move on with our lives. There's also in setting a huge bar for getting it right. Huge bar. Because, as I've explored in this show, in my other work, there will be little bleeps and bloops in the radio. We're gonna talk about a couple of examples in this episode where you think Oh, this is it. This is aliens, and then it turns out to totally not be aliens. And every time that happens, that makes people a little bit more nervous to fund setti. Because if you get excited about alien mega structures, which we'll talk about and then it turns out to be dust and then the next time you say no. Now it's alien. We found a Dyson. We found a thing that aliens built. They're like, Are you sure it isn't dust? Did you do your homework? Or are you just getting excited over nothing like, If you're not taking the field seriously, then why should we?
There are many scientists out there who are trying to change that who are trying to make SETI more rigorous, more scientific, more falsifiable kudos to them. Usually SETI is funded by random, super rich people, like the current example of the current epoch of SETI. There's the breakthrough Listen Project, which is funded by a bajillion ai Yuri Milner. You might be listening in a different epoch where SETI is funded by a a different, random, super rich person. There's also the problem in Set that we got nothing in which I'll detail in a little bit but broad sketch. We've over 100 radio observing programs have turned up empty, no signals of anyone out there. So it's just not exciting. It's not fun to keep looking for something and not find it. So it's hard to motivate SETI and continued funding for Setti when there's been decade after decade after decade after decade of nothing, and the only thing we can say is like Well, we need to listen harder. We need bigger telescopes. We need to look further. But again, that raises the falsifiable questions like like, how far do you go until you just stop?
How far do you go? Until you say, you know what? We might be alone. We might not be alone, but all the evidence suggests that we are alone. So let's go ahead and operate as if we were, and we'll funnel our money to something else. Yuri Milner Feel free to subscribe to patreon dot com slash PM Sutter. One of the big difficulties of SETI is that it's not like we're just listening for random alien TV that they're beaming across their planet and it leaks into space and we catch out. There's we can't we can't hear that. We have to rely on targeted communication where aliens have to know we're here. Build a big giant radio transmitter and blast a hello at us. That's what we're searching for. That's what said is it's It's searching for targeted communication, which is the height of arrogance. In my opinion, we're assuming that aliens would want to talk about us and talk to us. We're assuming that aliens would even pay attention to the fact that we're here. Almost all SETI searches to date have relied on targeted communications to us.
So good luck. It is possible to do general searches for undirected broadcasts. Once you get enough sensitivity, if you build a big enough radio array or telescope, you will be able to catch alien TV halfway across the galaxy. You'll pick it up, but at that level of sensitivity, that signal is so weak you have to compete with galactic noise and you have to cross your fingers that an artificial signal would be distinct enough from the background noise, which there is no guarantee of that whatsoever. We're hoping in the set search. We're hoping that alien signals just look artificial, that they repeat themselves in certain ways or have access to certain frequencies or change frequencies in certain ways, that nature simply doesn't. We have not seen any signals like that. Yeah, we see bleeps and bloops in the radio all the time. They're almost always one offs or we always end up finding a natural explanation for them. But so far we got nothing. We've been searching For over half a century, we've been searching with over 100 specific SETI search programs.
If aliens are out there, they're not calling us right now. They are not. However, radio emission is just one kind of what we call techno signatures. This is the signature of an intelligent species doing intelligent or or at least artificial things. As soon as we developed radio, we're like, Oh, maybe the aliens are broadcasting radio at. And then, as soon as we think of a new idea, we think, Oh, maybe the aliens are doing this. That's also a a kind of arrogance that as soon as we develop some sort of technology or have some sort of thought, we automatically assume aliens are gonna have the same technology and the same thought and do the same thing with what we that we do with that technology or thought. This goes into the whole detectable question, like why go after intelligent life rather than regular life? Because presumably intelligent life is making a lot of noise so they might be more detectable? An intelligent species might be easier to spot than bacteria floating in some alien ocean. Maybe that's assuming they do what we do, but, like 10 times louder or 1000 times louder and directed at us, the galaxy might be teeming for whatever definition of teeming you want with intelligent life.
But that doesn't mean they're going to make themselves noticeable, right? There could be intelligent aliens on proximo to I don't think there are, but there could be. But if they're fine with just the whole, you know, singing Kumbaya around the campfire thing, we're not gonna spot them. What if they invented radio and they laughed, and then they stopped with that whole radio thing? We wouldn't see him anyway, but a aliens might engage what in what we call mega engineering to build what we call techno signatures. Lots of jargon here, like there's the whole Dyson sphere thing. It's a concept invented by Freeman Dyson, hence the name where you enclose a star and you capture all of its solar energy. Uh, it's not really stable. It will break apart in a second. So instead of a giant sphere, you actually need a swarm of objects with solar panels on the inside, and they absorb all that solar energy. It's never been convincing to me if it's worth it. I've once did some back of the envelope calculations of like, if you want to build a Dyson sphere or a Dyson swarm or a Dyson, whatever octahedron, you need to build it out of something.
You got the materials available in your solar system. You got some rocky planets, you got some masters and comets. You got some giant planets. You're not exactly gonna build the Dyson sphere out of hydrogen helium. So right there, like 99% of the mass of the solar system is useless to you. Instead, you have to pull apart all your planets. You have to pull apart all your asteroids. You have to rip apart all your gas giants to get down to the rocky cores. So you have to spend all that energy to rip apart these planets. Then you need to spend even more energy to arrange everything you need to spend even more energy to get, like the photovoltaic cells like, Do you have enough lithium in your solar system to power this? That's an open question, and you gotta build it and you see, it's a lot of engineering, and it takes a lot of time and especially a lot of energy. And then you start recouping that energy. You, You you make that investment to build your sphere. You disassemble your solar system to get it all the rocky materials. Most of that rocky material is just carbon and oxygen, which is also not very useful. And then you build it and then you start collecting solar energy rough, back of the envelope calculations.
I made it take, like, a million years to get back the energy investment, you need to spend energy to rip apart your planets and build the thing. And then you need to collect that solar energy, and it will take it could take up to a million years. So why bother? After the million year mark, you're finally in the black energy wise, and it was worth the investment. You could have just sat there on your planet and and been better off for a million years. So it's not exactly clear to me that Dyson's spheres are worth it. Maybe that's a whole other episode. But let's say you did it. What would it look like? Like maybe they're just stupid or lazy. Or maybe it's a big art project and they want to build a Dyson sphere. Presumably, they would not call it a Dyson sphere. They'd have their own name for it. But then they did it. Let's say intelligent species in the Milky Way build a Dyson sphere. What would it look like? How would we detect it? Well, from our perspective, the star would look weird because if you were to close off the star, you would be absorbing all that solar radiation and using it to power.
I don't know, Video games. I don't I'm I'm just not exactly clear what you would do with all that energy. Uh, but you would do you would use it. But not everything is efficient. So eventually the energy would leak out in the form of waste heat. So instead of seeing a regular star that's like very tiny and very sharp and very bright, you'd see a very large, very fuzzy, very infrared super red star. It look like a fuzzy, dim but large star. So if you happen to see a star that looks that way, it might be you might be looking instead at the Dyson sphere, the outside of a Dyson sphere. We've looked for that in surveys of millions of nearby stars and found nothing. We've also surveyed hundreds of thousands of nearby Galaxies because if you can build one Dyson sphere, then you've basically also cracked the energy needs of interstellar travel. Trust me, if you have the energy to reassemble your solar system, you have the energy to hop from star to star. And so maybe in the history of the universe, you've had more than enough time to do this whole bunch in your galaxy, and you've transformed a whole bunch of stars into Dyson Spheres. You would shift the spectrum of your entire galaxy.
It would look redder. And when we don't see that there was lots of excitement a few years ago over Star observed with the Kepler Space Telescope. Its official name is K IC. 8462852, also known as Tabby Star or Boyajian Star, named after the Tabitha Boy Ain, the graduate student who wrote a paper about this crazy star that was dimming bright, uh, like radically by like big numbers like 2030% and then returning to normal and there was no pattern to it, and it seemed like a very odd star. And there are odd stars all over the universe. But what happened is another team of astronomers said, Hey, if there just so happens to be, I don't know, giant solar panels orbiting this star and occasionally blocking out the light you would get these sharp cutoffs and the brightness. And so, of course, everyone went wild, thinking this was perhaps evidence for a alien mega structure like they had built a Dyson sphere kind of sort of and got tired halfway through and quit, you know, typical engineering.
You know, Maybe it's tied up in red tape and they couldn't finish the project anyway. It turned out to be dust because if it was giant solar panels, then all wavelengths of light from the star should be blocked at the exact same moment in the exact same way. Because if you got a giant solar panel, it's just gonna cut the thing off. But instead, different wavelengths of light were getting cut off at different times and in different ways, and some wavelengths were making it through, and that's what dust does. So that was an example of Hey, look Maybe it's aliens. Oh, turns out to be dust. Another sign a techno signature is like you can intentionally mess with the chemistry of a star by dropping a bunch of rocks into it. It would change the spectrum and be a pretty reliable. Hey, we're here also. No trespassing sign. So we've looked for stars that say, Have a lot of weird radioactive. If you dump short half-life radioactive elements into a star, that's pretty artificial. That should. We've looked for that, not see anything. There's lots of other possible techno signatures. There could be artifacts left in the solar system.
If someone's been watching us for a while and they left something behind, they left their lighter back. You know, back here in the backyard. I don't know. Uh, maybe you could observe the illumination of the dark side of a planet. If you got lots of cities going on, maybe you can pollute your atmosphere and we could detect that there could just be wandering interstellar probes, minding their own business all all nothing. We've got nothing. I browsed through the archive. The I don't know if I've explained the archive to you before a RXIV dot org. It's a repository for all physics and astronomy and more. There are more fields that participated all free to access, free to download, free to read. You do not need a journal subscription. All physicists and astronomers published their work on this archive. You submit it to the journal for publication, and then you submit your your version of it to the archive. So it's freely available to everyone and you can search. You can search tach, no signature. You can search mega engineering. And, honestly, the the field in SETI here is is pretty depressing to me. There's not a lot of papers.
There aren't a lot of there isn't a lot of activity. There's not a lot of interest. It's all about like, Yeah, we did the thing. We did a search. We didn't find anything. We looked for this techno sign signature. We didn't find anything. We we listened with this program. We didn't hear anything nearly a century of searching for techno signatures, and we found nothing. The skies are silent, the stars are themselves. As far as we can tell we're all alone. Or if there is intelligent life in the universe, then we're effectively alone. This has led to an interesting question in the SETI universe about something called Active Set, which doesn't make a lot of sense, but we'll go with it where we broadcast ourselves. We send out we're the ones sending out the targeted communications. We're the ones sending out the O, obviously artificial signals at some promising candidates, like Oh, got a habitable planet over there. Boom! Here's a Here's a super bright radio message saying, Hey, how's it going?
How do y'all There's a debate about it because people are worried that once aliens find us, they will eat us or something. Personally, this is Paul Sutter's personal opinion. I find this argument ludicrous. If an alien is able to receive our signal one, it won't be for thousands of years tens of thousands of years from now. Two. Who knows if they'll even recognize it if they'll be able to realize that it's artificial three. If they do realize if they do get it and they do realize it's artificial because they may not, they may. They may just like Oh, look at that silly background noise. Whatever moving on. If they do realize it's artificial, they may have. Who? There's no guarantee they'll be able to understand it or decipher it. Who knows? We might be awash in alien radio TV signals and targeted communications right now, but we just don't get it. We could be like, Dang, we're all alone. Meanwhile, the the Galactic UN is saying, like, why don't these these hairless apes get it?
We've been saying hello for 60 years, maybe just throwing that out there. But no. Like what? What are they gonna do? They're thousands of light years away. They're gonna come eat us. Kill us. What? What do we have on the earth? We've got some water. Well, you can get water everywhere. You got some carbon and oxygen. You can get carbon oxygen anywhere. You have our culture, I guess. But, I mean, have you watched our TV? And the truth is, we've already done it. We've already announced our presence and we've been doing it for billions of years. The thing is, around 2.4 to 2 billion years ago, a bunch of bacteria single celled organisms swimming around the ocean, doing their thing emitting oxygen as a byproduct of their metabolism. The oxygen built up in the atmosphere to a critical level. We call this the great oxidation event, where there is actually so much oxygen in the atmosphere that it started to kill. Oxygen is a nasty, nasty element. You do not want to hang around with oxygen. Just take what you need to breathe and then move on.
Very reactive, very corrosive. And it all this oxygen started killing all the bags here, all the little bugs that were making it. It was global warming. One point. Oh, and they they killed themselves. And then But then they figured out how to eat the oxygen and use it for respiration. And then they went nuts to that. To this day, billions of years later, there's been a lot more oxygen in their atmosphere than there would be naturally, if they have. If aliens can see us and are within a radius of 2.4 billion light years, which is, you know, a decent fraction of that's the entire Milky Way out into Andromeda, it's a good chunk of our local patch of the universe. If they have the capability to observe the earth, then they can see the oxygen in our atmosphere. They know that this planet is alive and they've known it for billions of years. They already know we're here. They already know our planet is changing. And if they have been watching us for long enough, if they have the capability to detect oxygen in our atmosphere, then they have the capability to detect pollutants in our atmosphere.
They already know we're here, folks, the whole debate over active city is moot. We are on a living planet and we know how to find living planets. And if we can figure it out, someone else can. And anyone, any intelligent creature within a radius of 2.4 billion light years has known that this planet is alive. That's why Biosignatures are much more interesting than techno signatures. Yes, intelligent species might make a lot of noise but non intelligent species. Little Don't underestimate the power of little single celled organisms. They can throw a planet out of equilibrium. You look at Mercury. It's a dead world. It's in equilibrium, man. It's been that way for billions of years. You look at Venus who miserable but been that way for a really long time.
It's in equilibrium. You look at Earth. Not in equilibrium. It changes. Our atmosphere has changed. There should not be this much oxygen in our atmosphere. Oxygen is highly reactive, highly corrosive. It likes to party. It likes to get out of town. If we were born with this much oxygen, great, we will have lost it. And like like 1000 years, I'm exaggerating. It's more like maybe a million. We will lost all this oxygen to get this much oxygen in our atmosphere requires photosynthesis. It needs to be replenished things on our planet change with time to follow the seasons or to follow the amount of daylight there changes to the surface. Before life, the their earth had two colors blue and brown. Now we got three blue, brown and green life transforms minerals changes things in the atmosphere, in the soil, the dirt on the earth. The vast majority of the dirt on the earth is different than it was before Life biosignatures again.
This is just my opinion are much more interesting than techno signatures. We are searching for life not through Setti, but through settle. And if you skipped over the joke at the beginning of the episode, I'm sorry if that doesn't make any sense. We're searching for regular life on exoplanets. We've been doing it with Kepler, the Kepler Space Telescope with Tess transiting exoplanet survey. We're gonna do it with the James Webb Space Telescope if it ever launches. If you're listening to this in the future and I know you are, I hope the JWSD is launched by now. I've discussed the richness of exoplanets before. You know, these this amazing variety of worlds and configurations and systems that we would have never thought possible is that our wildest dreams weren't even capable of coming close to the majesty of solar systems and worlds out there. It's amazing, we think we think, based on very rough estimates. And this is we're just making stuff up here, but it's based on a few decent numbers. The number of earth sized planets around sun sized stars where those planets are in the habitable zone of their star, where liquid water can penitential exists in the Milky Way alone, there are approximately 5 million copies of the Earth.
Even if that's an overestimate by a factor of 10, that's still a lot of earths. That's still, uh, potential homes for life, potential homes for intelligent life just like this one. And we search for life by looking at atmospheres. We don't quite have the technology yet to do it on earth sized planet. We we can study the atmospheres of giant planets when they're close to the star that there's a strong enough signal there that we can see it. But the James Webb Space Telescope is is hopefully gonna do it for Earth sized planet. What we do is we wait for the planet to cross in front of the face of its star and for a brief moment of time, the light from the star filters through the atmosphere of that planet on its way to us, and it looks a little bit different. Some wavelengths of light are absorbed, some wavelengths of light are emitted, the atmosphere changes the light, and we can look for that little difference. And we can determine what the atmosphere is made of. If we happen to find an atmosphere with a whole lot of oxygen, that's a good sign that planet might be alive if I were an alien on the other side of the Milky Way galaxy or an android, and I was looking at our solar system.
That's how I would do it to figure out if our planet was alive. There's an entire field out here called astrobiology, studying the origins of life in our universe, the evolution of life in our universe, the distribution of life in the universe. Using Earth as just one example saying yes, OK, what were the conditions to le that led to life here on Earth? Where else might we find that? And then where else might we find life in general with conditions that are very different than what we find here on Earth? This is much more mainstream than SETI. Astrobiology is much more mainstream than SETI. Why, in some ways it's a lot less sexy than the search for intelligent life because it's we're just looking for bacteria, but it's also more scientific. Instead of just sitting here listening and crossing our fingers, we can actively search and study and develop interesting questions. We can develop testable and falsifiable hypotheses.
We can go digging in Martian dirt. We can study the light filtering through alien atmospheres. We can do things Astrobiology is asking cool questions about life in non Earthlike environments as an example. When I go to the archive and you can do this too, type the word biosignatures into the search box on archive. When I do it, I get a thriving and active research program with papers discussing. And this is just like today papers discussing the possibility of water worlds. These are worlds completely enlo by an ocean. A life on Neptune like planets. Uh, what other biosignatures the earth might reliably have besides oxygen in our atmosphere? Uh, predictions for the James Webb Space Telescope of false positives that could lead to a lot of oxygen in an at without their life being there And what other things we need to check proposals for future missions, energy requirements for motility. Uh, if you want your little critters to be able to move around, what kind of energy and chemically do they need and on and on and on and on and on, vastly different than the SETI work.
It seems interesting and and alive, and a lot of the work is focused on our own solar system. You know, the the steady work, the intelligent life. Yeah, there's there's no one intelligent here as far as we can tell. So we have to go to other stars, and there's no one around nearby blasting their radios at us. So we have to go even further. And the further you go in astronomy, the harder it gets. But looking for Biosignatures studying astrobiology? There's a lot of interest right here in the solar system because there's a lot of maybes and what ifs here in our solar system. Now a lot of these have not panned out like the Martian meteorite. In 1984 there is this Allen Hills meteorite, which was found in Antarctica. Turned out a giant rock smashed into Mars, threw a bunch of debris up into the space. Some of that just debris landed on the earth and ended up in Antarctica. There were some little, uh, microscopic structures in there that some people argued could only be formed by living creatures.
But there are also chemical ways to do it. There's a lot of interest in Mars in general. There's this whole question about liquid water. Uh, the the seasonal variability of liquid water on these crater slopes that that seems to not panned out there might be liquid water underneath the polar ice caps. There's a lot more methane in Mars than you might originally expect. Methane is also very volatile and tends to go away. It needs to be replenished. So what is replenishing it? It also tends to vary with the seasons. Maybe it's chemical. Maybe there's some interesting microbial life happening under the surface. We know that Mars was once habitable. We don't know if it was habit, but we know it was habitable. We know there were oceans and rivers and lakes and streams and nice, thick atmosphere on Mars. Back in the day, around the same time that Earth had life on it, Mars was looking pretty much the same. The solar system was a very different place 3 billion years ago. Maybe some of that life survived. There's been a lot of discussion recently about the discovery of Phosphine in the atmosphere of Venus.
Big news story. Apparently, you can. Also there's this phosphine. It's a it's a molecule that Life likes to make. Anaerobic life likes to make a lot of it on Venus. Turned out those observations were pretty sketchy, and you have to really, really want the signal to get there, and it it's more of an artifact of your signal processing algorithm rather than something actually happening on Venus. But those two aside, those two aside Mars and Venus aside, There's all this excitement about the subsurface oceans of Europa, Enceladus, possibly Calisto gay Titan, Pluto. Liquid water, oceans that we are know we know they're there, underneath the surface of these plants. Liquid water. Hey, life, there's Titan itself, which is absolutely fascinating with these hydrocarbon methane seas. Could there be life there? I don't know. We don't know. We've got missions planned to these moons of Jupiter. The Europa Clipper Mission. The juice mission that that stands for Jupiter Icy moon Explorer, not orange or pineapple, supposed to launch in the mid 20 twenties.
Take about a decade to get there. So maybe in the in, you know, with hopefully within my lifetime, we might know if there's the potential for life in these frozen moons of the outer solar system. So there's a lot of interest in Biosignatures. There's a lot of interest in astrobiology. There's a lot of interest in our own solar system. There's a lot of interest outside our solar system. But as exciting as all this is with set and biosignatures and methane titan, we haven't found squat. Nature is teasing us. Water is everywhere. Water is the most common molecule in the universe. It's hydrogen, which has been around since the Big bang and oxygen, which is made in stars like our sun, which are very common. So water is everywhere. Most of it is frozen or a gas, but liquid water turns out to be much more common than we had thought. Yeah, it's here, on the surface of the Earth, but there's more water in Europa than there is on the earth. Turns out it's very common in the outer parts of the solar system, and it is common in our solar system. It's common in another solar system, primary ingredient for life.
Right there is very common in our universe. Carbon is everywhere. Earthlike planets are probably basically everywhere. The building blocks of life are everywhere. I mean, come on, we found amino acids in a nebula. What's going on? All we keep doing is asking Enrico Fermi's paradox again and again and again. The building blocks of life are everywhere. There is not anything entirely super duper special about the Earth. We're here. Water is common. Carbon is a common. Oxygen is common. Earthlike planets are common. Sunlike stars are common. Habitable zones are common. There might be 5 million copies of the Earth in our galaxy. Where is everybody? Not just the intelligent species. Where's the bacteria? Why is Mars dead? Why is Venus dead? If Europa Enceladus Titan, if they turn out to be dead too. What's going on? If they turn out to be alive? Hooray! That's gonna be a watershed moment. I hope. I hope I'm alive for it. That would be fantastic to know if there is life elsewhere in our solar system right now.
And yes, I will settle for a bacteria. I don't care. That's just as exciting, just as exciting. But what's going on? Where is everybody? We don't know. My personal take on it is the reason why Setti is unlikely to be successful, whereas O the search for astrobiology will be more successful is the vast time and distance scales that operate in the universe. Fermi's paradox is only a paradox. If you assume the galaxy is small, if you assume that it's easy to transmit signals and information and signs of your presence from one part of the galaxy to another. We've been broadcasting radio for, what, 60 years? That's a 60 light year bubble. And honestly, honestly, Yes. Technically, our the sign of our intelligence has spread 60 light years. It's indistinguishable from the background radio noise of the universe and from supernova going off from stars forming they they generate a lot of radio mission that just drown us out.
If you're not on Proxima Centauri, you can't hear us. We are too weak. Our signals are too weak to stand above the background noise. Yeah, we've sent some targeted signals, but that's it. Shot in the dark. Literally. Unless you live on our next newspaper, you can't hear us. Which means unless aliens live on Proxima Centauri, we just can't hear them. Yes, we're gonna build better radio telescopes. Yes, we're gonna be more sensitive. Yes, we're gonna do more searches, but we don't know how detectable intelligent life is. But we do know how detectable any kind of life is. They can change their atmospheres. They can change their planets. Even a tiny little bacteria like you said, being aliens if they've been watching the Earth. If they've been paying attention to the Earth, they've known this planet is alive for potentially billions of years. They do not know if it's intelligent or not. Me personally. I don't think we're alone in the years. That's my opinion. It's not based on evidence. It's my opinion. It's my hope. I think there are in other intelligent creatures in the universe.
No, I don't think they visited us. But given how vast time and space is in our universe Galaxies 100,000 light years across universe, billions of years old, uh, we're effectively alone. We may not be alone, but we're effectively alone. That's OK. We can still hunt. We can still observe. We can still study and we can still find signs of life. And we can celebrate anything we find. If we see a planet with too much oxygen, we can celebrate that. We can study it. It's a that's a scientific question, right? If someone says hello to us, then yeah, we can celebrate that, too. But I'm here to root for the little guys, and I think it's OK to settle thank you to at Jelly sock on Twitter, Jack S on email, aka B on email, and Alyssa W on Facebook for the questions that led to today's episode episode and thank you to my top patreon contributors this month. That's patreon dot com slash PM So Matthew K, Justin Z, Justin G, Kevin Duncan, M Corey Do Barbara Gay Dude, Robert MNN and we have Chris Cameron, NAIA Aarones, Tom B, Scott and Rob H.
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