SETI: The Search for Extraterrestrial Intelligence, Part 1

about ourselves. A lot of the times we want to know what's out there because we want to know where we fit in. We want to know if there's intelligent life or life out there at all, because that puts who we are and what we are in some level of perspective. And that's one area where set comes into play, the search for extraterrestrial intelligence. Right, So, as long as there have been humans, um, there has been this question

of are we alone in the universe? Because you can't help but look up in the night sky and say, is that it? You know? Is there? Are we unique? There are all sorts of questions that roll out here. Now. Of course, astrophysicists astrobiologists, um, astronomers are all trying to answer this question, and they're looking more though, in the

infancy infancy of really this possibility of intelligent life. And when I say infancy, I'm talking more about Mars and the possibility of microbial life there, or Jupiter's moon Europa and the presence of water underneath the frozen oceans, or liquid hydrocarbon lakes on Saturdays moon Titan. So we have to look there first because we know that those are sort of the building blocks of microbial life, which then

evolves into something more significant or complex, I should say. So, of course this leads to this question of well, are we really unique? Um? Is life the flora and fauna on Earth unique to us? Is that it? Um? And this is a huge question and we have to unpack it a little bit. Yeah. I mean, as we've discussed before, when when you're talking about life, I mean, ultimately we have the one model to go on. So we inevitably we keep coming back to that, what is life and

so stuff on this planet? What are the parameters for life as we have seen it so far as we know it? And uh, and what are what's the chemical formula for what is required, what elements? When do we need to look for? It's uh, I often think about it. It's kind of like um, shopping for a new house. You know, you're looking at all right now, what what's what kind of neighborhood do I want to live in? What? What? What do I need to be close enough to? What

resources need to be nearby to make it agreeable? What? What type of neighborhood is is too hostile to me? Uh? You know, like one one area is going to be too fancy, too too rich, just excluding completely another area, uh, might be a war zone. You know. We have to say to take all of this into into account even when we're looking for extratrustrial life, because we're looking at where where else could life exist more or less like it exists here, You're right, So we really have to

turn to ourselves. And we know that the chemical composition of earth face life consists of hydrogen, carbon, and oxygen. So that accounts for more than of the atoms and the human body and in all other known life. So of those three, carbon is really the star of the show, since it can bond with itself and other molecules really easily,

and it's a very strong bond. Now, if you kind of take the lens here from from humans and um and another life on Earth, and you sort of go out a little bit into the universe, what do you find? You find the most common elements in the universe are hydrogen, helium, carbon, and oxygen. Okay, So what is this saying. This is saying that, uh, life is not chemically special, especially if you consider that the basis of it can be easily found in the universe and then harnessed here on Earth.

And if life on Earth were composed primarily of manganese or molly bendum, then we would have excellent reason to suspect that we're something special in the universe. But it's not. Yeah, all this stuff is everywhere. It's kind of you know, it's kind of like you know when you you're a certain age and you find this book that you really dig and you're like, oh, my goodness, is it the most n album? Say it's an album by a group, and you're like, how this is the most precious thing? This?

I love this, this album in this book so much. It speaks directly to me. The artist is speaking directly to me, and only I can really appreciate it in the way that I'm appreciating it now. And then you realize, oh, it's a nation nationwide bestseller, or it's it's on the top ten Billboard charts, or you know, the went triple platinum or whatever, and you realize, oh, actually, this appeals to a lot of people, and I am not special

in liking it. Yeah, and you discover that it's playing throughout the universe, right, the same music, and it's the same elements, those same ingredients that make us that are out there in the stars. But we've talked about this before, because you've talked about if his start implodes um, you know, it's throwing out all sorts of material into the universe.

And you know, there's that the great quote by Lawrence Cross says, you know the atoms in your right hand are in your left hand all came from that one star exploding. So it makes sense. This is this is the stuff that's making that soup. This is the base of the soup. Um. And if you take that logic, then you start to say, Okay, it's not unique. This is a recipe that could be executed elsewhere on the universe. Yes,

But of course the thing about recipes. Um, so we all know is that it's it's not merely enough to know what goes in, but you have to know, uh what amounts going You need to know is it is it a tablespoon of salt or a teaspoon of salt? Um makes the world of difference. Um, are certain substitutions allowed, which ones are not? How are you heating it? How are you preparing it to make all the difference in

in the ultimate outcome of the recipe? And likewise there is a lot of that to take into account, just chemically with with Earth and life on Earth. In his book The Autographs, Diyson points out the oxygen thing. You need a lot of free oxygen and that needs to be supported by some sort of a system on our planet's ported of course, by all the vegetation that we we have on this planet. So you have to have the right circumstances in place to allow the right chemical

situation to be in order. So evolution is kind of like the baking time, right. So if it takes ten billion years for a planet become hospitable, then that's ten billion years of baking time. And so you have to consider that when when we're talking about exo planets, and we're talking about them being just the right distance from the star or um from a sent or a moon to have the correct elements there for the baking. Right,

that's just one aspect of it. But again, the ingredients for the recipe your out there, which makes it so tantalizing of a question of whether or not there exists other life and intelligent life at that UM. Of course, we had to go back to something called the Copernican principle, uh to really sort of understand how life may not be that special in the first place. Yeah. And then this, of course kind from should say chemical life. Yes, this of course comes to us from a mid Polish astronomer,

Nicolas Copernicus. Um and uh. And basically the whole deal here is that we're nothing special, and that you cannot enter a scientific analysis of the universe with the idea that we're something special. There are a number of different

things that spin off of this, For instance, UM. In nineteen seventy four, astronomer Brandon Carter tackled the quandary of our anti anthropic coincidence, the idea that there are a number of coincidences that supposedly make life on Earth possible UM, and he hypothesized that these coincidence are part of the universe very structure, and the chance has nothing to do with it. He proposed two variants, the most important what we're talking about here is the strong anthropic principle UH.

And in this he drew on the Copernican principle UH, which again states that there's nothing special or privileged about Earth or humanity. Uh. We live in a universe capable of supporting life than than only life supporting universes are possible. You can really go down the rabbit hole with this, But essentially it's about putting aside any idea that we are special. Again, the the the album is a hit

around the universe that the building blocks are out there. Uh. We can't enter into any kind of an analysis of or even of a pondering of life else where in the universe if we're thinking that we're special in some way. Yeah.

And what I really like about the comparonic in principle is that it does show an evolution of understanding of our place in the universe, because you know, Comparnicas of sitting there saying at a time where everybody was thinking the opposite is saying, hey, the Earth is not the center of our solar system. And so, of course that was a crazy thought at the time. Yeah, because for the longest, Yeah, Earth has to be the center. We're the center God's blessed creation. So we should be right

there at the center. How can this whole thing not be about us? Right? We are it right? Um. But then there's this idea that evolves even more like, okay, hey, well we're not the center of the Solar system in the Milky Way, by the way, our Milky Way, our galaxy is not the center of universe. In fact, we're not quite sure what the center is. Is there a center? Um?

So you really do see this, This understanding become much more complex and nuanced as we get more and more data from the world around us, because now we understand that Earth is just one of billions of planets that are all bathing in the same sort of primary chemicals. Um. So that gets us to this area called the Drake equation. So we really have to talk about this before we can even sort of say, okay, we'll do aliens exist,

How would they exist? How would we contact them? All? Right, We're gonna take a quick break and when we come back even more on the search for extraterrestrial intelligence. Yes, the Drake equation. So the Drake equation is pretty widely known.

It's been spun off into a number of interesting little side projects, like there was a there's a really good episode of This American Life where that's a team of scientists try to use the Drake equation to determine whether they have a true love match out there in the world waiting for them, as opposed to is there another life form or other life forms elsewhere in the galaxy. Yeah, because I want to say this just at the front here, that the Drake equation is not something that is solvable.

It is it's really about probabilities and how to organize our thoughts about the data that we have in the missing data. Yeah, it's about taking the one big question, the one big probability is their life else from in the universe, and breaking it down into smaller questions, smaller

probabilities that we can tackle individually. So the entire equation looks like this, and and this is not gonna all make a lot of sense, but just in the in the in the interest of getting out there, it is in equals our star multiplied by F sub p multiplied by in sub multiplied by F sub F sub l multiplied by F sub i multiplied by F subc multiplied by capital l. And so all those numbers must by together help us to estimate the number in of technical

logical civilizations that might be able to detect us right now. Now, if you guys all bear with me, let me unpack that a little bit, because I do think it's interesting. Um our star is the rate at which stars have been born in the Milky Way galaxy over the last few billion years. That stars per year, okay, And then all the f factors in this are fractions. So F sub p is a fraction of stars that have planets, and sub e is the average number of habitable planets

in any planetary system. F sub l is the fraction of planets on which life actually begins. F sub i is a fraction of all those life forms that develop intelligency. How this becomes Tinier and jiner um. And then F sub c is the fraction of intelligent life that develop a civilization that uses some sort of transmitting technology. Finally, L, which is really important here, and we'll talk more about

this later l is the longevity factor. On average, how many years do those transmitters continue to operate, because, as we know, civilizations come and go. Yeah, Like I kind of like to think of it in terms of a video store, like you know, and some of you may ask, what what what is that? Because they are starting to disappear more and more. But like in the Atlanta we have this really cool video store called Video Drome. I still like to go there just to brows around for

nostalgia and nothing else. But you know, I walk into a video store and I have, you know, X number of videos at my disposal for possible rent. But then you have to you have to carve that down all right, of all the videos here, I can only check out ones that are checked in, so that dude decreases the number. Then maybe I'm only interested in seeing an English language film because I don't want to read subtitles tonight, So

then we have to cut that down. Then I must say I'm only interested in seeing a horror movie, so that cuts it down even more. And then I only interested in seeing a horror movie that I haven't already seen, so that cuts it down even more. And again you just get down to there are x number of films

that I could potentially rent this evening. Now, what I think is cool about this dract equation is that, yes, there's no righting answer right now, and this is just a way of organizing information because a lot of it does depend on who's plugging in the data and why right in the same way that my data I plug into this video drum equation could be different one day from the next. The deal is, though, is that astronomers

are actually getting at this equation right. They've already tried to figure out about three of those different fractions, So they're trying to figure out the fraction of stars planets, the average number of habitable planets, and the fraction of planets on which life actually begins. So they're getting to that.

So when I talk about exit planets that are habitable and that goldilocks not too hot, not too cold, that' from one aspect of it that they're beginning to collect data on um and they're beginning to say like, okay, well, now we can get these chemical signatures and try to figure out, you know, how much carbon is being produced there, how much method sane which you know something we'll talk more about as pretty plentiful here on Earth, and that's

a that's a huge signal if there's something going on on that planet, right probably probably cows as well as other you know, factors that that create methane that I won't go into. Uh, But anyway, my point is is that yes, this is, uh, this is somewhat of a thought experiment, but astronomers are scratching away at it and

they're getting some concrete information in there. Yeah. Um, I mean historically whether the estimate the results have varied again depending on what's going into it, and they varied from there being one one but one civilization out there two millions. So yeah, right, Again, there's a lot of data that needs to be plugged in here, but astronomers are if

if you will, plugging away at that. Now, I wanted to mention the Fermi paradox, and this is something I want you guys to all put in your back pocket as you consider all the other information that we talked about today. The Fermi paradox is from the Noble Prize winning physicist and Rico Fantom and he reasoned that if it takes life billions of years, should develop intelligence and

signal or travel to the stars. And if there are billions of worlds in the universe, and if the universe is over thirteen billion years old, then why haven't we been visited by an extra terrestrial or why isn't the galaxy crawling with extraterrestrials. This is something we'll get too later. But that's that's a good question, right, yeah, I mean it's Stephen Hawking brought up the same thing with time travel. You have if time travel was possible, is possible, will

be possible? When I have we not been visited by a time traveler. Like it's just kind of a basic, you know, show me level of of of analysis. Okay, they're aliens, great, show me one, show me the alien put it on the table for me to see because the time traveler erased our memory, and certainly you could, you can, you can roll out varying levels of conspiracy

and and explanations on top of it. But you know, at the at the very root, it's it's a question of all right, if they're aliens, then we should have seen them, We should see them, and then you can you can apply your own excuses as to why don't we have not Alright, Well, On that note, we're going to actually call this an episode. We're splitting the SETI episode up into two episodes, so this was part one. Part two will publish very shortly, so be on the

lookout for that in the time being. If you have any kind of feedback on part one, you can find us on Facebook and you can find us on tumbler. We are stuff to blow your mind on both of those and we use the handle blow the Mind on Twitter, and you can always drop us a line at below the Mind at Discovery dot com. For more on this and thousands of other topics, Is it how Stuff Works dot com