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Speaker 1: Welcome to stuff to Blow your mind from how Stuff

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Speaker 1: Works dot com. Hey you welcome to Stuff of all

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Speaker 1: your mind. My name is Robert Lamb and I'm Julie Douglas.

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Speaker 1: And you know, when you look at space explorestion, you

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Speaker 1: know we're looking outward, but then there's also a lot

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Speaker 1: of looking inward. Um. It's just about anything humans do.

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Speaker 1: You can sort of make a case for the selfishness

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Speaker 1: of it and the self absorption of it. So we

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Speaker 1: look out into space because we want to know something

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Speaker 1: about ourselves. A lot of the times we want to

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Speaker 1: know what's out there because we want to know where

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Speaker 1: we fit in. We want to know if there's intelligent

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Speaker 1: life or life out there at all, because that puts

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Speaker 1: who we are and what we are in some level

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Speaker 1: of perspective. And that's one area where set comes into play,

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Speaker 1: the search for extraterrestrial intelligence. Right, So, as long as

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Speaker 1: there have been humans, um, there has been this question

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Speaker 1: of are we alone in the universe? Because you can't

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Speaker 1: help but look up in the night sky and say,

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Speaker 1: is that it? You know? Is there? Are we unique?

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Speaker 1: There are all sorts of questions that roll out here. Now.

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Speaker 1: Of course, astrophysicists astrobiologists, um, astronomers are all trying to

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Speaker 1: answer this question, and they're looking more though, in the

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Speaker 1: infancy infancy of really this possibility of intelligent life. And

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Speaker 1: when I say infancy, I'm talking more about Mars and

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Speaker 1: the possibility of microbial life there, or Jupiter's moon Europa

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Speaker 1: and the presence of water underneath the frozen oceans, or

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Speaker 1: liquid hydrocarbon lakes on Saturdays moon Titan. So we have

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Speaker 1: to look there first because we know that those are

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Speaker 1: sort of the building blocks of microbial life, which then

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Speaker 1: evolves into something more significant or complex, I should say. So,

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Speaker 1: of course this leads to this question of well, are

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Speaker 1: we really unique? Um? Is life the flora and fauna

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Speaker 1: on Earth unique to us? Is that it? Um? And

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Speaker 1: this is a huge question and we have to unpack

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Speaker 1: it a little bit. Yeah. I mean, as we've discussed before,

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Speaker 1: when when you're talking about life, I mean, ultimately we

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Speaker 1: have the one model to go on. So we inevitably

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Speaker 1: we keep coming back to that, what is life and

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Speaker 1: so stuff on this planet? What are the parameters for

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Speaker 1: life as we have seen it so far as we

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Speaker 1: know it? And uh, and what are what's the chemical

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Speaker 1: formula for what is required, what elements? When do we

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Speaker 1: need to look for? It's uh, I often think about it.

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Speaker 1: It's kind of like um, shopping for a new house.

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Speaker 1: You know, you're looking at all right now, what what's

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Speaker 1: what kind of neighborhood do I want to live in? What? What?

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Speaker 1: What do I need to be close enough to? What

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Speaker 1: resources need to be nearby to make it agreeable? What?

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Speaker 1: What type of neighborhood is is too hostile to me? Uh?

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Speaker 1: You know, like one one area is going to be

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Speaker 1: too fancy, too too rich, just excluding completely another area, uh,

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Speaker 1: might be a war zone. You know. We have to

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Speaker 1: say to take all of this into into account even

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Speaker 1: when we're looking for extratrustrial life, because we're looking at

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Speaker 1: where where else could life exist more or less like

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Speaker 1: it exists here, You're right, So we really have to

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Speaker 1: turn to ourselves. And we know that the chemical composition

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Speaker 1: of earth face life consists of hydrogen, carbon, and oxygen.

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Speaker 1: So that accounts for more than of the atoms and

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Speaker 1: the human body and in all other known life. So

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Speaker 1: of those three, carbon is really the star of the show,

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Speaker 1: since it can bond with itself and other molecules really easily,

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Speaker 1: and it's a very strong bond. Now, if you kind

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Speaker 1: of take the lens here from from humans and um

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Speaker 1: and another life on Earth, and you sort of go

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Speaker 1: out a little bit into the universe, what do you find?

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Speaker 1: You find the most common elements in the universe are hydrogen, helium, carbon,

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Speaker 1: and oxygen. Okay, So what is this saying. This is

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Speaker 1: saying that, uh, life is not chemically special, especially if

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Speaker 1: you consider that the basis of it can be easily

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Speaker 1: found in the universe and then harnessed here on Earth.

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Speaker 1: And if life on Earth were composed primarily of manganese

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Speaker 1: or molly bendum, then we would have excellent reason to

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Speaker 1: suspect that we're something special in the universe. But it's not. Yeah,

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Speaker 1: all this stuff is everywhere. It's kind of you know,

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Speaker 1: it's kind of like you know when you you're a

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Speaker 1: certain age and you find this book that you really

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Speaker 1: dig and you're like, oh, my goodness, is it the

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Speaker 1: most n album? Say it's an album by a group,

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Speaker 1: and you're like, how this is the most precious thing? This?

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Speaker 1: I love this, this album in this book so much.

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Speaker 1: It speaks directly to me. The artist is speaking directly

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Speaker 1: to me, and only I can really appreciate it in

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Speaker 1: the way that I'm appreciating it now. And then you realize, oh,

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Speaker 1: it's a nation nationwide bestseller, or it's it's on the

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Speaker 1: top ten Billboard charts, or you know, the went triple

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Speaker 1: platinum or whatever, and you realize, oh, actually, this appeals

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Speaker 1: to a lot of people, and I am not special

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Speaker 1: in liking it. Yeah, and you discover that it's playing

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Speaker 1: throughout the universe, right, the same music, and it's the

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Speaker 1: same elements, those same ingredients that make us that are

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Speaker 1: out there in the stars. But we've talked about this before,

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Speaker 1: because you've talked about if his start implodes um, you know,

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Speaker 1: it's throwing out all sorts of material into the universe.

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Speaker 1: And you know, there's that the great quote by Lawrence

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Speaker 1: Cross says, you know the atoms in your right hand

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Speaker 1: are in your left hand all came from that one

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Speaker 1: star exploding. So it makes sense. This is this is

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Speaker 1: the stuff that's making that soup. This is the base

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Speaker 1: of the soup. Um. And if you take that logic,

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Speaker 1: then you start to say, Okay, it's not unique. This

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Speaker 1: is a recipe that could be executed elsewhere on the universe. Yes,

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Speaker 1: But of course the thing about recipes. Um, so we

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Speaker 1: all know is that it's it's not merely enough to

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Speaker 1: know what goes in, but you have to know, uh

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Speaker 1: what amounts going You need to know is it is

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Speaker 1: it a tablespoon of salt or a teaspoon of salt?

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Speaker 1: Um makes the world of difference. Um, are certain substitutions allowed,

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Speaker 1: which ones are not? How are you heating it? How

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Speaker 1: are you preparing it to make all the difference in

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Speaker 1: in the ultimate outcome of the recipe? And likewise there

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Speaker 1: is a lot of that to take into account, just

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Speaker 1: chemically with with Earth and life on Earth. In his

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Speaker 1: book The Autographs, Diyson points out the oxygen thing. You

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Speaker 1: need a lot of free oxygen and that needs to

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Speaker 1: be supported by some sort of a system on our

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Speaker 1: planet's ported of course, by all the vegetation that we

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Speaker 1: we have on this planet. So you have to have

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Speaker 1: the right circumstances in place to allow the right chemical

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Speaker 1: situation to be in order. So evolution is kind of

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Speaker 1: like the baking time, right. So if it takes ten

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Speaker 1: billion years for a planet become hospitable, then that's ten

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Speaker 1: billion years of baking time. And so you have to

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Speaker 1: consider that when when we're talking about exo planets, and

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Speaker 1: we're talking about them being just the right distance from

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Speaker 1: the star or um from a sent or a moon

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Speaker 1: to have the correct elements there for the baking. Right,

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Speaker 1: that's just one aspect of it. But again, the ingredients

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Speaker 1: for the recipe your out there, which makes it so

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Speaker 1: tantalizing of a question of whether or not there exists

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Speaker 1: other life and intelligent life at that UM. Of course,

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Speaker 1: we had to go back to something called the Copernican principle,

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Speaker 1: uh to really sort of understand how life may not

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Speaker 1: be that special in the first place. Yeah. And then this,

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Speaker 1: of course kind from should say chemical life. Yes, this

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Speaker 1: of course comes to us from a mid Polish astronomer,

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Speaker 1: Nicolas Copernicus. Um and uh. And basically the whole deal

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Speaker 1: here is that we're nothing special, and that you cannot

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Speaker 1: enter a scientific analysis of the universe with the idea

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Speaker 1: that we're something special. There are a number of different

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Speaker 1: things that spin off of this, For instance, UM. In

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Speaker 1: nineteen seventy four, astronomer Brandon Carter tackled the quandary of

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Speaker 1: our anti anthropic coincidence, the idea that there are a

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Speaker 1: number of coincidences that supposedly make life on Earth possible UM,

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Speaker 1: and he hypothesized that these coincidence are part of the

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Speaker 1: universe very structure, and the chance has nothing to do

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Speaker 1: with it. He proposed two variants, the most important what

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Speaker 1: we're talking about here is the strong anthropic principle UH.

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Speaker 1: And in this he drew on the Copernican principle UH,

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Speaker 1: which again states that there's nothing special or privileged about

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Speaker 1: Earth or humanity. Uh. We live in a universe capable

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Speaker 1: of supporting life than than only life supporting universes are possible.

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Speaker 1: You can really go down the rabbit hole with this,

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Speaker 1: But essentially it's about putting aside any idea that we

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Speaker 1: are special. Again, the the the album is a hit

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Speaker 1: around the universe that the building blocks are out there. Uh.

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Speaker 1: We can't enter into any kind of an analysis of

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Speaker 1: or even of a pondering of life else where in

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Speaker 1: the universe if we're thinking that we're special in some way. Yeah.

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Speaker 1: And what I really like about the comparonic in principle

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Speaker 1: is that it does show an evolution of understanding of

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Speaker 1: our place in the universe, because you know, Comparnicas of

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Speaker 1: sitting there saying at a time where everybody was thinking

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Speaker 1: the opposite is saying, hey, the Earth is not the

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Speaker 1: center of our solar system. And so, of course that

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Speaker 1: was a crazy thought at the time. Yeah, because for

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Speaker 1: the longest, Yeah, Earth has to be the center. We're

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Speaker 1: the center God's blessed creation. So we should be right

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Speaker 1: there at the center. How can this whole thing not

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Speaker 1: be about us? Right? We are it right? Um. But

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Speaker 1: then there's this idea that evolves even more like, okay, hey,

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Speaker 1: well we're not the center of the Solar system in

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Speaker 1: the Milky Way, by the way, our Milky Way, our

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Speaker 1: galaxy is not the center of universe. In fact, we're

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Speaker 1: not quite sure what the center is. Is there a center? Um?

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Speaker 1: So you really do see this, This understanding become much

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Speaker 1: more complex and nuanced as we get more and more

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Speaker 1: data from the world around us, because now we understand

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Speaker 1: that Earth is just one of billions of planets that

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Speaker 1: are all bathing in the same sort of primary chemicals. Um.

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Speaker 1: So that gets us to this area called the Drake equation.

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Speaker 1: So we really have to talk about this before we

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Speaker 1: can even sort of say, okay, we'll do aliens exist,

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Speaker 1: How would they exist? How would we contact them? All? Right,

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Speaker 1: We're gonna take a quick break and when we come

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Speaker 1: back even more on the search for extraterrestrial intelligence. Yes,

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Speaker 1: the Drake equation. So the Drake equation is pretty widely known.

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Speaker 1: It's been spun off into a number of interesting little

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Speaker 1: side projects, like there was a there's a really good

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Speaker 1: episode of This American Life where that's a team of

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Speaker 1: scientists try to use the Drake equation to determine whether

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Speaker 1: they have a true love match out there in the

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Speaker 1: world waiting for them, as opposed to is there another

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Speaker 1: life form or other life forms elsewhere in the galaxy. Yeah,

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Speaker 1: because I want to say this just at the front here,

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Speaker 1: that the Drake equation is not something that is solvable.

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Speaker 1: It is it's really about probabilities and how to organize

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Speaker 1: our thoughts about the data that we have in the

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Speaker 1: missing data. Yeah, it's about taking the one big question,

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Speaker 1: the one big probability is their life else from in

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Speaker 1: the universe, and breaking it down into smaller questions, smaller

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Speaker 1: probabilities that we can tackle individually. So the entire equation

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Speaker 1: looks like this, and and this is not gonna all

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Speaker 1: make a lot of sense, but just in the in

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Speaker 1: the in the interest of getting out there, it is

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Speaker 1: in equals our star multiplied by F sub p multiplied

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Speaker 1: by in sub multiplied by F sub F sub l

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Speaker 1: multiplied by F sub i multiplied by F subc multiplied

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Speaker 1: by capital l. And so all those numbers must by

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Speaker 1: together help us to estimate the number in of technical

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Speaker 1: logical civilizations that might be able to detect us right now. Now,

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Speaker 1: if you guys all bear with me, let me unpack

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Speaker 1: that a little bit, because I do think it's interesting.

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Speaker 1: Um our star is the rate at which stars have

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Speaker 1: been born in the Milky Way galaxy over the last

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Speaker 1: few billion years. That stars per year, okay, And then

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Speaker 1: all the f factors in this are fractions. So F

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Speaker 1: sub p is a fraction of stars that have planets,

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Speaker 1: and sub e is the average number of habitable planets

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Speaker 1: in any planetary system. F sub l is the fraction

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Speaker 1: of planets on which life actually begins. F sub i

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Speaker 1: is a fraction of all those life forms that develop intelligency.

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Speaker 1: How this becomes Tinier and jiner um. And then F

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Speaker 1: sub c is the fraction of intelligent life that develop

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Speaker 1: a civilization that uses some sort of transmitting technology. Finally, L,

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Speaker 1: which is really important here, and we'll talk more about

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Speaker 1: this later l is the longevity factor. On average, how

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Speaker 1: many years do those transmitters continue to operate, because, as

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Speaker 1: we know, civilizations come and go. Yeah, Like I kind

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Speaker 1: of like to think of it in terms of a

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Speaker 1: video store, like you know, and some of you may ask,

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Speaker 1: what what what is that? Because they are starting to

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Speaker 1: disappear more and more. But like in the Atlanta we

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Speaker 1: have this really cool video store called Video Drome. I

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Speaker 1: still like to go there just to brows around for

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Speaker 1: nostalgia and nothing else. But you know, I walk into

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Speaker 1: a video store and I have, you know, X number

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Speaker 1: of videos at my disposal for possible rent. But then

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Speaker 1: you have to you have to carve that down all right,

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Speaker 1: of all the videos here, I can only check out

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Speaker 1: ones that are checked in, so that dude decreases the number.

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Speaker 1: Then maybe I'm only interested in seeing an English language

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Speaker 1: film because I don't want to read subtitles tonight, So

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Speaker 1: then we have to cut that down. Then I must

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Speaker 1: say I'm only interested in seeing a horror movie, so

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Speaker 1: that cuts it down even more. And then I only

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Speaker 1: interested in seeing a horror movie that I haven't already seen,

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Speaker 1: so that cuts it down even more. And again you

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Speaker 1: just get down to there are x number of films

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Speaker 1: that I could potentially rent this evening. Now, what I

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Speaker 1: think is cool about this dract equation is that, yes,

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Speaker 1: there's no righting answer right now, and this is just

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Speaker 1: a way of organizing information because a lot of it

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Speaker 1: does depend on who's plugging in the data and why

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Speaker 1: right in the same way that my data I plug

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Speaker 1: into this video drum equation could be different one day

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Speaker 1: from the next. The deal is, though, is that astronomers

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Speaker 1: are actually getting at this equation right. They've already tried

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Speaker 1: to figure out about three of those different fractions, So

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Speaker 1: they're trying to figure out the fraction of stars planets,

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Speaker 1: the average number of habitable planets, and the fraction of

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Speaker 1: planets on which life actually begins. So they're getting to that.

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Speaker 1: So when I talk about exit planets that are habitable

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Speaker 1: and that goldilocks not too hot, not too cold, that'

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Speaker 1: from one aspect of it that they're beginning to collect

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Speaker 1: data on um and they're beginning to say like, okay, well,

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Speaker 1: now we can get these chemical signatures and try to

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Speaker 1: figure out, you know, how much carbon is being produced there,

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Speaker 1: how much method sane which you know something we'll talk

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Speaker 1: more about as pretty plentiful here on Earth, and that's

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Speaker 1: a that's a huge signal if there's something going on

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Speaker 1: on that planet, right probably probably cows as well as

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Speaker 1: other you know, factors that that create methane that I

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Speaker 1: won't go into. Uh, But anyway, my point is is

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Speaker 1: that yes, this is, uh, this is somewhat of a

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Speaker 1: thought experiment, but astronomers are scratching away at it and

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Speaker 1: they're getting some concrete information in there. Yeah. Um, I

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Speaker 1: mean historically whether the estimate the results have varied again

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Speaker 1: depending on what's going into it, and they varied from

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Speaker 1: there being one one but one civilization out there two millions.

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Speaker 1: So yeah, right, Again, there's a lot of data that

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Speaker 1: needs to be plugged in here, but astronomers are if

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Speaker 1: if you will, plugging away at that. Now, I wanted

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Speaker 1: to mention the Fermi paradox, and this is something I

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Speaker 1: want you guys to all put in your back pocket

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Speaker 1: as you consider all the other information that we talked

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Speaker 1: about today. The Fermi paradox is from the Noble Prize

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Speaker 1: winning physicist and Rico Fantom and he reasoned that if

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Speaker 1: it takes life billions of years, should develop intelligence and

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Speaker 1: signal or travel to the stars. And if there are

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Speaker 1: billions of worlds in the universe, and if the universe

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Speaker 1: is over thirteen billion years old, then why haven't we

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Speaker 1: been visited by an extra terrestrial or why isn't the

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Speaker 1: galaxy crawling with extraterrestrials. This is something we'll get too later.

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Speaker 1: But that's that's a good question, right, yeah, I mean

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Speaker 1: it's Stephen Hawking brought up the same thing with time travel.

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Speaker 1: You have if time travel was possible, is possible, will

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Speaker 1: be possible? When I have we not been visited by

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Speaker 1: a time traveler. Like it's just kind of a basic,

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Speaker 1: you know, show me level of of of analysis. Okay,

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Speaker 1: they're aliens, great, show me one, show me the alien

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Speaker 1: put it on the table for me to see because

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Speaker 1: the time traveler erased our memory, and certainly you could,

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Speaker 1: you can, you can roll out varying levels of conspiracy

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Speaker 1: and and explanations on top of it. But you know,

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Speaker 1: at the at the very root, it's it's a question

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Speaker 1: of all right, if they're aliens, then we should have

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Speaker 1: seen them, We should see them, and then you can

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Speaker 1: you can apply your own excuses as to why don't

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Speaker 1: we have not Alright, Well, On that note, we're going

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Speaker 1: to actually call this an episode. We're splitting the SETI

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Speaker 1: episode up into two episodes, so this was part one.

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Speaker 1: Part two will publish very shortly, so be on the

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Speaker 1: lookout for that in the time being. If you have

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Speaker 1: any kind of feedback on part one, you can find

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Speaker 1: us on Facebook and you can find us on tumbler.

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Speaker 1: We are stuff to blow your mind on both of

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Speaker 1: those and we use the handle blow the Mind on Twitter,

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Speaker 1: and you can always drop us a line at below

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Speaker 1: the Mind at Discovery dot com. For more on this

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Speaker 1: and thousands of other topics, Is it how Stuff Works

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Speaker 1: dot com