# Basis of science's belief that extraterrestrial life is likely? **URL:** \ **Category:** Factual Questions\ **Created:** [November 9, 2010, 7:59pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078 "2010-11-09T19:59:16Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 9, 2010, 11:58pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/41 "2010-11-09T23:58:01Z")
> [@Whack-a-Mole](#): > > You can nitpick all you like. > > You are correct that we just do not know. There could be only us or there could be billions of planets with life on them out there. > > Currently there is no way to say and we can only guess. > > The point is what would you do if you were a betting man? > > Pretend you are forced to put all your money and worldly possession up on a single bet (you have no choice in my hypothetical). This is an all or nothing bet…double your net worth or lose it all. > > You have to bet if the Earth is the only planet in the whole universe with life on it or if at least one other planet, besides the earth, has life on it. Once you place your bet the answer will be revealed and with the magic of hypotheticals we will pretend that answer is indisputably correct. > > So, which way would you place your bet? Given Blake’s views, isn’t this kind of like asking him to bet on the probability that the sentence I’m thinking of in my head is false? He has no basis for making a bet. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 9, 2010, 11:59pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/42 "2010-11-09T23:59:12Z")
Given that one of the terms in the Drake Equation From wikipedia: > [@](#): > > [The Drake equation](http://en.wikipedia.org/wiki/Drake_equation) states that: > > ``` > N = R^{\ast} imes f_p imes n_e imes f_{\ell} imes f_i imes f_c imes L \! > > ``` > > where: > > ``` > N = the number of civilizations in our galaxy with which communication might be possible; > > ``` > > and > > ``` > R* = the average rate of star formation per year in our galaxy > fp = the fraction of those stars that have planets > ne = the average number of planets that can potentially support life per star that has planets > fℓ = the fraction of the above that actually go on to develop life at some point > fi = the fraction of the above that actually go on to develop intelligent life > fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space > L = the length of time such civilizations release detectable signals into space. > > ``` Since one of the terms in the equation is “fℓ = the fraction of the above that actually go on to develop life at some point”, I don’t see how you can use the Drake equation to say how likely it is that a planet capable of supporting life will go on to develop life at some point. It is an unknown value, and we can plug in whatever number seems good to us. It could be .97, or 0.00000000000001. The Drake equation is just a way of trying to make explicit our assumptions about how likely we are to find extraterrestrial life. But we can only guess at most of those terms. We know pretty well how many stars there are in the galaxy, and in the last decade we’ve determined that planets are pretty common, and we’ve found a couple of bodies that are at the right distance from their star that liquid water might exist. But even if liquid water might exist at that distance, it doesn’t prove it does exist–the Earth and the Moon are at the same average distance from the Sun, and yet the Moon isn’t covered with liquid water. And so all the Drake Equation does is give us more things to disagree about. But at least we’d be disagreeing on a higher level. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [November 10, 2010, 12:03am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/43 "2010-11-10T00:03:53Z")
I’m just going to throw in a quick plug for “At Home in the Universe” by Stuart Kauffman. It’s a decade or two old now, but he argues convincingly for the idea that the emergence of life, rather than being vanishingly unlikely, could actually be all but inevitable given a system of sufficient chemical complexity. He backs this up with computer simulations. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 10, 2010, 12:04am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/44 "2010-11-10T00:04:33Z")
Light is light, heat is heat, water is water, chemical stability is chemical stability, and energy flow in an open system is energy flow in an open system. There’s no orgone field or or any particular specialness about earth’s placement in the universe that anyone can point to and say “This is why we won the lottery of abiogenesis” There’s not even proof that abiogenesis ever occurred on earth. If folks want to claim that there’s something special, or unique, about earth’s place in the universe, they ought to make an effort to point out something that can be verified as a special uniqueness. Otherwise, [Occam](http://en.wikipedia.org/wiki/Occam%27s_razor) tells us we’re just another gas covered rock in space. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [November 10, 2010, 12:06am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/45 "2010-11-10T00:06:25Z")
> [@xtisme](#): > > We now (approximately) the conditions necessary to have life originate. Do we? If so then why are there so many papers in premier journals that posit an extraterrestrial origin of life? There are serious journal articles that posit that the first amino acids and even proteins originated in interstellar gas clouds. Could you tell me what you believe these approximate conditions for the origin of life are, and how you ascertained them. > [@](#): > > We know that there are … billions of years of windows in which some non-zero number of those planets would have the conditions and materials in which life COULD originate on them. Do we? For example if life really does require an anomalously large, Earth type moon to exist \*before \*it gets seeded from a nebula, just as two possible factors, then what are the odds of that happening? It requires a large planetoid in an irregular orbit striking at precisely the right speed and angle to knock off a large chunk of the planet and have it go into orbit. After this has happened and the planet cools, it then needs needs to pass through a seeding nebula. How we know that there are billions of planets with such moons that subsequently passed though a seeding nebula for billions of years? > [@](#): > > Even leaving aside the non-zero probability that like from this planet could have been spread through impacts, that’s a huge number of chances for life to be in the universe during windows of time stretching billions of years. But this is a total non sequitur. If only one planet in 10^9999 ^999 ever has the right conditions for life, then how can you possibly conclude that there are huge number of chances. At that probability the chances are so close to zero as makes no difference. > [@](#): > > It’s not a ‘conclusion’…it’s a belief, as was said in the subject of the OP. THAT is the basis by which ‘science’ posits that ‘extraterrestrial life is likely’. As Dio is fond of saying, if it requires faith then it isn’t science. > [@](#): > > Um, they HAVE told you how they reached the conclusions they reached. You may not agree, and since we don’t know the answer there is no way to determine who is right and who is wrong, but you can’t say no one has told you how they reached the conclusions they reached. There is no way to know a lot of things in science, so extrapolation and theory are used. No, nobody has told me how they calculated the probability of life arising on Earth. If I am mistaken then please quote where somebody explains how they arrived at the figure they used. > [@](#): > > Because based on experimentation and theory into the conditions and possible methods that caused life to originate it seems ridiculously pessimistic. Actually, based on experimentation and theory into the conditions and possible methods that caused life to originate it seems ridiculously optimistic. And this is the problem with argument through assertion. I can assert the exact opposite.. Which experiments lead to that conclusion? What conditions? > [@](#): > > Also, I’ve never seen any scientists posit such a low probability for anything outside of something like magic or leprechauns spontaneously originating somewhere in the universe. Scientists have no idea and can have what the probability is. Zero degrees of freedom, remember The low numbers must be as acceptable to scientists as any higher. If it’s not then they aren’t doing science. > [@](#): > > Considering that humans are taking the first steps to creating life ourselves, your assertion seems extreme to me. What does the action of an intelligence have to do with anything? Humans are also creating race cars. Does that mean that the odds of a race car spontaneously generating are high? I honestly can’t see what relevance this statement has to the discussion. > [@](#): > > We have a sample size of one, no doubt. So what? I’ve seen theories that spring up about a single bone from a single species that lived 10’s of millions or 100’s of millions of years ago. And? I honestly don;t know what point you are trying to make here. What precisely is the relevance of single samples of bones to the discussion. > [@](#): > > That’s what science is all about…making theories and testing them. And this theory (that there is life in the universe) is certainly testable…heck, we are testing for it right here in our own solar system.p So it’s being tested. So far the tests have all totally failed to find any life elsewhere, right? So how does this invalidate a position that life never arose elsewhere? > [@](#): > > I’m not making a declaration You did make a declaration though. I;m happy enough now that you have retracted it. > [@](#): > > …I’m saying that this is why ‘science’ (by which I presume the OP means a large number of interested or involved scientists) believe ‘that extraterrestrial life is likely’. Meanwhile many others think that it is exceedingly unlikely. The pertinent point being that there is exactly the same evidence either way. > [@](#): > > Seems reasonable to me…certainly more reasonable than your > ‘probability against it may be greater than the total number of subatomic particles in the universe’ based on what we know. Why does it seem more reasonable? All you do is keep repeating the same assertion in different forms, without ever saying why you believe that the odds of life originating on Earth was greater than the total number of subatomic particles in the universe. What exactly is it that “we” know that gives you reason to believe this? > [@](#): > > It’s a testable theory, and one that will probably be tested for as long as there are humans around with the ability and desire to test it. Nobody is arguing that some theory may be testable. The argument is whether the basis is logical. So far, on those grounds, it has failed. All the testing supports the notion that there is no life outside Earth, correct? So any contention to the contrary has to rely on the logical underpinnings of the theory, correct? ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [November 10, 2010, 12:11am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/46 "2010-11-10T00:11:04Z")
One implicit assumption of modern science is the “averageness” of our position in the universe. This assumption is built in because the human tendancy is to assume we’re special, and that the universe (literally) revolves around us. Assuming we’re “nothing special” has served science much better. (I’d include a cite but I can’t remember the formal name for this principle). Of course, to the OP, it’s that unfortunate word “belief” again. I don’t think scientists believe that there is life out there to the extent that if the data showed a sterile universe (bar us) they would refuse to accept it. It’s not a religion. It’s more that the _starting point_ is to assume the Earth is not exceptional. ---
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [November 10, 2010, 12:12am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/47 "2010-11-10T00:12:23Z")
Just an aside: it never ceases to amaze me how the religious will insist that it’s impossible for life to have arisen by any means that doesn’t include an intelligent creator. Impossible??? IMPOSSIBLE??? How does ANYONE who believes in an all-powerful creator that just “is” have the TEMERITY to use the word “impossible” about anything at all, much less the origin of life?? AND expect to be taken seriously??? REALLY? \<—Seth and Amy ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 10, 2010, 12:16am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/48 "2010-11-10T00:16:02Z")
Back to the lottery idea. I guess the reason I don’t like the analogy is that we know that the odds of winning the lottery are small, so we know that the population of lottery winners is biased. However, we don’t know the value of the likelihood of life arising. If the probability is large, then our sample size of 1 isn’t biased. If the probability is small then we know our sample is biased. But we don’t know. However, I think a better analogy is to dice rolling. Let’s say Bob goes to a casino and plays a dice rolling game. We don’t know how the game works, but we know that Bob played for only a million years, and won the game. Given that he won the game in that time period, what can we say about the probability of winning? That is, if he got to roll the dice a million times a year, and did it over a million years, and won, we could use [Bayesian probability](http://en.wikipedia.org/wiki/Bayesian_probability) to work out an idea of how hard the game was likely to be. I’m not sure exactly how to do this, because Bayesian reasoning makes my head hurt. ---
**Author:** ![Diogenes\_the\_Cynic](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@Diogenes\_the\_Cynic](https://boards.straightdope.com/u/Diogenes_the_Cynic)\ **Post date:** [November 10, 2010, 12:17am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/49 "2010-11-10T00:17:02Z")
> [@Grateful-UnDead](#): > > I have a vague recollection that Carl Sagan and some of his fellow cosmologists put together a list of some forty or fifty physical criteria that were required for life to exist on a planet. > > These criteria included such things as the location of the star in the galaxy, the type of star, proximity to that star, proximity to other stars, physical composition of the planet, size of the planet, age of the planet, etc etc. > > Given the extreme improbability of any planet meeting all of the specified criteria, the conclusion drawn was that life anywhere other than on earth is extremely improbable Actually, it’s a mathematical certainty that the conditions will be met billions of times. They’ll just etnd to be spread very far apart. ---
**Author:** ![Diogenes\_the\_Cynic](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@Diogenes\_the\_Cynic](https://boards.straightdope.com/u/Diogenes_the_Cynic)\ **Post date:** [November 10, 2010, 12:19am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/50 "2010-11-10T00:19:27Z")
> [@Stoid](#): > > This is the scientific summation of my thoughts exactly. There’s nothing scientific about it. ---
**Author:** ![Diogenes\_the\_Cynic](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@Diogenes\_the\_Cynic](https://boards.straightdope.com/u/Diogenes_the_Cynic)\ **Post date:** [November 10, 2010, 12:24am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/51 "2010-11-10T00:24:37Z")
> [@Stoid](#): > > Yes, this is another issue I have… why in the world would smarty-pants scientists make the silly assumption that life only comes in the “needs water & oxygen in a narrow range of temperatures” variety? They don’t assume it, but they know this combination works, so they’re being conservative by only considering what they already know can happen. ---
**Author:** ![Grateful-UnDead](https://avatars.discourse-cdn.com/v4/letter/g/ccd318/32.png) [@Grateful-UnDead](https://boards.straightdope.com/u/Grateful-UnDead)\ **Post date:** [November 10, 2010, 12:27am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/52 "2010-11-10T00:27:02Z")
> [@Diogenes\_the\_Cynic](#): > > Actually, it’s a mathematical certainty that the conditions will be met billions of times. They’ll just etnd to be spread very far apart. Oh??? I suggest that the first step would be to reconstruct the list of criteria; then apply those criteria to our own galaxy. Seems to me the odds of finding another planet that met the criteria would be negligible. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 10, 2010, 12:30am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/53 "2010-11-10T00:30:28Z")
> [@Diogenes\_the\_Cynic](#): > > Actually, it’s a mathematical certainty that the conditions will be met billions of times. They’ll just etnd to be spread very far apart. You’re going to have to produce some numbers before this claim has any credibility. Note by the way that the above comment is coming from someone _sympathetic_ to your position. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [November 10, 2010, 12:31am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/54 "2010-11-10T00:31:56Z")
> [@Whack-a-Mole](#): > > You can nitpick all you like. You made a statement of fact in GQ. I called you on it, and you then admitted that you had no basis whatsoever for the claim. That is not nitpicking. That is the whole reason we are here. This forum is for factual answers. As it transpires your statement wasn’t fact, though you presented it as one. > [@](#): > > You are correct that we just do not know. There could be only us or there could be billions of planets with life on them out there. > > Currently there is no way to say and we can only guess. So you have gone from total disagreement with me, to utter and total wholehearted agreement? Good. We both agree. > [@](#): > > The point is what would you do if you were a betting man? Not bet. There is going to be a cockfight in a tin shed in downtown Hanoi tonight. Two birds are fighting, we’ll call them A and B. Which rooster are you going to bet on would you bet on if you were a betting man? Your question is literally that ridiculous. You have no information whatsoever upon which to place your bet. Why on Earth would you make the bet in the first place? And if you did place the bet, why would you believe that either choice was better? Really, you have just admitted that we do not know whether life is ubiquitous or unique. Your own words: “there is no way to say and we can only guess.” Yet for some reason you are prepared to take bets that it is ubiquitous. :dubious: > [@](#): > > Pretend you are forced to put all your money and worldly possession up on a single bet (you have no choice in my hypothetical). This is an all or nothing bet…double your net worth or lose it all. I’ll offer you the same conditions on my bet. I mean it, really. We’ll see whether you really believe what you are saying or whether you know this is nonsense. Here are the conditions. We’ll have a doper select a random date, another select a random city and two more select random numbers. Then we’ll put them together. The result is the date, gym, boxer and match number you are betting on. You will have to put all your money and worldly possession up on a single bet on that boxer, you get to choose whether to bet on a win or a loss. If you lose I get it all. If you win I’ll double it. Of course you have to make your decision to gamble before the numbers are selected so that, as you yourself said, “there is no way to say and you can only guess” which way to bet. So which way do you want to bet? Will your boxer win or lose. Your bet is at least as ridiculous as this. You admit yourself that “there is no way to say and we can only guess” what the result is. > [@](#): > > So, which way would you place your bet and why? The same right back at you. ---
**Author:** ![Diogenes\_the\_Cynic](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@Diogenes\_the\_Cynic](https://boards.straightdope.com/u/Diogenes_the_Cynic)\ **Post date:** [November 10, 2010, 12:36am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/55 "2010-11-10T00:36:51Z")
> [@Grateful-UnDead](#): > > Oh??? > > I suggest that the first step would be to reconstruct the list of criteria; then apply those criteria to our own galaxy. > > Seems to me the odds of finding another planet that met the criteria would be negligible. There are 500 billion stars in our galaxy. If the proper planetary conditions occur on one in a billion stars then it would happen 500 times in our galaxy, and there are hundreds of billions of other galaxies. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [November 10, 2010, 12:36am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/56 "2010-11-10T00:36:57Z")
> [@Lemur866](#): > > Given that one of the terms in the Drake Equation > > From wikipedia: > > Since one of the terms in the equation is “fℓ = the fraction of the above that actually go on to develop life at some point”, I don’t see how you can use the Drake equation to say how likely it is that a planet capable of supporting life will go on to develop life at some point. It is an unknown value, and we can plug in whatever number seems good to us. It could be .97, or 0.00000000000001. > [@Blake](#): > > Well since this is GQ, can you please show us the equations that you used to ascertain these probabilities? > > > [@Diogenes\_the\_Cynic](#): > > > > Look at the Drake equation posted above. It’s not magical thinking. Seems like **Dio** disagrees with you. 😃 Since he is refusing to even address our criticisms, it seems that he has realised how silly what he said was. It would be nice if he would admit it though. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [November 10, 2010, 12:42am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/57 "2010-11-10T00:42:11Z")
> [@Lemur866](#): > > Back to the lottery idea. > > I guess the reason I don’t like the analogy is that we know that the odds of winning the lottery are small, so we know that the population of lottery winners is biased. That is the whole point of the analogy. It illustrates that using self selected winners will result in an unreliable probability _where the odds of winning are small_. Now assume that the odds of life originating on any planet are small. What does the selection of our planet due to our living here do to our ability to predict the odds of life arising? Do you agree that if the odds were small we could not get an accurate probability? That any probabilities we calculate will be grossly overblown if the odds are low? If so then the analogy is perfect. ---
**Author:** ![Diogenes\_the\_Cynic](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@Diogenes\_the\_Cynic](https://boards.straightdope.com/u/Diogenes_the_Cynic)\ **Post date:** [November 10, 2010, 12:42am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/58 "2010-11-10T00:42:33Z")
There isn’t any point to arguing with creationists. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 10, 2010, 12:45am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/59 "2010-11-10T00:45:15Z")
> [@Diogenes\_the\_Cynic](#): > > There are 500 billion stars in our galaxy. If the proper planetary conditions occur on one in a billion stars then it would happen 500 times in our galaxy, and there are hundreds of billions of other galaxies. For your argument to have creditability, you need to tell us what the probability of life arising on an earthlike planet is, and how you arrived at that probability. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [November 10, 2010, 12:46am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078/60 "2010-11-10T00:46:39Z")
> [@Diogenes\_the\_Cynic](#): > > There are 500 billion stars in our galaxy. If the proper planetary conditions occur on one in a billion stars then it would happen 500 times in our galaxy, and there are hundreds of billions of other galaxies. And if the proper planetary conditions occur on one in a 10^87 stars? Then of course it’s a near certainty that life doesn’t exist anywhere else. The point \*\*Dio \*\*refuses to admit is that my figure is precisely as plausible as his. We both have exactly the same amount of evidence and logic for each of our figures. I have asked \*\*Dio \*\*multiple times in this thread to show us how he obtained his figure, but he just handwaves to the Wikipedia article Drake Equation", even though the article itself notes that the equation can produce any answer at all with exactly the same validity. [Previous page](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078.md?page=2) [Next page](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560078.md?page=4)