# Basis of science's belief that extraterrestrial life is likely? **URL:** \ **Category:** Great Debates\ **Created:** [November 10, 2010, 3:43am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137 "2010-11-10T03:43:11Z")\ **Posts on this page:** 20\ **Page:** 3
**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, 5:50am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/41 "2010-11-10T05:50:05Z")
> [@silk1976](#): > > Hence, based on simple probability - it is a good bet that there is life elsewhere. Cite! Since you claim that this is based on probability, you will be able to show us the probability equations used and the resulting probability, yes? I am eager to see these, especially the part that determines in the probability of life arising on an Earth-like planet. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [November 10, 2010, 5:53am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/42 "2010-11-10T05:53:44Z")
> [@Diogenes\_the\_Cynic](#): > > No, I don’t mean that part. I mean (among other parts) this part: > > That follows a summary of the failures to so far disprove a biotic origin. Life is still the best hypothesis. If you disagree name a better one. I don’t have to. Do you know the difference between a hypothesis and a theory or an established fact? This is a hypothesis. From your own quote: > [@](#): > > there is "strong evidence that life may have existed This is not a statement of fact, as you put forth above: > [@DtC](#): > > That’s abiogenesis twice in one solar system. I’m not arguing that it might or might not be true, only that we don’t now know whether it is or not. ---
**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, 5:54am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/43 "2010-11-10T05:54:47Z")
The question has been answered over and over again. Incessently shrieking, “Cite!” is not a refutation. Abiogensis was a chemical process. The conditions which led to that process were not unique to earth. Abiognesis is not magic, just molecules bumping together. If it can happen here, it can happen elsewhere. It’s not an extarordinary assumption. What’s extraordinary is inssisting that the conditions on earth are unique without being able to cite anything that’s unique about them. ---
**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, 5:55am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/44 "2010-11-10T05:55:50Z")
> [@John\_Mace](#): > > I don’t have to. Do you know the difference between a hypothesis and a theory or an established fact? I didn’t say it was a fact, I said it was the strongest hypothesis. ---
**Author:** ![JThunder](https://avatars.discourse-cdn.com/v4/letter/j/e95f7d/32.png) [@JThunder](https://boards.straightdope.com/u/JThunder)\ **Post date:** [November 10, 2010, 5:57am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/45 "2010-11-10T05:57:40Z")
**Diogenes** , you specifically said, “That’s abiogenesis twice in one solar system.” You most certainly did present it as an established fact rather than a mere hypothesis. ---
**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, 5:59am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/46 "2010-11-10T05:59:27Z")
Well, I didn’t mean to. I meant to say something like, “that would be twice.” Poor phrasing. Still, that probably is life on that rock. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [November 10, 2010, 5:59am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/47 "2010-11-10T05:59:43Z")
> [@Diogenes\_the\_Cynic](#): > > I didn’t say it was a fact, I said it was the strongest hypothesis. You said: > [@](#): > > That’s abiogenesis twice in one solar system. That is a statement of fact. If you want to take it back, that’s great. Please do so. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [November 10, 2010, 6:00am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/48 "2010-11-10T06:00:50Z")
> [@Diogenes\_the\_Cynic](#): > > Well, I didn’t mean to. I meant to say something like, “that would be twice.” Poor phrasing. Still, that probably is life on that rock. “That would be twice” is still a statement of fact. ---
**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, 6:02am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/49 "2010-11-10T06:02:25Z")
Yes it would be because it would be conditional. ---
**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, 6:04am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/50 "2010-11-10T06:04:46Z")
> [@John\_Mace](#): > > It could be, but why would it be? Which is just an argument from ignorance. All you are saying is that we don’t know it is unique, so it must be unique. > [@](#): > > Yes, it does, provided a large enough sample size. Really? So because the man who got struck by a meteorite was the same as a given sample population that allows you to determine how common meteor deaths are? In that case, predict how common will meteor deaths be if I tell you that the sample is 10? How common if I tell you that the sample size is 10, 000, 000? How common if 10^87? Please show your working. Our sample size is one. Is that large enough > [@](#): > > Except that his ordinariness is only one part of the equation. The other part being the frequency of meteorite strikes. No, the frequency of meteorite strikes is what you need to calculate. It is the required answer, not a constant. You said that planets that you can calculate how likely life is to arise (the probability event) by knowing how many planets are similar to our single sample planet, Earth. Using this a logic you must also be bale to calculate how many people get struck by meteorites by knowing how many men are similar to the single man in history who got struck by a meteorite. You need to tell me how common meteorite strikes are based on similarity of victims in order for your assertion to hold up. To keep things clear, meteorite strikes and the origin of life maybe events so rare that the number of possible candidates has negligible effects on their occurrence. It wouldn’t matter if the man who got struck by a meteor had a billion billion identical twins, there would still only have been one man ever struck by a meteor. Although the number of potential candidates might seem to increase the number slightly, if the odds of it happening even once are less than the total number of particles that have ever existed, then increasing the number of similar people has no appreciable effect on the outcome. The number of similar people could be infinitely high, and it would still be unlikely to happen twice. Do you agree? ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [November 10, 2010, 6:08am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/51 "2010-11-10T06:08:00Z")
> [@Diogenes\_the\_Cynic](#): > > Yes it would be because it would be conditional. It would be only if it were true. We don’t know that it is true. You were wrong in your original statement, and anything short of acknowledging that is a dodge. The data from Mars is interesting, but completely uninformative wrt to the OP of this thread. It tells us nothing because it is not conclusive. ---
**Author:** ![Saganist](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Saganist](https://boards.straightdope.com/u/Saganist)\ **Post date:** [November 10, 2010, 6:16am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/52 "2010-11-10T06:16:28Z")
I’m with you entirely here, **Blake** , except for one point. You argue that the anthropic principle invalidates our observation that on this planet, life originated quite rapidly. But wasn’t the salient bit not that it developed rapidly to avoid catastrophes, but that it developed almost as soon as conditions reached the point that it would survive? Sure, the AP requires it to develop quickly, but doesn’t the observation of the short time between good conditions becoming available and life appearing say something about the probability being greater than infinitesimal? ---
**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, 6:25am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/53 "2010-11-10T06:25:28Z")
> [@John\_Mace](#): > > It would be only if it were true. We don’t know that it is true. Hence the “would.” This is getting stupid. > [@](#): > > You were wrong in your original statement I just didn’t phrase myself well well. I meant it is an “if…then” type point, but feel free to revel in ths small victory if you like. ---
**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, 6:28am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/54 "2010-11-10T06:28:53Z")
> [@Whack-a-Mole](#): > > You have assiduously evaded making the bet. It is a pretty straightforward thing. No, I told you, it’s a pointless bet with unknowable odds. Why would I take it? > [@](#): > > You did not quote my whole piece where I showed that the conditions to produce the precursors to life have been replicated on a lab table plus a slew of other evidence. No, I addressed the issue. I will try again. 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? It seems like an utter red herring, but if you can show me the equations or argument that allow you to plug in directed intelligent action and derive the probability of a random event producing the same result, then I’ll concede the point. > [@](#): > > You are right that in the end we do not know the real odds. Right, so you agree. We don’t know the odds. We have no idea what the odds are. Yet you are still prepared to take a bet despite admitting both that you don;t know the odds and can not know the odds. You admit that the odds could be a million to one against, or they could be a million to one for. Yet for some crazy reason you expect me to take the bet. I’ll take your bet with the unknowable odds when you take mine. Deal? > [@](#): > > You took exception in the other thread that no life was more unlikely than life. This despite the evidence we do know that life is tenacious and survives in remarkably unlikely places a human could never exist in right here on earth. This is the biggest noon-sequitur I have ever seen. This is derived life, not proto-life or early life. How does it tell us a damn thing? So life can survive anywhere. Ho does that tell you a damn thing about where it can arise? My laptop can work in the tropical rainforest, do you really think that means that it must be possible to \*build \*a laptop in the non-sterile raindrenched forest? A lion can survive in the desert in 40o heat with no food for weeks on end. Do you think this means I can leave a day old cub in the desert in 40o heat with no food for weeks on end? Life survive on bare rocks, in hypersaline water and in radioactive waste. Do you really believe that it is equally probable for life to arise in all those places Do you actually believe these things, or are you attempting the most blatant non-sequitur I’ve seen on these boards? > [@](#): > > The point though, which again I will note you avoided, is if you had to bet if there where life elsewhere in the universe besides on earth which way would you bet? I have answered this at least three times, quite explicitly. Since you yourself admit that we don’t know the odds. Since you yourself admit that you don’t know the odds and can not know the odds. Since you yourself admit that the odds could be a million to one against, or they could be a million to one for. Since you yourself admit all those things, then I would refuse to take the bet. If I had to take it because somebody held a gun to my head I would flip a coin. Heads I bet yes, tails I bet no. If you really want me to I will flip a coin and tell you my hypothetical answer. Much more interesting is that you will apparently bet yes, despite admitting that the odds could be a million to one against, or they could be a million to one for. Why would you take such an indeterminate bet for such high stakes? > [@](#): > > That is probably the simplest question you have been asked in this discussion and it is the one you refuse to answer. Why is that? You can answer life or no life…just give your reasons for that answer. OK, now I have lost all respect for you. > [@Whack-a-Mole](#): > > [The point is what would you do if you were a betting man? > > > [@Blake](#): > > > > Not bet… 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.]([http://boards.straightdope.com/sdmb/showpost.php?p=13122864&postcount=54](http://boards.straightdope.com/sdmb/showpost.php?p=13122864&postcount=54)) So I clearly and unambiguously answered your question when it was asked, with my reasons why laid out in detail. You can either apologise for blatantly slandering me, or I will not dignify your dishonest presence with any further responses. ---
**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, 6:49am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/55 "2010-11-10T06:49:19Z")
> [@Saganist](#): > > I’m with you entirely here, **Blake** , except for one point. > > You argue that the anthropic principle invalidates our observation that on this planet, life originated quite rapidly. But wasn’t the salient bit not that it developed rapidly to avoid catastrophes, but that it developed almost as soon as conditions reached the point that it would survive? Sure, the AP requires it to develop quickly, but doesn’t the observation of the short time between good conditions becoming available and life appearing say something about the probability being greater than infinitesimal? No. Imagine that life \*did \*only arise rapidly enough to avoid extinction once in the entire universe and that the odds against this happening were so high that it would never, ever happen again even if we could watch the next billion universes come and go. How would the Earth we live on look different today if that were truth? Of course it wouldn’t look any different at all, which is why this data point tells us nothing. The planet _required_a short time between good conditions becoming available and life appearing in order for anybody to \*observe \* the time that it takes life to form. You can’t use the factors that dictate your observation procedure as part of the analysis of the observations. That’s completely invalid. ---
**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, 6:52am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/56 "2010-11-10T06:52:09Z")
Why Diogenes, why can’t you answer my questions? Even if the probability of life arsing on any planet is the low one,nothing in this contention requires Earth to be special. Let’s assume hypothetically that the probability on any given planet is 1/10^87. That is the probability on all planets, 0n any planet. On any given planet. That includes Earth. Earth is not special in any way. It is exactly like all other planets in that regard. The probability of life arising on Earth is not special. In fact it is identical to every other planet in the entire universe, and that probability is 1/10^87. There are no conditions that exist in Earth that don’t exist elsewhere. Earth is totally unremarkable. It has exactly the same probability as life arising, and that probability is 1/10^87. Yet because it is so improbable it can’t have arisen elsewhere. So why is it necessary to show that Earth is special when the entire case hinges on Earth being totally ordinary. How do you know that here is nothing special about the conditions on earth that led to replicating RNA molecules. You stated this nonsense as fact. How do you even know what conditions on earth that led to replicating RNA molecules? PLease provdie a cite. Hell, how do you even know that conditions on earth that led to replicating RNA molecules? PLenty of published scientits disgaree with this hypothesis. So how come you can state it is a fact. I look forward to seeing your references for this outrageous claim. FOR THE SEVENTEENTH TIME IN THIS THREAD. Since this is GQ, can you please show us the equations that you used to ascertain these probabilities? Because this is GQ, and not the forum for baseless opinions, so you must have calculated such probabilities before declaring what they are smaller than. SEVENTEEN TIMES DIO HAS BEEN ASKED THIS QUESTION. ---
**Author:** ![Saganist](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Saganist](https://boards.straightdope.com/u/Saganist)\ **Post date:** [November 10, 2010, 7:04am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/57 "2010-11-10T07:04:19Z")
> [@Blake](#): > > Of course it wouldn’t look any different at all, which is why this data point tells us nothing. The planet _required_a short time between good conditions becoming available and life appearing in order for anybody to \*observe \* the time that it takes life to form. You can’t use the factors that dictate your observation procedure as part of the analysis of the observations. That’s completely invalid. That’s not what I said. What is required is a rapid development of life from beginning to established foothold. _Not_ a short time between good conditions and the beginning of life. Unless you are positing life can only begin at the beginning of a planet’s history. If the probability of life forming on an Earth-like planet was super super low, then we might expect to see the beginning point here appear anywhere from 1-5 billion years after conditions arose. The fact that it started early can be taken as evidence that it isn’t that low. disclaimer: Specific numbers were pulled out of my ass for illustration purposes. ---
**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, 7:58am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/58 "2010-11-10T07:58:41Z")
> [@Saganist](#): > > That’s not what I said. What is required is a rapid development of life from beginning to established foothold. _Not_ a short time between good conditions and the beginning of life. I don’t understand the difference between these. Can you elaborate? > [@](#): > > If the probability of life forming on an Earth-like planet was super super low, then we might expect to see the beginning point here appear anywhere from 1-5 billion years after conditions arose. The fact that it started early can be taken as evidence that it isn’t that low. We might, and nobody is arguing that this is illogical. The problem is that, as I said in the OP, _exactly the same evidence_ can be used to support the contention that proto life \*needs \*to arise in conditions where it can rapidly become robust life, and that if it does then it is doomed never to become life at all. IOW if the probability of life forming on an Earth-like planet was super super low, then we would \*never \*expect to see the beginning point appear any time except immediately after it was capable of arising, because even if protolife arises ubiquitously, it is only when it does so on a planet where conditions don’t allow to rapidly become robust life that it manages to survive. In all other cases it becomes extinct. Since the conditions where it can rapidly become robust life are necessarily rarer than conditions where it can, the fact that it started early can be taken as evidence that it is much lower than estimates based on gross conditions would predict. What you are saying isn’t actually wrong, but because we only have a sample of one, and the exact same evidence has been used to support the exact opposite case, it becomes a meaningless data point. It can’t be used to convincingly support either theory because it can be used to support both. \*For clarity, we will refer to abiogenic macromolecules and particularly self-replicating macromolecules as protolife. - This post hinges on us accepting the contentions of Miller _et al_ that if life doesn’t arise rapidly it can’t arise at all. ---
**Author:** ![Measure\_for\_Measure](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/measure_for_measure/32/557_2.png) [@Measure\_for\_Measure](https://boards.straightdope.com/u/Measure_for_Measure)\ **Post date:** [November 10, 2010, 8:05am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/59 "2010-11-10T08:05:24Z")
> [@Blake](#): > > No, you haven’t. You’ve just handwaved about viruses (which are non-living but require complex, pre-existing cellular machinery to reproduce)and undefined self-replicating molecules. > > For you argument to be even semi-plausible you need to tell use where this occurred? On Earth? Another planet? Benthic Oceans? Palagic Oceans Atmosphere? What were the precursors and how did they arise? What was the original self-replicator, and how did it obtain raw materials? > > When you have answered those very basic questions, with evidence, then you argument will be semi-plausible. But all **Voyager** has to establish is that the odds of life arising on an earth-like planet\* are somewhere north of 1 x 10-9. He shouldn’t have to ID the original self-replicator, merely point to a plausible process. The reply might be that self-replicating processes that we know of are nano-rare. (Cite?) I confess I’m losing track of the burden of proof here. - whatever that means. ---
**Author:** ![Saganist](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Saganist](https://boards.straightdope.com/u/Saganist)\ **Post date:** [November 10, 2010, 8:11am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/60 "2010-11-10T08:11:30Z")
> [@Blake](#): > > I don’t understand the difference between these. Can you elaborate? Say protolife begins at t1 and robust life at t2. You are saying the anthropic principle requires us to observe a short (t2 - t1) and therefore we can’t infer anything from that observation. I agree with that. Now say the good conditions for life start at t = 0. But there is no requirement for t1 to be close to 0, correct? (Why would life have to start only near the planet’s beginning?) So then if the probability is super low, we should see t1 to be at least somewhat large. If we observe that it is actually small, that supports a hypothesis that the probability is actually not so low. The difference is between the time span of life development and its initial point. [Previous page](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137.md?page=2) [Next page](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137.md?page=4)