# 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:** 14\ **Page:** 12
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [November 12, 2010, 3:05pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/221 "2010-11-12T15:05:05Z")
> [@Frylock](#): > > Do you not see the difference between the following two claims? > > A. There is probably not any extraterrestrial life. > > B. We cannot conclude anything about whether there is probably extraterrestrial life. > > **Saganist** , as you said, makes claim B. But that is different than claim A. > > In other words, in paraphrase, you just told me "Of course Saganist is saying A. After all, in his last post, he said B! > > But that doesn’t make any sense, since B and A are not just different claims, they’re _incompatible_ with each other. > > Do you not see the distinction between the two claims? And you can not see that I’m concentrating on B. ---
**Author:** ![wintertime](https://avatars.discourse-cdn.com/v4/letter/w/c68b51/32.png) [@wintertime](https://boards.straightdope.com/u/wintertime)\ **Post date:** [November 12, 2010, 3:07pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/222 "2010-11-12T15:07:57Z")
One more thing, I still have no idea what formula you propose to use, GIGObuster. If you could elaborate on the math involved and the reasoning behind it, I might become less confused. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [November 12, 2010, 3:10pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/223 "2010-11-12T15:10:16Z")
> [@wintertime](#): > > But this is no problem at all, **GIGObuster**. Our observations show that certain building blocks of the life that we know, exist beyond our planet, a number of experiments (done for example by the group around Michel Nuevo at the Ames Research Institute) support not just the observations but also improve our understanding about the processes behind these phenomena. Other observations indicate that locations exist for these building blocks to gather and to find an environment that makes chemical reactions among them possible. > > The idea that life may exist out there is supported by such findings and no observation or experiment so far disproves such a possibility. > > We also do know pretty well the characteristics of the one solar system that contans life and the planet where it is located. > > So, I see no reason to refuse to search for life; it might exist and we even have an idea where looking for it first might prove to be useful. > > We can come to such conclusions without having any idea at all about the probability of life within the observable universe. > > We can even support the search for it while facing people who believe firmly in the uniqueness of life on earth by pointing out that such an endevour will invariably lead to an improved understanding of the cosmos as well as life itself regardless of the success of the search. > > In no way do we have to know enough first for a computation of probabilities to look further. I think, it’s actually counter-productive to give anything the appearance of probable or, shudder, certain success when we, in fact, know so little (I am looking at you, AI researchers of the 80s). Well, that is not the focus I was concentrating with, I also agree with what you say here. The problem was affirming that we had can not conclude anything, not quite. I guess I need to mention that the conclusion is not the problem but the refusal to check if the probabilities (that should change those conclusions) are affected by new discoveries. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [November 12, 2010, 3:25pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/224 "2010-11-12T15:25:03Z")
> [@wintertime](#): > > One more thing, I still have no idea what formula you propose to use, GIGObuster. If you could elaborate on the math involved and the reasoning behind it, I might become less confused. Well, to clarify further the beef I had is that some were posting as if a formula and the reasons to dismiss new evidence as meaningless were already agreed upon. Even the Drake equation was not supposed to be a law, it was supposed to be just a guideline like even Drake mentioned. But as that equation is being mentioned a lot I think it should be taken into account but with a huge modification: All the parts of the equation dealing with intelligent life and civilizations should be dropped as AFAICR those items in the equation are truly controversial or with less support. Or I should say, that is not what most of the research on astrobiology is focused on, and SETI was/is not effective or doing it wrong regarding intelligent life out there so far. ---
**Author:** ![wintertime](https://avatars.discourse-cdn.com/v4/letter/w/c68b51/32.png) [@wintertime](https://boards.straightdope.com/u/wintertime)\ **Post date:** [November 12, 2010, 4:24pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/225 "2010-11-12T16:24:27Z")
But the Drake equation is totally worthless: most of its factors are pure speculation and the f[sub]l[/sub] factor is the one we are trying to solve, not N. So you’d have to reformulate (ist this the correct term in English?) the equation – which is simple, of course, but doesn’t help you at all, even if you discard some factors because a) we still don’t have any numbers for f[sub]p[/sub] and n[sub]e[/sub] that lead to = Planets with life and b) have no experimental or observational evidence that the factors involved are sufficient to come to such a conclusion in the first place. The fact that we have _not yet_ observed the spontanous occurrence of life under controlled conditions rather indicates that we miss something: either in the elements involved or the processes or their succession or the time it needs or some combination of reasons. So, we can’t even tell right now, what conditions need to be fulfilled for life to plop into existence – as I said before, we don’t even know for sure if life on earth actually started here, so we can’t say with certainty that the conditions of the young earth were sufficient – we only know that those conditions were suitable for life to exist, to multiply and to evolve. With so little knowledge, how can anyone talk with confidence about probabilities? I don’t mean to say that we will stay as clueless as we are today, but right now, we are. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 12, 2010, 4:37pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/226 "2010-11-12T16:37:31Z")
nevermind ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 12, 2010, 4:38pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/227 "2010-11-12T16:38:39Z")
> [@GIGObuster](#): > > And you can not see that I’m concentrating on B. What do you mean? You keep ascribing _A_ to people, not B, and you keep arguing against _A_, not B. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 12, 2010, 4:42pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/228 "2010-11-12T16:42:40Z")
> [@GIGObuster](#): > > Well, that is not the focus I was concentrating with, I also agree with what you say here. The problem was affirming that we had can not conclude anything, not quite. I guess I need to mention that the conclusion is not the problem but the refusal to check if the probabilities (that should change those conclusions) are affected by new discoveries. It’s trivially obvious that the observed existence of earthlike planets increases the probability of extraterrestrial life. Who do you think is disagreeing with this? But if the other factors that go into the probability calculation are miniscule enough, then the amount by which the observed existence of earthlike planets raises the probability of extraterrestrial life is so insignificant as to be not worth mentioning. Blake and others are arguing that _for all we know_, the other factors are extremely miniscule. (And for all we know, they’re not. We just don’t know.) Therefore, they conclude, validly, that _for all we know_ the observed existence of earthlike planets doesn’t raise the probability of extraterrestrial life _to any meaningful extent_ (and for all we know, it does. We just don’t know.) ---
**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 12, 2010, 5:29pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/229 "2010-11-12T17:29:30Z")
Let’s pretend the probability of life arising on an Earthlike planet is 1 in 10^87, to reuse a random number that Blake was fond of. We already know that there are ~10^11 stars in our galaxy. If planet formation was extremely rare, like was often speculated in the past, it might be that most stars had no planets, and so there might have been only 10^8 “earthlike” planets in our galaxy. But now we know that planets are pretty common, and so we can guess there’s something like 10^10 or even 10^11 “earthlike” planets in our galaxy. So that improves our odds by a factor of 1000–instead of 1 star in a thousand having planets, we can guess that close to all of them have planets. And so the odds of finding a planet with life in our galaxy improves from 1 in 10^79 to 1 in 10^76! Even though it improves our odds of finding a planet with life by a factor of 1000, it still doesn’t improve our chances by that much, because with those odds the stars will grow cold before we’re likely to find such a planet. Of course, if the odds of finding life on a suitable planet turn out to be 1 in 10, or 9 in 10, then discovering that there are lots of planets is a very hopeful sign. But improving the odds a thousand-fold isn’t much help unless the odds are really good in the first place. Yeah, you’re a thousand times more likely to win the lottery if you buy 1000 tickets rather than one. But buying a thousand tickets doesn’t make it likely that you’ll win the lottery. MORE likely, yes, but still not likely. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [November 12, 2010, 7:23pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/230 "2010-11-12T19:23:17Z")
> [@wintertime](#): > > But the Drake equation is totally worthless: most of its factors are pure speculation and the f[sub]l[/sub] factor is the one we are trying to solve, not N. Historically Fl depends on the number of systems out there that will have 2 planets capable of developing life. So once again, no planets: no way to go up. The original estimation was that if one gets to find a system were 2 planets are capable of getting life then: > **[Drake equation](https://en.wikipedia.org/wiki/Drake_equation)** > > The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy. > The equation was formulated in 1961 by Frank Drake, not for purposes of quantifying the number of civilizations, but as a way to stimulate scientific dialogue at the first scientific meeting on the search for extraterrestrial intelligence (SETI). The equation summarizes the main concepts which scientists must contemplate when considering th... > [@](#): > > fl = 1 (100% of these planets will develop life) Of course that is a big assumption, but the pessimistic estimates gave this: > [@](#): > > fl = 0.13 meaning that we are most likely alone. (Of course intelligent life out there is not the focus of astrobiology so that is why I dope it from the discussion) > [@](#): > > Alternatively, making some more optimistic assumptions,\*\* assuming that planets are common, life always arises when planets are favorable\*\*, 10% of civilizations become willing and able to communicate, and then spread through their local star systems for 100,000 years (a very short period in geologic time): The latest news is that, yes, planets are common. So once again, I do question why some think it is odd to not give better odds when new planets are being found. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [November 12, 2010, 7:40pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/231 "2010-11-12T19:40:09Z")
(Of course intelligent life out there is not the focus of astrobiology so that is why I \*\*drop \*\*it from the discussion) Correcting that, and I do question if we are not capable of making better estimates with the information currently available and I do think it is more reckless to not make any effort with the information available. For all I know researchers in the field are not stopping just because some think so. [http://www.newscientist.com/blogs/shortsharpscience/2009/02/how-many-intelligent-civilisat.html](http://www.newscientist.com/blogs/shortsharpscience/2009/02/how-many-intelligent-civilisat.html) > [@](#): > > Now, Duncan Forgan of the University of Edinburgh in Scotland has attempted to constrain the numbers a bit better. > > In a paper (pdf) published in the International Journal of Astrobiology, he says estimates using the Drake equation are limited in accuracy because they rely on average values for parameters such as the lifetime of a civilisation capable of communicating with Earth. > > To estimate a distribution of values instead, he created a computer model of the Milky Way’s stars, generated planets around them, and assigned life to some planets in the habitable zones of their stars. Then he used equations that take into account the random nature of evolution to determine if that life went on to develop intelligence. By running the model again and again, he came up with a range of values, and put errors on the various estimates. > > He looked at three different scenarios for how life could develop, and here’s what he found (from a university press release): > > > [@](#): > > > > The first scenario assumes that it is difficult for life to be formed but easy for it to evolve, and suggests there are 361 intelligent civilisations in the galaxy. > > > > ``` > > A second scenario assumes that life is easily formed, but it struggles to develop intelligence, and suggests that as many as 31,513 other forms of life are estimated to exist. > > > > Finally, he examined the possibility that microbial life could be passed from one planet to another during asteroid collisions, which gave a result of 37,964 intelligent civilisations in existence. > > > > ``` And notice that I’m not thinking of Intelligent life, the possibilities then of just simple life forms out there are better than the number of civilizations. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 12, 2010, 9:34pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/232 "2010-11-12T21:34:20Z")
> [@GIGObuster](#): > > So once again, I do question why some think it is odd to not give better odds when new planets are being found. Posts 228 and 229. These directly contradict the idea that anyone here is saying what you’re saying they’re saying. We’re all saying that _yes_, more planets equals raised odds, but _no_, this doesn’t mean it’s particularly likely that there is extraterrestrial life out there. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [November 12, 2010, 10:38pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/233 "2010-11-12T22:38:17Z")
> [@Frylock](#): > > Posts 228 and 229. > > These directly contradict the idea that anyone here is saying what you’re saying they’re saying. > > We’re all saying that _yes_, more planets equals raised odds, but _no_, this doesn’t mean it’s particularly likely that there is extraterrestrial life out there. Hey, no problems then. 🙂 I’ll let the researchers do their speculation and research regardless if some say that it is not particularly likely that there is extraterrestrial life out there. ---
**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 13, 2010, 10:31pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/234 "2010-11-13T22:31:36Z")
Thought you guys might enjoy this… [http://www.ted.com/talks/john\_hodgman\_s\_brief\_digression.html](http://www.ted.com/talks/john_hodgman_s_brief_digression.html) [Previous page](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137.md?page=11)