Do you believe in Extraterrestial Life?

Yes, hence god spontaneously out-of-nowhere decided to create the universe. And as he is infinite, it was without effort or premeditation.

By hypothesis, God didn't spontaneously out-of-nowhere decide to create the universe any more than you spontaneously out-of-nowhere decide to brush your teeth in the morning.
 
By whose hypothesis?

'By hypothesis' is the English translation of the Latin phrase 'ex hypothesi'. It means, roughly, 'according to the assumptions'. People who posit the existence of God usually take him/her to be a volitional agent. It's ridiculous to object to that view by saying "oh so I guess God just spontaneously decided to create the universe." That would be something like saying "Oh look at that architect, he's always just spontaneously, out-of-nowhere designing buildings."

I'm not arguing for the plausibility of the God hypothesis. I just think that you should object to it on different grounds. It's practically begging the question against somebody if you give the kind of objection you did when the person is positing the existence of a volitional agent as the cause of some phenomenon. Unless of course, your objection was more subtle than that. If so, then I'd be happy to see some elaboration.
 
Yes.
As my preamble...I firmly believe we are not alone in this universe and for that, I also believe that what we commonly think a form of extraterrestial life is something either humanoid or a form of bacteria. Could you imagine the possibilities of what other forms of life out there exists in space? For all we know, there could possibly be alien life forms similarly depicted to those in films such as Pitch Black, Aliens, etc.

Discuss Your Thoughts and Keep it Clean. I would like to hear your thoughts.

Personally Yes i do..

there is a great chance that there is some form of life on a far away planet somewhere in the universe.. We can never judge what they are like if they are there. like that one dude said possibly they are smoe beasts like in Alien or some other weird creature. only time will tell and if we dont find out in this lifetime oh well. :p
 
I really agree with the detailed answer that a moogle gave to this in his post earlier. Well done a moogle, I am glad you wrote that instead of me having to bother.

Richard Dawkins has mentioned in his books that there is likely to be life elsewhere in the universe and that it may well not be carbon based like we are, but possibly silicon based (or based on various alternatives). One thing he says with confidence is that all evolution will follow the principle of Darwinian natural selection.

We must assume that intelligent aliens will not feel any bond with us and will be, at worst, hostile and, at best, indifferent. Thus advertising our presence in space and trying to get aliens to contact us is a very stupid idea.
 
We must assume that intelligent aliens will not feel any bond with us and will be, at worst, hostile and, at best, indifferent. Thus advertising our presence in space and trying to get aliens to contact us is a very stupid idea.

What cause would there be to assume that?
What would intelligent aliens have to gain from hostility towards us?
For them to be intelligent, they would need to have interest in understanding. If we were the only aliens they had encountered, why would they not merely be interested in us?
 
What cause would there be to assume that?
What would intelligent aliens have to gain from hostility towards us?
For them to be intelligent, they would need to have interest in understanding. If we were the only aliens they had encountered, why would they not merely be interested in us?

If they came over, they would probably want to kill us so we were not a threat to them in the future; use us for experiments; steal Earth resources, or make an interglactic space by-pass.

They would only need to understand us as much as we need to understand the primitive creatures we evolved from (if they are carbon based).

There is a chance they would identify with the predicament of a particular group of people who seem to be facing the kind of difficulty that nearly wiped them out when they were at that stage of development. Then they might give those people a helping hand, that is conceivable. If they think said group really are so very alike to themselves.

If they are not carbon based they may want to study us like we would study a strange species. No reason to assume this would be in any way a good postion for us to be in.:ill:
 
I believe in ET :)

Our planet was created in a process that is repeated throughout the universe - so the likelyhood of similar planets that could support life is rather large.

But who says that a planet supporting life has to be similar to ours? Our understanding of life is based on what we have observed. Scientists (well, that kind of theological scientist that aren't really scientists) predict that there any many kinds of priomordial soups that could create something similar to the self replicating RNA that started off life here on Earth.

Of course, even if the planets supporting life are similar to ours, eons of evolution would make any life form out there completely incomprehensible to our ideas of life. Finding new life forms would probably completely re-write our ideas of biology and possible intelligence as well.

I don't believe all the conspiricy theories about visiting aliens though :rolleyes:
 
I really agree with the detailed answer that a moogle gave to this in his post earlier. Well done a moogle, I am glad you wrote that instead of me having to bother.

Richard Dawkins has mentioned in his books that there is likely to be life elsewhere in the universe and that it may well not be carbon based like we are, but possibly silicon based (or based on various alternatives). One thing he says with confidence is that all evolution will follow the principle of Darwinian natural selection.

We must assume that intelligent aliens will not feel any bond with us and will be, at worst, hostile and, at best, indifferent. Thus advertising our presence in space and trying to get aliens to contact us is a very stupid idea.

Which book(s) specifically? I'd be interested in seeing how he rationalizes such a far-out concept such as silicon based lifeforms, given that we have no inkling as to how such a lifeform could sustain itself, or what sort of a definition it's "life" would entail. I'd also be curious to see as to what grounds he determines it is "likely" that life exists elsewhere, and just how "likely" he believes it is and why.
 
Which book(s) specifically? I'd be interested in seeing how he rationalizes such a far-out concept such as silicon based lifeforms, given that we have no inkling as to how such a lifeform could sustain itself, or what sort of a definition it's "life" would entail. I'd also be curious to see as to what grounds he determines it is "likely" that life exists elsewhere, and just how "likely" he believes it is and why.

The environment we live in isn't the environment such a lifeform could evolve in. Looking at carbon, and removing the knowledge we already have regarding carbon-based lifeforms, I'm pretty damn sure it would seem the same for carbon. From observations we have on earth we can't say that such a lifeform would not be able to sustain itself, as the way it sustains itself would be entirely foreign to any concept of the natural world we have here.

It is likely because of the sheer amount of chances for it, simple. I'm pretty sure there isn't enough bandwidth on this forum for the amount of zero's that would go after just how many chances there are for a situation that could develop into life on some other planet in the universe, most likely thousands of other planets, millions of other planets; and if the universe is infinite (which seems sorta likely), INFINITE other forms of life.
 
I doubt that there are aliens are out there, but if God did create another earth like planet or along the same themes of Earth, its probably so far away from us that we will never ever ever shmanever meet.

Having said that, I personally don’t see the point in occupying much of my time with such trivial, or perhaps mind blowing and impossibly gigantic matters, as the belief in aliens. Stick to the glorious and divine creation of Earth is my tentative motto.

Plus, who needs a bunch of aliens invading our countries taking our jobs and being all dirty n shit?
 
The Hopis believe in extraterrestrials. I found this site absolutely fascinating. http://thebeloveddisciple.org/ Once I started reading I couldn't finish until I read the last page (sort of like when I read the book "No One Here Gets Out Alive") ;)

I think if I had read this material earlier in my life it may not have had as much impact. Even now parts of it seem hard to swallow and "out there." I'm not sure what to say without going into a lot of personal shit, but I will say that a lot of it hit some personal buttons for me. I'm definitely not an expert in astronomy, so I don't know if what the writer claims has any validity. Perhaps a very good (honest) writer, or a good BS artist. *shrugs*

Comments welcome.
 
Which book(s) specifically? I'd be interested in seeing how he rationalizes such a far-out concept such as silicon based lifeforms, given that we have no inkling as to how such a lifeform could sustain itself, or what sort of a definition it's "life" would entail. I'd also be curious to see as to what grounds he determines it is "likely" that life exists elsewhere, and just how "likely" he believes it is and why.

I was recently reading "The Blind Watchmaker" again, in parts, so that may be the book that contains all the references I mentioned. It is certainly where he makes the statement of considering that any extra-terrestrial life would be subject to evolution by natural selection.

I have a few other Dawkins references that I just googled for.

Skeptic: How likely do you think it is that "intelligent" life exists somewhere else in the universe?

Dawkins: At first glance, one might think that the really difficult step is getting life at all. Then once natural selection has gotten going (since the origin of life is really the origin of natural selection), you can proceed by an orderly progressive sequence through the evolution of some kind of information processing apparatus on to intelligence. On the other hand, if you look at what's actually happened on this planet, it probably took less than a billion years from the origin of the planet, under fairly unfavorable initial conditions, to produce life. But intelligence of a high order has only come about in the last couple of million years, perhaps. So it does seem that on this planet at least there has been a rather short interval from the origin of the planet to the origin of life and then a very, very long interval between the origin of life and the origin of intelligence.

http://209.85.135.104/search?q=cach...tra+terrestrial+life&hl=en&gl=uk&ct=clnk&cd=4

This is better:
Suppose life's origin on a planet took place through a hugely improbable stroke of luck, so improbable that it happens on only one in a billion planets. The National Science Foundation would laugh at any chemist whose proposed research had only a one in a hundred chance of succeeding, let alone one in a billion. Yet, given that there are at least a billion billion planets in the universe, even such absurdly low odds as these will yield life on a billion planets. And — this is where the famous anthropic principle comes in — Earth has to be one of them, because here we are.
http://209.85.135.104/search?q=cach...xtraterrestrial+life&hl=en&gl=uk&ct=clnk&cd=1

He has a lot more than this one paragraph on the subject to say in this article.
By the way, I don't actually think the origin of life was as improbable as all that. I think the galaxy has plenty of islands of life dotted about, even if the islands are too spaced out for any one to hope for a meeting with any other.

Peter Ward, in his book "Life as we do not Know it", says that silicon-based life is possible. Publisher's Review says
Ward, an investigator with NASA's Astrobiology Institute, believes researchers might be taking the wrong approach by looking only for earthly DNA-based life forms. Truly alien life, he argues, might have completely different origins; even Earth has untold numbers of viruses composed entirely of RNA, and scientists have created similar genetic material in laboratories, so who's to say silicon-based life-forms are impossible?
http://209.85.135.104/search?q=cach...l+life+silicon+based&hl=en&gl=uk&ct=clnk&cd=5

Also there is a good explanation of silicon-based life in the 3rd paragraph down here http://ourworld.compuserve.com/homepages/Stephen_Nottingham/DNA5.htm
 
I was recently reading "The Blind Watchmaker" again, in parts, so that may be the book that contains all the references I mentioned. It is certainly where he makes the statement of considering that any extra-terrestrial life would be subject to evolution by natural selection.

I have a few other Dawkins references that I just googled for

Thanks, I'll have to have a look.

Skeptic: How likely do you think it is that "intelligent" life exists somewhere else in the universe?

Dawkins: At first glance, one might think that the really difficult step is getting life at all. Then once natural selection has gotten going (since the origin of life is really the origin of natural selection), you can proceed by an orderly progressive sequence through the evolution of some kind of information processing apparatus on to intelligence. On the other hand, if you look at what's actually happened on this planet, it probably took less than a billion years from the origin of the planet, under fairly unfavorable initial conditions, to produce life. But intelligence of a high order has only come about in the last couple of million years, perhaps. So it does seem that on this planet at least there has been a rather short interval from the origin of the planet to the origin of life and then a very, very long interval between the origin of life and the origin of intelligence.

Hmm, I don't know how I feel about this one. It makes a vast amount of assumptions about how things would progress elsewhere (in favor of extra-terrestrial life) based on how things work here (natural selection, replication, etc), but then completely disregards the aspects of life here that would make it difficult for life to transpire elsewhere. He seems very much an idealist, I'll have to read the actual book to see what rational/scientific reasoning he has to support these idealist notions.

Suppose life's origin on a planet took place through a hugely improbable stroke of luck, so improbable that it happens on only one in a billion planets. The National Science Foundation would laugh at any chemist whose proposed research had only a one in a hundred chance of succeeding, let alone one in a billion. Yet, given that there are at least a billion billion planets in the universe, even such absurdly low odds as these will yield life on a billion planets. And — this is where the famous anthropic principle comes in — Earth has to be one of them, because here we are.

Ugh, not this again. I don't find the argument "there are billions of planets so there's bound to be a few with life" and "since we have life, we must be one of them" very compelling nor reasonable. Sir Frederick Hoyle calculated the probability of the spontaneous generation of just the proteins of a single amoebae to be a probability of as one chance in ten to the 40 thousandth power. 1/10^40000 And that's on a planet capable (and many would argue well suited) for sustaining life (Earth). Who knows how many or few of the rest of the planets in the universe are even conditioned to support life? Planets who simply could not sustain life would have to be removed from the equation. His whole argument rests on the assumption that all planets (which he factored into his estimations) have the potential to sustain life as we know it, and the rest of it on the assumption that life can take other forms than Carbon (silicon being one of the only few alternatives, and even then we know of no process by which this could be achieved).

By the way, I don't actually think the origin of life was as improbable as all that. I think the galaxy has plenty of islands of life dotted about, even if the islands are too spaced out for any one to hope for a meeting with any other.

There's a far cry between "I think" and "I have empirical or experimental data which highly suggests this is the case." I wonder if Mr. Dawkins realizes that he's using his credentials as a respectable scientist to substantiate his own personal, unverified beliefs. That doesn't seem very intellectually responsible by my reckoning. But once again, I guess I'll give him the benefit of the doubt until I can read his book.

Ward, an investigator with NASA's Astrobiology Institute, believes researchers might be taking the wrong approach by looking only for earthly DNA-based life forms. Truly alien life, he argues, might have completely different origins; even Earth has untold numbers of viruses composed entirely of RNA, and scientists have created similar genetic material in laboratories, so who's to say silicon-based life-forms are impossible?

That's great, but where does the RNA come from? This theory still has to conquer the spontaneous generation mountain, as well as the fact that silicon is much less "friendly" to the concept of life than carbon (even if it is remotely possible, concievably).

Also there is a good explanation of silicon-based life in the 3rd paragraph down here http://ourworld.compuserve.com/homep...ngham/DNA5.htm

Great, it's the only other element that can form long chains (polymers). Polymers do not a life form make. It's only other credentials are citing episodes of Star Trek...are you serious?
 
What Dawkins says in The Blind Watchmaker about Sir Fred Hoyle:

Boeing 747 macromutations are the ones that really are ruled out by the complexity argument just given. They get their name from the astronomer Sir Fred Hoyle's memorable misunderstanding of the theory of natural selection. He compared natural selection, in its alleged improbablility, to a hurricane blowing through a junkyard and chancing to resemble a Boeing 747. As we saw in Chapter 1, this is an entirely false analogy to apply to natural selection, but it is a very good analogy for the idea of certain kinds of macromutation giving rise to evolutionary change. Indeed, Hoyle's fundamental error was that he, in effect, thought (without realising it) that the theory of natural selection did depend upon macromutation. The idea of a single macromutation's giving rise to a fully functioning eye with the properties listed above, where there was only bare skin before, is indeed, just about as improbable as a hurricane assembling a Boeing 747. This is why I refer to this kind of hypothetical macromutation as a Boeing 747 macromutation.
 
As far as I can tell that's only star formation theory. To my knowledge we have never actually (verifiably) observed the formation of a star...

...We have witnessed many deaths of stars, but to my knowledge there hasn't been a case where we have seen, beyond a doubt, a star forming.

We will likely never actually observe the formation of a star, as under the current most widely accepted star formation theory, it would take millions (billions?) of years for it to actually occur. The death of a star is (sometimes) very dramatic, so it is much more easily observed. Both the births and deaths of stars were once only theories, (supernovas were once only a predicted occurrence of what should happen during the end of a large star's life, we actually had to look for them to gain concrete evidence) but we now know them to be real from photos, and even an ancient supernova observed and recorded in ancient china (although back then they didn't fully understand what they were seeing).

Star formation on the other hand, can never be photographed or observed because it would take way too long according to theory. Unless of course we had billion year life spans and the patience to watch nebulas for that long. Or perhaps a time lapse camera that took a picture every few hundred years or so, with the hopes that someone would still be around at the end to view the results.

I'm not trying to say that the theory is 100% correct, but given the evidence, its enough for me to believe it. If I only believed what I could physically see, I would lead a very empty and delusioned life.

We have but 5 senses and some various extensions of them, so who knows what exists beyond our capability of observation. Homing pigeons, for example, can detect magnetic fields with a sort of 6th sense, while we humans must use other things to translate data to suit one of our 5 senses (watching or feeling the pull between two magnets, for example). Otherwise we would never know that magnetic fields existed. For all we know there could be other forms of life among us physically, but existing in some way as to evade our senses. A bit far-fetched, I know, but it isn't impossible when you truely think about it. (Read Isaac Asimov's "Hostess" for an interesting fictional short story dealing with such an idea.)

As for the possibility of life elsewhere in the universe, while I'm aware of the extreme good fortune we've had on earth that has allowed life to make it thus far and even to gain a foothold in the first place, I think its fairly self centered to believe ours to be the only likely planet harboring semi-intelligent life. There are just too many possibilities.

I can't remember his name, but there is an astronomer who actually came up with a formula to determine a star system's chances of harboring an earth-like planet and thusly the chance for life as we know it here. The formula takes into account the possibility of a planet being the "right" distance from the sun, whether it has a large moon, (some argue that without our moon life would have never happened as we know it here) The presence of large Jupiter-like planets in close proximity, which would likely throw smaller nearby planets out of the solar system or swallow it before life could begin, and some other things I can't remember. In the small area of our galaxy we have so far examined, he believes there to be about 100 star systems that fall into the possibility of sustaining earth-like life.

Of course they are just possibilities, and no one has ever seen a planet outside our solar system. The only current way to detect other planets is to watch a star's wobble as it pulled upon by other large masses (planets). We have only been able to detect extremely large planets (like Jupiter) with current technology, so we're quite far off from hard evidence of earth-like planets of course, but the fact that they believe there to be some 100 possibilities just in our corner of our galaxy is astounding when you figure the sheer number of stars in the universe.

For a common visualization of the number of stars that we know to exist, it is said that if you had a grain of sand to represent every star, and they were all put in hopper cars on a freight train roaring past you at a railroad crossing, it would take THREE YEARS for the train to pass. Theres also the "each grain would fill all the beaches in the world" analogy. That’s a lot of fucking stars, and a lot of possibilities.

As for the notion of Aliens being hostile, I have mixed feelings about this. In our own common sense they would likely see us as competition/lab rats/potential resources, I agree. But one thing to think about is if they shared our competitive/destructive traits, would they be able to survive themselves before gaining the technology for interstellar travel?
 
From "The Blind Watchmaker"

Begin by giving a name to the probability, however low it is, that life will originate on any randomly designated planet of some particular type. Call this number the spontaneous generation probablility, or SGP. It is the SGP that we shall arrive at if we sit down with our chemistry textbooks, or strike sparks through plausible mixtures of atmospheric gases in our laboratory, and calculate the odds of replicating molecules springing spontaneously into existence in a typical planetary atmosphere. Suppose that our best guess of the SGP is some very very small number, say one in a billion. This is obviously such a small probability that we haven't the faintest hope of duplicating such a fantastically lucky, miraculous event as the origin of life in our laboratory experiments. Yet if we assume, as we are perfectly entitled to do so for the sake of argument, that life has originated only once in the universe, it follows that we are allowed to postulate a very large amount of luck in a theory, because there are so many planets in the universe where life could have originated. If, as one estimate has it, there are a 100 billion planets, this is 100 billion times greater than even the very low SGP that we postulated. To conclude this argument, the maximum amount of luck that we are allowed to assume, before we reject a particular theory of the origin of life, has odds of one in N, where N is the number of suitable planets in the universe. There is a lot hidden in that word 'suitable', but let us put an upper limit of 1 in 100 billion billion for the maximum amount of luck that this argument entitles us to assume.

Think about what this means. We go to a chemist and say: get out your text books and your calculating machine; sharpen your pencil and your wits; fill your head with formulae, and your flasks with methane and ammonia and hydrogen and carbon dioxide and all the other gases that a primeval non-living planet can be expected to have; cook them up all together; pass strokes of lightning through your simulated atmospheres, and strokes of inspiration through your brain,; bring all your clever chemist's methods to bear, and give us your best chemist's estimate of the probablility that a typical planet will spontaneously generate a self-replicating molecule. Or, to put it another way, how long would we have to wait before random chemical events on the planet, random thermal jostling of atoms and molecules, resulted in a self-replicating molecule?

Chemists don't know the answer to this question. Most modern chemists would probably say that we have to wait a long time by the standards of a human lifetime, but perhaps not all that long by the standards of cosmological time. The fossil history of earth suggests that we have about a billion years - one 'aeon', to use a convenient modern definition - to play with, for this is roughly the time that elapsed between the origin of the Earth about 4.5 billion years ago and the era of the first fossil organisms.

this goes on and on, so you had better get the book!

The conclusion basically is that is it hugely far more improbable that Earth is the only planet that life evolved on than that there are others. It is up to you to choose to believe the far far less probable idea and think Earth is the only planet that life, intelligent or otherwise ever evolved upon. But if we are being logical, probablility should matter to us.
 
We have but 5 senses and some various extensions of them, so who knows what exists beyond our capability of observation. Homing pigeons, for example, can detect magnetic fields with a sort of 6th sense, while we humans must use other things to translate data to suit one of our 5 senses (watching or feeling the pull between two magnets, for example). Otherwise we would never know that magnetic fields existed. For all we know there could be other forms of life among us physically, but existing in some way as to evade our senses. A bit far-fetched, I know, but it isn't impossible when you truely think about it. (Read Isaac Asimov's "Hostess" for an interesting fictional short story dealing with such an idea.)

I'm not opposed to the idea of beings transcendent of our 5 standard methods of perceptions (i.e. beings who exist in more or higher dimensions than we do), or beings of a metaphysical nature, but here I'm only speaking purely of beings who exist within the 4 dimensions that we do in the way that we do. Who knows what exists out there (or in there) when you open up the field of metaphysics (ghosts, angels, demons, who knows).

For a common visualization of the number of stars that we know to exist, it is said that if you had a grain of sand to represent every star, and they were all put in hopper cars on a freight train roaring past you at a railroad crossing, it would take THREE YEARS for the train to pass. Theres also the "each grain would fill all the beaches in the world" analogy. That’s a lot of fucking stars, and a lot of possibilities.

One thing I'd like to point out is the stars we can see. There's a good book on this subject called "Starlight and Time" by Dr. Russell Humphreys. A lot of the stars we're seeing through the pictures taken by satellites like Hubble are images of stars from millions of years ago. Light takes a certain amount of time to travel, so some of the stars we're currently seeing may not even exist at this present moment, they could have gone supernova 1000's of years ago and we wouldn't know it for a long time (just as in the same way we wouldn't know our own sun changed for around 8 minutes or so). It's a rather odd thing to think about, that much of the universe that we are seeing, we are seeing back in time.

I'm not trying to say that the theory is 100% correct, but given the evidence, its enough for me to believe it. If I only believed what I could physically see, I would lead a very empty and delusioned life.

I just don't find the evidence for post Big-Bang star formation to be very compelling. But I do, of course, agree with your second statement there. I speak only of scientific likelihood as we perform science as human beings (within the realm of logic and our 5 senses), a purely rational basis. As I said, once we get into higher dimensions and metaphysics, the possibilities are endless. I speak only of the current data and knowledge we possess, and the likelihood thereof based on those factors.

Boeing 747 macromutations are the ones that really are ruled out by the complexity argument just given. They get their name from the astronomer Sir Fred Hoyle's memorable misunderstanding of the theory of natural selection. He compared natural selection, in its alleged improbablility, to a hurricane blowing through a junkyard and chancing to resemble a Boeing 747. As we saw in Chapter 1, this is an entirely false analogy to apply to natural selection, but it is a very good analogy for the idea of certain kinds of macromutation giving rise to evolutionary change. Indeed, Hoyle's fundamental error was that he, in effect, thought (without realising it) that the theory of natural selection did depend upon macromutation. The idea of a single macromutation's giving rise to a fully functioning eye with the properties listed above, where there was only bare skin before, is indeed, just about as improbable as a hurricane assembling a Boeing 747. This is why I refer to this kind of hypothetical macromutation as a Boeing 747 macromutation.

Umm, Hoyle fully understood the process of natural selection and the theory of evolution, it's Dawkins who is getting ahead of himself. Hoyle's calculations only refer to the most basic forms of life. Dawkins' defense rests solely on the mechanics of natural selection, and therein lies the problem. Natural Selection only applies to a population of organisms capable of reproduction or replication. Prior to that point, natural selection is meaningless, it's purely about chemistry then. He basically turned Hoyle's calculations into a strawman fallacy by misrepresenting what Hoyle was arguing. If you take into consideration the fact that natural selection can only occur once an organism gains the ability to replicate, what is Dawkins left with? Precisely the absurdly astronomical odds of spontaneous generation that Hoyle and other scientists have produced, I'm fairly certain. So the Boeing 747 macromutation isn't even a macromutation, it's a transition of chemistry into biology, the macromutations only apply to the phase of biology. So I'm afraid Hoyle's point still stands.

Begin by giving a name to the probability, however low it is, that life will originate on any randomly designated planet of some particular type. Call this number the spontaneous generation probablility, or SGP. It is the SGP that we shall arrive at if we sit down with our chemistry textbooks, or strike sparks through plausible mixtures of atmospheric gases in our laboratory, and calculate the odds of replicating molecules springing spontaneously into existence in a typical planetary atmosphere. 1. Suppose that our best guess of the SGP is some very very small number, say one in a billion. This is obviously such a small probability that we haven't the faintest hope of duplicating such a fantastically lucky, miraculous event as the origin of life in our laboratory experiments. 2. Yet if we assume, as we are perfectly entitled to do so for the sake of argument, that life has originated only once in the universe, it follows that we are allowed to postulate a very large amount of luck in a theory, because there are so many planets in the universe where life could have originated. If, as one estimate has it, there are a 100 billion planets, this is 100 billion times greater than even the very low SGP that we postulated.To conclude this argument, the maximum amount of luck that we are allowed to assume, before we reject a particular theory of the origin of life, has odds of one in N, where N is the number of suitable planets in the universe. There is a lot hidden in that word 'suitable', but let us put an upper limit of 1 in 100 billion billion for the maximum amount of luck that this argument entitles us to assume.

Think about what this means. We go to a chemist and say: get out your text books and your calculating machine; sharpen your pencil and your wits; fill your head with formulae, and your flasks with methane and ammonia and hydrogen and carbon dioxide and all the other gases that a primeval non-living planet can be expected to have; cook them up all together; pass strokes of lightning through your simulated atmospheres, and strokes of inspiration through your brain,; bring all your clever chemist's methods to bear, and give us your best chemist's estimate of the probablility that a typical planet will spontaneously generate a self-replicating molecule. Or, to put it another way, how long would we have to wait before random chemical events on the planet, random thermal jostling of atoms and molecules, resulted in a self-replicating molecule?

Chemists don't know the answer to this question. Most modern chemists would probably say that we have to wait a long time by the standards of a human lifetime, but perhaps not all that long by the standards of cosmological time. The fossil history of earth suggests that we have about a billion years - one 'aeon', to use a convenient modern definition - to play with, for this is roughly the time that elapsed between the origin of the Earth about 4.5 billion years ago and the era of the first fossil organisms.

1. That's a bit disingenuous, he simply says "suppose" and then goes to build his entire argument off of that supposition. Every estimation I've seen has been MUCH larger than 1/1000000000.

2. Once again, that's a very feeble argument. The sheer numbers of planets does not mean a thing. The only things that matter are the numbers of planets that have the potential to sustain life, and if our own solar system is any indication, that's a very slim chance per solar system. So if you take into consideration the fact that not all planets (and I'd venture as to say very few per solar system) are going to even have the POTENTIAL to sustain life, the "100 billion planets" argument seems to dwindle into nothing. Sheer numbers of planets is irrelevant, only the number of planets that can possibly sustain life matter, and there's pretty much no way to know that, so I think Mr. Dawkins has a little too much wishful thinking going on in his science.

The conclusion basically is that is it hugely far more improbable that Earth is the only planet that life evolved on than that there are others. It is up to you to choose to believe the far far less probable idea and think Earth is the only planet that life, intelligent or otherwise ever evolved upon. But if we are being logical, probablility should matter to us.

If we're being truly logical, then it's not quite so likely as Mr. Dawkins posits. Read what I said in point 2. That cuts down heftily on the 100 Billion odds he keeps touting around. If you factor in the difficulties of life spontaneously arising on even a planet well suited for life, and couple it with the number of planets who even have the potential to start life, and couple that with the odds of planets who have the potential to sustain life, the probability grows very much more slim, hence the conclusion I have come to: It is not very likely.