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#31
05-21-2007, 08:05 PM
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Re: Chance of Life Elsewhere
Admittedly making probabilistic estimates from a data sample of one is very tricky.
Clearly p > 0 but what else? I think it is very suggestive that life appears to have developed around 4 billion years ago, about as soon as it was able to. [ QUOTE ] Suppose the "some chance" you figure is 1 in a googolplex. Even though there is then "some chance" you would still say it's "probably not" the case. [/ QUOTE ] If the mechanism whereby life developed on earth was very unlikely around 1 in a googolplex and consequently Earth is the only planet with life, then the chance that it would develop within the first few million years on the one planet it did develop on would have DS frothing at the mouth crying miracle. The Anthropic principle gets us around being on the one place in the universe that life evolved, but does not expliam why it evolved so quickly. My instinct says p is quite high, probably extremely close to one for earth like planets. The only out is to show that N, the number of earth like planets is extremely small. So what’s so special about our Sun, and what’s this crap about Gliese 581 c. 
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#32
05-21-2007, 08:23 PM
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Re: Chance of Life Elsewhere
Once you assume that there are a non infinite number of planets in the universe (a good assumption), then there are values of p such that the statement "there is probably no other life in the universe than ours" is correct
so, no, your conclusion does not follow from the premise
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#33
05-21-2007, 08:30 PM
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Re: Chance of Life Elsewhere
[ QUOTE ]
Once you assume that there are a non infinite number of planets in the universe (a good assumption), then there are values of p such that the statement "there is probably no other life in the universe than ours" is correct [/ QUOTE ] obviously. [ QUOTE ] so, no, your conclusion does not follow from the premise [/ QUOTE ] [img]/images/graemlins/confused.gif[/img] [img]/images/graemlins/confused.gif[/img] What has that got to do with my estimation of p?
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#34
05-21-2007, 08:34 PM
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Re: Chance of Life Elsewhere
[ QUOTE ]
Once you assume that there are a non infinite number of planets in the universe (a good assumption), then there are values of p such that the statement "there is probably no other life in the universe than ours" is correct so, no, your conclusion does not follow from the premise [/ QUOTE ] i assume you are talking to me. Let me clarify what I was trying to say: It is illogical for anyone to say the statement "there is probably no other life in the universe than ours" sure they can get lucky and be right, but i'd still call them 'wrong' for thinking that
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#35
05-21-2007, 08:47 PM
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Re: Chance of Life Elsewhere
[ QUOTE ]
i assume you are talking to me. Let me clarify what I was trying to say: It is illogical for anyone to say the statement "there is probably no other life in the universe than ours" sure they can get lucky and be right, but i'd still call them 'wrong' for thinking that [/ QUOTE ] If you are claiming they were wrong because they are making a statement without knowledge of N and p, then, you have an argument. But, if I were to say "there is probably life on other planets", do you make the same statement?
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#36
05-21-2007, 08:48 PM
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Re: Chance of Life Elsewhere
[ QUOTE ]
[ QUOTE ] Once you assume that there are a non infinite number of planets in the universe (a good assumption), then there are values of p such that the statement "there is probably no other life in the universe than ours" is correct [/ QUOTE ] obviously. [ QUOTE ] so, no, your conclusion does not follow from the premise [/ QUOTE ] [img]/images/graemlins/confused.gif[/img] [img]/images/graemlins/confused.gif[/img] What has that got to do with my estimation of p? [/ QUOTE ] sorry, wasnt directed at you. I just used quick reply
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#37
05-21-2007, 08:55 PM
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Re: Chance of Life Elsewhere
"What is the probability a randomly selected planet is earth-like" is a question I'd like to have addressed.
We've got oxygen, hydrogen, and carbon in sufficient amounts (and bonded in a manner that's apparently conducive to life) and we're the appropriate distance from a star such that water can exist in liquid form. How probable is each of these requirements? I imagine that there is some acceptable range of atmospheric composition/density, rotational/orbital variation (to cause energy to absorb differently over different places, creating climatic stability), and total solar insulation recieved that a planet can have in order to cause water to be in liquid form. That is to say, planets of various sizes and with different energy input rates could feasibly be 'earth-like'. It doesn't seem unlikely at all to me that planets like earth aren't extremely uncommon. (Much of my post addresses the largely theistic idea that life on any random planet is extremely unprobable. One argument I specifically had in mind can be found right here. I think many of their parameters are irrelevant, or could be variable in relation to other parameters.)
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#38
05-21-2007, 08:59 PM
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Re: Chance of Life Elsewhere
In fact, I just did a quick scroll through the link I provided for a quick laugh. I suggest you do the same.
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#39
05-21-2007, 09:04 PM
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Re: Chance of Life Elsewhere
[ QUOTE ]
If you are claiming they were wrong because they are making a statement without knowledge of N and p, then, you have an argument. [/ QUOTE ] That's all I'm saying. plus a little more: no one has knowledge of N (besides maybe a lower bound)
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