There's a difference between scientists saying, "it sure seems like there should be life, based upon probability" and "I'm sure there is" or "I believe there is." I have no problem with spending funds sending robots out to anywhere and everywhere to look for life. I have no problem, really, with SETI. I do think that the best use of our money, by far, has been to look back down at earth, but there's room for R&D type things. I do have a problem spending funds on astrobiologists wasting time on their computers with 3D programs rendering what alien life supposedly looks like. That kind of thing is the realm of video game companies (it's fantasy, not science).
Yes, assuming you mean 1/(3*10^24) and not (1/3)*10^24. Remind me what that number is supposed to represent? barfo
1/(3*10^24) is correct. It is a number that illustrates how life can be rare, in spite of the big number of stars and planets that are assumed to make up the universe.
Not necessarily. The climate could be so harsh that life is either extinguished completely, or barely survives. You are assuming that life elsewhere will behave like - and have the advantages of - life here on earth. There's no basis for those assumptions. Considering our ability to see out there is very very limited, maybe we just haven't seen it yet. Where is the Higgs Boson? I don't see anyone in this thread arguing that it is a fact that there is life on other planets. We really haven't looked very many places. Do you quit looking for your car keys if they aren't in the first couple places you look? They can't be seen, so they must not exist. The moon does not indicate anything about how life would be so common we'd be finding it most places we look. If anything it indicates the opposite. Sure, that's a possibility. Another possibility is that life elsewhere fails to adapt. barfo
How does it illustrate that? 15.34912205555... That's the number that illustrates a red-haired supermodel will sleep with me tonight. barfo
If they are just being silly (creating scary monsters) then I agree. If they are making an honest attempt at figuring out what life forms could be supported on a planet with environmental conditions X, Y, and Z, then I see nothing wrong with it. But since this is the first I've heard of it I don't really know what you are talking about. Although I'm sure you have a link. barfo
The probability argument is hollow. One view is that there are 3*10^22 possible places for life, so it's very likely it exists. This excludes the chance that life does start, and other factors (like can it exist near binary stars? That's 60% of all star systems right there). If the chance that conditions for life is 1/(3*10^24), the actual probability is 1:100. The actual chance may be more like 1:10^100000000000000, and it's a freaking miracle that life even started on Earth. That's the only way to look at it, unless there is life found elsewhere.
I assume you mean the one you are about to make. I have no idea what you mean by "The actual chance may be more like 1:10^100000000000000". Seems like you are just making up numbers to suit your argument, which puts the lie to your claim "That's the only way to look at it." barfo
I'm pointing out the flaw in the "universe is so big, life must exist" argument. The only way to look at it argument is why scientists repeat experiments done by other scientists.
Ok. I'm not arguing for that position, myself. I don't have a position on life outside earth. It might exist, it might not. Maybe they'll find out before I die, maybe not. No idea what you mean by that. Are you saying that SETI should be repeated in case the first experiment was flawed? barfo
If you were, I'd ask, "What are the odds life starts on a planet suitable for life?" No. Scientists are supposed to be skeptical so they repeat experimental results instead of just accepting what others tell them is true.
And I'd only be able to give you an educated guess, because obviously no one knows the true odds. And obviously, some will make different estimates than others. No idea what you are talking about still. Who is just accepting what others tell them, and what experiments should be repeated? barfo
Seen the Drake Equation? When I put in my estimates, I get 1.65e-7 http://www.activemind.com/Mysterious/Topics/SETI/drake_equation.html Use 100B 50% .33 <---- I figure this one to be MUCH lower. .001% .001% 100% 1/100,000
Yeah, so? Is there some reason I should take your assumptions more seriously than anyone elses? Obviously the Drake equation can lead to a very wide range of outcomes depending on what your assumptions are. barfo
The more "religious" astrobiologist/SETI types (Carl Sagen, for one) comes up with 10,000 planets with intelligent life, CURRENTLY, just in the Milky Way. If you don't change anything on that calculator, you get 1000.
Didn't Sagan croak? I saw him talk once, in the mid-70s. Anyway, like I say, what comes out depends upon what goes in, and none of us know the right input. barfo
http://en.wikipedia.org/wiki/Rare_Earth_hypothesis N* is the number of stars in the Milky Way. This number is not well-estimated, because the Milky Way's mass is not well estimated. Moreover, there is little information about the number of very small stars. N* is at least 100 billion, and may be as high as 500 billion, if there are many low visibility stars. ne is the average number of planets in a star's habitable zone. This zone is fairly narrow, because constrained by the requirement that the average planetary temperature be consistent with water remaining liquid throughout the time required for complex life to evolve. Thus ne = 1 is a likely upper bound. We assume . The Rare Earth hypothesis can then be viewed as asserting that the product of the other nine Rare Earth equation factors listed below, which are all fractions, is no greater than 10−10 and could plausibly be as small as 10−12. In the latter case, N could be as small as 0 or 1. Ward and Brownlee do not actually calculate the value of N, because the numerical values of quite a few of the factors below can only be conjectured. They cannot be estimated simply because we have but one data point: the Earth, a rocky planet orbiting a G2 star in a quiet suburb of a large barred spiral galaxy, and the home of the only intelligent species we know, namely ourselves. fg is the fraction of stars in the galactic habitable zone (Ward, Brownlee, and Gonzalez estimate this factor as 0.1 [7]). fp is the fraction of stars in the Milky Way with planets. fpm is the fraction of planets that are rocky ("metallic") rather than gaseous. fi is the fraction of habitable planets where microbial life arises. Ward and Brownlee believe this fraction is unlikely to be small. fc is the fraction of planets where complex life evolves. For 80% of the time since microbial life first appeared on the Earth, there was only bacterial life. Hence Ward and Brownlee argue that this fraction may be very small. fl is the fraction of the total lifespan of a planet during which complex life is present. Complex life cannot endure indefinitely, because the energy put out by the sort of star that allows complex life to emerge gradually rises, and the central star eventually becomes a red giant, engulfing all planets in the planetary habitable zone. Also, given enough time, a catastrophic extinction of all complex life becomes ever more likely. fm is the fraction of habitable planets with a large moon. If the giant impact theory of the Moon's origin is correct, this fraction is small. fj is the fraction of planetary systems with large Jovian planets. This fraction could be large. fme is the fraction of planets with a sufficiently low number of extinction events. Ward and Brownlee argue that the low number of such events the Earth has experienced since the Cambrian explosion may be unusual, in which case this fraction would be small.
