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jtur, five orders of magnitude isn't very much if we're considering a universe with a trillion galaxies and a trillion stars in each one. That would be... hmmm... ok, gotta do it this way:
1,000,000,000,000,000,000,000,000
OK... 25 orders of magnitude to play with. Lopping off five doesn't really affect the odds in a meaningful way.
But in terms of intelligent life reaching a level of interstellar communication/transportation there's a single great unknown that we won't be able to even guess at until we achieve it. It's quite possible that intelligent life will always hit a stage where they can destroy their livable environment in a war and it's quite possible that such destruction is inevitable. We can *hope* it's not.... but I think that's about all we can do at this point.
OK... back to writing out Graham's number on my chalkboard here...
If you'll reread what I wrote, you'll see that 5 orders of magnitude (x 100,000) is how the odds change, depending on whether you're talking about the philosophical possibility of life on a planet, or the actual existence of it in real time. There has been intelligent life on this planet for only 1/100,000 of its existence, and an alien observer would have found none, if they had checked Earth out 99,999 times at 46-thousand year intervals. They might have logically concluded that there is no intelligent life on earth.
Five orders of magnitude has, in my post, nothing to do with the chances of finding life, but only with the differential between finding life under Circumstance A or Circumstance B.
Five orders of magnitude has, in my post, nothing to do with the chances of finding life, but only with the differential between finding life under Circumstance A or Circumstance B.
Ahh! Very true! Apologies for the misinterpretation!
Last edited by Michael J. McFadden; 11-02-2010 at 01:51 PM..
Actually, I had a further thought, though I'd guess others have had this before me. Given what we know, and given the possibility of what we may soon know, there are some pretty real calculations we can make.
We can roughly estimate the number of stars in the observable universe. We can roughly estimate the number of stars of our general G-or-close-to-it type in the observable universe (resting upon a reasonable assumption that other galaxies are similar in composition to our own).
We can roughly estimate what proportion of stars have at least gas-giant style planets (from the nearby stars where we've searched and found/not-found such things).
And then taking a jump:
We can, from our current cosmological theories about solar system formations, make a reasonable estimate of how many such stars with such planets would also be likely to have planets in venus to mars range orbits with a substantial rocky core and water (assuming for the moment that we'll limit life to carbon-based water-evolved-dependent forms)
And then taking a possible near-time-future jump:
We can hope to soon determine whether there is or has been any form of life on Mars or Venus, and, if so, perhaps be able to determine somehow whether it is different enough from Earth-based life to have come about independently (as opposed to some sort of spores being carried after an asteroid collision or a little green man planting expedition or such things). This is the real sticking point: *IF* we find such life then all the rest of the estimates become workable. If we *DON'T* find it, then the question stays pretty wildly open ended as speculations about the initial origins of life would seem to involve too many variables to even guess at a probability as far as I know.
And then at the end adding in the five orders of magnitude factor noted by JTur....
We may be able to, in the not too distant future, come up with a reasonably based estimate of how many planets there are in our universe that currently house intelligent life!
As noted, this sort of thing has probably already been done and done better by people who know what they're talking about.
He poses two scenarios, and based on the only life we know, that we are likely to snuff ourselves out after a short duration of 'intelligence', which ain't very intelligent. But for intelligents civilisations that to become intelligent enough to not self eradicate themselves, the numbers become significantly higher.
The real question is, if an intelligent civilization came here, they would be vastly more intelligent as they have mastered interstellar travel, would they see us as intelligent, or merely tool using primates on the inevitable path of self annihilation.
We seem too involved in the argument of which god is the right one, and fighting wars to settle the argument, without any proof any god exists, to call our civilization intelligent.
The problem with the Drake equation (also referred to as the SETI Equation) is that every component of it is an unknown and most of them can not be estimated. So one can not obtain a known from nothing but unknowns.
LOL! OK... it looks like I was doing a "Drake's Equation" on my own! Thanks for the video Nomander! My one big difference is the question of estimating the probability of life developing. Without any data at all beyond our own planet I think Sagan is totally off base making any estimate at all about it. That uncertainty, combined with the uncertainty of technological life evolving significantly beyond the capabilities of terminal nuclear wars (which uncertainty he does make a nod to at the end, although you could fudge it by saying something like "There's gotta be at least one civilization in a million that doesn't blow itself up!") make this sort of equation pretty meaningless.
On the other hand though I'd argue that he vastly underestimates the likelihoods with his tenth times a tenth that life would eventually culminate in radioastronomical civilization. Intelligence would seem to be quite strongly a natural and almost inevitable product of continued evolution as it improves chances of survival, and as intelligence grows then such level of civilization is also almost inevitable.
I would agree that intelligent life forms would be likely, given the number of galaxies and stars there are. The universe is a big place... Very big.
I agree...the universe is a very big place.
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Speculations & Estimations
