The Drake Equation predicts life in the universe, yes, that's very true,
No, that's not true.
The Drake Equation is just that, an equation.
It makes no predictions at all.
Only by putting in values for the many variables can you use it to make a prediction.
But, as TR put it so well:
Telemachus Rex said:
the Drake equation has terms that we have no ability to estimate. We can make guesses, but not informed estimates.
And so people make informed estimates on a few of the variables and guesses at the others.
According to Wiki, these are the "current best estimates" (but with few citations given)
R* = 7/year
fp = 0.5
ne = 2
fl = 0.33
fi = 0.01
fc = 0.01
L = 10,000 years
Which yields a value of 2.31 for our Galaxy.
http://en.wikipedia.org/wiki/Drake_equation
But as we come up on 3 years since Kepler's launch the data already suggests that the "best estimate" for
fp, the number of stars with planets at .5 is WAY too high.
Consider that Kepler is looking at data from ~170,000 stars out of about 500,000 in it's field of view with over 300,000 left out because they are not likely to be conducive to life (too small/dim)) and so far we have only ~2,300 candidates and only 33 confirmed planets. While this number of confirmed planets will go up, still it is not looking like it will be anywhere near the 80,000 planets you would need for
fp to equal 0.5 for just the 170,000 being looked at. Indeed the number of .01 seems like a more realistic value for
fp.
But more importantly, the value
ne = the average number of planets that can potentially support life per star that has planets, at 2 is WAY too high (so far we have found NONE among all the planets we have studied), so at this point we have 1 out of 33 that is in the habitable zone, but not likely to be habitable, or an implied value of less than .03. Again, we think this number is likely to go up but a value of .2 now also seems quite high.
Just changing those two values in the current "best estimates"
R* = 7
fp = 0.01
ne = .2
fl = 0.33
fi = 0.01
fc = 0.01
L = 10,000 years
Gives a value of .005 planets in our Galaxy with intelligent life.
Or not at all likely.
But consider, even that value is based on the assumption that .33 of the habitable planets go on to develop life.
Personally I think that considering our 4+ Billion year history and yet life only forming once over that time frame, that .33 for
fl is WAY too high.
Indeed that number could be MUCH smaller and a value on the order of .0000001 for
fl is not unreasonable.
Then there is
fi = the fraction of the above that actually go on to develop intelligent life, and again, considering that it's taken 4 billion years for this to occur and only once of all the millions of species that have existed and millions that currently exist, this number, at .01, is also (IMHO) likely WAY too high.
Indeed a value on the order of .0000001 for
fi is again, not unreasonable.
R* = 7
fp = 0.01
ne = .2
fl = 0.0000001
fi = 0.0000001
fc = 0.01
L = 10,000 years
Which (if my numbers are more reasonable (and you can't actually prove they aren't)) would say the likelyhood of intelligent life in our Galaxy is .000000000000014
Or an absurdly remote possibility.
Even given ~80 Billion other Galaxies in the Universe that would still imply the chance of other intelligent life in the Universe as but .001
Or not very likely at all.
Arthur