What are the probablilities that mankind is alone in the entire universe? After looking at the Hubble pictures I just can’t believe that we are the only fortunate sentiate conscious beings. It really disturbs me to even consider that of all the combinations and permutations we are totally alone in the known universe. This post probably belongs in a different forum but I am just awe struck by the ultimate vastness of what we know as the universe and that there could be much, much more than we are even aware of.
To calculate the probabilities we need some solid numbers. How many stars are there, what percentage of these stars have planets capable of sustaining a form of life, what percentage of potentially life-bearing planets develop life, how many biospheres have the ecological niche that allows the development of what we would call ‘intelligence,’ and how long does an ‘intelligence’ last before evolving to a level we cannot comprehend or dying off.
This is basically what is called the Fermi Equation, and depending on what numbers you plug in you can legitimately come up with any number of technological cultures in the Galaxy from one (just us) to where you can’t turn over an asteroid without findin gnew life and new civilizations.
So, the only good answer we can give to the ‘Are we alone’ question is ‘So far as we can tell now, yes.’
I agree with that statement and I’m also in agreement with the OP. It seems impossible to me that we’re alone in the universe. The incredibly hard question is how do we judge that? What we ‘know’ as life may not be…um…universal. Carbon based life is all that we know and all we’ll be able to notice. I’d guess this whole thread could be moved to GD over that assumption.
There are to many things we find out daily about our own little rock…I think basing ‘life’ in the universe on what we ‘know’ is a bit presumptious.
I promise, I don’t own a tin-foil hat! 
I would be much more surprised to find out that we are alone than if other life forms were to be found.
The only way I could see that we might be the only life force is if we are the beginning of life in the universe.
We just did this thread the other day. I think it was in GD…
I can understand that. I never venture into GD though. I hate being outclassed so handily! 
Drake Equation, actually. The full equation is
N = Rf[sub]p[/sub]n[sub]e[/sub]f[sub]l[/sub]f[sub]i[/sub]f[sub]c[/sub]L
Where
R is the rate of star formation within the Galaxy, expressed in stars per year;
f[sub]p[/sub] is the fraction of stars that form planets;
n[sub]e[/sub] is the average number of planets each such star possesses, which are capable of supporting life;
f[sub]l[/sub] is the fraction of those planets where life actually occurs;
f[sub]i[/sub] is the fraction of life-bearing planets where intelligence arises;
f[sub]c[/sub] is the fraction of intelligent life-bearing planets where intelligent beings develop the ability to communicate beyond their own world; and
L is the length of time, in years, that such communications remain detectable.
Sorry. Always conflating it with the Fermi paradox.
Factual answer: Not enough data, please try back in 100-200 years.
Gut answer: We haven’t seen any evidence of large, solar system scale heat emissions; we haven’t been colonized by a species able to do .1c in the 1 billion years life has existed here. Therefore if life is out there it’s very rare or rarely spacefaring.
I’ve never posted in any of the other “Is There Life Out There?” threads so I’ll get this off my chest: Knock it off with the Drake equation!
Frank Drake’s credentials are not questioned. But I need to get him over to dinner to ask whether he was ever serious at all about that equation. It’s certainly valid as it does express the number of technological, intelligent, communicating civilizations in the Galaxy. But when four out of your seven factors are WAGs I start for the hosted bar, Frank.
I have a shorter version: N = S*f[sub]mm[/sub], where
S equals the number of stars in the Galaxy;
f[sub]mm[/sub] equals the fraction of those stars with technological, intelligent, communicating civilizations. Much easier to remember and only one WAG as opposed to four.
This is more of a debate than a factual question. Rather than move this thread to GD, I’ll close this one and direct further comment to a recent GD thread: http://boards.straightdope.com/sdmb/showthread.php?t=247126
bibliophage
moderator GQ