How fucking depressing is it that we may be the wise elder civilization? 
Answers to this question are necessarily short on evidence, and thus tend mainly to reflect the opinions and biases of those offering them.
There’s the old story about the Emperor’s beard: No one is ever allowed to set eyes on the Emperor of China, but the question arises: how long is his beard? Thousands of the most intelligent and revered citizens are asked, and their answers are carefully averaged. This yields a number of great precision - which unfortunately bears only a coincidental relationship to the truth.
The very fact that the various species of life on Terra have shown significantly different metabolic pathways to success indicates to me (a layman in the realm of biology) that is highly likely for life to come into existence where there is enough energy deferential between complex self-replicating molecules and their environment to allow a net decrease in entropy.
This could be happening right now in the atmosphere of Jupiter or the surface of Titan. In the oceans of Europa or even the buried ruins of the departed ecosystem of Mars.
Life appears to be, even in the most extreme realms of our planet, to be ubiquitous.
The question is whether intelligent life is unique to Terra.
I pause and then I laugh.
There are quite literally billions upon billions of galaxies, each of which have billions of star systems.
The probability that we, H. sapiens, are the only sapient species in the Universe is so infinitesimal that I am unwilling to calculate it.
But, as Doctor Fermi said, “So, where are they?” (That’s probably a misquote).
I am sure that topic has already been discussed before I joined.
When this question comes up, I like to point out that life on Earth managed just fine, as far as we can tell, for billions of years before human-level intelligence happened along. We have this deep-seated biased view that our intelligence is both inevitable and, at some level, what evolution is FOR. Even if we know that’s not quite right, it seems to be really hard to shake that feeling.
As to this:
Actually, we should really sincerely hope that we ARE just that. The reasoning (which didn’t originate with me, though I’ve forgotten who I first heard it from), goes like this. The Fermi paradox suggests that there should be lots of intelligent life out there, but we don’t detect it. Therefore, we could conclude that there is some massive roadblock somewhere between “single cell emerging from primordial ooze” and “intergalactic empire” that seems to be universally - or nearly universally - insurmountable. Now, since we don’t know where that roadblock is, it’s either behind us, or ahead of us. If we go out There and find lots and lots of civilizations roughly at our level of intelligence, then we can assume that the roadblock, whatever it is, is still to come. If, however, we go out There and find no life even remotely close to our level of intelligence or complexity or what have you, then we could conclude that somehow, without knowing it, humanity has amazingly managed to get past this roadblock, and the universe is our oyster, and ours alone. It’s a bleak outlook, but an interesting one.
Spectacular fame and fortune would be yours if you could reliably show that this probability was below, say, 90%. Your contribution to science would be immeasurable. If you are indeed able to, you certainly should.
If you don’t, it’s reasonable to conclude that you, like others, currently lack the evidence that would make this possible.
*“Tell me, just how far have you looked?” * :dubious:
Our experience and our field of vision is so small that basing any negative assumptions on the fact that we haven’t seen them yet is absurd.
Therefore, whoever happens to be sitting on the Dragon Throne must be the Emperor . . .
That could greatly simplify a coup d’etat. 
You’re looking at it the wrong way. It doesn’t matter how many billions of galaxies there are - all that matters is how many galaxies there are that are close enough to us that we could feasibly detect other intelligent life.
The universe is 13.7 billion years old. The early universe could not support life, as it was composed almost entirely of light elements like hydrogen, helium, and lithium. Until recently, it was believed that it took several generations of star birth and death before heavy elements required for life were available in the quantities required for rocky planets to form, and some estimates for how early rocky planets could have been formed were as late as 7 billion years after the big bang, or about 6.7 billion years ago.
New evidence from Kepler shows this may not be the case, but even if it was possible for some rocky planets to form earlier, it probably still took a very long time for there to be enough heavy elements to make rocky planet formation common. And it’s still the case if you assume that a technological civilization capable of reaching us would need abundant metals.
So let’s assume that the phase of the universe that led to widespread creation of planetary systems like ours didn’t start until 7 billion years ago. Let’s further take Earth’s 4.7 billion years as the timeframe it takes for intelligent life to appear. That puts the earliest possible date for a technological civilization at about 2.3 billion years ago.
So, it would be impossible for us to know about any civilizations farther than 2.3 billion light years from us, as any evidence of them would not be able to travel here in time. That’s still a gigantic number of stars and planets, but it’s not infinite or anywhere near big enough for us to state that any probability at all becomes certainty. There are about 3 million large galaxies within 1 billion light-years of us, and 60 million dwarf galaxies. That’s a far cry from the 7.3 trillion galaxies in the visible universe.
But realistically, our chance of detecting another civilization dwindles rapidly with distance. And replicating probes face energy constraints that could prevent them from attaining anything close to a significant fraction of the speed of light on average. So it could be that the universe is infested with probes slowly making their way here, but the math is such that it will take an extremely long time. n Or perhaps a ‘Von Neumann infestation’ would be localized within a galaxy and not easily spread to other galaxies in any realistic time frame.
If we get more realistic about our chances of detecting another civilization, we need to limit our search to our own galaxy. - and probably only to the half of it on ‘our’ side of the galactic center, since it obscures the other half of the galaxy in visual and radio noise (well, not half, but the spiral arms and gas clouds also obscure stars, so let’s go with it as an approximation).
The milky way has ~200 billion stars. Eliminate half of them that might be obscured. Then, eliminate all the stars in the galactic center, since radiation levels and interactions between masses would make life exceedingly unlikely. So you’re left with the stars in the outer spiral arms.
The spiral arm of our galaxy that we’re in, the Orion Arm, has about 600 million stars in it, over a distance of 5000 light years. Add in the Sagittarius and Perseus arms, and we’re at maybe 3.5 billion stars as a guess.
Of those, many are too young, or of the wrong spectral type. Some are in bad neighborhoods dense with matter. Some are in regions close to supernova that happened in the last 4 billion years, or were in the path of a gamma-ray burst. It doesn’t take too many assumptions to get the possible candidate stars down into the millions instead of billions or hundreds of millions. And once you’re down into that range, you’re well within the odds for intelligent life not existing.
For example, there are millions of species on earth that evolved without rising to high intelligence. So maybe life exists on millions of planets, but of those planets that have life there’s only a 1 in 100 million chance that a technological civilization will arise. That would mean it’s more likely than not that the sphere around us in which we could reasonably hope to detect an alien civilization is unlikely to contain one, even if the larger universe is teeming with them.
Now, these numbers are all just educated WAGs. The point, however, is that you can certainly construct a reasonable hypothesis for why we haven’t detected an alien race, even if there are millions of such races in the universe.
Well, you get wisdom by making mistakes. We may eventually be very wise indeed.
And then there is another huge leap, beyond intelligent life, to a technological, life form.
While non-intelligent species have lasted for a long time, our intelligence has taken us from a small range in Africa to being all over the world, so intelligence clearly has some reproductive advantages. Whether or not there is a selection bias for intelligence, you have to start with a brain big enough to support intelligence, and how that happens is not clear.
Definitely - but perhaps a species of dinosaur would have developed hands and intelligence given some more time. Earth has undergone several extinction events, some worse than the one that killed most of the dinosaurs. Perhaps a planet which did not would have developed an intelligent species much faster.
Even a ten million year difference in the development of intelligence, which is not all that much, would lead to very different intelligent races extant. for all we know they may not send out probes, they may be their probes. Saying that a spacefaring civilization will send out probes is assuming they are just like us with more reliable hardware. It is kind of like the Greeks assuming the ships of the far future would be just like theirs with bigger sails.
I’d bet that a highly advanced civilization would have done away with flesh bodies. You could be immortal, have backups, and experience all that we do with perfect fidelity since our senses just transmit analog signals to our brains, signals that can be simulated.
What that kind of being wants is beyond our imagination.
Just don’t destroy the one named Kirk.
I’ve always hated that speech. First it got torn almost verbatim from the first pilot, second, it sounds like a random page from Gene’s typewriter got mixed into the real script.
</hijack>
Yes please 
CAPT
My opinion (and see below, as I admit that it has a gigantic flaw in it) is that this is almost certain to happen. There is simply so damn much potential energy out there, just dying to be used. Tons of tinder-dry brush, needing only a spark; tree limbs just ready to fall; fruits and nuts and seeds chock full of nutrients. (And animals full of nutrients!) There is also the vast potential in chipped-rock tool-making.
“The secret is to bang the rocks together, guys.”
Hm… I just Googled, and, apparently, the earliest stone tools were made around 2.6 million years ago. This kinda undermines my theory of inevitability…
That isn’t just a speculative fiction either. In the late cretaceous we already had medium sized, bipedal, social pack hunters with grasping hands and decently large brains. Without the extinction event it is very plausible that these sort of animals might well have developed into an intelligent civilization.
Considering that we went a hundred thousand years or more before we started on the road to technology and have really only had anything relatively advanced for 200 years, it isn’t entirely infeasible to postulate a species as intelligent as Humans that did grow and expand but never passed that certain point in social and technological development. If say, even a million years ago there was a species that grew into the tens of millions but never passed roughly the level of the pre-contact North Americans before dying out, how much real evidence of their existence would persist?
Was there any evidence of the Easter Islanders?
Stone tools would persist.
And how would we know when they were made and used other than our own assumptions about who made them and when?