Knowledge is good

All we had was unicellular life - most of that being simple bacteria or archaea.

I have spent a lot of time thinking about the Fermi Paradox lately. I don't think multicellular life is a given let alone technological life.

If it's happened here, the universe is just simply too large for it to not have ever developed elsewhere. I'd not be surprised if beings as advanced as humanity, or perhaps even slightly more so, have developed elsewhere, for the same reason. It'd just be a lot less common.

The 'wildcard', if you will, however, that many laypeople don't consider when pondering the likelihood of our (humans on earth) ever discovering proof of the existence of other intelligent life in the universe ... is TIME.

The odds that 'our time', the period in which we're 'around' and technologically advanced enough to detect the 'signs of life' than emanated from some distant planet for some likely astronomically short timeframe, JUST happens to intersect perfectly so we DO detect their existence ... are so incredibly low it's ridiculous. IOW, that 'evidence' of 'life elsewhere' would have to travel it's thousands or millions or maybe even billions of years ... and then just SO happen ... to be reaching our little spot in the universe ... RIGHT when we humans are around to pick up on it.

I just don't see that ever happening, that necessary intersection across the vastness of time and space.

300 Billion stars times 300 Billion galaxies is a huge number.

But it did take 3.5 billion years here (maybe the fossil record is incomplete). That is a significant portion of stable stellar life. A dolphin in the Andromeda galaxy is never going to be detected by us.

Just because it happened here does not mean that it is common throughout the universe.

As you said time is another factor. Perhaps we may detect remnants of a Type II civilization around another star system in our galaxy or a Type III residing in another galaxy. Imaging of the entire sky out to 8 billion light years looking for partially or totally occluded galaxies seems to be the best approach outside of the planet searching we are already doing (which has the side benefit of detecting Type II civilizations). The best SETI science seems to be the galaxy and star characterization and cataloging we are already doing.

ALLOW for creatures at least as advanced as us ... to develop. We are de-facto evidence of this reality.

And given the hugeness of the number of total stars that we'd calculate as you describe, it's only common sense that it would happen with at least SOME regularity. Even if it's only 1/1,000,000,000,000 (i.e. a trillion) planets that meet all the needed criteria, that's still many, many planets.

But because I think that any life that developed as advanced as us would've developed based on very similar physics-based 'principles', i.e. competition for resources and natural selection and survival of the fittest (only because I cannot conceive of another 'method' that could eventually produce a 'human-like' species), I think it's unlikely that any of them DON'T end up consuming all their resources and dying the f*** out, just like we're going to do ... SHORTLY.

Ergo, we're only going to leave a TINY BLIP of a 'signature' in this vast universe, and only creatures that happen to 'become advanced like us', and do so at JUST THE RIGHT tiny, tiny sliver of time, and at JUST THE RIGHT distance, such that our 'blip' reaches them ... at a time when they're actually able to 'see it' ... would ever possibly detect that 'we were here'.

Bottom-line I'd be unsurprised if NO species, on any world that's ever existed in the universe ... has ever been 100% certain of the existence of another intelligent, off-planet species ... in the universe. I think there's a very good chance that no species has ever known POSITIVELY ... that they weren't 'alone' ... although I'd bet a good number of them have concluded it's mathematically UNlikely they're the only advanced species to have EVER existed in the Universe.

How do you leave "Kilroy was here" for millennia, observable from light years away? It's one thing to send off a Voyager type probe, on the off chance that it passes through a right system at right time and is even noticed - leaving an omnidirectional signal that is lasting in time is much harder.
Other than interfering with a star to introduce a signal that shouldn't be there (which we are not capable of doing) how do you leave graffiti for other intelligent life?

Perhaps a partially mined star (not sure what the signal would look like).

And it has a tail!

We all know that the earth is only 6,000 years old and this is another plot by satan to test our faith!

Sheesh....

It's a whole bunch of years but when we talk about a million (small number)
it is exactly nothing. I am in my 70's and realizing that I am going over the
rainbow too soon and that I have wasted seventy-some years, I could have
done so much more. I just thought I was too important ... and say, I live another
30 or so, what a waste.

Was meant to mock the young earth creationists who occasionally lurk here...

I built a calendar (I did not invent it) covering everyday
from Creation (a hypothetical term) to the present day,
it is a couple million lines, so I could cross-reference
Jubilee Dates. I can give you the date that Adam was
born and the date that he died. My curious discovery is
you have to add 12 years to everybody's age because
"Begat" means "Bar-mizveh so all those old-timers, including
Methuselah lived an extra twelve years.

Didn't fall of the flat earth's edge before we got to discover them.

Wow!

K&R, thanks for posting, packman!

Cephalization?

Motile?

Dickinsonia Rules...