Sqrl said:
Well the earliest formation of stars and galaxies that we can confirm is a bit more than 13 billion years ago so it is certainly possible for some strange ET to have started from there. With that said the early generation stars and solar systems were devoid of heavier elements and were composed of the lighter elements hydrogen, helium, etc.. The formation of late generation stars from the heavier elements resulting as a biproduct of the life of early generation stars provided the heavier elements that are integral to life as we know it. Specifically the formation of a terrestrial planets with iron cores rather than gas giants.
Honestly I'm not sure what the timeline is for the earliest terrestrial planets and it could very well have happened several billion years before the formation of earth. With that said with the way stars form from the remains of old stars utilizing the heavier elements the previous generation produced it certainly seems possible that we could be part of the first generation.
Unfortunately we have very little information about planet formation as a universal process because we only have our solar system to learn from and only recently are capable of locating exoplanets. There is a better than very good chance that the fundamental process of accretion is applicable to other solar systems in our galaxy, particularly in our open cluster (basically stars that formed along with ours but have since become gravitationally unbound).
The real key to the OP's question is that we estimate around 300 Billion stars in the Milky Way and we aren't even the biggest galaxy in our local cluster. In general galaxies range from tens of millions to trillions of stars. Then the estimate is about 100 billion Galaxies in the known universe. Using 100B galaxies with an avg of 200B stars we get a ridiculous 20 million quadrillion potential cradles for life. If only 1% of galaxies are capable of forming life and only 1% of stars have planets and only 1% of planets can potentially have life and only 1% of the potential planets actually do produce life we would still have 200 trillion different planets where life formed.
If we further say only 1% of these planets ever sees multicellular plants and of those only 1% of planets have life leave the ocean and of those planets only 1% see higher animal life and of those only 1% of planets sees intelligent life and of those planets only 1% of intelligent lifeforms survive into the space age....well that is still 20 thousand space aged civilizations in the known universe.
I have to think the odds are excellent that there is at least one other intelligent civilization and I would honestly estimate that it's probably much closer to around 10 million spaced aged civilization throughout the known universe. But that's just my own gut feeling about the percentages at each step.
The problem is that using that 20,000 space aged civs number means that only 1 in every 5 million galaxies would have one such civilization. The distance to our closest neighboring star system is ~4.36 light years which is about 275,000 times further than the distance between the earth and the sun. Most galaxies are around 100,000 light years in diameter and galaxies are spaced out millions and billions of light years away from each other.
For example it's estimated that in ~2.6 billion years we will merge with our nearest galactic neighbor andromeda which is about 2.5 million light years away. If you remove the closest 5 million galaxies which would statistically not have a space aged civ the next closest would be trillions and trillions of light years away. Even at ungodly technological capabilities it's astronomically improbable that they would have even noticed us to bother with the hassle of a visit to our neck of the woods.
/end rambling
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