I
imamartian
Why?
With a choice as you say of billions
Well, there are many many stars in the universe, but most of them are not likely to have a life-friendly rock whizzing round them.
Of the few remaining likely planets, if life were to spring up, life on earth had a mighty long journey before we turned up:
Basic timelineLife on Earth
3.8 billion years of simple cells (prokaryotes),
3 billion years of photosynthesis,
2 billion years of complex cells (eukaryotes),
1 billion years of multicellular life,
600 million years of simple animals,
570 million years of arthropods (ancestors of insects, arachnids and crustaceans),
550 million years of complex animals,
500 million years of fish and proto-amphibians,
475 million years of land plants,
400 million years of insects and seeds,
360 million years of amphibians,
300 million years of reptiles,
200 million years of mammals,
150 million years of birds,
130 million years of flowers,
65 million years since the non-avian dinosaurs died out,
2.5 million years since the appearance of the genus Homo,
200,000 years since humans started looking like they do today,
25,000 years since Neanderthals died out.
(courtesy of wikipedia)...
our ability to 'make contact' has only been in the last hundred years or so...and in the next hundred years, or even thousand years, robots might have taken over the planet, or we may well have destroyed it ourselves.
So what are the chances of our 1000 year window of opportunity overlapping with another planets?
