Didn't see the movie. As a matter of fact, was more curious about another (partial) space opera, about a planet named "Melancholia" that ends up destroying the set. An update on "When Worlds Collide" - but in a way a little more plausible.
From time to time had heard of the notion that life on earth got its head start from elsewhere. Francis Crick, one of the discoverers of DNA back in the early 50s, about a decade or so later went around suggesting that life on Earth got started, maybe if some aliens had stopped by and left their garbage here.
Or other variations, that elementary lifeforms or advanced organic chemistry compounds are abundant galaxy wide and drift around, or that places like Mars where it could have got an earlier start, contaminated the earth via impact debris from other collisions that got knocked off the surface. We've got the martian meteorites of recent arrival, picked off glacier surfaces in Antarctica or Greenland - but the arguments that microbial formations were anything that once lived - far short of a scientific consensus - but the search goes on.
What I have heard about the movie though is that there is some Space Odyssey early scene of an alien 3.5 billion years ago seeding the earth with some bacteria or something - and then, like "The Search for Spock" or "Nemo", people from Earth take off looking for the guy.
Well, exo-planets aren't exactly like the moon hanging around nearby in the sky. If the little green men from billions of years back came from planet Zong orbiting star Zing, both Earth and Zing-Zong are orbiting the center of the galaxy. Their paths are arbitrary. They are two stars in a crowd of a couple hundred billion. What would place them in proximity now? How could you tell?
And what do you know! From what I hear it's like the identical twins that were raised by adoptive parents. We named our dogs fido; so did the aliens. We grew up to be firemen. So did the aliens. And it all started with archeobacteria or whatever. The aliens must have got impatient about their plans having to wait until the Pre-Cambrian for anything multi-cellular to show up. But they had a dream, ... I guess. How did the dinosaurs fit into the scheme? I guess they needed to have a 200 million year jungle picture episode. All gets wrapped up in the 23rd century though, right?
That business about "Melancholia". I don't know if the director had any idea, but as the exo-planet picture has been getting clearer, part of the clarity is that a whole lot of planets get ejected out of star systems. Maybe one for every star. Space is pretty empty, true, but I can remember when people debated about whether there were any planets at all, much less whether they were any running loose like the home of Ming the Merciless, the planet Mongo. Maybe a chilled down Neptune. 2012, 2013 a chance in a million, true. But if aimed right,an interloper like that could put a kabosh on an eterna corporate party on a paradise earth.