General Discussion

We know how life was able to evolve on earth. There is no reason to believe that with billions of planets with essentially the same conditions as earth has had for billions of years, that there wouldn't be life forms. Certainly the simplest life forms (single cell) must exist in millions or billions of places. But moving up that pyramid, you need lots of things to break your way to evolve to higher forms. You need a sun that provides steady energy, not a sun that is in a giant or dwarf phase. You need an atmosphere. Mars once had much more of an atmosphere than it has today. You need a stable, mostly circular orbit to avoid temperature extremes, and an absence of cataclysmic events.

You probably need a molten core, as our earliest life probably sprung from vents in the oceans. And so on. Simple life forms will be very common, IMHO, but higher life forms require good luck. At the rate that we are destroying our planet, we will not evolve to a much higher life form. But among the bullions of solar systems, it is almost certain that there will be many places where life has surpassed our level.

The problem is travel. At this point, we have no way to travel faster than the speed of light, and not even any interesting theories about that. So for now, we can pretty much rule out the whole Star Trek/Star Wars transportation mode. If we could travel at the speed of light (we can't), it would take us over 4 years to take a one-way trip to Proxima Centauri, which is the closest star to us. If we wanted to leave the Milky Way and go to another galaxy, the closest one would take us over 2 million years if we traveled at the speed of light.

But in Einstein's space/time theories, there is at least the possibility of distortions (wormholes) that could allow one to take shortcuts to distant places. Maybe that is possible, and maybe a race of critters much smarter than us has figured it out. But from where I sit, that is science fiction with no real basis in science. But who knows? A master race may have answers that we can't possibly envision. If we have been visited by intergalactic space aliens, they certainly seem to have been both mysterious and clumsy about it.