In the movie Solaris, psychologist Chris Kelvin is sent to a space station orbiting a distant planet to investigate an odd phenomenon: deceased loved ones of the crew members are appearing on the ship. So, the planet they're orbiting reads Kelvin's mind, learns everything it can about his late wife, and replicates her.

What makes this story really interesting is that the replicants are not complete recreations; they are based merely on the memories of those who remember them. I generally don't pay any attention to movie critics, but I found the following except from Roger Ebert's review of the 2002 remake to be surprisingly poetic:

"In other words, Kelvin gets back not his dead wife, but a being who incorporates all he knows about his dead wife, and nothing else, and starts over from there. She has no secrets because he did not know her secrets...The deep irony here is that all of our relationships in the real world are exactly like that...We do not know the actual other person. What we know is the sum of everything we think we know about them. Even empathy is perhaps of no use; we think it helps us understand how other people feel, but maybe it only tells us how we would feel, if we were them."