That photo of the Hubble Deep Field really messes with me... in fact any photo like that. You have to realise: somewhere out there, in fact, most likely, many, many places out there, are planets where everything we have and will experience has already happened. Whatever end-point human evolution is driving towards (massive environmental degradation, simulacrum-building, rise of a superhuman elite, space-travel, true self-knowledge, total mastery over the physical world, whatever) - its already happened. Over and over again. By people/things we will never meet and never know about.
Feels very disheartening.