Best science fiction story of all-time nomination thread

[Dominic]

as you can all tell, I'm extremely bored tonight.

so...this time i'll do a seeded elimination tournament.

Two rules:

No novellas or novels...ONLY short stories. I'll define it as one you should be able to read in one sitting without a problem.

No stories less than ten years old.

I'll nominate the obvious one first:

Nightfall - Isaac Asimov

and one of my favorites:

The Cold Equations - Tom Godwin

and one more from the modern era:

Blood Music - Greg Bear


so let's here 'em...