A similar idea is the Japanese concept "mono no aware", or roughly "the awareness of things passing" -- a central, inevitable poignancy that comes from the impossible contrast of ourselves against the universe.
You said you've read a lot of existentialist literature so this might be redundant, but I'd check out Haruki Murakami's work if you haven't already: I can't think of an author who more immerses in -- and emerges from -- a sense of cosmic loneliness.