I do not have the complete answer but here's what I've worked out so far:
"Link a phrase which means being depressed,"
A phrase which means propitious future,
A golden future or a bright future?
Something utilizing the phenomenon which results when film is exposed for a long time,
expsosing a film to light uses a phenomenon which is called: Photoelectric.
And the scientific process by which liquids(or gases) turn to solids.
well if you freez liquids or gases they become solid, so lowering the temperature. the scientific names for it are Deposition and Solidification.
At first i thought it was:
Carl sagan, because of his statement A Pale blue dot, (but the only thing matching there is blue, you might say (for the birght future, everything falls pale by comparison) but still that would only give me 3 words (Pale blue dot) where i have 4 sentences which might even give me more than 1 word each.
Then i though:
It might be albert einstein, when you think about photoelectric you might not directly think about him but this was a part of his work.
So no real answers yet, but maybe this helps others. I'll surely update this when I figure out more.