This puzzle may or may not be easy [ENDED, Solution posted]

Here's some questions on itstoohard.com

No hints, please.
Giveaway ends in 7 days.
EDIT: It's "now" instead of "know" in #5, of course. Sorry for that.

Let's clarify some things.
It is indeed a contributor giveaway. The amount of contributions needed is 0.99$.
And I might as well give some hints now instead of waiting a few days. First of all, remember that this quiz has a theme. Which is a bit more narrow than you might've thought. #4 is two words. At the time of writing #5 has never been featured in the giveaway, at least a public one.

34 entries. Giveaway ended. I'll post the solution in a few days.

Answers:
1) electron
The hypothesis being one-electron universe.
2) Schrödinger's cat
3) Higgs boson
Aka "god particle". Sorry for my attempts at rhyming it was there in case youtube video gets down.
4) particle physicist
Brian Cox / Brian Cox
5) Quantum Conundrum

There was also a bonus giveaway inside the main one. It was Akrham Asylum.