[Sashimister]

この中で主人公が大学の講義で
in this (movie) the protagonist in the lecture of the university
in questo film il protagonista in una lettura dell'universita'
Good.

宇宙物理学者という立場で議論する場面があって/それが
there's a scene of where it's discussing an poin of view of an astrophysicist
You cannot cup up a sentence like this. A phrase ending in が is never good. It's more natural to cut it after the あって.
it's >> he is

自分的にすごくすごく考えさせられた
typical of me (?), it made me think a lot
Incorrect. "It personally made me think very hard." It's pretty childish to say すごくすごく.

「決定論」と「ランダム論」について語っていて
It talks about "Determinism" and "Random theory"
Good.

物事は起こるべくして起こっている決定論と
the determinism occurs when things happening in natural way?
"Determinism in which things happen because they were meant to happen"

すべて偶然にすぎないというランダム論
the random theory everything is only accidental
"Random theory that says everything happens accidentally."

僕の考えはやはりどちらとも言えない
still I can't say my thoughts on both ?
"In my opinion, I cannot say either is right."

すべては運命づけられていると考える場合もあるし
?
"There are cases where I feel everything is pre-determined."

やはり全ての事象が偶然で成り立っているとも考えられ る
also/still all the events ?
"I can also feel that everything happens accidentally."