I think it's a bit overwritten. It just reads awkwardly for things that are very simple. It's often confusing. Do you really need to describe the room as "the world around it"? Do you need to describe a door as a "portal"? Some of these descriptions are just too much. I'm not totally against cute language. For example, I really liked "It rises high above the child like a cobra reared back before striking" because that paints a strong picture in my head. But otherwise, I think you're overdoing it.
The first action paragraph in the cavern is very confusing. "LIGHT floods the tunnel for a brief moment. Only long enough to hurry through the doorway and slam it behind them. They walk with urgency, doom invading their postures." Slam what behind them? And who is them? I thought we were talking about light, but now we're talking about two unintroduced people. It keeps making me stop and reread.
Further down the page you say "Karl and Otto set to strapping him to the machine." Why not just say Karl and Otto strap him to the machine? Set to strapping is just overly wordy and this type of language just slows down everything.
Some lines are just filler. Things like "But he is on a mission" or "One could hardly believe that this baby, this inkling of existence, will someday be the cause of so many deaths" aren't very necessary and don't add much. "It’s only a child for chrissakes." Is he thinking that? Does he say that? How do you show that on screen? Maybe you don't give enough credit to the reader to know what's going on in their heads.
And unfortunately, the story is a cliche. It's a first-date question (What would you do if you could go back in time?). It's eye-rollingly silly and I feel this idea can be done in some other novel way.