Brian Earl Spilner said:
They clearly set it up when they brought back Superman.
In Endgame, Tony literally spends what seems like a few hours one night and somehow figures out time travel without further explanation.
Let's not pretend one is good and the other is ridiculous.
In fact, travelling faster than the speed of light (which yes, is impossible) actually would mess with time, whereas whatever Tony did is literally just handwaved away. We see a 3D projection of something that somehow passes for an explanation.
Your obvious DC hate boner and Marvel bias is showing with that one.
Tony figures out time travel based on the info Scott gave him, from actually having been in the Quantum realm. In other words, Scott's real-world experience gives Tony a new perspective by which to come at the problem. Is it ridiculous that he then figured it out in one night? Sure. But the filmmakers at least go to the trouble of properly setting it all up and then very clearly explaining the rules and implications.
In that sense, it legitimately *is* less ridiculous than what Justice League attempts because of the context provided and the stakes that are made crystal clear. Again, I'm not talking about the science itself. I'm talking about the effort on behalf of the filmmakers to give the audience a general understanding and proper expectations.
As for traveling near the speed of light, though, if you really *do* want to get technical with it, the only time traveling that Flash could technically do is forwards not backwards. Traveling near the speed of light would cause him to age slower than everyone else, a la Interstellar. In that sense, time would move slower for him and faster for everyone else, which would, for all intents and purposes, make him a time traveler. But there's no going back in time via fast-as-light travel. At least with the Quantum realm, and quantum mechanics in general, we don't yet know enough about that field to know that we can't somehow utilize quantum technology to travel back in time.
Ha, and re: my "DC hate boner," I've gone out of my way to compliment aspects of MoS and BvS here on the board in recent weeks, after my rewatches of each. That, and I even made an attempt to not be completely negative in my rant on the previous page (which, again, is more of schtick than anything) by saying I really like the Batman/Affleck aspect in these movies, with a follow-up saying I genuinely like Snyder as a person. But if my hate boner is still irrational or unfair, your devotion to and excuse making for things like DCEU and the prequels is just as bad, only on the other end of the spectrum.
It's all good, though, and that's one of the reasons I like you. Otherwise, may we unite in our love of Avatar, Succession, and the myriad other things we *do* agree on on this board.