Elaboration:
Imagine Spacetime as a movie film reel. All of time (past, present, future) exist at the same time just like all the frames of that movie exist on that reel. If you want to time travel you go to the frame location on that reel. That location we call a WHEN but it is also a WHERE on the reel. Also, when physicists state that time and space are interwoven a film reel analogy encapsulates that theory well. So, time travel could be simply going to a specific coordinate in Space.
Theoretical Physicist Sean Caroll uses the film strip analogy in this video:
Sean Carroll Explains Presentism and Eternalism
See also:
https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time)
The illusion of time : past, present and future all exist together
Is Time A Single Block? Eternalism And The Andromeda Paradox
Time: Do the past, present, and future exist all at once? | Big Think
Disclaimer: Obviously, I have been watching too many Youtube videos and none of the concepts are my own. But I did think of the WHERE VS. WHEN regarding time travel analogy as I haven’t seen anyone state it that way yet.
Would that mean we have no free will, and our lives and destiny is already predetermined?
Basically, yeah. I can’t think of a reason free will would actually exist given what we currently know about the universe. It’s all just math, and we run on the same math as the rest of the universe. All we are are complex chemical reactions. There’s just no reason to think there’s anything that makes us special.
That said, our understanding of the universe is decidedly incomplete.
Doesn’t matter either way.
If you have free will, you can think you don’t and do as if your destiny is already settled.
If you don’t have free will, then it doesn’t matter if you feel like you have free will and continue to think that you can influence your destiny.
Either thinking doesn’t really matter because we can’t know for sure if we do have free will or not so you can’t make an informed decision.
So choose whatever interpretation you like and be your best self.