But if time travel is a thing, imagine the whole new time nightmares! Oh you went back a year with your phone? Now all your TLS root certs are invalid because you’re before the start date. Or you have files/emails/whatever that are dated in the future. I guess you can get to that state by just setting your clock forward but I imagine some stuff would break.
The professor that taught my algorithms & data structures course said if we were going to keep one book it should be the one for that course. I followed that advice and it’s the one textbook I still have. It’s been 8 years since graduation and I haven’t opened it once. I tend to just read Wikipedia if I need to understand a particular algorithm or data structure.