'help! I am stuck in a time loop; can I use it to get jacked?'

The Question

My question for you has to do with the movie Edge of Tomorrow.

In that movie, Tom Cruise's character relives the same alien-v-human battle over and over and over again, eventually figuring out how to defeat the bad guys through some combination of choreography (that spaceship is going to blow at precisely this time, so he better not be standing by it) and time-loop-acquired fighting skills. He becomes increasingly adept as a warrior, albeit with the assistance of a fancy exoskeleton, after training loop after loop with Emily Blunt's character.

My question, though, is whether one could actually, truly train for something in a time loop? His body resets at the beginning of each loop. So he is never, say, reaping the benefits of his muscles tearing during exercise and then recovering bigger and stronger (or however exactly it works--I'm not a scientist). And even if he had a great memory, and could truly hold onto all the abstract knowledge of the fighting training he's receiving, could he really actually translate that knowledge into action without being bodily with that knowledge over some extended period of time? I used to do some jiu jitsu, and I remember the massive disconnect between watching someone demonstrate a move and then feeling what that move felt like in my own body (already a huge step) and then actually using that move in a live sparring situation. The movements need time to sink into your bones! And I don't know how, physically, that would happen if your body resets every day. Tom Cruise's guy would simply have no muscle memory, in any sense of the term.

So I guess I think the answer here is "no." But I'm curious to know what you think!

Thanks--and thanks more broadly for the work that you do. I've learned a lot, and gotten a lot stronger from reading your writing. And congrats on the book--I need to get my hands on a copy.

The Answer

[spoilers for Groundhog Day, Palm Springs, Edge of Tomorrow, The Time Machine, and On the Calculation of Volume ahead]

This is a very valid question for those of us who are, or may become, stuck in time loops. Unfortunately, the answer rests not with some inherent quality of time loops in general, but the rules governing the time loop. It’s a similar question in nature to, when you become a ghost, or when you time travel, what dictates your clothes coming with you, versus not? Almost always, the clothes come with you. But then what is the limit of something “coming with” you through the transition? Can you just bring anything you’re touching? Does it have to be wrapped around your body? If you can’t bring anything you’re touching with you, why don’t you show up in the new instance naked? Do you bring the food in your stomach with you? What about foreign objects in your stomach? And so on.