Sasha [They/Them]

You know how the universe isn’t broken? Well it’s possible it could break and you can’t predict or stop it.

A slightly higher level explanation is that the universe might be in this state which is like a ball sitting in a little divot on the side of a hill, and if something bumps it out of that divot it could roll to the bottom. If that ball rolls to the bottom then it could cause particles to stop behaving the way we expect them to so things like chemistry and life stop being possible.

That makes sense, and I think it literally just is the Deustchian model at least according to this source. It’s been a long time since I read the original paper so I guess I misremembered it as a slightly different thing, though further reading suggests this might be a flawed explanation of his own theory, so I’m just thoroughly confused now haha.

I can think of a number of problems with how it would work, depending on the way you set it up it could result in something like “wormholes” to the future just randomly opening up constantly and everywhere just due to the way probability works. There are certainly a lot of interesting mathematical phenomena that arise from time travel like that.

What you described to me sounds exactly like what I’m referring to, so I’m not sure tbh. I’m referring to the many worlds interpretation of quantum mechanics.

Travelling to the future is so easy that you can’t not do it

Multiverse theory doesn’t really allow jumping like that though, each term in the wave function is independent and that’s kinda the point.

At best a time machine can just allow for further splitting of those terms, but that doesn’t actually mean anything special because we can do that without time travel by just measuring particle spins.

The only saving grace of GR based time travel is that we don’t actually know if the weak energy condition is physical. It probably is, but technically it could be a false assumption.

From a quantum perspective the Deutschian and similar models are honestly pretty compelling. They essentially require matching up the past and present in a consistent way that can remove paradoxes.

These make the most sense because it’s entirely possible to write down spacetimes that contain “closed time like curves” (CTCs) ie. paths connecting past and present and you can then just let physics play out on these models (or more commonly using black box quantum circuits). The only consistent way to do it is to make sure the past and future side of such curves agree. It’s not my area at all, just something colleagues of mine did, but from memory there are nice approaches using the path integral formalism that work really nicely in these scenarios.

All that’s to say that I don’t think time travel leads to anything changing, the past will have always agreed with whatever time travel happens in the future.

Having worked very briefly with the spacetimes that produce CTCs, I don’t expect we’ll be able to time travel because they usually violate the weak energy condition.

https://en.m.wikipedia.org/wiki/Quantum_mechanics_of_time_travel

Honestly most of this album, but Bicycle Spokes in particular.

Great movie btw

I’d been thinking about this for a bit today, I used to own it but I see it pretty differently now.

I kinda realised that I’d basically done all my growing up over the last 4 or so years. That wasn’t my past, I was in someone else’s life and I didn’t know how to play that character. I didn’t grow or change or do anything interesting, I just coasted to some destination I was meant to reach to finish a story I wasn’t meant to be part of.

Now, I’m living my life instead, making my own decisions, liking the person I’ve become and telling my own story. The only downside is that I started with 20 years of baggage that I’ve gotta slowly get rid of.