Is the notion that we could create a craft that travels faster than the speed of flight more absurd, less absurd, or equally as absurd as the notion that we could create a perpetual motion machine?
From my current understanding, it’s less absurd. Again the pedantic ones would say this is still not FTL but again to them who cares? We are not breaking laws of physics and we get from point a to point b fast.
No matter how we do it, we end up violating causality. Even if we can only create micron-sized warp drives, there are still some huge implications. We could probably build a machine that executes nondeterministic algorithms, for example — doesn't matter that P≠NP if we nevertheless have a way to solve such problems in P time.
I've also wondered about the implications of a causality-violating miniature warp field, and the hypothetical application I found most intriguing is the possibility of it allowing information to be sent back in time from the future.
Of course it would have the limitation that you could only send information back to a point after the "time machine" had been switched on, and you could only communicate to entities in the future who knew of your time machine's existence and design, but that's enough of a pinhole to send lottery numbers back through.
This has probably been considered before in fiction, where presumably the author thought about the other practical problems, like the time machine being on a rotating and Sun-orbiting Earth, meaning that the spatial distance between the time machine's location on subsequent days can be considerably large (relative to reference frame of the Sun). I don't know what the engineering consequences of that are.
> This has probably been considered before in fiction
"Thrice Upon a Time" by James P. Hogon, 1980. [1] It plays with interesting implications. In the book, sending a message to the past changed that version of the past.
My under standing is temporal communication in our universe is likely to be different. You couldn't change your past, so somehow things would line up no matter what you did.
But perhaps you could impact events you had not yet measured, since that impact, and your after-sending sampling of them, would leave a lot room for impact without contradicting any information you had at the time you sent.
For instance, you send a message back to your collegue to buy a stock yesterday, and you haven't seen him since last Tuesday. So nothing weird would have to happen to achieve consistency. Presumably your friend bought the stock, knew not to tell you until tomorrow to give you time to have sent that back to him. If the colleague tried to tell you earlier, something would stop him - because obviously he wasn't able to before you sent the message.
A good way for the colleague to risk their life since a serious accident would be the best way for time to prevent a determined colleague from changing the universe!
That means things in the time loop (from received time to sent time) could get very weird to achieve consistency.
> For instance, you send a message back to your collegue to buy a stock yesterday, and you haven't seen him since last Tuesday. So nothing weird would have to happen to achieve consistency. Presumably your friend bought the stock, knew not to tell you until tomorrow to give you time to have sent that back to him. If the colleague tried to tell you earlier, something would stop him - because obviously he wasn't able to before you sent the message.
I just don’t see how this works in the extremely simple case where you send the message to your past self. Using the colleague just tries to sidestep this. What physically happens if you attempt to send a message to yourself that you don’t remember receiving in your past? Does the system just consistently malfunction? Does it turn out that you had an accident between receiving and sending that caused memory loss?
It's not like you always, at any moment, remember every single moment of your life. You send it back, and then you remember it. You couldn't have remembered it before you've sent it back, but as soon as you did, you remember reading it.
Makes perfect sense to me. I see no reason why the memory wouldn't spontaneously form.
It definitely steps around P=NP. You could try a large number of costly experiments and "send back" the working solution. The parallel experiments collapse into one.
You can send canary messages back to yourself to know if you're in danger, assuming it's you on the other side.
But perhaps the signals from the future are actually from an advanced adversary, such as an AI, and they're telling you to make moves that will lead to your demise (or the rise of the adversary).
The future adversary knows your actions and can send crafted messages to nudge you to the desired outcome. Perhaps similarly to the "P=NP" parallel explorations in the future from the past, the future has parallel simulations of your past behavior to optimize the future outcome.
