## Comment: Re:me dumb (Score 1) 130

Well, there are several "kinds" of wormholes. In one, the distance really is 3 ticks, in every way that matters, and the fact that there's also a 10-tick path (which used to be the shortest path before the wormhole) means nothing, as there are an infinity of circuitous paths. But that's not this kind of wormhole.

`MeA1----------A2B1>>>>>>>>>>B2`

To see the problem, imagine 2 wormholes, A and B, each with widely separated endpoints. In my reference frame, the endpoints A1 and A2 are stationary - I'm standing by A1 and can send a message instantly to A2. The endpoints B1 and B2 are stationary relative to one another, but are moving close to c relative to A. In B's reference frame, my message goes back in time.

If my message gets relayed A1-A2-B2-B1 just as the endpoints pass, I'll get it before I send it. In my reference frame, A1-A2 is instant, but B2-B1 goes back in time. In B's reference frame, A1-A2 goes back in time, and B2-B1 is instant. Either way, it's a causal mess.

A simpler example: you can get a straightforward time machine simply by accelerating one end of a wormhole up to relativistic speed for a few years, and then bringing it back, parking it at rest near the other end. Like the twin who visits a distant star and returns, one end will be "younger" than the other. Now the wormhole moves you back (or forward) in time by a few years when you traverse it.