Nice explanation, this made more sense to me than most of the explanations I have heard about this before.
But, wouldn't this just constrain the possible features of a wormhole? The issue is fixed if traveling/observing through the wormhole has the same time dilation:
Both through telescope as through the wormhole, the clocks can be observed to go slower. After 20 years at A, both the telescope as observation through the wormhole show 10 years have passed at B.
If we don't stop B from spinning:
The regular space traveler takes 5 years, as observed from A, to reach B, so reaches B at A:25 years, B:12,5 years. If they leave immediately after arrival, they'll end up again at A at A:30y, B:15y.
Otoh, the wormhole travel leaves at A:20y ends up at B at 10y and gets back to A immediately: A still at 20y and B at 10y.
Mixed travel:regular travel starts at A:20, B:10y, reaches B at A:25y, B:12,5 and jumps back through the wormhole at the same time as seen from A and B.
Exactly ! Why don't we suppose traveling/observing through the wormhole has the same time dilation ?
I've heard of FTL=time-travel a couple of years ago for the first time and I would love to be able to argue with someone knowledgeable about it to understand. I hoped this HN thread would have answers. However all the answers here seem to have holes in same.
I'm starting to wonder if FTL=time-travel isn't like Schrödinger's cat: a hypothetical thought experiment terribly misunderstood by the masses.
Both through telescope as through the wormhole, the clocks can be observed to go slower. After 20 years at A, both the telescope as observation through the wormhole show 10 years have passed at B.
If we don't stop B from spinning: The regular space traveler takes 5 years, as observed from A, to reach B, so reaches B at A:25 years, B:12,5 years. If they leave immediately after arrival, they'll end up again at A at A:30y, B:15y. Otoh, the wormhole travel leaves at A:20y ends up at B at 10y and gets back to A immediately: A still at 20y and B at 10y. Mixed travel:regular travel starts at A:20, B:10y, reaches B at A:25y, B:12,5 and jumps back through the wormhole at the same time as seen from A and B.