3 ms·
Doesn't this boil down to time-reversal? I doubt CPT symmetry is relevant here, so I'd be very surprised if it didn't simply reverse the rotation.
by Filligree 3y ago
Doesn't this boil down to time-reversal? I doubt CPT symmetry is relevant here, so I'd be very surprised if it didn't simply reverse the rotation.
- eafer 3y agoThe rotation is not reversed though (at least not with the same speed), that's why it's always been interesting.
- ChadNauseam 3y agoA normal sprinkler works by a pump pushing water out the nozzle. Wouldn't a time reversed sprinkler be a situation where water is flying into the sprinkler and depressing the pump? in that case I would expect the rotation to be reversed.
- Filligree 3y agoWell, yes. Isn’t that the situation the article is describing? Suction isn’t a real thing, so- Wait. Is this meant to imply it’s running underwater?
- ChadNauseam 3y agoYes, in the thought experiment it runs underwater. It's fine though because it can run underwater in both cases, so that doesn't ruin the symmetry. The article implies a situation where the pump is running in the opposite direction as normal, sucking the water in. That's not time-reversed though (eg in the time reversed version, the pump generates electricity instead of consuming it, because the water is pushing it instead of it pushing the water)
- marcosdumay 3y agoNo. A nozzle behaves differently if you plug it the other way around, and that does not break CPT symmetry.