[EY quote on the covariance of physical law for a spinning body]
Edit: You are correct from a classical physics standpoint that if you are in a windowless room on a merry-go-round, you can tell whether the merry-go-round is standing still versus spinning at a constant speed.
As far as I can tell, what I’m saying holds even for non-spinning accelerating objects, and under quantum physics. According to QFT, a sufficiently sensitive thermometer accelerating through a vacuum detects a higher temperature than a non-accelerating thermometer would. This appears to be a way for a thermometer to tell whether it’s accelerating without having to “look” at distant stars & such.
Hm, I’m not sure the thermometer can conclude that it’s accelerating from seeing the black body radiation. I think it’s equivalent to there being an event horizon behind it emitting hawking radiation (this happens when you accelerate at a constant rate). The thermometer can’t tell if it’s next to a black hole or if it’s accelerating. Could be wrong though, but I vaguely remember something along these lines.
I don’t see anything incorrect in what you say. (Sounds to me like a direct consequence of the equivalence principle, although I’m no GR expert.) But I’m assuming away the possibility of rogue black holes in this hypothetical, since I’m wondering whether a sufficiently sensitive sensor could detect its own acceleration even inside an otherwise empty universe (or at least without reference to the rest of the cosmos).
I think I misunderstood what you and Silas were talking about. (Note though that my train thought experiment was about a train with a constant velocity. The billiard ball technique works to detect acceleration of the train even if no rotation is involved.)
Yes, all acceleration is absolute, not relative. You don’t need hypothetical esoteric effects to detect it, a usual weighing scale will do. Gravity throws a bit of a quirk in it, of course.
I’m simultaneously reassured (that my intuition’s correct) & confused (about SilasBarta & Eliezer’s remarks, since they read to me like they contradict my intuition). Maybe I should post a comment on the Sequences post rather than continuing to press the point here, though.
[Edit: originally linked the wrong Sequences post, fixed that.]
As far as I can tell, what I’m saying holds even for non-spinning accelerating objects, and under quantum physics. According to QFT, a sufficiently sensitive thermometer accelerating through a vacuum detects a higher temperature than a non-accelerating thermometer would. This appears to be a way for a thermometer to tell whether it’s accelerating without having to “look” at distant stars & such.
Hm, I’m not sure the thermometer can conclude that it’s accelerating from seeing the black body radiation. I think it’s equivalent to there being an event horizon behind it emitting hawking radiation (this happens when you accelerate at a constant rate). The thermometer can’t tell if it’s next to a black hole or if it’s accelerating. Could be wrong though, but I vaguely remember something along these lines.
I don’t see anything incorrect in what you say. (Sounds to me like a direct consequence of the equivalence principle, although I’m no GR expert.) But I’m assuming away the possibility of rogue black holes in this hypothetical, since I’m wondering whether a sufficiently sensitive sensor could detect its own acceleration even inside an otherwise empty universe (or at least without reference to the rest of the cosmos).
I think I misunderstood what you and Silas were talking about. (Note though that my train thought experiment was about a train with a constant velocity. The billiard ball technique works to detect acceleration of the train even if no rotation is involved.)
Yes, all acceleration is absolute, not relative. You don’t need hypothetical esoteric effects to detect it, a usual weighing scale will do. Gravity throws a bit of a quirk in it, of course.
I’m simultaneously reassured (that my intuition’s correct) & confused (about SilasBarta & Eliezer’s remarks, since they read to me like they contradict my intuition). Maybe I should post a comment on the Sequences post rather than continuing to press the point here, though.
[Edit: originally linked the wrong Sequences post, fixed that.]