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Nov
22
comment “Reality” of length contraction in SR
@Frank: sure, the analogy isn't perfect due to the non-Euclidean nature of Minkowski space, but the intuition you get from this isn't totally wrong; relativity of simultaneity, time dilation and length contraction are essentially about 'perspective'
Nov
22
comment “Reality” of length contraction in SR
Think of this way: if you tilt furniture so it fits through the door, did you really change its width?
Nov
22
comment “Reality” of length contraction in SR
@Frank: the clock shows accumulated time, but a rod doesn't accumulate anything; the different observers in relative motion could compare the (apparent) length of the path they took, though, and then they'll end up with different values; you can construct 'paradoxes' that way (think about adding stationary distance markers along the way travelled by a meter stick - basically a variant of the ladder paradox)
Nov
22
comment “Reality” of length contraction in SR
@Frank: the length of the rod only depends on the instantaneous relative velocity and is independent of the path taken
Nov
22
comment Needed small explanation of the notation in this paper
@Fluctuations: Right (modulo a factor of $1/2$ depending on the chosen convention)
Nov
22
comment Needed small explanation of the notation in this paper
@Fluctuations: $\delta_{jk}$ is the Kronecker-delta (a rank-2 tensor), but you only anti-symmetrize over one of its indices, leaving $k$ fixed
Nov
22
awarded  Custodian
Nov
22
reviewed Edit suggested edit on Needed small explanation of the notation in this paper
Nov
22
revised Needed small explanation of the notation in this paper
improved formatting
Nov
22
comment Needed small explanation of the notation in this paper
see en.wikipedia.org/wiki/Antisymmetric_tensor#Notation
Nov
22
revised “Reality” of length contraction in SR
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Nov
22
answered “Reality” of length contraction in SR
Nov
21
revised Can all fundamental forces be fictitious forces?
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Nov
21
answered Can all fundamental forces be fictitious forces?
Nov
21
comment Can all fundamental forces be fictitious forces?
but also keep in mind that there are classical forces corresponding to quantum YM fields (cf Wong's equations) - they just aren't terribly useful
Nov
21
comment Can all fundamental forces be fictitious forces?
wouldn't a link to something about Kaluza-Klein theory be more appropriate instead of classical YM?
Nov
19
answered Passage of time on a faster-than-light (FTL) vessel
Nov
17
comment How, in practice, could instantaneous signalling violate causality?
note that any superluminal signal comes with a critical frame where is appears instantaneous; for an explicit example of how superluminal signals violate causality, see en.wikipedia.org/wiki/…
Nov
16
revised Physical meaning of the angular momentum
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Nov
16
answered Physical meaning of the angular momentum