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Feb
5
comment Gravity: Is there curved space besides curved spacetime?
@AlfredCentauri: I'm talking about general spacetimes. How would you define spatial geometry in a Schwarzschild spacetime? Aribtrary non-homogeneous, non-insotropic spacetimes? Preferred spatial slicings may exist on a case-by-case basis, but in general, I do not believe there's such a thing as spatial geometry
Feb
5
revised Gravity: Is there curved space besides curved spacetime?
added 68 characters in body
Feb
5
comment Gravity: Is there curved space besides curved spacetime?
@AlfredCentauri: in GR, there isn't really such a thing as spatial geometry - a more appropriate way to think about it is as the matter distribution being layered
Feb
5
answered Gravity: Is there curved space besides curved spacetime?
Feb
4
revised “Reality” of EM waves vs. wavefunction of individual photons - why not treat the wave function as equally “Real”?
added 9 characters in body
Feb
4
answered “Reality” of EM waves vs. wavefunction of individual photons - why not treat the wave function as equally “Real”?
Feb
1
comment A question on Lagrangian dynamics an the velocity phase space
I didn't see anything wrong with your description, but I don't have the time to re-read more carefully right now
Feb
1
comment Can a metric in General Relativity, Supergravity, String Theory, etc., be asymmetric?
it's effectively "usual sort of metric plus an extra field" anyway. Einstein actually addressed that criticism: symmetry of the tensors is non-essential for the formalism; instead, he demands 'transposition symmetry' of the laws and links it to charge conjugation
Feb
1
revised Vector question, differentials, Electromagnetism
answer 2nd question
Feb
1
answered Vector question, differentials, Electromagnetism
Jan
31
comment Can a metric in General Relativity, Supergravity, String Theory, etc., be asymmetric?
@innisfree: the field in question is no longer the metric tensor representing gravity, but the field, from which you need to derive all other objects of the theory; I'd have to look up how you get to the metric (there were approaches where the metric is just the symmetric part, but I don't remember if this particular theory is one of them)
Jan
31
answered Can a metric in General Relativity, Supergravity, String Theory, etc., be asymmetric?
Jan
31
comment Is it correct to say that falling object are standing still?
it's an interpretation based on general relativity: objects in free fall are at rest, which can be checked with an accelerometer
Jan
30
answered Is $ds^2$ just a number or is it actually a quantity squared?
Jan
30
comment Non Hermitian Quantum Mechanics
see arXiv:1008.4680 for a short overview and arXiv:0810.5643 for the full package
Jan
29
comment Why is the Klein Gordon equation of second order in time?
see also arXiv:quant-ph/0307059
Jan
27
answered Is $∣1 \rangle$ an abuse of notation?
Jan
26
comment Coordinates for FLRW metric
@user3229471: it will not vary between coordinates that agree on spatial slicing
Jan
26
comment Coordinates for FLRW metric
@user3229471: the distance within a spatial slice is well-defined; length-contraction is only possible because observers in relative motion do not agree on spatial slicing...
Jan
26
awarded  Cleanup