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visits member for 2 years, 2 months
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Jul
2
awarded  Curious
Jun
18
awarded  Yearling
May
26
answered How to picture a quantum field?
Apr
16
comment Energy in an electromagnetic wave
See my answer to this question: physics.stackexchange.com/questions/66977/…
Dec
9
accepted Proof of the inverse square law for a uniformly bright sphere
Dec
9
comment Proof of the inverse square law for a uniformly bright sphere
Thanks, I was mistaking the line going from P to the tangent of the sphere as the hypotenuse. But now I can appreciate, the hypotenuse is in fact the horizontal line in the figure. I see now this makes sense as it is ofcourse the tangent which is perpendicular to the radius.
Dec
9
asked Proof of the inverse square law for a uniformly bright sphere
Oct
20
awarded  Custodian
Oct
20
reviewed Reject suggested edit on Getting started general relativity
Sep
10
comment Expansion of the universe and strain
Clearly, for all practical purposes the expansion of "metal blocks, glass rods, skeletal systems" is completely negligible. So I don't think you are right to say " Some people will insist that there is no such effect, but this is simply wrong." I think it would be better to say " Some people will insist that there is no such effect, and this is essentially correct as the effect is completely negligible, although strictly speaking not exactly equal to zero".
Aug
15
comment Dark age of universe when all fusion process ceases?
@BenCrowell to calculate the probability of a white dwarf tunneling to a black hole, I would think you need quantum gravity and so presumably we don't actually know what that probability is and it could potentially be zero.
Aug
8
comment Newtonian approximation in cosmology
Thanks,that is very helpful.
Aug
8
accepted Newtonian approximation in cosmology
Aug
7
revised Newtonian approximation in cosmology
formatting fixed
Aug
7
revised Newtonian approximation in cosmology
formatting fixed
Aug
7
asked Newtonian approximation in cosmology
Aug
1
comment Why is information indestructable?
In simple language the way I understand it is according to QM we can describe the world with a wave function. That wave function's equation of motion is reversible so if you know the wave function at one point in time you can use the wave function evolution equation to predict what the wave function will be in a future or a past time.
Jul
21
revised A column falls, how will it break?
added 36 characters in body
Jul
21
answered A column falls, how will it break?
Jun
24
comment How does dark matter halo outside a galaxy help to explain galaxy rotation curve?
Nice answer, but I wouldn't say $\rho \propto 1/r$ is uniform.