665 reputation
313
bio website
location
age
visits member for 2 years, 11 months
seen 6 hours ago

May
18
comment Entropy of a system of gravitationally interacting particles
Gravitationally collapsed systems are not in thermodynamic equilibrium, see pg 378 of Binney and Tremaine, "Galactic Dynamics", 2nd ed.
May
11
answered Cosmology: collisionless vs collisional fluids?
May
7
comment Could there be a dark matter planet?
The minimum halo mass of dark matter is model dependent with some dark matter models allowing earth mass halos and other requiring the minimum halo size to be much larger.
Apr
24
comment Could the missing antimatter lie outside the observable universe?
This is related to the idea of a multi-verse. It would need some way of the asymmetry to vary during inflation. I'm guessing there are some models that could do this, but haven't looked into it in too much detail.
Apr
17
comment Is a single photon also a Maxwellian wave?
See my answer to this question:physics.stackexchange.com/questions/66977/…
Jan
11
comment How did Einstein arrive at the right hand side of his general relativity tensor equation?
The RHS contains no information until you specify $T^{\mu\nu}$. One can use the Newtonian limit to help with that.
Jan
5
awarded  Excavator
Jan
5
revised Are gravitational time dilation and the time dilation in special relativity independent?
Fixed typo in first sentence of paragraph 2.
Jan
5
suggested approved edit on Are gravitational time dilation and the time dilation in special relativity independent?
Nov
28
comment Is there uncertainity of position of the perfectly homogenous radiating body?
I don't understand your question. All measurements have some uncertainty associated with them. For example, if it is a faint source, there is Poisson noise.
Nov
11
comment Why does the measurement of some observable $A$, the measured value is always an eigenvalue of the operator?
Its essentially an axiom of quantum mechanics.
Nov
3
comment How do we physically apply the operators of quantum mechanics on a particle?
As stressed by @AlfredCentauri your question is somewhat confused. A measurement does not correspond to operating on a state with the associated quantities operator.
Nov
3
comment How do we physically apply the operators of quantum mechanics on a particle?
OK, I think I see what you mean, but I still maintain that last paragraph is a bit unclear and the answer would probably be better with the last paragraph removed.
Nov
3
comment How do we physically apply the operators of quantum mechanics on a particle?
@AlfredCentauri The last phrase "but which value will be measured is not determined by the state" is not quite right. I think you should rather say "but which value will be measured has a probability which is determined by the state"
Nov
1
comment How do we physically apply the operators of quantum mechanics on a particle?
In practice I don't think one usually does measure it in that way. Although quantum mechanics of course is perfectly correct, there is not always a straightforward correspondence between the basic theory and what is done in practice. Generally, the momentum of a charged particle is done by measuring it radius of curvature in a known magnetic field. If you want to prepare a particle in a particular momentum state this can be done by having two parallel plates with a small hole in each of them so the particle has to be traveling in a straight line between the holes to get out.
Oct
31
comment What is the mystery of turbulence?
I agree with your answer and am mystified by these supposed quotes from wikipedia: "According to an apocryphal story, Werner Heisenberg was asked what he would ask God, given the opportunity. His reply was: "When I meet God, I am going to ask him two questions: Why relativity? And why turbulence? I really believe he will have an answer for the first."[4] A similar witticism has been attributed to Horace Lamb (who had published a noted text book on Hydrodynamics)—his choice being quantum electrodynamics (instead of relativity) and turbulence. " I hope they were joking!
Sep
25
revised Lorentz transformations and gamma matrices
minor edit
Sep
25
asked Lorentz transformations and gamma matrices
Sep
22
awarded  Popular Question
Sep
17
comment Origin of cusps in simulated dark matter halos
I think those extra comments are not in line with stack exchange conventions and I suggest you remove them.