1,238 reputation
1514
bio website
location
age
visits member for 2 years, 1 month
seen 38 mins ago

Oct
22
comment What do I see if I move quickly past a charge surrounded by iron filings?
If 4-force in one inertial frame is zero then it will be zero in any other inertial frame too (simply because a zero vector is preserved under a linear transformation). For simplification replace iron fillings with a tiny magnet. Then in the rest frame this magnet doesn't feel any force because i) it can not respond to its own magnetic field ii) it is not moving relative to the charge. So the total 4-force on it is zero as observed in rest frame. Hence in any other frame too it will remain zero.
Oct
22
comment Do Christoffel symbols commute?
Do Christoffel symbols commute? As matrices they do not. See @Ron's answer. does $\Gamma^{e}_{db}\Gamma^{c}_{ea} = \Gamma^{c}_{ea}\Gamma^{e}_{db}$? Yes, because they are just numbers.
Oct
22
comment Do Christoffel symbols commute?
Ron's answer has quite useful information, and moreover its not irrelevant to OP's question. +1
Oct
22
comment Do Christoffel symbols commute?
They are just numbers; so yes, they commute.
Oct
22
comment What really is Spacetime?
Most physicists believe that i) Spacetime was created at big bang. ii) Energy controls its "shape" and "size" iii) If in some region of space you can create a high energy density then you can even create a hole in space time. iv) however nobody knows what spacetime would look like at such high energies, or even if it would exist or not. In particular, there is no agreement among physicists as to what should be a quantum theory of spacetime.
Oct
22
comment What really is Spacetime?
+1 good question :)
Oct
21
comment How to determine the probabilities for a cuboid die?
I think general solution to your conditions would be $P_{ab}=f(ab,bc,ca),P_{bc}=f(bc,ca,ab),P_{ca}=f(ca,ab,bc)$, where $f$ is a function which is symmetric in its second and third arguments, and goes to zero when its first argument goes to zero. For example $f(x,y,z)=x^n/(x^n+y^n+z^n)$ for any $n$ is also a solution.
Oct
16
comment Why less temperature at high altitude
In places of high altitude too we have ground to heat up the air then why its still cold. It is ( as @CrazyBuddy pointed out) just because of low pressure ?
Oct
14
answered State normalization in Dirac's formulation of quantum mechanics
Oct
14
comment Grassmann paradox weirdness
In classical field theory $\psi$'s are of course usual complex valued fields. When you quantize you are bound to require that they satisfy anticommutation relations (for otherwise some things go wrong in quantum theory). So the "ring" is ring of operators on Hilbert space. However if you take path integral approach to quantization then you have to treat $\psi$'s as anticommuting variables so that your results agree with results of Hilbert space formalism.
Oct
9
comment How to think of the harmonic oscillator equation in terms of “acceleration = gradient”
Sorry, now i understand. Your equation comes from inclusion of some force term in usual geodesic equation. But then if you take $k$ in your equation to be negative of the $k$ in OP's question and if $\Gamma$'s vanish then we'll get harmonic oscillator equation!
Oct
9
comment How to think of the harmonic oscillator equation in terms of “acceleration = gradient”
Shouldn't your equation be $k\,x^{a} = \Gamma_{bc}{}^{a}{\dot x}^{b}{\dot x}^{c}$ ?
Oct
9
suggested suggested edit on How to think of the harmonic oscillator equation in terms of “acceleration = gradient”
Oct
9
comment Definition of CFT
Sorry, I meant invariance is stronger condition than covariance; and in CFT correlation functions may not be conformally invariant. right ?
Oct
9
comment Definition of CFT
Hi Ron, i think correlation functions are only required to be conformally covariant.
Oct
9
awarded  Fanatic
Oct
8
comment How can perturbativity survive renormalization?
Anyone who has downvoted should at least leave a comment so that others may know what is wrong with this answer. I personally think it is correct. +1
Sep
29
awarded  Custodian
Sep
29
comment Proof of Canonical Commutation Relation (CCR)
@ColinMcFaul Thanks :)
Sep
29
reviewed Approve suggested edit on Proof of Canonical Commutation Relation (CCR)