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648125
bio website arXiv.org
location Europe
age 48
visits member for 3 years, 7 months
seen 19 mins ago

I'm a theoretical physicist.


3h
comment Correct tetrad index notation
Comment to the question (v4): Please double-check formulas. E.g. fifth eq. has indices $IJ$ in wrong position.
5h
comment Tensor Notation Puzzle
OP writes (v1): So, I think I understand the usage and motivation for this positional offset. I am curious and thus the puzzle as to why so many texts (almost all of the current raft of GR texts) totally ignore any type of explanation for the use of positional index notation. It seems OP understands the notational issue and is only asking a primarily opinion-based question about the author's choice of presentation.
9h
comment Integration by parts
$\int d^x~~~~?$
10h
comment Physical reasoning and mathematical problems
The question (v3) seems like a too broad list question.
1d
comment Why does matter gather as discs around massive objects?
Possible duplicates: physics.stackexchange.com/q/26083/2451 , physics.stackexchange.com/q/93830/2451 , physics.stackexchange.com/q/12140/2451 and links therein.
1d
comment Advanced Gravitational Waves?
Hi RandomDSdevel, to rollback click the 'edited' button.
2d
comment Having trouble understanding some stuff about delta functions
Possible duplicate: physics.stackexchange.com/q/47934/2451
2d
comment Covariant Nonlinear Transformation in two inertial frames
Related: physics.stackexchange.com/q/12664/2451
2d
comment Teach me Wick's theorem the honest way
Related: physics.stackexchange.com/q/18078/2451 , physics.stackexchange.com/q/24157/2451 , physics.stackexchange.com/q/108631/2451 , physics.stackexchange.com/q/130622/2451 and links therein.
2d
comment Does the Noether's theorem apply to local symmetries?
Possible duplicates: physics.stackexchange.com/q/66092/2451 , physics.stackexchange.com/q/112367/2451 and links therein. Related: physics.stackexchange.com/q/26990/2451 , physics.stackexchange.com/q/61205/2451 and links therein.
2d
comment Index notation with Navier-Stokes equations
Wikipedia doesn't seem to help.
Oct
22
comment What is $g$ when traveling quickly around a planet?
Hi Friend of Kim. If you haven't already done so, please take a minute to read the definition of when to use the homework tag, and the Phys.SE policy for homework-like problems.
Oct
22
comment These two operators commute…but their eigenvectors aren't all the same. Why?
$\uparrow$ Agree.
Oct
22
comment Do we exist in multiple dimensions?
Related: physics.stackexchange.com/q/10527/2451 , physics.stackexchange.com/q/83492/2451 and links therein.
Oct
22
comment These two operators commute…but their eigenvectors aren't all the same. Why?
It is interesting to note that the theorem talks about diagonalizable operators (rather than selfadjoint operators, although admittedly the latter is what is relevant for QM). Being diagonalizable is a generic property. Being selfadjoint is a special property.
Oct
22
comment Topology of phase space
Comment to the question (v3): See V.I. Arnold, Mathematical methods of Classical Mechanics, $\S49$.
Oct
22
comment Non-integrability of the 2D double pendulum
Comment to the question (v4): The total external torque $\tau_z=\frac{dL_z}{dt}$ (produced by gravity) around the suspension point, is rarely zero. Hence $L_z$ is not an integral of motion in the presence of gravity.
Oct
22
comment Index notation with Navier-Stokes equations
Hi @miro2: ...and a reference to the use of the disputed notation?
Oct
22
comment In QED, why is the $e^- + e^+\leftrightarrow\gamma$ process forbidden on-shell?
Related: physics.stackexchange.com/q/13513/2451 , physics.stackexchange.com/q/22916/2451 , physics.stackexchange.com/q/12488/2451
Oct
22
comment Dielectric slab counter-intuitive formula?
Comment to the question (v6): Consider to add a reference for the formula to make the question more accessible.