819 reputation
38
bio website folk.ntnu.no/jabirali
location Norway
age 24
visits member for 2 years, 8 months
seen 9 hours ago

I'm currently a student of Applied Physics and Mathematics, and enjoy tinkering with computers in my spare time.


9h
awarded  Citizen Patrol
14h
comment Are fundamental forces always attractive/repulsive, i.e. parallel to the separation?
If you take into account that electromagnetic fields propagate at the speed of light, then two electrons moving past each other will not be repulsed by the location that the other electron is, but by the location that the other electron was. Thus the observed force is not along the line connecting the electrons at that moment. But I guess you still count that as a repulsive force then?
14h
comment Are fundamental forces always attractive/repulsive, i.e. parallel to the separation?
So you're asking for examples of when Newtons third law doesn't apply? :)
16h
awarded  Enthusiast
Dec
16
comment probability amplitude and path integrals
@TAbraham, you use the same action $S[q]$ in classical mechanics and in the path integral formulation of quantum mechanics. The difference is that in classical mechanics, the particle takes the path of stationary action; while in quantum mechanics, the particle takes all of the paths. But it can be showed that the path of stationary action is usually the dominant part of the path integral due to positive interference, which is why the principle of stationary action works so well in classical mechanics.
Dec
15
revised Rotation systems. Problem interpreting an equation
Converted the equations to LaTeX
Dec
15
suggested approved edit on Rotation systems. Problem interpreting an equation
Dec
14
comment What specific type of light on the EM spectrum has the longest wavelength and has been defined?
For any given light wave, the exact wavelength actually depends on the observer due to the Doppler effect. So the question of what is the shortest/longest wavelength doesn't really make sense, because you can in principle choose to make any given emission have an arbitrary wavelength by just travelling really really really fast relative to the source.
Dec
11
answered Does there exist a hyperbolic relationship between frequency $\omega$ and wavenumber $k$?
Dec
10
comment Rigorously prove that electric field is zero in a perfect conductor
@FraSchelle, note that $\rho$ is the resistivity, not the charge density. So the equation $\mathbf E = \rho\mathbf J$ is just another way of writing Ohm's law, not a reference to Gauss' law.
Dec
7
answered Are solutions coordinate invariant?
Dec
7
comment How close can an observer approach the black hole in an unpowered flyby without falling into it?
Do you mean hypothetically (i.e. a point-particle approaching a black hole with nothing else around), or realistically (i.e. a big spaceship approaching a rotating black hole with an accretion disc etc)?
Dec
6
comment Can a strained diamond actually become conductive?
If you're not only interested in pure diamonds, you may find it interesting that boron-doped diamonds are semiconducting at room temperature, and even becomes superconducting near the absolute zero.
Dec
6
comment Relationship between Energy and Time
According to Noether's theorem, the conservation of energy is a result of the physical laws governing the universe not changing with time (technically, energy is conserved in a any system with a time-translation invariant Lagrangian.)
Dec
4
comment Green function for interacting system
There are many different kinds of Green's functions (time-ordered, retarded/advanced, Matsubara, Keldysh, etc.), and I don't think it is obvious what your notation means. Perhaps you could add the definitions of the quantities that you refer to, and provide some more context for your question?
Dec
3
comment Speed of light definition
By the way, note that the magnetic permeability contains a factor $\pi$ by definition; it is a result of how the SI unit ampère is defined in terms of magnetic forces between conductors.
Dec
3
comment Speed of light definition
Because $\pi = 3.1415926535897932384626433832795028841971693993751058\ldots$ is also an exact number?
Dec
2
revised Magnetic field at infinity
added 4 characters in body
Dec
2
answered Magnetic field at infinity
Dec
2
answered Can a single technology be used to observe light at any wavelength?