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location Jena, Germany
age 31
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If you like electrodynamic problems with solutions and their connections to current research, please visit www.problemsinelectrodynamics.com


Jan
6
comment Classical Mechanics & Coordinates
1. a good mathematical description of a physical system, 2. velocities are replaced by momenta, 3. lets you find equations of motion in 2.'s, 4. is the application of 3....
Nov
12
awarded  Yearling
Oct
22
comment Electrical circuits problem
"My issue is, what about on the grid?" I have slight problems to understand what you are talking about. Could you put your question in a simpler terminology leaving out your speculations?
Sep
20
awarded  Popular Question
Aug
25
awarded  Good Question
Jul
29
awarded  Nice Question
Jul
6
revised Interaction ranges in the Standard Model - Electrodynamics vs QCD
rolled back to a previous revision
Apr
23
comment Why doesn't a stationary electron lose energy by radiating electric field (as per coulomb's law)?
Where did you read that accelerated charges radiate? In that reference, please look at the derivation, which should answer your question.
Mar
21
comment Where do the conservation laws come from?
Nick: I would start to understand the nature of conservation laws from the perspective of the invariance of the action with respect to transformations. This is basically Noethers theorem but maybe a little more intuitive. For example, charge conservation can be derived from gauge invariance of S, link.
Mar
9
comment Does the intensity of dipole radiation fall as $1/r^2$ or $1/r^3$?
please look for the farfield of the dipole radiation which is what you are asking for.
Mar
8
comment Does the intensity of dipole radiation fall as $1/r^2$ or $1/r^3$?
second link in google for "dipole radiation". Hope this helps.
Feb
23
awarded  Popular Question
Feb
10
comment Least-action classical electrodynamics without potentials
@JerrySchirmer Yes, you are right, I had a typo, my interaction term should of course be $j_\mu A^\mu$ as you state. However, the equations of motion of CED are Maxwells equations and in them, there are no potentials which is all I am saying. Anyways, real matter interactions are of course hard to handle in CED as we can see for example in the cumbersome derivation of radiation reaction.
Feb
6
comment If you could reverse gravity, what velocity would you achieve on leaving Earth?
@Nathaniel a reversion of gravity here just means that you change the equation of the potential from $\Delta \phi \propto -\rho$ to $\Delta \phi \propto +\rho$. Such a system has a well-defined potential energy just with reversed sign from the usual form and you can just equate the energies. There is no further argumentation of a "reversed earth" needed and the integral is not necessary although it doesn't hurt.
Feb
5
comment If you could reverse gravity, what velocity would you achieve on leaving Earth?
@Nathaniel no, you don't have to do that. Potential energy and gravitational potential chare a quite similar name for a reason - it's a conservative system and all you have to do is look at energy conservation. Your answer is nice but you may consider shortening it.
Feb
5
comment Least-action classical electrodynamics without potentials
@JerrySchirmer This is true, if we write the interaction term in the Lagrangian as the usual $\partial_\mu A^\mu$. However, if you come back to Maxwells equations and Lorentz force, $\propto j_\nu F^{\mu \nu}$, the potentials are not included in any equations of motion in CED. Btw: Who made my comment an answer?!
Feb
4
answered Least-action classical electrodynamics without potentials
Feb
4
comment If you could reverse gravity, what velocity would you achieve on leaving Earth?
@kηives I don't know, I think for such a straight forward question I prefer just to help the questioner to get the answer her/himself :)
Feb
2
comment If you could reverse gravity, what velocity would you achieve on leaving Earth?
Equate gravitational potential energy at r = R_earth with kinetic energy and you're done. :)
Jan
17
comment If human energy use were to increase by 2.3% per year, would we use all solar energy by 1400 years?
Not understandable question and a link to the explanation - smells like promotion. May I put my website here as well?! ...