3,150 reputation
11442
bio website cedrich.net
location Geneva, Switzerland
age 29
visits member for 4 years, 10 months
seen Aug 21 at 10:49

#STOPSHELL


Jun
12
comment Do the planets really orbit the Sun?
Thanks for that detailed answer. I fully agree one can use any reference frame, yet some are more "natural" than others. Your answer shows also that it is a complex matter and that the statement "planets orbit the barycenter" doesn't really explain anything per se.
Jun
10
comment Do the planets really orbit the Sun?
Your edit gives additional information. I conclude from it that saying that the earth orbits the barycenter of Sun-Jupiter (very close to the real barycenter of the solar system) is at best an anecdotal situation, there is no mathematical reasoning implying that the earth in the 3 body problem orbits the barycenter.
Jun
6
comment What is the use (/ meaning) of $F =ma$?
The question is so weird that I don't know if this really answers OP's questioning.
Jan
4
comment Why do neutrons repel each other?
@Marek: You cannot really say that the Coulomb force don't play a role in nuclear physics ... And regarding the magnetic moment and VdW forces, it plays a role in experiments with neutrons at very low energies (almost at rest), so I think it is a good complement to other answers. That being said I can admit that it is not the most comprehensive answer I ever posted.
Dec
27
comment Why do neutrons repel each other?
"parts about proton-proton and neutron-neutron are completely wrong" : "parts" like me answer is so damn long. @Marek altough you most of the time provides good answers, the way you interact is once again quite strange ... In addition you cannot say that coulomb force cannot be discussed in this case ... It plays a role in nuclear physics, even if in some cases it can be neglected (in any case one have to discuss why).
Dec
14
comment The Concepts of Path Integral in Quantitative Finance
As there's a few votes to reopen and a great answer, I reopened.
Nov
26
comment Hubble's law and conservation of energy
@Marek: If one does'nt know about time symmetry, it is almost impossible to consider that just reading your (correct) answer.
Nov
24
comment Rope tension question
OK but a tensor is not a matrix...
Nov
24
comment The Impossibility ( or Possibility) of Solving $N$-Body Problem
@Ngu: strange definition of analyticity.
Nov
23
comment What's with the very slightly larger mass of the neutron compared to the proton?
@Frederic: Yes I would, in a process called $\beta^+$, which is energetically acceptable because it appears in a bound state (a nucleus) and the binding energy has to be considered. I meant that it is incorrect because of the "is": a neutron "is" a proton and an electron, meaning something like a intimately bound state or something like that.
Nov
21
comment Resonance in a gravitational field?
"Resonance in a gravitational field" makes me thing about that: en.wikipedia.org/wiki/Orbital_resonance . But your question is strangely stated..
Nov
21
comment Gravity and Collision of two continuous mass distributions
@Rajesh: At first your question was not clear at all... I interpreted by "point mass" a geometrical point affected with a mass. A classical scattering problem like the one of a charged point-like particle.
Nov
20
comment Gravity and Collision of two continuous mass distributions
I think you are all going too far with this black hole thing, my opinion is that he is just asking the different between the scattering of point-like particles and the scattering of spheres; this can be treated due to gravitational or electrostatic interactions (if the spheres are charged). No big deal with GR. Unless the question is very very strange ...
Nov
19
comment Wi-Fi in the presence of very strong magnets?
The frequencies at least have to be in a similar range.
Nov
18
comment Can a superconducting wire conduct unlimited current?
"A superconductor also expels all magnetic fields from inside itself (Meissner effect)," This is true only for type I SC or for type II below the first critical field. Usually magnets are type II operating between the critical fields, in that case the field penetrates the material partially.
Nov
18
comment Can a superconducting wire conduct unlimited current?
"A superconducting magnet quench can produce a sizeable explosion!" True but this has nothing to do with superconductivity itself.
Nov
17
comment What makes a space a real space?
When I am talking to my mother I don't use the word "space" and when I am solving a physical problem I formulate it mathematically... What's the difference between your question and "Why would we interpret something that seems to move as something really moving ?" ?
Nov
17
comment What makes a space a real space?
Real space if not a very well defined concept: we just use it when we want to distinguish from another space we are using, like reciprocal space.
Nov
17
comment What makes a space a real space?
Please stop with this "philosophy" tag: either your question is a valid question about physics as a science and it doesn't need this tag or this is not a valid question and it should be closed.
Nov
17
comment Is it possible/correct to describe electromagnetism using curved space(-time)?
The answer of Eric is really interesting and correct and explain that in their general form, Maxwell equations can be applied in the case of a curved space-time. But I think the question was: the basic gravitational potential is similar to the electrostatic one, so can we describe electromagnetism using general relativity. As you accepted the answer, you should maybe modify to question to make things clear.