# All Questions

746 views

### Noether theorem and classical proof of electric charge conservation

How to prove conservation of electric charge using Noether's theorem according to classical (non-quantum) mechanics? I know the proof based on using Klein–Gordon field, but that derivation use ...
900 views

### Does the increase of (relativistic) mass, while flying near speed of light, has any impact on astronauts? [duplicate]

Possible Duplicate: Would travelling at relativistic speeds have any impact on human biology? I am asking myself this question for a few day. What is the answer on: Does the increase of ...
259 views

### What's up in this SPAWAR video?

Here is a video presentation of infrared recordings of anomalous heating in a deuterium palladium cell: ( youtube video) (see also this presentation if you want more detail, and have time). There are ...
237 views

### Homogeneous gravitational field and the geodesic deviation

In General Relativity (GR), we have the geodesic deviation equation (GDE) ...
870 views

### How can mass affect spacetime?

In General Relativity Theory, mass can warp spacetime. However, in my view interaction only occurs between pieces of matter. Spacetime is not matter; how can it be affected by matter?
720 views

### Finding radius of Earth through observation of Sun's motion

The question I'm about to pose is from a physics book I had recently bought. Since I am very interested in physics I am quite keen in understanding how this question can be solved. Before I present ...
89 views

### How were the crystal lattices of elements determined to perfection ? (Ex:- That of a copper is a cubic lattice ) [duplicate]

Possible Duplicate: How can crystal structures be determined using X-ray diffraction? Are there any simple means in order to verify the nature of complex lattices like that of Triclinic , ...
6k views

### How to derive the period of spring pendulum?

So I wanted to find out how to (simply, if that's possible) derive the formula for a period of spring pendulum: $T=2\pi \sqrt{\frac{m}{k}}$. However, Google doesn't help me here as all I see is the ...
1k views

### Investigating damped Harmonic Motion in a Spring?

I'm going to conduct an investigation into the dampening of a spring. Essentially, what specific factors could be investigated? Currently I'm planning to investigate the effect of changing the mass ...
201 views

### Potential for charge distribution, finiteness

Consider a potential for charge distribution: $$v_H(\mathbf{r}) ~=~ \int \frac{\rho(\mathbf{r'})}{|\mathbf{r}-\mathbf{r'}|}d\mathbf{r'}$$ where $\rho(\mathbf{r'})$ is the charge density. This ...
182 views

### Write $\epsilon_{\mu\nu\alpha\beta} F^{\mu\nu} F^{\alpha\beta}$ as a total divergence $\partial_\mu G^\mu$

I have the following homework problem in theoretical electrodynamics: Show that the gauge invariant Lagrange density $\epsilon_{\mu\nu\alpha\beta} F^{\mu\nu} F^{\alpha\beta}$ can be written as a ...
98 views

### Magnetic force on capacitor

I have this problem: I have a capacitor formed by two parallel square-shaped plates, of side $a$, and with distance $d$ between them. They're asking me out of other things, the magnetic force as a ...
258 views

### Banach Space representations of physical systems

I think most physicists mostly model physical systems as some kind of Hilbert space. Hilbert spaces are a strict subset of Banach spaces. Questions: Can physical systems really have non-compact ...
412 views

361 views

### Gravitational redshift derivation

When we derive gravitational potential it is dependant only on (rest) mass $m$, but i have seen a derivation of gravitational redshift equation placing relativistic mass $\widetilde{m}$ instead of ...
193 views

### What examples are there of fuzzy concepts in astronomy?

What examples are there of fuzzy concepts in astronomy? In particular, how fuzzy are the boundaries between different types of stars? As an example of a fuzzy concept I'm thinking of the planet/brown ...
416 views

### What are the easiest ways to get data out of a FITS file without a library?

There are FITS libraries for most programming languages (see this list), but FITS is a simple enough format that it should be pretty easy to extract data without the need for such libraries or ...
280 views

### How does a warp field interferometer work?

Assume I have a solid grasp of undergraduate physics. From what I've read the warp field interferometer is supposed to be a sort of Michelson interferometer, except instead of adjusting the ...
532 views

### Chern-Simons term

In the literature I can only find Chern-Simons terms ( i.e. for a 3-dimensional manifold $A \wedge dA + A \wedge A \wedge A$) for odd-dimensional manifolds. Why can't I write such forms for ...
831 views

### What is the meaning of the word “Principle” in Physics?

What is the meaning of the word principle in Physics? For example in the "action principle". Is it an action law, an action equation, or an unproved assumption? (I have an idea what an action is). ...
53 views

### Gravitational potential energy with regards to annihilation

Given particles A, B, C and D, where: A and B have an equivalent mass C and D have an equivalent mass, both larger than A (or B) D is the antiparticle of C. A and B start close to C, but with ...
298 views

### Spinning spheres colliding

In an ideal environment with no friction, in a vacuum, what happens to the velocity of the spin of two spheres spinning in perfect parity at two different velocities when they come into contact?
119 views

### Is there a limit to the charge of a body?

Can a body be limitlessly charged? Suppose a sphere of radius $R$. Can it be charged limitlessly?
249 views

### What's the difference between divergences that can be corrected and those that can't

I'm confused by renormalization . If a lagrangian has a term with negative mass dimension , why can't the divergences be absorbed into lagrangian coefficients? What's the difference between ...
206 views

### Quantum mechanics in macroscopic systems

I don't understand the superposition principle in quantum mechanics or the collapse of wave-function (I think it's impossible for me to understand it) My question is: Is it possible to demonstrate ...
### Could one argue that h (Planck constant) and $\hbar$/2 (Dirac constant) are in fact independant constants?
This question comes from Georgi, Lie Alegbras in Particle Physics. Consider the algebra generated by $\sigma_a\otimes1$ and $\sigma_a\otimes \eta_1$ where $\sigma_a$ and $\eta_1$ are Pauli matrices ...