# All Questions

689 views

### Thermodynamics of evaporation

If water is introduced in a container maintained at 20 °C in vacuum conditions, a gaseous phase will appear and the pressure will stabilize at the vapour pressure for the given temperature inside the ...
786 views

### Is contextuality required in quantum mechanics?

I still don't really understand what contextuality means in reference to quantum mechanics. If someone could give a clear definition that would be great. It sounds like it means you can't always ...
308 views

### Is GR vacuum equation unique?

The title question would be too long if I tried to specify it clearly. So let me be more clear. Consider the class of theories having the following properties: The langrangian density is only ...
1k views

### What combinations of realism, non-locality, and contextuality are ruled out in quantum theory?

Bell's inequality theorem, along with experimental evidence, shows that we cannot have both realism and locality. While I don't fully understand it, Leggett's inequality takes this a step further and ...
143 views

### Why is there independent motion of Earth's magnetic poles?

Earth's N and S magnetic poles "wander independently of each other and are not at exactly opposite positions on the globe" [from WIKI's "Earth's magnetic field"]. Can these independent motions be ...
507 views

### How much power to keep surface of aluminum plate at given temperature?

I want to heat one side of an aluminum plate enough to hold the other side of that plate $100K$ above ambient. I'm willing to assume that the heated side of the plate is "well" insulated (along with ...
731 views

### Light “diode” and 2nd law of thermodynamics

If I had a light "diode" - an object that only allowed light (at least for a range of frequencies) to travel through it in one direction, would this necessarily allow violations of the 2nd Law of ...
623 views

### Gravitational lensing or cloud refraction?

My current understanding of gravitational lensing follows When a star or other massive body passes between us and another star, the phenomenon generally labeled 'gravitational lensing' occurs. The ...
121 views

### Light bending surfaces and energy funneling properties

In the last year there has been fuzz regarding metamaterials studied for the purpose of cloaking, and it seem to me they are somewhat glorified 2D waveguides, but in any case it seems a reasonable ...
162 views

### What are the statistics of three to five bosons?

This should be a very easy question. If you look at the bottom of "Identical Particles" in Wikipedia, you see Table 1, which gives you the two particle statistics for bosons, fermions and ...
787 views

### What is energy in string theory?

Facts agreed on by most Physicists - GR: One can't apply Noether's theorem to argue there is a conserved energy. QFT: One can apply Noether's theorem to argue there is a conserved energy. String ...
438 views

### Is there a rest frame for the Higgs boson?

If there is a non-zero expectation value for the Higgs boson even in "vacuum", since the Higgs boson has a mass unlike photons, then I would expect it to have a rest frame. So why doesn't a non-zero ...
655 views

### Energy in magnetic fields

If I calculate the energy contained in the electric field for an electric dipole p in an electric field E, I get (ignoring the terms independent of orientation): $U = - \vec{p} \cdot \vec{E}$ which ...
807 views

### Does GR provide a maximum electric field limit?

Does GR provide a limit to the maximum electric field? I've gotten conflicting information regarding this, and am quite confused. I will try to quote exactly when possible so as not to confuse ...
2k views

### Does Heisenberg's uncertainty under time evolution always grow?

Recently there have been some interesting questions on standard QM and especially on uncertainty principle and I enjoyed reviewing these basic concepts. And I came to realize I have an interesting ...
297 views

### Web references for Nelson's “Quantum Fluctuations”?

Edward Nelson's book "Quantum Fluctuations" (Princeton UP, 1985) gives an alternative way to introduce trajectories, quite different to the trajectories of de Broglie-Bohm type approaches. I've read ...
2k views

### How can there be net linear momentum in a static electromagnetic field (not propagating)?

I understand from basic conservation of energy and momentum considerations, it is clear in classical electrodynamics that the fields should be able to have energy and momentum. This leads to the usual ...
434 views

### Young's experiment or why the light can't be described as a particle [closed]

Who hasn't heard about the double-slit experiment? It figures in any book of quantum physics. But there is something no one can explain to me : I understand why the light cannot be described only as a ...
844 views

### Velocity of Voyager 1

I was reading Wikipedia which stated ....Voyager 1's current relative velocity is 17.062 km/s, or 61,452 kilometres per hour (38,185 mph)..... It travels away from sun. So sun's gravity must ...
222 views

### Can T-duality resolve spacelike singularities?

Schwarzschild singularities are described by the Kantowski-Sachs metric with a contracting S2. Of course, T-duality doesn't apply to S2. But what about a Kasner-type singularity with two contracting ...
732 views

### Why is the AdS/CFT approach to superconductors rarely cited in condensed matter publications?

Let me put things into perspective by comparing with other applications of string theory. Nowadays review papers written by cosmologists about inflation models often discuss string theory scenarios ...
2k views

### What is the most energy efficient way to boil an egg?

Starting with a pot of cold tap water, I want to cook a hard-boiled egg using the minimum amount of energy. Is it more energy efficient to bring a pot to boil first and then put the egg in it, or to ...