2
votes
2answers
611 views

Who proposed the bulk-edge correspondence principle?

Who proposed the bulk-edge correspondence principle? The principle is often quoted in counting the number of zero energy states localized on the interface between two insulators with distinct band ...
3
votes
2answers
254 views

Boundary Element Method or Boundary Integral Method Computational Aspects

I have to solve a Helmholtz equation inside a simply connected domain. I know that in general the boundary integral can be written as, $$\phi(x)=\int_V G(x,x') \rho(x')\ d^3x'+\int_S ...
1
vote
1answer
611 views

Finding particles in the classically forbidden regions [duplicate]

Have particles ever been found in the classically forbidden regions of potentials? For example, in a square well: has an experiment been able to find an electron outside the rectangular well (i.e. in ...
1
vote
1answer
185 views

Entangled Electrons

What attribute would help determine in a spaghetti of tangled-entangled electrons, which two are the respective entangled electron pairs, since obviously there is an attribute other than charge or ...
17
votes
2answers
2k views

Evidence of why the Standard Model is a successful theory of particle physics

When discussing physics with laypersons, I'm often in the situation where I have to explain what the Standard Model is, and why it's a successful theory of particle physics. To help in such ...
1
vote
1answer
373 views

Calculating equipotential lines and current density in a rectangular conductor

(This isn't homework, I'm trying to make an illustration for an article I'm writing.) Let's say that I have a thin rectangular bar of uniform conductivity, and I have point probes at various places: ...
1
vote
2answers
296 views

What indicates if an object will bounce back?

If I throw a small rock (m = 1kg) at a big rock (100kg) the small rock rebounds. Let's say my weight is 80kg, if I would jump into a big rock instead of bouncing back I would move in the same ...
5
votes
1answer
439 views

Output of a beamsplitter with photon number (Fock) state inputs

Given a beamsplitter drawn below, where $\hat{a}$ and $\hat{b}$ are input modal annihilation operators, transmissivity is $\tau\in[0,1]$, and output modal annihilation operators are ...
2
votes
1answer
80 views

Effect of aircraft speed on barometer

Many aircrafts depend on several types of static pressure sensors (barometers) to find the altitude. I assume this sensor need to be located outside the aircraft main body, so that it has a contact ...
1
vote
0answers
69 views

Point of rotation appears as an ellipse when calculated from gps coordinates

First question here. Feel free to write if I posted in the wrong place. While rotating a ship as accurately as we can around some point within the ship, we can calculate the point of rotation from ...
2
votes
3answers
234 views

Moving coil contradiction of Faraday Induction

In Faraday's Induction Experiment, the e.m.f. induced in the induction coil becomes zero when the relative velocity of the coil and the magnet becomes zero. But one can also argue from a stationary ...
8
votes
2answers
1k views

Gravitational slingshot maximum

I have recently read an article about gravitation slingshot assist used by Voyagers 1-2, and was thinking on why this hasn't been used for travel between solar and other systems. I mean sligshot can ...
4
votes
1answer
100 views

Has the possibility of Higgs boson being a composite particle excluded already?

I heard some theory, such as technicolor, predicts the Higgs-like particle discovered at LHC should be a composite particle (correct me if I am wrong). Has this possible been completely excluded ...
2
votes
0answers
44 views

Is Gravity a part of the Strong Nuclear Force? [duplicate]

In episode 7 season 5 of Through the Wormhole, they say that gravity could just be a manifestation of the strong nuclear force and that the force carrier are a pair of Gluons. Is this valid in anyway? ...
2
votes
1answer
132 views

From where does the sound come from when two charged objects meet in real life?

I am sure all of us have played with rubbing things and producing static electricity and when I was charging my comb by rubbing it on my hair and watching it attracting a small piece of paper, I heard ...
1
vote
0answers
29 views

where does the energy for capillary action come from? [duplicate]

I think capillary action occurs because water molecules have a little magnetic field with poles so they can stack up on each other somewhat. When it happens though, where is the energy derived from to ...
14
votes
4answers
2k views

Is the frequency of light restricted?

What are the factors that limit the frequency of light? Can it have wavelengths ranging between zero and infinity?
0
votes
1answer
125 views

At what gap width between two plates does convection not occur?

Does the Grashof number lead to the answer? The Wikipedia article (https://en.wikipedia.org/wiki/Grashof_number) yields an equation for vertical plates $$Gr_L = \frac{g\beta(T_s-T_\infty ...
0
votes
0answers
38 views

Electron transition creating Photons

If the transition of the electrons result in production of photons, Is photon creation is instantaneous? If Yes,At what moment rightly the photon gets created? Else, Will the photon be stationary ...
1
vote
2answers
310 views

Phase space derivation of quantum harmonic oscillator partition function

I would like to derive the partition function for the quantum Harmonic oscillator from scratch: $$\tag{1} Z = \int dp \, dx\, e^{-\beta H}.$$ The free particle appears in many textbooks. $H = ...
2
votes
1answer
49 views

Color in Different media

When a light wave passes from one medium to other, the wavelength of the light wave changes and the frequency remains constant. If then color of the light waves depends on changing wavelength or ...
1
vote
1answer
70 views

Critical size and Radioactive Nuclei

Nuclear fission requires the mass of the fissile material above the critical mass. So that the explosion takes place at least in the case of a nuclear bomb. But once a single nucleus got involved in ...
5
votes
1answer
269 views

What is physical meaning of $|\phi|^2$ in quantum field theory and pedagogical spontaneous symmetry breaking?

If wavefunction is $\phi$, we know that $|\phi (x)|^2$ represents probability of finding a particle at $x$. Now let us talk about some pedagogical example in spontaneous symmetry breaking in QFT, ...
2
votes
0answers
25 views

Equation describing the motion of an object attracted to magnet [closed]

Imagine there is a strong magnet at (0, 0). There is a horizontal rail on y=1 on which a ferromagnetic object rides. The object ...
4
votes
3answers
222 views

Complex Dirac field in antiparticle description

I understand that the Dirac equation has negative and positive sets of solutions and this contributes to its quantization by a superposition of two Fourier modes represented as creation and ...
0
votes
1answer
122 views

In general, could any ad-hoc relationship of constants be useful?

In general; if one creates an ad-hoc relationship of constants, can we use it to solve equations OR is it just an abstract/artificial math construct? I'm a grad student and as we all know, these ...
10
votes
3answers
2k views

How accurately can I expect to measure the gravitational constant with a club of college students?

I am a math instructor with almost no experimental physics background, but I run a math and engineering club that is interested in doing some experiments. I have read up a bit and see some obvious ...
1
vote
2answers
298 views

Rotational inertia of a ball

This question refers to the solution of problem 12 here. It involves a spherical shell of mass $M$ filled with frictionless fluid of mass $M$ rolling down an inclined plane. (This is problem 12 of ...
1
vote
2answers
131 views

Is the concept of rest mass correct?

Is the concept of rest mass correct? All these years, we (me, and my classmates of Undergraduate 1st Year) have been accustomed to the concept of rest-mass, and the relativistic transformation of ...
0
votes
1answer
1k views

Why do objects of a given color appear white under light of that color?

Under light from the sun, a red object will scatter the red component of light, and absorb all others. Hence, the human eye perceives it as "red". White objects scatter all wavelengths of light. ...
0
votes
1answer
86 views

Multiple planets orbiting a star

One way of detecting exoplanets orbiting around a star is the Radial velocity method. Can this be used to detect multiple planets? Wouldn't the star orbit the center of mass of the whole system with ...
2
votes
1answer
103 views

Why do we take the value of the constant in Coulomb's law as $\frac{1}{4\pi\varepsilon_0}$? [duplicate]

Why do we take the value of the constant in Coulomb's law as $\frac{1}{4\pi\varepsilon_0}$?
1
vote
2answers
109 views

Where does energy go when performing a useless effort?

I went to school one day, so I thought I was able to get this simple one.. but it looks like I'm not anymore. :( One lonely little spaceship is resting into space. It has a small fuel capacity that ...
1
vote
0answers
110 views

Does the skin effect and the proximity effect cancel each other out?

I'm interested in how the Skin Effect and the Proximity Effect interact with each other. From what I can understand: The Skin Effect is when AC current 'collects' on the skin of conductors due to ...
1
vote
0answers
73 views

Bose-Einstein Condensate

In lieu of recent research showing the possibility of obtaining the Bose-Einstein condensate Nq, in certain polymers is there any statistical mechanical way of figuring out the frequency with which ...
1
vote
0answers
54 views

Detect missing frequencies in a frequency distribution

I have photons with a frequency distribution where one frequency is completly cut out. For example a frequency distribution like that: My question is: How precise can the position (frequency) of ...
1
vote
1answer
116 views

Is this air cooling idea feasible?

Massive heat wave here and I don't have an air conditioner. I was investigating how commercial air conditioners work and to my surprise found that they use merely evaporation rather than a ...
0
votes
1answer
87 views

Molecular field meaning in Liquid Crystal Theory

Given the Frank-De Gennes free energy $F = \int f(\boldsymbol{p},\nabla\boldsymbol{p}, ...)\ d\boldsymbol{x},$ for liquid crystals (see De Gennes-Prost, p. 107, formula 3.21), the vector ...
1
vote
1answer
573 views

How to get the time derivative of an expectation value in quantum mechanics?

The textbook computes the time derivative of an expectation value as follows: $$\frac{d}{dt}\langle Q\rangle=\frac{d}{dt}\langle \Psi|\hat Q\Psi\rangle=\langle \frac{\partial\Psi}{\partial t}|\hat ...
0
votes
1answer
842 views

Does the universe have an edge/boundary/barrier? If yes, what is at the edge? [duplicate]

My question related kind of to asking what the shape of the universe is. Say a hypothetical alien civilization built an faster-than-light spaceship. If they keep flying would they end up where they ...
0
votes
4answers
533 views

A vehicle moves from rest to a certain distance. Would the distance time graph always be curved?

A vehicle moves from rest to a certain distance. Would the distance time graph always be curved ? Why cannot it be a straight line ? For example, a car moving from rest to 100m, with a constant ...
1
vote
1answer
357 views

How do I calculate motor efficiency from voltage, current and RPM?

I have a setup where a motor is spinning at a constant (known) RPM, under no load. I know the power going into the motor (voltage * current), and I can find out the rotational kinetic energy of the ...
-3
votes
1answer
140 views

How to get funding for research on something that can revolutionize the quantum world! [closed]

I think this can revolutionize the quantum world! Any ideas on how to impress physicists to get a full fledged funding for research?
2
votes
2answers
196 views

How does a system interact with environment in quantum mechanics? When would this interaction occur? What is it?

As title says, how does a system interact with environment? I realize that this interaction can lead to interference terms and non-diagonal terms in density matrix being reduced (quantum decoherence). ...
15
votes
5answers
3k views

Is the future already determined?

I've always wondered (and was re-inspired to explore further from these two videos) that if at a single point of time we know about the complete state (position, momentum, spins, everything.) of every ...
1
vote
2answers
97 views

Frequency difference of absorbed and emitted photons?

In a transparent medium, how does the frequency of incoming light compare to the exiting light? I thought it was the same, but doesn't there have to be an energy difference in two electron states in ...
5
votes
2answers
2k views

How would an X-ray mirror work?

I was wondering if light can be reflected how can someone reflect X-ray of what material does it need to be made of and is its design completely different to that of our original mirrors? Does this ...
2
votes
3answers
888 views

How was Newton able to guess that gravitational force is inversely proportional to distance squared?

This question is puzzling me since I learnt about the gravitation law in school. Why did Newton guess/assume that gravitational force is inversely proportional to the square of distance? Did he ...
0
votes
2answers
224 views

How to feel or sense magnetic fields from earth?

I know that earth has magnetic fields/forces, but why we don't feel them? So if I hold a magnet and earth's magnetic field is positive and my magnet is from the positive side, then why the magnet does ...
1
vote
2answers
307 views

Balloon gas temperature experiment in water

In this problem set I have a passage that describes an experiment that looks at the changing temperature as an air filled balloon rises to the surface from the bottom of a water filled tank. The graph ...

15 30 50 per page