# All Questions

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### Eigen energy of the Landau levels in a tilted magnetic field

The problem pertains to a fermi gas in a tilted magnetic field confined by a harmonic potential in the z direction. I chose the vector potential $(0,ax-bz,0)$. I obtain the following hamiltonain with ...
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### Impulse in perfectly elastic collision

I am implementing this simplified model at the moment, and I am trying to get my head around the physics concepts behind this model. Event-Driven Simulation So the model has two parts, first is ...
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### Could baryon asymmetry be explained by the big bang as a pair production event?

If the big bang is considered as a vacuum fluctuation then might we assume an antimatter/ anti-baryonic universe was created at the same time as our matter universe. If there is some theoretical way ...
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### Homework question

It is a worksheet given by the school which I'm unable to solve; please solve it. .
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### what is the focal length of the lens @ the far point

How to find the focal length at the far point if focus objects clearly from 50cm to 600cm . Representing the eye as a simple lens 2cm from the retina.
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### Will temperature,pressure and volume effect the value of universal gas constant in any way?

effect of variables on constants Will temperature,pressure and volume effect the value of universal gas constant in any way?
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### Is there any place in the universe where time passes more quickly than in the milky way?

I also understand that due to the relative orbital velocity, time on Earth is dilated compared to the centers of the solar system and galaxy. Is there a place that the Milky Way rotates around, and ...
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### Invariance of State Vector under Two Operations

I am trying to understand why if you measure one non degenerate operator you get a new state w1v let's say with w1 eigenvalue, then let's say u measure a new operator that has degenerate eigenvalue v ...
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### Applications of exponential family Markov random fields in statistical physics

Ising model and its relatives are popular in statistical physics. Are there any physical systems that can be characterized by exponential family Markov random fields (e.g., the one in http://arxiv.org/...
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### Why is it that only thermal energy is available in a particle propagating throughout a space-charge layer in a plasma (not kinetic)?

In this PDF on page 5 the author explains that a particle moving through a space-charge (electron density in a plasma) gains only thermal energy. Should there not also be kinetic energy?
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### Bigger tire/Smaller Tire

On a track, bigger tires have more contact therefore more traction. However, it comes at a cost of more unsprung weight. Therefore, the 0-60 time is slower as tested by Car And Driver. This was tested ...
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### Name of electric force

during a lab experiment, i noticed that a metal ball has a much harder time rolling on metal rails when their is a current passing through it and the rails. I was wondering why and if there was a name ...
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### What am I doing wrong in this error propagation question? [on hold]

I got the right values for the certain values (A x B). However, whenever I multiply the uncertainty values (𝛿A x 𝛿B), I still can't seem to get the right answer. Here are the two problems I'm stuck ...
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### Is there an angular velocity operator in quantum mechanics?

In classical mechanics we can write as velocity of a rotating object $\vec{v} = \vec{\omega} \times \vec{r}$ or in analogy the momentum $\vec{p} = m (\vec{\omega} \times \vec{r})$ using the angular ...
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### Can osmosis go the other way?

There is an effect called diffusio-osmosis, by which a flow is induced close to walls, and is ultimately caused by the repulsion of solute molecules by the solid wall around the pore. See this older ...
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### How far would an arrow go in a space station and still be deadly?

So I was answering a question on the WorldBuilding SE site and one aspect of my answer made me wonder. Imagine you are on a massive space station of unlimited size. If you were to fire an arrow from ...
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### Is critical mass of fissile material the same in gravitational fields with different force?

Let's take plutonium-239 for example. $10\, Kg$ (sphere $9.9\, cm$) need for a nuclear reaction. Are we talking about these numbers in Earth environment with $\approx 9.8\, m/s^2$ gravitational ...
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### I can't grasp the idea of how Newton's laws are coordinate dependent? Could anyone suggest me any book for problem solving in classical mechanics [on hold]

I am reading Classical mechanics by Goldstein and have crossed 55 pages and still couldn't grasp how Newtons law is coordinate dependent. And I problems in Goldstein are extremely difficult is there ...
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### Electric field of a line charge, along itself

look at the pic : What is the electric field in along the line of charge with charge density $\lambda$ and length $L$. Is the electric field zero along the line without any difference in height?
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### Electro-magnetic fields and Faraday Cages

If you have an area that is affected by an electromagnetic field, would it be possible to build a Faraday cage and then build a device INSIDE the Faraday cage so that it would work (as opposed to ...
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### Discharging a capacitor

Suppose I have a charged capacitor, meaning there's a voltage (electric potential difference), say, $2V$, between its two plates. We don't know the electirc potential of the individual plates, right? ...
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### Quantitative measurement of electrostatic induction

How is it with the electrostatic induction measurement? Everywhere you can read about the effect of electrostatic induction but I still can't found any detailed explanations or quantitative ...
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### Is there a maximum power rating for fiber optics cables?

I'm at an internship and I've been tasked with projecting the image with a projector in a direction different than where it would normally go. I am looking into fiber optics, but it doesn't seem like ...
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### Quadrupole moment of point charges?

We know that due to expansion, the Quadrupole potential equals $$1/4\pi \epsilon r^3 . \int (r^\prime)^2(\frac32. \cos^2\theta^\prime-\frac12)\rho(r^\prime)d\tau$$ but what is the equation for point ...
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### Orbiting in space

Background I'm making a game where a spaceship needs to orbit another object in space at a set distance. Space is, unlike other game, like space is in reality. Friction less. (at least to my ...
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### How does the uncertainty product $\Delta x \Delta p$ behave for the bound states of the triangular potential?

As has been remarked earlier, if you take an unbounded potential $V(x)$ (so that all the eigenstates are bound) and you look at the uncertainty product $\Delta x\Delta p$ as a function of the index $n$...
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### Examples of other hierarchy problems

The commonly quoted version of the hierarchy problem (at least, the one that I have heard), is concerned with the surprisingly low mass of the Higgs. We would expect the Higgs mass squared to have ...
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### Notation to represent frequency and acceleration in preparation for algorithms

I hope this is the right place to ask. IMO it's the most appropriate SE site. I would have chosen mathematics; I didnt because I am using units such as force and Hz, and want equations to have ...
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### Running Constant Values At Very Low Temperatures

From Wikipedia Coupling Constants, using QED as an example. I realise that the one-loop beta function in quantum chromodynamics is negative. If a beta function is positive, the corresponding ...
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### Quantum mechanics: charged particel in magentic field [on hold]

Suppose a particle is moving in an uniform magnetic field $B$ in the $z$ direction. How do we find the time dependence of the position coordinate operators. I tried to work in the Heisenberg picture, ...
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### Reciprocal Time Dialation in Special Relativity [duplicate]

I'm trying to understand theory of special relativity, but there is one thing that really makes me confused which is reciprocal time dilation in special relativity. In special relativity, the time ...
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### Chiral spin liquid flux states on the Kagome lattice

Short version: Is it possible to arrange the fluxes for the Kagomé lattice with triangle flux $\phi_\triangle=\frac{\pi}2$ and hexagon flux $\phi_{hex}=0$ using a single unit cell? Longer version: I ...
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### Lorentz surfaces, conformal metrics and eigenvalues

From what I understand of Lorentz surfaces (spacetimes of dimension 2), it seems that, according to Kulkarni's theorem, two reasonable enough Lorentz surfaces (I am only interested in surfaces with ...
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### How to find speed (not velocity) of a body during a projectile reaching an height $h$ twice? (Please read description- I want to do it my way) [on hold]

If a body is projected at an angle (theta) with horizontal, it reaches a a certain height h two times. Within this time, find the speed (not velocity) of the object? I was trying to solve it by the ...
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### Is a sea of massive gravitons what ripples when galaxy clusters collide and is it what waves in a double slit experiment? [on hold]

Dark matter has been recently theorized to consist of massive gravitons. If the massive gravitons interact with matter then could they be what relates general relativity and quantum mechanics?
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### Books recommendations for my theoretical physics library [duplicate]

long story short: I got a big prize from my scholarship, which consists in a lot of money for books, and I mean a lot: almost USD\$ 3000. Thus, I am going to buy lots of books, of course! So I'm ...
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### Would Einstein and de Broglie have agreed it is the sea of massive gravitons which waves in terms of gravitational and wave-particle duality waves? [on hold]

If 'empty' space is a sea of massive gravitons which matter moves through and displaces then would Einstein and de Broglie consider it to be the medium for gravitational and wave-particle duality ...
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### What would happen if a ball flew through the open window of a car?

I asked a science teacher this question a while ago but I did not receive a clear answer. Now, I was hoping someone on this Physics site could shed some light on my conundrum, I've been wondering for ...
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### Quantum vacuum thruster and conservation of momentum [duplicate]

I have been reading about the quantum vacuum thruster on Wikipedia and I think I understand the idea of virtual particles being created and destroyed but what I don't understand is how this is ...
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### Find the momentum the force creates on the corners of the rectangle [on hold]

In this problem there is horizontal force of 100 N pointing away from the right top corner and the task is to find the moment it causes at every corner. The sides of the rectangle are 5 and 3 meters. ...
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### How to apply the time evolution operator on a 2 level system

I'm struggling to understand how to actually solve analytically the time evolution of a given initial state with the Hamiltonian $$H =\epsilon*\sigma_z + \Delta*\sigma_x,$$ ...
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### Need clarity about relativity/magnetism explanation

Please bear with me - this is not a duplicate question.... From what limited knowledge I have gathered, it seems that when two wires in parallel are carrying equal current, the electrons moving in ...