All Questions

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reversible cellular automata

Let's suppose a cellular automaton has a value $b(r,t)$ belongs to $Q$ at site $r$ and time $t$, where $Q$ is the set of possible states at each site. Let $N(r, t)$ be the values of the states of all ...
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Circular polarisation

If we have a planar and harmonic EM wave, with $B$ field: $$B=A\left(\begin{array}{c} 1\\ i\\0 \end{array} \right)e^{-i(\omega t-\vec k\cdot\vec r)}$$ and with it's corresponding $E$ field. This is ...
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Conservation of Momentum from Recoil Speed [closed]

A gun has a recoil speed of 2 m/s when firing. If the gun has a mass of 2kg and the bullet has a mass of 10g (0.01 kg) what speed does the bullet come out at? The gun has zero total momentum before ...
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Can negative energy explain black holes?

I think black holes are peculiar and I want to know if there is a relation to negative energy. Does negative energy have positive mass and therefore can explain the nature of black holes? IS there any ...
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Estimate the difference between two sets of atoms

I've been working on amorphous structures derived from a crystalline one (using MD) containing $N$ atoms. I want to prove that these structures are different and to quantify their "differentness". One ...
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How to check units?

I've got: $Q=\frac{Er^2}{k}$ how to check the units? I start with $\left[\frac{\text V}{\text m} \, \text m^2\right]$, tried replacing $[ \text V ]$ with $\left[ \frac{\text J}{\text C} \right]$, but ...
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Formulation of the Three-Body Newtonian problem

I am trying to understand three body problem in Newtonian space. I want to make formulation of differential equations for known initial conditions for the case with: Identical three masses ...
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Why is Heisenberg's uncertainty principle not an experimental error since it is the error created by photons striking on elementary particles?

Why is Heisenberg's uncertainty principle not an experimental error since it is the error created by photons striking on elementary particles?
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Annihilation and creation operator - $\phi$ and $\pi$ for Klein-Gordon Field

Introduction and Notation Let $\phi(\vec{x})$ be the real Klein-Gordon (quantum) field, written as: ...
942 views

Stark effect in two level atomic, laser-driven system?

In a two level atomic system (Rabi oscillating problem) the perturbative potential is oscillating / sinusoidal because it comes from the electric field from the laser. Now stark effect is the ...
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Can there be energy with no force or energy with no power?

I think that both force (number of newtons) and power (p=ui(?)) implies that there is energy so we can't have force without energy and we can't have power without energy(?) But can there be energy ...
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Can someone please derive $T=2\pi\sqrt{l/g}$ or prove it without using calculus?

I don't know much calculus, but I want to know that how one derives the formula to find time period $T$ of a simple pendulum.
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Does the Standard Model plasma develop a spontaneous magnetisation at finite temperature?

Reference: arXiv:1204.3604v1 [hep-ph] Long-range magnetic fields in the ground state of the Standard Model plasma. Alexey Boyarsky, Oleg Ruchayskiy, Mikhail Shaposhnikov. The authors of this paper ...
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Electric charge and the distance

The strength of an electric field is: $E = 200\ \mathrm{N/C}$ The potential (of the test charge) is: $V = 600\ \mathrm{V}$ $\epsilon_r=1$ I need to calculate the distance between this point and the ...
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Energy-momentum conservation without translation symmetry?

As I checked, the energy-momentum tensor defined as ${T^\mu}_\nu=\frac{\partial {\cal L}}{\partial(\partial_\mu \phi)}\partial_\nu \phi-{\cal L}{\delta^\mu}_\nu$ at the solution $\phi$ of equation of ...
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What is the status of Witten's and Vafa's argument that the QCD vacuum energy is a minimum for zero $\theta$ angle?

The argument, which I reproduce here from Ramond's `Journies BSM', is originally by Witten and Vafa in ($\it{Phys}$. $\it{Rev}$. $\it{Lett}$. 53, 535(1984)). The argument is that for $\theta = 0$ ...
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effect of internal forces to a glider's descent

This is a continuation of a previous question, with more thinking applied, thanks to a helpful comment. Imagine a glider is airborne in a breezeless sky. The glider is 3 KM high, is traveling at 100 ...
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Nuclear reaction: creation of deuterium

A proton p collides with a neutron(at rest) n at relatively low-energies and creates a 'deuterium-core' d: $$p+n->d+\gamma$$ Find the wavelength for the photon as a function of the proton's ...
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Besides transmutation, is there any way to “speed up” the decay rate of radioactive material?

I'm well aware of transmutation as a way to effectively make radioactive material decay faster, however that isn't really what I mean. Doing a quick Google search I found references to several ...
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What if the lid of a pressure cooker was suddenly released?

My dad and I have tried to calculate the strength of the explosion if the lid was suddenly freed. We took some measures: Lid mass: $0.7 \textrm{kg}$ Lid surface: $0.415 \textrm{m}^2$ Internal ...
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Number of configurations of the universe

I have read that quantum mechanics says that the amount of possible particle configurations is $10^{10^{122}}$ to be exact in the universe. Do we know this figure to be exactly true to the exact ...
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General Relativity Paradox - Different local times of two frames a constant distance apart

Suppose there is a habitable star with a significantly large mass, and thus a huge gravitation field. It has a clock on it that ticks each local second. And it also has a mirror. This is Star A. ...
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How to describe heat transfer between two solid materials?

A general equation for dealing with heat transfer between one material and a region of insulating material. I've seen basic heat transfer equations for one material, but I'd love to see an explanation ...
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Going through a ring of black holes

Mathematician here with a speculative physical question -- feel free to boot me if the level isn't right. Suppose one finds, or builds, a constellation of several black holes arranged in a circle. ...
An electric charge $Q$ is distributed through out a nonconducting sphere of radius $r_ 0$ and has a spherical cavity of radius $r_1$ centered at the sphere's centre. Assume the charge $Q$ is ...