Newest Questions
244,127 questions
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Supersymmetric Hamiltonian for particle on a line with internal degrees of freedom
I was going through David Tong's Supersymmetric Quantum Mechanics
https://www.damtp.cam.ac.uk/user/tong/susy/susyqm.pdf
On page 8, (1.7), is the expression for the Hamiltonian correct? When I ...
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origin of energy stored in an electric field
I've understood that in a device like a capacitor the energy stored in the electric field between the plates corresponds to the work done by an external source in charging it, so similarly an electric ...
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1
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9
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Apparent pressure difference between two points at same elevation in a siphon
Consider the following diagram of a siphon (from wikipedia):
I am concerned with finding the pressure difference between points B and C, using Bernoulli's theorem. Liquid is incompressible, all flow ...
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The Æther, the speed of light and gravity [closed]
I've been thinking about several things lately, and one of them is the Æther, because when people say that electromagnetic waves don't need to be propagated by a medium, I immediately see that they're ...
-4
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1
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45
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Could other theories account for the presence of Cosmic Microwave Background (other than a Big Bang)? [closed]
Some scientists say CMB is "proof" of the Big Bang event, as no other source accounts for its presence (that I know of). However, I can think of a few things that seem to do so:
Over a long ...
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1
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Infinitely many coserved currents in a free QFT
In a (1+1)-D integrable quantum field theory (e.g. the sine-Gordon model), there is a tower of infinitely many conserved currents with increasing spins. During a scattering, the existence of such a ...
- 366
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9
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Conservation of Power After Separating Reflected Waveguide Wave
Background: I was reading A General Waveguide Circuit Theory which mentioned that the sum of the average power of forward and backward waves is different from the average power of their sum. I ...
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Path integral formulation for selective paths in an energy shell $\delta(H(x,t)-E)$
Path integral formulation for selective paths in an energy shell $\delta(H(x,t)-E).$
I'm looking for a detailed calculation of this constrain condition.
All the publication I have access to didn't ...
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49
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Does gravitational information travel through a black hole or around a black hole?
I would like to know if information can travel through black holes. If a mass falls into a black hole will the radius grow via information traveling along the event horizon or through the black hole?
...
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Spacetime curvature and light deflection [closed]
Could you tell me if this reasoning is correct?
Radius of curvature in spacetime caused by the Sun 338421512319 meters
Radius (physical) of the Sun 696340000 meters
338421512319/696340000 = 486
The ...
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Why integral curves of a null vector must be null geodesics?
In many General Relativity literature, the following question takes as a very obvious fact but I don't understand why or how it holds.
Why integral curves of a null vector on a null hypersurface is ...
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Problem book in quantum mechanics [duplicate]
Can someone recommend problem book in quantum mechanics ? Without theory (or only as reference), with many problems/exercises.
(not Flügge)
5
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1
answer
163
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Does the value of the gravitational constant change due to dark matter?
Dark matter possess its own gravity. So doesn't it would mean that we will obtain different values of gravitational constant by doing experiments at different places?
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1
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answers
25
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Time of flight to energy conversion (Jacobian) [duplicate]
Say we record intensity as a function of wavelength $f$($\lambda$) . I want to plot this as a function of energy ($E$), given that $E = hc/ \lambda$. I read that by the conservation of energy, this ...
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Is there a relationship between the contact points and coefficient of kinetic friction I am not aware of? [closed]
I have been working on a project to determine the kinetic coefficient of friction by sliding a puck down a ramp that I have glued a number of ball bearings onto (photo below).
According to Amontons’ ...
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51
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Why are exponential factors dimensionless? [duplicate]
Why are exponential factors dimensionless? While solving a question from JEE Advance MCQ, I faced a problem. The question was, the pressure depends on distance as P= (α/β)exp(-αz/kθ), where α, β are ...
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2
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67
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Is mass a representation of the amount of energy, or is it just another form of it?
I've just started learning about Nuclear Physics, and here's something I'm not able to quite understand.
I have been taught the following:
During a nuclear reaction, mass-energy is conserved.
During ...
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1
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62
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How to solve for orbital path from velocity vector and starting pos?
I’m trying to solve for an orbital path, $C$ (preferably a parametric equation of $(X(t),Y(t))$ such that at $t=0$, it equal the starting pos), from a starting vector $V$ and position $P$. I also have ...
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What is the relation between the polarization $\mathbf{P}$ and the electric field $\mathbf{E}$ in piezoelectric and flexoelectric materials?
I'm currently trying to understand electromechanical coupling effects in dielectric media, especially the link between the polarization density field $\mathbf{P}$, and the electric field $\mathbf{E}$, ...
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22
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Series and parallel resistance problem [duplicate]
Determine the equivalent resistance between terminals “M” and “N”
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3
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2
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79
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Statistical mechanics and the distribution of phases of oscillation
Imagine an elliptical region of phase space $\{(q,p)\in \mathbb{R}^2:p^2/2m + kq^2/2=E\}$ of constant energy $E$ for a 1D harmonic oscillator. Since all points on the ellipse have the same energy, ...
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Explicit FLRW Killing vector fields
Could someone please tell me if there is an article or book that explicitly lists the killing vectors for the FLRW metric with generic $K$ curvature?
\begin{equation}
ds^2 = -dt^2 + a(t)^2\left( \frac{...
12
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1
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498
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Why does a mosquito net block the breeze?
When my window is fully open, I can feel the breeze from outside. But when I put on my mosquito net, the breeze gets blocked almost completely. Why does mosquito net block the breeze, even though its ...
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Derivation of gravitational redshift by Schutz
In section 5.1 of 'A First Course in General Relativity' Schutz derives the gravitational redshift relation the following way:
'Let us imagine performing an idealized experiment, first suggested by ...
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27
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Why do speed of different colours of light vary in glass but are the same in vacuum? [duplicate]
Light is an electromagnetic wave and therefore it follows the wave equation.
$\frac{\partial^2 \psi}{\partial t^2}= v^2 \frac{\partial^2 \psi}{\partial x^2}$
Now with some maths, the wave equation can ...
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What should I do to understand Physics from scratch? [closed]
I have problems understanding physics even though I am interested in this field. Education in our country does not convey the full extent of science. I mean, I don't understand how a physics formula ...
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Good Question 135 [closed]
Вот что я понял:в зажигалке есть Пьезо элемент, который: мне не известно реформирует воздушную структуру во время прохождения электричества через воздух или вытесняет воздушную структуру на пути ...
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49
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Noether theorem and conservation of charge
I'm trying to found an elegant, simple and very detailed proof of the conservation of charge using Noether theorem using various sources (websites, textbooks, scientific papers) in different languages....
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Classical field theory in terms of the first jet bundle
I am searching for a resource which defines Classical Lagrangian field theory in terms of the first jet bundle of some Fibre bundle $E$, meaning the Lagrangian is the jet prolongation of a bundle ...
2
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92
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Huang's derivation of the grand canonical ensemble [closed]
I am reading Huang's "Statistical Mechanics", and can't understand the derivation in chapter 7.3.
7.3 GRAND CANONICAL ENSEMBLE
Although the canonical and the microcanonical ensemble give ...
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