All Questions

Suppose a ball is dropped vertically downward, but it also given some spin along a horizontal axis. Then when the ball bounces, it will presumably pick up some horizontal velocity. Is it possible for ...

If you cancel out some quantum field modes using two 'casmir' plates you decrease the average energy density in the region and gain potential energy in Casmir force approximately proportional to the ...

I'm hoping to use this stackexchange to solve a gate decomposition problem, but I am stumped, so hoping for help. These definitions come from the Xanadu Strawberry Fields whitepaper on Table VI and ...

In Polchinksi's Sec. 10.1, the $bc-\beta\gamma$ SCFT is introduced with action $$S_{BC} = \frac{1}{2\pi} \int d^2z (b \bar \partial c + \beta \bar \partial \gamma)$$ and supercurrent $$T_F = -\...

In SEM, in order to 'focus' the electron beam, an aperture is used (which usually is metal); what happens to the metal after so many electron hits the metal constantly? since metals are usually are ...

Let's say there are three points A,B and C: A represents the displacement between points A and B (4 cm to the east) and B represents the displacement between the points B and C (3cm to the northwest)....

In Feynmann's Lectures on Physics, chapter 41, part4, In the derivation of the Browian expression for the mean square distance Feynmann's starts off with the lengevin Equation $ m\frac{d^2 x}{dt^2} ...

This is a problem from one of the past papers that I am doing in preparation a resit exam that is coming up soon: Consider the derivation of the heat capacity for conduction electrons in a metal. a) ...

I have been looking for ages but cannot find derivations of the capacitance formula $$C=\varepsilon_{0}\varepsilon_r \frac{A}{d}$$ on the Internet. I would really appreciate it if someone could point ...

I was reading the book "Quantum Physics" from Eisberg & Resnick about the expected value of the electron radial coordinate, which it defines as \begin{align} \overline{r_{nl}} = \int_{0}^{\infty}...

[From The Oxford Solid State Basics by Steven H Simon] (2.1) Einstein Solid a) Classical Einstein ( or "Boltzmann") Solid: Consider a three-dimensional simple harmonic oscillator with mass m and ...

I think I have fundamental confusions with how VLBI works. I don't know why: Resolution increases when incident rays meeting to a focal point from a farther separation along an axis perpendicular to ...

I have a question regarding Misner, Charles W.; Thorne, Kip S.; Wheeler, John Archibald (1973), Gravitation ISBN 978-0-7167-0344-0. It is a book about Einstein's theory of gravitation. In page 166 of ...

I want to understand what 1 kg represents. For example: I know that 1 second is equal to $9\ 192\ 631\ 770$ transitions from the microwave radiation that a cesium-133 atom (at $0$K) emits, if it's ...

Problem: Consider two concentric, infinite thin, homogeneous charged spherical shells centered on the origin with $r_1 < r_2$ and charge $q>0$ respectively $-q$. Calculate the electrical field ...

Is it true that if a single-trace operator, say, $O$ acquires an anomalous dimension $\gamma_o$, then the anomalous dimension of the double-trace operator $O^2$ is $2\gamma_o$? If no, can anyone ...

I have seen in many references that the field equations for a quantum field in curved space time is mentioned to be 'manifestly co-variant'. The procedure that has been followed to arrive at these ...

If a spacecraft moving in a stable speed or acceleration and suddenly stopped did a astronaut will continue moving forward ( such as a man in a train) ?

So I have questions where 2 pulleys are present, and when one of them is fixed to a rigid support on one end, it is said that tension is inversely proportional to acceleration. On the other hand, ...

If I have a 2 mode squeezed state of light, emitted from some nonlinear parametric process, then the more it is squeezed, the larger the variance of one quadratures $X$, while the variance of the ...

I think there's a tension between two claims I've read: The standard model is Yang-Mills theory with gauge group $SU(3) \times SU(2) \times U(1)$. Here the $U(1)$ factor is data on the same level as ...

I want to know the exact difference between '''Fermi normal coordinates''' and ''Riemann normal coordinates'''? Here is a same question, but it's hard for me to understand. Difference between Fermi ...

I'm watching some GR lectures by Schuller (more or less rushing through them so bear with my ignorance here please) in Lecture 10: Metric Manifolds. He's talking about geodesics in a manifold with a ...

A typical second-order diagram for the self-energy gives integrals such as: $$\int \int d \omega^\prime \omega^{\prime \prime} g(\omega-\omega^{\prime})g(\omega^{\prime \prime})g(\omega^{\prime}+\...

Consider a rectangle of specified length and width, we randomly distribute $n$ points on it. What's the probability of finding no point in an interval of length $x$ and let the width be fixed as '$w$...

Given is next relation: $S = a [NVE]^{1/3}$ and $a$ is a constant. I have to find the Equation of state. So I started by using some thermodynamic identities: $\frac{\delta S}{\delta E} = \frac{1}{T}$ ...

I'm an amateur researcher, who's interested in plasma physics and space weather. I'm trying to find a professional physicist, who would be kind enough, to give me a professional opinion about a model ...

If I have a bottle or container with X fluid ounces of water at temperature Y (say, fridge temperature or room temperature), and I put ice or ice sticks (composed of water) in it that make up Z fluid ...

The Earth generates a gravity field based on local mass, but which mostly appears to act as a point source, though local fluctuations in the crust density and mass affect the gravity in a given region ...

I was reading an article https://arxiv.org/abs/0907.0500 in which they write about manifold in band parameter ,like in first line in my picture , and then they call it band parameter . can some ...

Given a superfield (in 0+1 spacetime + 2 superspace coordinates) $$X(t,\theta_1,\theta_2) = x(t) + \theta_i \psi_i(t) + \theta_1 \theta_2 F_{12}(t)\tag{1}$$ and given the standard supercharges ...

I'm struggling to understand Mermin's article "Is the moon there when nobody looks?". Is it possible to reduce the number of measurement modes from 3 to 2? For example, with an experimental setup with ...

The main question was: A car travelled 50 metres in 5 seconds with constant acceleration and initial velocity being zero. What will be the velocity after 15 seconds? I tried to solve by this way, $...

Why is the dimensional formula of distance travelled by a particle in nth second of time same as that of velocity? It's really confusing for me to understand this, after all it's distance but still ...

Does anyone know where the differential equation of covariance matrix comes from? $$\frac{dC(t)}{dt}=AC(t)+C(t)A^T+D$$ where C is the covariance matrix, ...

I don't know the relation between the experimental wavenumber that I can obtain from the Fourier spectrum of the simulated pattern and the theoretical critical wavenumber that gives me the linear ...

When we rub a comb on our head and held it near pieces of paper then they get attracted because of induced opposite charge.

I have read this question: The thickness of a puddled sheet of water https://en.wikipedia.org/wiki/Surface_tension#Puddles_on_a_surface The liquid mass flattens out because that brings as ...

First, look at the first paragraph of the second page. It says: The things that you can see at some time are the inside of the light-cone at o. I don't get it. Suppose an event happened outside ...

We are going through "Bertrand Spacetimes" by Dr Perlick, in which he first gave the idea of a new class of spacetimes named as Bertrand spacetimes after the well-known Bertrand's Theorem in Classical ...

Whenever I look at a bright light source and then turn my eyes away I see a large black dot blocking a part of my vision. Does this has something to do with Physics as it involves light or it is ...

"An object of mass m is tied to a string of length L and a variable horizontal force is applied on it which starts from rest and pulled slowly until the string makes an angle $\theta$ with the ...

I am studying Higher Level Physics and for my Physics IA I am doing an experiment determining the effect of the voltage between two parallel plates on the on the frequency of a pendulum in between the ...

Given a Gaussian-preserving interaction (including a unitary operation and losses) for a Gaussian input, I want to know if there is an "easy" way to compute the Quantum Fisher information without ...

An electron has a speed of $2\cdot10^4 m/s$, then it goes inside an electric field $\vec{E}=900 N/C$ with direction to positive Y-axis. Without considering the weight force of the electron, the time ...

I'm currently working my way through the Course volume one. Unless I've completely missed it, the authors omit any discussion of Noether's theorem, instead deriving various conservation laws on a case ...

Let's say that Hotter Gas A loses heat to Colder Gas B. Heat is transferred from A to B in such a way that the overall entropy increases. This can be proven with equations, but what is the intuition ...

When we connect two reservoirs kept at $\mu_{1}$ and $\mu_{2}$ respectively the potential difference is given by $(-e) V=\left(\mu_{1}-\mu_{2}\right)$. While if the conduction of electrons occurs ...

I thought about a problem that I could'nt solve myself. let's say we have a cylinder with mass M and radius R, rolling on the floor without slipping. The velociy of the center of mass is V1 and the ...

We write rms formula as $$v_{rms}=\sqrt\frac{\int_a^b[f(x)]^2dx}{|b-a|}$$ I know if we take arithmetic mean average voltage will be 0. So we want all voltage values to be positive. Why don't we do ...