# All Questions

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### annealed randomness vs quenched randomness

what is meaning of annealed randomness and quenched randomness? in this article used this phrase to compare the model and earthquake data.
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### Do diamagnetic ferrofluids exist?

I am wondering if there are ferrofluids or 'diafluids' that exist which are repelled by a magnetic field?
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### Space and absolute 0

If two objects like black holes or soild matter are separated by space, let's assume billions and billions of light years. While all other possible energy has left the area, and no new sources. Like ...
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### Magnetic field outside the solenoid

I found solution to problem 257 from "300 Creative Physics problems" hard to understand. In that problem we have very long solenoid with coil wounded in one layer. Data such as: density of turns, ...
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### The spatial Schwarzschild metric

The Schwarzschild spacetime is defined by the following line element \begin{equation*} ds^2 = - \left( 1 - \frac{2m}{r} \right)dt^2 + \frac{1}{1-\frac{2m}{r}}dr^2 + r^2 d\theta^2 + r^2\sin \theta^2 d\...
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### Spacetime as a coset of a symmetry group

In the introduction to his nice PNAS paper on symmetry, David Gross said Einstein’s great advance in 1905 was to put symmetry first, to regard the symmetry principle as the primary feature of ...
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### How to derive an expression for entropy generation in a diffusive, reacting continuum

I'm trying to understand a derivation from "The Thermodynamics of Linear Fluids and Fluid Mixtures," by Miloslav Pekař and Ivan Samohýl (2014). The derivation produces an expression for the entropy ...
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### Reference for open XX spin chain with external magnetic field

I would like a reference on the diagonalization of an open XX spin 1/2 chain with homogenous external magnetic field. I am new to the subject and I haven't been able to find a reference for it. Edit: ...
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### Proper time and asymptotic flatness

I'm trying to understand the concept of asymptotic flatness in general relativity, and came up with the following question: If the proper time $\tau$ is infinite for a timelike geodesic, does it mean ...
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### How to create linear parallel magnetic field lines

I am trying to make ferrofluids create a flat surface between two points. Most of the magnet configurations I have seen have field lines that arc. So I'm asking if there are any circumstances where ...
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### The force of a spring

I am new in continuum mechanics and I want to prove the formula which gives the force given by a spring : $$F_{max}= \frac{Ed^4(L-nd)}{16(1+\nu)(D-d)^3 n}$$ where : $E$ – Young's modulus $d$ – ...
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### How to understand the instant state collapse in all references?

When a subsystem A of an EPR pair AB is measured, it's usually said that the state of B collapse instantly, and also this is true for all observers according to relativistic quantum information. ...
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### How Quantum is EGY Duality Relation

I know that the Englert-Greenberger-Yasin (D^2+v^2=1 for a laser) duality relation is often considered an equation quantifying Wave-Particle Duality. However, when I was playing around with the ...
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### What sorts of problems does asymptotically safe gravity face as a potential quantum gravity solution?

I've recently read an article by Ethan Siegel over at Forbes (he also blogs at Starts with a Bang) on asymptotically safe gravity as a possible alternative to string theory. I read the author's blog ...
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### angular momentum of electromagnetic wave

EM waves that are circularly or elliptically polarized have angular momentum. Is there any experiment that proves/shows this ? like shine a light on something and it rotates ? The correspondence is ...
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### How to measure the Fermi velocity in Dirac materials?

Suppose that one has a Dirac material (e.g., graphene), i.e., a system where there exists a number $N$ of identical Dirac cones (linear dispersion) at the Fermi energy $E_F=0$. How can one measure ...
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### Unsolved Potentials in Path Integral

I just started learning on path integral on my own. It seems that the path integral method is not always able to be solved, depending on the potential. On the other hand, these potentials are ...
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### Removing conductive silver paste from a stainless steel plate

I've been doing some STM experiments on TMD material held down with silver paste. is there any recommend solvent for removing the paste? I was going to use IPA or ethanol in a sonic bath...any ...
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### T invariance in flavored meson system

Consider Kaon CP conjugate states $\left|K^{0}\right>$ and $\left|\bar{K^{0}}\right>$. The physical states i.e, eigenstates of effective hamitonian can be written as \left|M_{a}...
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### Substantial uneasiness as to the Joule free expansion (unresolved in spite of many readings)

Ok so, to do things well, let me present the set-up: we have an insulated container that is partitioned into two equal halves, one of which contains an ideal gas with parameters P1, V1 and T1, the ...