Newest Questions
247,383 questions
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Stuck on a mechanics problem - cannot get another constraint equation
So I started off with momentum conservation and noticing that $v_B = v_D = w$ due to the symmetry:
$$mu = mv_A + mv_C + 2mw \Rightarrow \boxed{u = v_A + v_C + 2w}$$
Now energy conservation gives us ...
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Path problem in circuit simulation
I ran this on falstad.com. The current goes through all the lines expect the middle line and the line with no resistor. Current ususally flows through the one with less resistance then why it going ...
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Generalized Forces (Monogenic) and Potential Energy
I've been studying Lagrangian mechanics and came across a curious equation that relates the derivatives of potential energy with respect to generalized coordinates to the temporal derivatives of ...
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Simple addition of the recession and the peculiar velocities in relation to the cosmological and the Doppler redshift composition
If one divides a change in proper distance by the interval of cosmological time where the change was measured (or takes the derivative of proper distance with respect to cosmological time) and calls ...
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What is an inertial coordinate system? [duplicate]
A lot of posts have been made about the nature of inertial coordinate systems, but I did not find one that answered my doubts. I have a masters in math and am starting my PhD in mathematical physics ...
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What particles, molecules, or even macroscopic objects can we create based on the relation $m=E/c^2$? [closed]
I can imagine the solar fusion process that creates energy from mass, based on the equation $E=mc^2$. I can "see" this energy as light and feel this energy as heat, but I cannot fully ...
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Total internal reflection for TM polarized light [closed]
I submitted an assignment, I had derived the TM polarization for TIR using a vertical interface between $n_1$ and $n_2$ and arrived at:
$$\arctan\left(\frac{{n_1}^2}{{n_2}^2}\frac{\sqrt{n^2 \cos^2\...
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Fock space and Minkowski space in QFT [closed]
I have a doubt regarding Quantum Field Theory. If I am not mistaken, here we start working with Fock spaces, which are formed by the tensor product of infinite Hilbert spaces. These have a scalar ...
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Applying Noether's theorem to gravitational lagrangian
I'd like to get a better understanding of stress-energy tensors in general relativity. It is clear to me that due to equivalence principle energy of the gravitational field cannot be localized, and ...
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How to intuitively visualize shape of the magnetic field the way it is?
As the title suggests, it follows Biot-Savart Law that the direction of the magnetic field is always perpendicular to the current.
$$\vec B =\frac{\mu_0 I}{4\pi} \int \frac{d\vec \ell \times \hat r}{r^...
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Is separability of the Hilbert space in quantum mechanics physically motivated, or is it purely an axiom?
Teschl's Mathematical Methods in Quantum Mechanics lists a set of "Axioms of Quantum Mechanics", of which I will reproduce only the first two.
Axiom 1.
The configuration space of a quantum ...
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Proof that the Gauss-Bonnet/Euler term is the exterior derivative of a Chern-Simons 3-form
I am trying to prove that the Gauss-Bonnet term is the total derivative of a Chern-Simons 3-form. Working in the language of differential forms, we have that the Gauss-Bonnet/Euler term is given as:
\...
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The actual cause of gravity at it's fundamental [duplicate]
I just had this question in my mind that where does gravity come from fundamentally even though I am just 16 years old I had this lingering though of the actual deep root of gravity though it is said ...
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universe, quantum-mechanics [closed]
The Fluid-Fabric Hypothesis: A Unified Model of Spacetime and Quantum Vacuum
1. The Conceptual Framework
The model proposes that the Universe is not an empty vacuum, but a multi-layered hydrodynamic ...
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Diagonality of density matrix in microcanonical ensemble [closed]
I'm reading Pathria's Statistical Mechanics. In section 5.2, he discusses the form of the density matrix $\rho$ in the case of the microcanonical ensemble (MCE). Let $\Gamma$ denote the number of ...
