# All Questions

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### Are massive gravitons as the dark matter fluid more correct than the notion of WIMPs?

Accepted at APS Physical Review D: Massive gravitons as dark matter and gravitational waves Precursor: Bigravitons as dark matter and gravitational waves The massive graviton is a viable ...
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### Equal transit time fallacy and Newton's laws of motion

I've seen the equal transit time theory being used to explain aerodynamic lift [basis is Bernoulli's principle] several times. However recently I've been told that there is NO physical compulsion for ...
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### What is the difference between crystals and solid? [on hold]

In condensed matter physics, what are the differences between crystals.
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### Weight Detection Under Concrete/Asphalt

Consider that a weight sensor was embedded in a road. Would cars that drive over it trigger the sensor? I was thinking it'd look something like this (if we ignored the downward force that the ...
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### What is the difference between the Lorentz force in a cloud chamber and the repelling/attracting force between magnets?

In a cloud chamber charged particles are bend by a magnetic field where the Lorentz force is causing the bending. But when a ferromagnetic material is attracted or repelled by a magnet it is more or ...
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### What is the angular divergence of sun-rays?

I just want to find a number and I could not. Does anyone has it or can calculate it easily? Just in geometric optics, without diffraction, atmospheric effects and etc. Update: I think for me will be ...
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### What is the meaning of a negative Galactic longitude?

What is the meaning of negative longitude in Galactic coordinate system, for instance in this article? Does the longitude $-65^\circ$ equal $295^\circ$?
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### Can circular polarized light be cancelled?

I can cancel the light output from an LED screen by placing a linear polarizer at 90 degrees from the linear polarizer built into the LED display. OLED displays use circular polarizers instead of ...
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### Reducing coefficient of friction by vibrations?

Very simply put, if one places a block of some material on a level surface and pushes it horizontally, a certain coefficient of friction is measured. If one tightly couples an oscillator of some sort ...
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### Does the use of $\gamma=\left(1-v^{2}/c^{2}\right)^{-1/2}$ automatically assume a (+ - - - ) metric? [on hold]

In Special Relativity, does the use of $\gamma=\left(1-v^{2}/c^{2}\right)^{-1/2}$ automatically assume a (+ - - - ) metric convention? For introductory textbooks, the Lorentz factor is is always ...
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### Before Dark Energy was discovered

I'm really confused on this topic. Pardon my French if my questions seem really stupid. Before Dark Energy was discovered in 1998 did scientists know that the cosmological constant calculated, I ...
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### Does the vacuum have a zero Seebeck coefficient?

I was considering how at very high energies (e.g the Schwinger Limit) the vacuum starts having properties we would normally associate with "materials", such as non-linear polarizibility. The Seebeck ...
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### Answer true or false? [on hold]

True or false? Q: The magnitude of displacement is equal to distance covered in a given interval of time if the particle ___. A: moves with constant acceleration
I was trying to derive the Lorentz transformation with the following... $$\frac{t'}{t} = \frac{c-v}{c},\qquad \frac{t}{t'} = \frac{c+v}{c}$$ After adding gamma \frac{t'}{t} = \gamma\frac{c-v}{c},\...
So I'm trying to learn more about headphones. I have a small piston that is in a small sealed volume (the earcup, say it is $25\, cc$). And there is a front volume between the piston and the ear (...