John Duffield
  • Member for 6 years, 10 months
  • Last seen more than a month ago
Difference between magnetic and electric fields
-1 votes

I need to understand the concept on how to distinguish between electric fields and magnetic fields. Note the Wikipedia electromagnetic field article : "Over time, it was realized that the electric ...

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Feynman diagram of electron- electron interaction and cool down of an electron gas
-1 votes

Reading this answer I wondered if during an electron-electron interaction real photons have to be emitted. They don't. The virtual photons of the electromagnetic interaction are virtual. They aren't ...

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How do we know that gravity is spacetime and not a field on spacetime?
4 votes

How do we know that gravity is spacetime and not a field on spacetime? We don't because it isn't. I should explain that spacetime is an abstract mathematical space, not real space. The Earth is ...

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Why does the universe need quantum superposition?
1 votes

Why does the universe need quantum superposition? Because of the wave nature of matter. Check out the Wikipedia quantum supposition article: "Quantum superposition is a fundamental principle of ...

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Is intrinsic spin conserved?
-5 votes

Is intrinsic spin conserved? Generally speaking, yes. It's conserved like angular momentum is conserved. See the Einstein-de Haas effect which "demonstrates that spin angular momentum is indeed of ...

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Does the Lorentz invariance of Maxwell's equations apply here?
-2 votes

Does the Lorentz invariance of Maxwell's equations apply here? Yes. Lorentz invariance is pretty universal. The "laws of physics" don't change when you and your laboratory go from being at rest to a ...

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Can you ride Hawking radiation away from a black hole?
-12 votes

Can you ride Hawking radiation away from a black hole? No. Let's go through this carefully. Suppose you were held by a very strong rope at constant Schwarzchild coordinate $r = 2M (1 + \epsilon)$ ...

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How do coherent isotropic radiators evade the hairy-ball theorem?
-8 votes

How do coherent isotropic radiators evade the hairy-ball theorem? By having a toroidal topology. The concept of a spherical electromagnetic wave is a nice fiction It is not a fiction. which ...

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Yang–Mills and Mass Gap
-11 votes

The successful use of Yang-Mills theory to describe the strong interactions of elementary particles... Who says it's successful? The nuclear force remains one of the unsolved problems in physics: "...

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Do accelerated charges radiate or not?
1 votes

Do accelerated charges radiate or not? It depends. A falling charged particle doesn't radiate. Nor does a charged particle accelerating because of a static electric field. Cyclotron radiation and ...

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Does law of inertia has anything to do with speed of light?
Accepted answer
4 votes

Does law of inertia has anything to do with speed of light? Yes. Inertia is resistance to change in motion. It doesn't take much effort to get a skateboard moving, or to stop it moving. But it takes ...

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Is the Big Bang defined as before or after Inflation?
-2 votes

Is the Big Bang defined as before or after Inflation? The word "defined" makes this a question about opinion rather than fact. I always try to stick to the facts determined from empirical evidence. ...

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At what electromagnetic frequency does the wavelength = the wave height?
-7 votes

At what frequency does the wavelength = the height of the wave amplitude ? At 7.7646 x 1020 Hz. The associated wavelength and amplitude is 3.861 x 10−13 m. The electron Compton wavelength is 2.426 × ...

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What is the source of the electric charge on the electron?
1 votes

What is the source of the electric charge on the electron? Geometry. Google on Percy Hammond electromagnetism. An individual electron possesses an electric charge. Note though that an electron's ...

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Are there experiments, simulations or evidence about charge conservation violation?
-3 votes

Charge conservation is the principle that electric charge can neither be created nor destroyed. Yes, though it might be good to mention net charge. We can create charged particles in pair production ...

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Different cold dark matter density parameters from early- and late-Universe observations
0 votes

The $\Lambda$CDM model, the standard model of cosmology, implies that today's cold dark matter (CDM) density parameter is $\Omega_c=0.2589±0.0057$. Thus, according to the cosmological standard model, ...

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(Physics Newbie) Reaching the edge of the expanding universe
Accepted answer
1 votes

Say you have a space ship so fast that it was able to instantly reach... I don't think there could be any such ship, but hey ho, I'll go with the flow. ...the edge of the expanding universe. We ...

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What exactly does the *frequency* of a photon mean?
2 votes

How is colour perceived when shot by a single action “photon pistol”? The same way it's perceived normally. First: Suppose you had a single action photon pistol. You fire photons at an observer ...

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Do photons truly exist in a physical sense or are they just a useful concept like $i = \sqrt{-1}$?
3 votes

Do photons truly exist in a physical sense or are they just a useful concept like i = sqrt(-1) They truly exist in a physical sense. Reading about photons I hear different explanations like "...

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Why is the speed of light said to be constant when we know it slows down in a medium?
1 votes

Why the speed of light is said to be constant? Because of the tautology wherein we use the motion of light to define the second and the metre, then use them to say what the speed of light is. See ...

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Can electrons be non-fundamental in higher dimensions?
-3 votes

Can electrons be non-fundamental Yes, definitely. We can make electrons along with positrons in pair production. We can also destroy electrons and positrons in annihilation. So they aren't really ...

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How can "nothing" be warped?
-2 votes

How can “nothing” be warped? It can't be. There's nothing to warp. However... It is said that space is empty, a void, a “nothingness.” Space is the lack of anything. Who said that? Einstein didn'...

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Can I use the work done to calculate power of a motor?
-1 votes

Can I say that work = energy? No. Because it isn't. Work is the transfer of energy. I am trying to calculate the energy/ power required to push a plate up and down in a liquid. Energy is not the ...

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What mechanism creates the difference between left and right in the universe?
-8 votes

What mechanism creates the difference between left and right in the universe? None. Or, more general, what mechanism creates the distinction between two opposite directions in the universe. ...

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Charged particle as observed from an inertial and a non-inertial frame of reference
-4 votes

A charged particle fixed to a frame S′ is accelerating w.r.t an inertial frame S. For an observer A in the S frame, the charged particle is accelerating (being attached to frame S′) and therefore, he ...

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Why is it not possible to measure the individual neutrino mass from $\beta-$decay?
-2 votes

Why do we have to rely only on neutrino oscillations, to measure the mass squared differences of neutrinos? I don't think we do. It's just a hypothesis. Why is it not possible to measure the ...

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How does a photon travel the speed of light while it is absorbed in a molecule?
-6 votes

How does a photon travel the speed of light while it is absorbed in a molecule? By going round and round. Since photons always travel the speed of light and continue to exist after they are ...

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How much does surface gravity of a star shift color and who observes the shift?
-2 votes

Reading Richard Muller's new book Now he explains that since the gravitational field near the surface of star causes time to run slower relative to time further away from the surface, the frequency of ...

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Rainbow Blackhole?
2 votes

Can white light be broken into its component colors when gravitationally shifted by a black hole, in a manner similar to what a prism does? No. Gravity affects all light in the same fashion, ...

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Does earth rotate in a shorter time at 0m than at 5000m?
-2 votes

Does earth rotate in a shorter time at 0m than at 5000m? No. If it did, it would be twisting, and it isn't. The Earth's rate of rotation relative to the fixed stars is the same at all elevations. It ...

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