# Tagged Questions

The special theory of relativity describes the motion and dynamics of objects moving at significant fractions of the speed of light.

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### trouble reconciling doppler shift for energy and momentum of light

[See late addition at bottom for what currently remains unresolved in this question.] I have seen the assertion in a couple of places that if you trap light in a reflective resonator, or any other ...
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### How does the wave function change upon a boost? [on hold]

I was recently thinking about Lorentz invariance description of a particle. In special relativity is based on the invariance of $$\text{constant} = c^2t^2 - x^2 - y^2 - z^2$$ I was wondering if ...
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### Lorentz-invariance of step function

I was reading about the Lorentz invariant integration measure $\int \frac{d^3k}{2E_K}$, and ways to prove that this was Lorentz invariant. Many of the proofs I have read use the step function (or ...
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### What happens to forces when a charge travels at near c?

Suppose 3 electrons are travelling at $c - 1$mm at 1 cm distance The charges are at rest relative to one another in their frame, but what happens to fundamental forces Fe and Fg? What Fe does A get ...
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### Is it possible that all “spontaneous nuclear decay” is actually “slow neutrino” induced?

This thought was inspired by a comment from the current leading answer, by @Sentry, to the question Where are all the slow neutrinos? This [slow-neutrino induced nuclear decay] will still be an ...
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### “Reality” of length contraction in SR

I was in argument with someone who claims that length contraction is not "real" but only "apparent", that the measurement of a solid rod in its rest reference frame is the "real length" of the rod and ...
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### With respect to what can't we travel at the speed of light? [closed]

According to theory of relativity the speed of light in vacuum is ultimate. But since objects move relative to each other, with respect to what can't we travel at the speed of light?
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### How fast does matter grow more massive when accelerating? [on hold]

I am wondering since it is understood that mass of matter increases as its velocity increases, how fast does this process occur if it is a physical process? For instance, if a mass initially at rest, ...
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### Length Contraction in Relativity

Let's suppose we have a one dimensional rod made of elementary point particles, in contact with each other placed along the x-axis.If the rod is moving along x-axis then we know (because of relativity)...
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### Minimum and Maximum Speeds of a Mass [on hold]

I understand that it is impossible for a object with rest mass to travel at $c$ (the speed of light) due to time limitations. I also understand that the speed of an object is calculated using a frame ...
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### How can a photon have no mass and still travel at the speed of light?

I've read a number of the helpful Q&As on photons that mention the mass/mass-less issue. Do I understand correctly that the idea of mass-less (a rest mass of 0) may be just a convention to make ...
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### Action at a Distance [duplicate]

Since photons move at $c$, do they experience time or distance? If they don't, doesn't this explain action at a distance? From the point of view of the photons, there is no time, so the action at a ...
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