# Questions tagged [special-relativity]

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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### Mandelstams for $2\to 2\to 3$ process

2 initial particles become two other particles, from which one decays into 2. Let $p1$ and $p2$ be the momenta of the initial particles, $p3$ the momentum of the decaying particle, $p5$ and p6 the ...
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### Is it enough just to check the effect of a boost in the z-direction to prove the covariance of an expression for the lorentz transformations?

Is it enough to check the effect of a boost in the z-direction to prove the Lorentz invariance of an expression for the $L^\uparrow _+$ transformations? My argument why this is true is that we can ...
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### Rest Mass Energy

What exactly is the Rest mass energy? I know the usual goes Like it is total energy stored in mass $m$ that is in Rest. so for someone moving relative to the frame that the mass $m$ is in (a rest ...
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### Does relativity of simultaneity affect the outcome of an experiment?

I'm trying to understand the first postulate in special relativity. My take on that is that the outcome of an experiment does not depend on the observer (inertial frame of reference). However, since ...
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### How to understand $W=pc$ in Feynman's Lectures on physics?

Pictures below are from 34-3 of Feynman's Lectures on physics. I can't understand the red line. The $p$ is momentum, $c$ is light speed. I can't understand the red line. I feel the author think $pc$ ...
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### How does Lorentz contraction take place for a cylinder moving in a direction parralel to the flat surface of cylinder?

So I know that Lorentz contraction does not occur in the transverse direction. However for a particle in a relative frame moving across the diameter of the flat surface of cylinder it should witness ...
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### Does coordinate acceleration match proper acceleration when $v=0, s=0$?

Alice and Bob are riding in their rocket at arbitrary proper acceleration through an arbitrary region of spacetime. Bob steps out of the space ship right next to Alice, such that at $t=t'=0$, $v=0$, ...
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### Seemingly equivalent linear form of the Sagnac effect

This is a derivative of the question regarding the Sagnac effect. Judging from the metric $ds^2=-dt^2+(rd\phi)^2$ for a constant $r$ for this question, it should be no different from that on a line ...
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### Special relativity and accelerating twins

Imagine two twins synchronise their clocks and then twin A quickly accelerates to velocity v. After a time T twin B quickly accelerates to 2v and catches up with twin A. Which one will be younger? How ...
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### Radiation from a stationary charge relative to earth for a free falling observer

It is my understanding that if we have a charge at rest on earth, a free falling observer will see it radiating, as the charge is in an accelerated frame of reference. This observer can in principle ...
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### The principle of relativity and why Inertial frames attribute the same velocity to one another

In introductory texts introducing relativity, it is always assumed that frames measure the same velocity for each other. For example if frame S' moves at velocity v with respect to respect, then S ...
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### Does the Wigner little group classification of particles have consequences for classical field theory?

Does the Wigner little group classification of particles have consequences for classical field theory? In particular, I'm curious whether it can be used to predict the two propagating modes for ...
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### Could this kind of total energy of a particle be possible: $E_{tot} =\gamma mv^2$ (new question)? [closed]

I was told that i could ask new question instead of continuing old question. I hope this new question has better clarity. (I have completely rewrited this question what i asked 8 years ago. It needed ...
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