# 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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### Length contraction doesn't affect the perpendicular direction...but it seems as if it can

A is a stationary observer watching B who is moving relative to A. Both of them hold two identical light clocks and each shoots light rays to estimate the lengths of their clocks. A's light ray will ...
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### Particle Creation by a Classical Source (on-shell mass momenta)

It is noted in Peskin and Schroeder's QFT text that the momenta used in the evaluation of the field operator $\phi(x)$ are "on mass-shell": $p^2=m^2$. Specifically, this is in relation to ...
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1 vote
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### Relativistic Doppler shift moving source in a circle

I am looking to understand the value for the relativistic doppler shift in the following scenario. We have a source moving in a circular pattern around a center. Now, if the observer would be in the ...
• 21
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### Failures on deriving the Lorentz factor: using light clocks to calculate the dilation on space and time

I wanted to check my understanding of special relativity and set up one experiment that could lead to deriving the Lorentz factor. Usually, the deriviation for the Lorentz factor is explained using a ...
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### Why a moving charge creates a rotating magnetic field around itself?

I want to understand the why using relativity, since it helps see in a more intuitive manner what is going on. So, when we see Lorentz transformation and how it manipulates spacetime diagrams, there ...
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### Clarification question about definition Lorentz covariance for an arbitrary higher rank tensor

What does it mean for a tensor of rank N to be Lorentz covariant. For a scalar (rank 0) it simply means that it is Lorentz invariant, in other words it remains unchanged under Lorentz transformations. ...
Let us assume I get into a rocket, and I quickly reach a speed close to $c$. In my reference frame, I can reach a star at the end of the galaxy in a few days, due to length contraction (and observer ...