# 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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### Why and how Dirac cones are “tilted”?

Given a Weyl Hamiltonian, at rest, $H = \vec \sigma \cdot \vec{p}$, A Lorentz boost in the x-direction returns $H = \vec\sigma\cdot\vec {p} - \gamma\sigma_0 p_x$ The second term gives rise to a ...
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### Images traveling faster than light

Please help me understand my mistake(s) in this reasoning. I will write as if I knew exactly what I'm talking about for the sake of clarity, but I of course don't. Consider observer A and its ...
1answer
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### Thought experiment and possible contradiction between electromagnetism and special relativity

I have designed a simple and qualitative thought experiment through which I have encountered an inconsistency in the relativistic electromagnetism. A point charge $+q$, with respect to the lab ...
0answers
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### Einstein's train experiment-Do waves from lightning flashes meet after the same number of cycles for all observers?

In Einstein's thought experiment about moving and stationary observers and two lightning flashes, let's say that we replace the lightning flashes with a pulses of mono-chromatic light, with both ...
0answers
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### Compressed length of a moving body [closed]

This question is on behalf of someone else without access to a computer so any further clarification or responses may be delayed. The question comes in the form of photos of the original questions as ...
3answers
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### How to derive addition of velocities without the Lorentz transformation?

Lorentz contraction and time dilatation can be deduced without Lorentz transformation. Can you deduce also the theorem of addition of velocities $$w~=~\dfrac{u+v}{1+uv/c^2}$$ without Lorentz ...
0answers
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### Proof of skewsymmetry of electromagntic function in Minkowski spacetime

I have been studying special relativity from the Gregory Naber's book: "The geometry of Minkowski spacetime" and I found a very strange proof. In Section 2.1, just before of equation 2.1.2. the book ...
1answer
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### Why do electrons have rest energy?

E=mc² so inserting the value of m and c we get 0.511 MeV for electron but then what does this energy account for coz according to me electrons are not made up of any particles so this doesn't account ...
1answer
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### Special Relativity Frame Ambiguity [duplicate]

If I have some predefined coordinate system — “my rest frame,” then I pick an “inertial frame” moving at some velocity with respect to my “rest frame.” Special relativity states that in the rest frame,...
1answer
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### What is the length of 1 second in meters

If time is treated as a fourth dimension of spacetime, what is relation between length and time units? Or in other words, how can I convert time units to length units, for instance seconds to meters?
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### Transverse Relativistic Doppler effect in Non-inertial reference frame

If I have a Non-inertial reference frame in Earth (rotating camera or just my rotating head with eyes) and I am watching the Moon. If my Non-inertial reference frame in Earth rotating with the speed ...
0answers
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### Work on two charges in mutually retarded field

Consider two particles with charges $q$ and $Q$ and with an initial distance of $3L$. Now I move each charge a distance $L$ closer to the other, such that the final distance is $L$. The initial and ...
1answer
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### Moving clocks observed with different observers

If a clock is moving near to speed of light with constant velocity it'll slow down, but if I were to observe from the clock will the observer on Earth slow down?
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### Why can't we measure the one-way speed of light?

I believe the problem is because we need to synchronize clocks. But ok let's assume we can't do that. Can't we just use some external reference - Eg The Sun & Solar Noon? For example given the ...