All Questions
Tagged with refraction special-relativity
68
questions
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Can the Dirac Hamiltonian accommodate a variable speed of light?
The Dirac Hamiltonian has the form1
$$\left[\beta m c^2+c\sum_{n=1}^3\alpha_np_n\right]$$
where $\alpha_n$ and $\beta$ are Hermitian matrices, and $c$ is the speed of light.
My question: Is there a ...
- 411
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2
answers
101
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How do we know that light cannot travel faster than it does?
We assume the speed of light in vacuum is its maximum speed but can we not assume that it could be faster, or slower?
- 21
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Is there a medium less dense than vacuum, in which light can travel faster than $c$? [closed]
Is there a medium less dense than vacuum, in which light can travel faster than $c$? If not, can we make it?
- 659
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Relativistic equations are medium dependent?
Einstein proposed that light travels with a universal velocity from Maxwell's equations on electromagnetism. But light has different velocity in different mediums, so does this imply that the ...
user208263
41
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5
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Is light actually faster than what our present measurements tell us?
It is well established that the light speed in a perfect vacuum is roughly $3\times 10^8 \:\rm m/s$. But it is also known that outer space is not a perfect vacuum, but a hard vacuum. So, is the speed ...
user182521
12
votes
2
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Deriving the law of reflection for a moving mirror in relativity
I am following a training course and came across this proof, from my colleague, that the ordinary law of reflection $\theta_i = \theta_r$ does not hold in relativity:
Let $S$ be a perfectly ...
- 2,547
4
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5
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1k
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Stellar aberration in a water-filled telescope
I read that when the stellar aberration of light is measured with the help of a telescope filled with water, the value of the aberration is equal as in the case of a telescope filled with air.
Just ...
- 6,841
4
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3
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758
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Speed of light in a medium in different frames of reference
Relativity states that speed of light in a vacuum is the same regardless of the observer. Does the same hold if the light is travelling through a medium?
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Refraction vs Special Relativity
Special relativity postulates that the speed of light (while traveling through vaccum) is a constant ($c = 3 \times 10^8 m/s$). But, when light is refracted and change the medium in which it's ...
- 61
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1
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76
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Gain medium and the speed of light
I am currently studying optics, and when taking a closer look at refractive indices, I stumbled across gain mediums.
On Wikipedia it states that gain mediums can have a refractive index of $n<0$.
...
- 111
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Maximum speed in water
Is there a limit of maximum speed in water? Is it a finite value or the speed in water can take any possible value?
- 149
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Could we travel faster than the speed of light in a medium, but slower than the speed of light in vacuum? [duplicate]
It is well accepted that nothing with mass can travel at the speed of light in vacuum, $c$. Now let's say that a light wave is traveling through a medium that slows the wave's speed significantly (...
- 163
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The speed of light and it's variation through different media? [duplicate]
Does the speed of light vary?
Special Relativity says it's constant in all Inertial frames; but what if it was to travel through different media?
- 21
2
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1
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Problem on speed of light in a refractive medium
Here's the problem:
A beam of light moves in a slab of refractive index n in positive x direction. The slab itself is also moving in the positive x direction with respect to the lab frame. What is the ...
- 81
4
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3
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How can the speed of light change in the medium when we know that it is always equal to $c$? [duplicate]
How can the speed of light change in the medium when we know that it is always equal to $c$? If we say the speed of light is changing in the medium, it will contradict the Einstein's law of special ...
