All Questions
10
questions
1
vote
1
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149
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How does a refractive index of less than one not violate relativity?
If I am not mistaken, this video says that X-rays travel faster in glass than in a vacuum. Special Relativity says that information can not travel faster than the speed of light in a vacuum, so what ...
3
votes
3
answers
1k
views
Can an object move faster than the speed of light in a medium? [duplicate]
In water the speed of light changes to $2.25 \cdot 10^8m/s$. Can a electron travel faster/travel at the same speed in water. I don't see any violation of SR. So shouldn't it be possible for an ...
- 1,333
1
vote
0
answers
190
views
Is the speed of light universal for all mediums? [duplicate]
We know that the speed of light is constant in a vacuum and has the value c= 3× 10^8 m/s.
But in a medium such as glass(refractive index=1.5) the speed of light is 2× 10^8 m/s. Now considering the ...
- 141
-1
votes
3
answers
630
views
What is Cherenkov radiation? [duplicate]
What is Cherenkov radiation? I came across this concept when I was learning SR.
Why can't particles moving at speed of excess of speed of light in the medium. Why it does not violate the limitation ...
user221098
2
votes
2
answers
101
views
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
3
votes
5
answers
1k
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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
2
votes
1
answer
237
views
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
9
votes
3
answers
294
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Alongside a light ray (in another medium)
It is a said fact that the speed of light is insurmountable. But can the validity of this fact be questioned in another medium?
If I pass a beam of light in, say water (here the light speed is ...
- 1,630
4
votes
1
answer
594
views
Theoretically if you passed the speed of light in a medium, would there be a sonic boom equivalent?
I know that it is technically impossible to reach the speed of light in vacuum since the mass of the object travelling would reach infinity. However in a medium, would there be some sort of ...
- 151
16
votes
2
answers
2k
views
What happens if light/particles exceeded the speed of light for a particular medium?
While the speed of light in vacuum is a universal constant ($c$), the speed at which light propagates in other materials/mediums may be less than $c$. This is obviously suggested by the fact that ...
- 1,187