All Questions
46
questions
0
votes
0
answers
33
views
Does light accelerate? [duplicate]
If considering the general formula for acceleration, ie.
Δ V/ΔT, we would get zero as the velocity of light is constant and does not change.
However, what about when photons travel through different ...
- 133
0
votes
3
answers
90
views
Is it possible to distinguish the type of space according to the speed of light in vacuum? [duplicate]
Why is the speed of light 300 000 km/s? The speed of light is slower in glass, water and diamond. Is the speed of light in water, glass and diamond also absolute? Can we calculate the material such as ...
- 101
0
votes
0
answers
108
views
Do photons moving at $c$ slow down when entering a medium or take a longer path and only appear to slow down and what happens to time? [duplicate]
Imagine a photon leaving a vacuum and entering a medium, say, air. I have 2 questions:
Some claim that the photon is slowed by the medium so its speed becomes less than $c$. Is that true or does ...
- 29
0
votes
1
answer
59
views
Relativistic Effects on Electromagnetic Wave Propagation
So for a recent lab I had to calculate the length of a conductor by measuring the time it took a signal to reflect off of the open end. I used the very simple principle of $v=st$ and, knowing that the ...
- 1
1
vote
1
answer
149
views
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 ...
-1
votes
1
answer
95
views
What is the acceleration of light (photon) in vacuum? [duplicate]
We all know that the speed of light is 299792458m/s, but what is the acceleration of photons? That is to say, does the photon have a speed transition from zero to the speed of light?
- 39
-1
votes
2
answers
243
views
Is the speed of light in is uniform non-vacuum medium constant for all observers? [duplicate]
I am running at $5 \text{ ms}^{-1}$ and holding a torch pointing in the direction of motion. This torch has a large block of glass attached to the end. Would a stationary observer see the light as ...
0
votes
0
answers
59
views
According to SR, massless objects must travel at the vacuum speed of light, yet light slows down in a medium. So why isn't light massive? [duplicate]
So I've already asked a similar question on Quora and the askphysics forum on Reddit, but haven't gotten many helpful answers. I did get one good answer that said that light SOMETIMES gains mass in ...
- 2,327
7
votes
3
answers
2k
views
Is the speed of light through a medium invariant, just like the speed of light through vacuum is invariant? Also, do time dilation etc. still occur?
So, we know the speed of light through a vacuum is $c$.
Let us say that both our observers are moving past each other at speed $v$ in a medium in which the speed of light is $c'$.
So, does the usual ...
- 4,476
4
votes
1
answer
140
views
What do you 'see' if you are stationary relative to a photon in a refractive medium?
A particle with zero rest energy/mass must always be at $c$ in all referentials, even why, if you could get to its referential it would have zero total energy, effectively not existing in that ...
- 223
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
vote
2
answers
193
views
Is it possible to reduce the speed and frequency of a light wave to zero in a liquid medium?
Assume that two mirrors are located in a huge liquid medium – say, deep down on an ocean floor – with a refractive index of $n'$ as measured by an observer $A$ standing on the beach platform at rest ...
- 2,503
1
vote
2
answers
58
views
Restoration of the speed of light [duplicate]
If you can slow down the speed of a photon, how does it speed back up to the speed of light once the slowing down is disabled?
- 712
1
vote
2
answers
142
views
Help understanding the speed of light in media with refractive index < 1
I have read the standard explanations on this, but I still have trouble with convincing myself that information is not propagating at faster than the speed c in media of refractive index less then ...
- 1,087