All Questions
12
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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
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108
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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
-1
votes
1
answer
95
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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
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59
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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
4
votes
1
answer
140
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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
1
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2
answers
147
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Does $E^2=(mc^2)^2+(pc)^2$ hold for light travelling in an optically dense medium?
The rest mass of photon $m_0=0$ and photon travels at the speed of light in vacuum. So the energy of photon in vacuum is given by $$E_{vacuum}^2=(m_0c^2)^2+(pc)^2=(pc)^2$$ $$E_{vacuum}=pc=\gamma m_0c^...
- 451
1
vote
1
answer
110
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Do all photons have the same proper time in different environment?
All photons have the same speed. In "space" (I mean when there is practically no matter) a photon will travel a distance faster than a photon in matter. But the speed is still the same.
Do 2 photons ...
- 121
2
votes
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
1
vote
3
answers
818
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If light slows down while passing through a material, does it speed back up while in a vacuum?
Light slows down while passing through, say, water. After passing through the water, does the light speed back up to the "speed of light"? If so, how and why?
- 143
2
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0
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286
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Can time pass for a photon if it's moving in a medium? [duplicate]
If time does not pass for a photon traveling at the speed of light, which can only occur when traveling in a vacuum, what happens when it is slowed down by traveling through non vacuum space like ...
- 21
11
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2
answers
2k
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Do photons age in a medium?
According to special relativity, time starts to slow down as we increase our speed and eventually stops once we get to the speed of light. By that logic, photons don't age in a vacuum state as, to us, ...
user34284
-2
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4
answers
2k
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Why is the speed of light considered as a fundamental constant if its speed changes with medium resulting in refraction? [duplicate]
I know that the speed of light, the universal constant of gravitation and the Planck's constant are considered to be the three fundamental constants of the universe. But, why is speed of light ...
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