I guess, in quantumelectrodynamics, there are probabilities for a photon to have velocities higher or lower than c, when measuring over very short distances. What does happen to the relativity stuff then?
2007-06-25 16:42:30 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Physics
This is actually a really good question
No the photon always travels at the speed of c (in a vacuum). If we look at light as a wave, the velocity of portions of the wave can exceed C. However the velocity is averaged out with other slower moving portions. Light comes in wave packets called photons. The velocity of the wave packet also known as the group velocity is always c.
To examine light as a particle within the realm of quantum mechanics using the Schrodinger wave equation and Heisenberg uncertainty principle presents several problems and requires relativistic treatment.
2007-06-25 16:46:25 · answer #1 · answered by kennyk 4 · 1⤊ 0⤋
It is true that photons always travel at velocity c; but c is not a fixed number: it depends on the medium in which the photon travels. The velocity of light is given by
v = â[1/mu*epsilon], where mu and epsilon are electrical properties of the medium.
In fact, the ratio of light velocity from one medium to another is called the index of refraction.
What is constant is the velocity of light in a vacuum; but that is based on the assumption that mu and epsilon of free space are constant. There are some theories that imply that those numbers have changed (or are changing) over time.
2007-06-25 23:55:56 · answer #2 · answered by gp4rts 7 · 0⤊ 1⤋
The [U.S.] National Institute of Science and Technology (NIST) formerly the National Bureau of Standards (NBS) is confident enough of the speed of light in a vacuum that it is actually defined as 299,792,458 meters per second. This means that this number is probably used in some way to define the unit of the meter and/or the second.
2007-06-26 02:38:14 · answer #3 · answered by devilsadvocate1728 6 · 0⤊ 1⤋
The velocity can never exceed c, in a vacuum it is a constant c.
2007-06-29 12:18:37 · answer #4 · answered by johnandeileen2000 7 · 0⤊ 0⤋
One must be careful. The speed of light is constant only for a particular medium.
2007-06-25 23:53:03 · answer #5 · answered by Edward 7 · 1⤊ 1⤋
small correction, gp4rts: c doesn't change, its always 3e8 m/s, simply by definition. c is the value given specifically to the speed of light in a vacuum. the speed of light V (or whatever you wish to call it), is what changes based on the medium light is traveling through.
2007-06-26 00:08:38 · answer #6 · answered by Anonymous · 0⤊ 1⤋
probabilities are to play with to help in understanding realities. c will never ever change in this demension relativity speaking. Just like pi is a constant in this demension!
2007-06-25 23:59:54 · answer #7 · answered by j r g 1 · 0⤊ 1⤋
It is absolute constant at 299792458 m/s
2007-06-30 15:12:30 · answer #8 · answered by Abhinesh 4 · 0⤊ 0⤋