Photon and matter

>>8530534
>massless particles must propagate at c
Lrn2vacuum fgt pls

>>8530534
c is the speed of a massless particle specifically in vacuum (different then the speed of a massless particle in a non-vacuous medium) you dense twat.

>>8530540
>>8530538
So photons really propagates at speeds lower than c? Why does that happen? I mean microscopically why is the photon deaccelerated?

>>8530546
It isn't. It travels at c, always.
In water or glass, the photon is absorped and emitted by the electrons in the media and increasing the time it takes to transverse the material.

>>8530546
it's not.
>>8530538 and >>8530540 are retarded.

>>8530546
>>8530534
Speed != velocity

>>8530563
Thanks that's what I was thinking about, do you have any source that says more about that?

File: images (6).jpg (19KB, 493x298px)

19KB, 493x298px

Bumping for sources

>>8530563
couldn't be more wrong

must be a canadian

File: 1481232316315.jpg (21KB, 400x246px)

21KB, 400x246px

It seems like I found a huge inconsistency in your physics /sci/. Impressive you could achieve a consensus on the answer

File: images (2).jpg (15KB, 384x384px)

15KB, 384x384px

Holy fuck/sci/, you're better than this, don't let this thread die without a proper answer

>>8530534
http://physics.stackexchange.com/questions/1898/do-photons-gain-mass-when-they-travel-through-glass

Go watch the fucking Sixty Symbols video.

Or better yet, get a Physics PhD.

>>8530534
>How the hell aren't these 2 statements inconsistent?
the former statement is a macroscopic statement:
if you send an electromagnetic wave through some medium and measure the time it needs to cross 1 m it will turn out to be slower than when traveling vacuum. a macroscopic description is correct in saying the wave slowes down while passing through the medium. on a microscopic level it is not true: the wave never slows down BUT it is absorbed and reemitted by the molecules making up the medium. in between the electromagnetic wave is propagating with c.

>>8530563
>the photon is absorped and emitted by the electrons in the media
so the absorption and emission are what take time?
>mfw group velocity, phase velocity and drift velocity

File: where.png (5KB, 300x200px)

5KB, 300x200px

>>8530534

>>8532952
I'm telling you guys, if they could just pull the answers directly out of your heads, they would NEVER pay you.

>>8530534
It's an issue simply of macro and micro. In the big picture a laser will travel more slowly through a fiber optic tube, zoom in though and the photons will travel from atom to atom at c but make be absorbed by atoms and re-emitted and reflected until they get to their destination.

>>8530540
>>8530546
>>8530563
>>8531158
>>8532239
>>8532301
>>8532407
>>8532635
>>8533286
I expected more from you /sci/. Congratulations on passing highschool physics and looking no further.

>>8532327
Is the only person who is correct. The simplistic explanation is that when photons pass through a medium they interact with the charge and create a quasi particle with effective mass. Therefore the photon ceases being mass less and does not propogate at c. Asked and answered.

>>8530534
>Electromagnetism tells us that electromagnetic waves changes its velocity of propagation according to the medium it is propagating into.
Correct.

>Special relativity tells us that massless particles must propagate at c
Wrong. special relativity tells us that all observers agree on the velocity of things traveling at c. Classical field theory tells us that only massless things can do this, and what the value of c is. Electromagnetism is a classical field theory that predicts the value of c can vary from place to place with the presence of matter.

Jesus /sci/ why the fuck are you struggling with this

>1. Electromagnetism tells us that electromagnetic waves changes its velocity of propagation according to the medium it is propagating into.

The wave is always travelling at c. As was mentioned earlier in the thread the reason that it is effectively slowed is because its absorbed by the particles in the material and then remitted. This has a time dependence.

2. Special relativity tells us that massless particles must propagate at c

They do

>>8535026
Its not wrong faggot, massless particles MUST travel at c, a rapid Google search will tell

>>8535044
You have shitty reading comprehension.
When I said this was wrong:
>Special relativity tells us that massless things must propagate at c
I wasn't referring to the fact that massless things move at the speed of light. I said you were wrong about what special relativity has to say on the matter. Special relativity is a theory of coordinates. It predicts that all inertial coordinate systems, regardless of momentum with respect to one another, will measure the speed of light to be the same. The existence of massless things and their motion is understood without the use of special relativity (Maxwell).

Special relativity is not properly equipped the talk about massless things by themselves. This is illustrated by the fact that a transformation which boosts the velocity of one coordinate system to be moving at the speed of light relative to another does not exist in the theory. The purpose of special relativity is to investigate the dynamics of massive and massless things with respect to different observers.