Why doesn't light go faster than c?

[sophiecentaur]

@Danger, splendid.

@DarioC, it's not just the little round balls, it's the whole wave/particle concepts. Waves and particles were words coined to describe quantum objects long before the whole concept of a quantum object was even the tiniest spark in someone's mind.

...

That is just the same as asking 'what is a photon really'. Which is an invalid question. I might snip out a bit from one of Feynman's lectures and post his answer to the 'is it a wave or particle' question.

That's all quite true and anyone who demands an answer to advanced questions in elementary terms will usually be disappointed.

But it has to be true to say that the wave model explains a lot of phenomena very well so it is well worth using. (Which is more than can be said for the bullet model).

 

[my_wan]

I must admit, I exaggerated a bit when I said 'you have to go to another universe'. Because there are some experiment where they have found the 'space' is not completely isotropic in all directions from earth. Speed of light may be different in different regions inside the universe.

Yes. In General Relativity the speed of light light is not an absolute constant but in some sense varies with gravitation depth. However, since gravitation depth also determines determines the spacetime metric for local observers the local speed of light is always constant at all gravitational depths. You can also have two observers, both in flat spacetime, which nonetheless have differing gravitational depths. The easiest example is an observer inside a uniform massive hollow sphere such that no gravitational acceleration is locally present. Yet this observer will still be gravitationally time dilated by the same amount as an observer on the surface where gravitational acceleration is at a maximum.

This implies that the observer in another Universe with a higher or lower speed of light may still measure their local speed of light as the same constant we do. No different from the speed variability under General Relativity.

 

[YummyFur]

this is Feynman's take on the wave/particle thing http://youtu.be/7HKOm8fffgU

 

[OCR]

I know that definitions are difficult when discussing this type of subject matter , and maybe this is being 'picky', however...

Speed of light may be different in different regions inside the universe.

Using the word inside, wrt 'the universe', also seems to imply an outside, wrt 'the universe'.

I believe the common thinking is, there is no outside... the universe.

Maybe a better way to express the thought would be...?

"Speed of light may be different in different regions of the universe".




Again, definitions...

Same with 'particle', it a very very very tiny little bit of something, just as Democritus supposed.

A 'bit of something' could depend on how the definition of the word 'particle' is applied.

http://en.wikipedia.org/wiki/Particle

http://en.wikipedia.org/wiki/Elementary_particle

By the bye... your name is somewhat disturbing on a couple of different levels, and

I can't figure out which one I like best

I have absolutely no ambiguity about that... lol



OCR

 

[YummyFur]

A 'bit of something' could depend on how the definition of the word 'particle' is applied.
OCR

Like this for example...

...and as for particle, that's just a word that we call bits of atoms, but it's not the same word in the sense of its meaning as say the other way we use particle in the classical world.

 

[Danger]

I have absolutely no ambiguity about that... lol
OCR

Oboy...:uhh:
At least one of you had damned well better be female, or I'll never live this down.

 

[YummyFur]

Ok, it's a comic by cartoonist Chester Brown, circa early 90's.

 

[YummyFur]

As opposed to non quantum terms?

 

[Neandethal00]

I know that definitions are difficult when discussing this type of subject matter , and maybe this is being 'picky', however...

Using the word inside, wrt 'the universe', also seems to imply an outside, wrt 'the universe'.

I believe the common thinking is, there is no outside... the universe.

Maybe a better way to express the thought would be...?

"Speed of light may be different in different regions of the universe".


OCR

I hesitated a few seconds before using the words inside universe.
But then again, I'm one of those few people who 'thinks' (not believe)
the universe if finite.

 

[rcgldr]

One puzzling issue is the fact that photons are emitted from electrons at c, inspite of the velocity of the electrons. In the case of lasers, the photons are emitted with the same velocity (and phase?) as the photons that triggered the release.

Regarding acceleration, light curves in gravitational fields, which is acceleration in terms of the direction of velocity so there is acceleration in a Newtonian universe. Can the curving only be explained in GR?

As a side question, how long does it take for an electron to emit a photon (it seems it would be related to the size of a photon / c), and transition to a lower energy state?

 

[Danger]

Regarding acceleration, light curves in gravitational fields, which is acceleration in terms of the direction of velocity

I'm not sure that you can count that as an acceleration, since the light 'perceives' its path as a straight line. It doesn't curve within space; the space itself is curved.