Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Fluid_thinker on 14/04/2009 16:48:29

Title: Does light create an equivalent of a sonic boom?
Post by: Fluid_thinker on 14/04/2009 16:48:29

Sounds can create a bow wave at the leading edge that ultimately results in a sonic boom.

Does the same happen with light?

If so, does that not mean that the bow wave is travelling faster than light?

Title: Does light create an equivalent of a sonic boom?
Post by: Vern on 14/04/2009 16:58:20

My own concept of photon anatomy has the photon composed of saturated points of electric and magnetic fields. Radiating out from the points the same electric and magnetic fields diminish in amplitude. So that concept might resemble a particle with bow waves. But even in this speculative concept, the speed-of-light restriction holds.

I like that better than the accepted QM concept of a wave function, which is more a mathematical concept. In the accepted Quantum Mechanical theory it would be difficult to visualize the photon. It is simply a wave function that exists in a spacial area that is undetermined until it is observed. When observed the wave function collapses and the photon instantly is seen as a particle as it interacts with the observer. We don't even know for sure that the photon exists between interactions. It is only observed when it interacts with an observer.

An observer is anything capable of interacting with the photon.

Title: Does light create an equivalent of a sonic boom?
Post by: lightarrow on 14/04/2009 20:53:33

Quote from: Fluid_thinker on 14/04/2009 16:48:29

Sounds can create a bow wave at the leading edge that ultimately results in a sonic boom.

Does the same happen with light?

Yes:
http://en.wikipedia.org/wiki/Cherenkov_radiation

Quote

A common analogy is the sonic boom of a supersonic aircraft or bullet. The sound waves generated by the supersonic body do not move fast enough to get out of the way of the body itself. Hence, the waves "stack up" and form a shock front.

In a similar way, a charged particle can generate a photonic shock wave as it travels through an insulator.

Quote

If so, does that not mean that the bow wave is travelling faster than light?

No:

Quote

It is important to note, however, that the speed at which the photons travel is always the same. That is, the speed of light, commonly designated as c, does not change. The light appears to travel more slowly while traversing a medium due to the frequent interactions of the photons with matter. This is similar to a train that, while moving, travels at a constant velocity. If such a train were to travel on a set of tracks with many stops it would appear to be moving more slowly overall; i.e., have a lower average velocity, despite having a constant higher velocity while moving.

Title: Does light create an equivalent of a sonic boom?
Post by: Vern on 14/04/2009 21:41:55

Cherenkov radiation; of course; I didn't think of that. Thanks for the correction, lightarrow.[:)]

Edit: The reason I didn't think of Cherenkov radiation is that it is actually produced by a particle, not a light beam, as I assumed from the OP [:)]

Title: Does light create an equivalent of a sonic boom?
Post by: Fluid_thinker on 15/04/2009 11:18:26

So the Speed of Light limit is maintained due to the Cherenkov factor being based on the Light being in a non vacuum e.g. water. in effect slowing the light.

But in a vacuum are you saying there is no bow wave.

Title: Does light create an equivalent of a sonic boom?
Post by: lightarrow on 15/04/2009 11:27:33

Quote from: Fluid_thinker on 15/04/2009 11:18:26

So the Speed of Light limit is maintained due to the Cherenkov factor being based on the Light being in a non vacuum e.g. water. in effect slowing the light.

But in a vacuum are you saying there is no bow wave.

Exactly.