Photon dimensions

The motion (and location) of a photon is governed by its wavefunction, which contains all of the information about its "dimensions." To find the size of the region occupied by the photon, the uncertainty principle requires that you give up knowledge about its wavelength.

Two photons with different energies will have different wavefunctions, and these can certainly overlap.

 

Yes, they can overlap in the same volume, but the fields add and you get just one combined wavefunction.

 

You can't really define the energy density of a single photon. But you can calculate the number of photons per unit volume from the radiation intensity and the photon energy (E=h*freq).

 

Very helpful. Thanks.

 

I quote marlon from one of the threads in the Quantum Forums as he explains the crux of the matter so eloquently;

 

If you click on the "archive" links and then on the "View full version" link on the page that pops up, the threads are formatted properly.

 

You could measure the EM energy density before and after a photon is absorbed, and call the difference an equivalent energy density for the photon. But if the volume is different, you get a different answer. A photon really has no defined volume, so you are confusing classical and quantum concepts.

 

Anantchowdhary, I think we should think how the properties of the macro world can be explained in terms of the sub-atomic world not how the sub-atomic world can be explained in terms of the macro world.

 

Does "pain" occupy space? What about the color indigo or the saltiness flavor? Do they occupy space?

I'm not trying to be funny here, but it appears that this may be the only way to demonstrate to you why your assertion simply has no answer, unless you want to make one up.

I also don't understand why, after a link to a previous thread on the identical question, that we're repeating everything all over again.

Zz.

 

Can you show me evidence that allows you to claim that "it occupies spacetime"? It appears that you used this several times, but you made no such support to how you would know such a thing.

Zz.

 

Er.. there is a problem with logical consistency here. You simply cannot make a connection like this in physics and expect to get away with it. Just because A does something to B doesn't mean that A=B. A photon can also cause the emission of an electron. Does that mean it is also an electron? Or "occupies the space of an electron"?

Zz.