Re: Voting on LIGHT (was energy with Q)

[Richard L Bowman <rbowman@BRIDGEWATER.EDU>]

Jack Uretsky wrote regarding my question about the length or size of a photon:

>         I don't understand what you mean by the "size" of a photon.  The
> word "size" should imply a measurement of some sort.

My question may be simply a misdirected attempt to try and create a
synthetic model (wave+particle) for a photon in my own understanding. But
what I was referring to was the envelope that emerges as one combines waves
with slightly differing wavelengths, e.g., as one does in quantum mechanics.

> Here is one way that you can't measure the size:
>         Shine a laser beam on an aperture with a shutter and put a photon
> counter on the other side of the aperture.  Open the shutter for some
> time interval, and keep shortening the interval.  If the photons had a
> size L then there should be no clicks in the counter when the shutter is
> open for times shorter that L/c.
>         The experimental result, I am assured, is that there is no time
> interval so short that the beam cuts off.  The click rate in the counter
> just gets slower and slower as the time interval gets shorter and shorter.
> The interpretation is that the shutter merely reduces the probability that
> a photon gets through the aperture.

The problem with this experiment is that the shutter must be some sort of
mechanical device and thus it has a minimum speed at which it can close. So
one can only talk about a lower limit for the length of a photon (unless I
am not understanding the experiment). For example for a one-meter long
photon, the shutter would have to operate (open and close) in about a
nanosecond or less. Is this possible?

Richard Bowman
Dept. of Physics
Bridgewater College, Bridgewater, VA  22812 USA
http://www.bridgewater.edu/~rbowman/