Photon mass (was: [Still off-top] Physics)

[Larry Martell]

On Sat, Mar 5, 2016 at 12:36 PM, Gene Heskett <gheskett at wdtv.com> wrote:
> On Saturday 05 March 2016 10:46:04 Thomas 'PointedEars' Lahn wrote:
>
>> Gene Heskett wrote:
>> > I've never heard of a massless photon,
>>
>> That is unfortunate as it should be common knowledge by now.
>>
>> > and they do exert a push on the surface they are reflected from, […]
>>
>> Photons exert a force on surfaces because they carry *momentum* or, as
>> it had been understood in terminology that is obsolete now, a non-zero
>> “*relativistic* mass” (that had been distinguished from “rest mass”).
>>
> To have "momentum" imply's mass in the real, we can measure it world.
>
> However with my lack of education, I have a hard time reconciling that
> they travel at C speed, when the classical math says that anything with
> mass traveling at C speed will have aborbed enough energy in getting to
> C speed, that its mass is then infinite. But its obviously not.
>
> I once used relativity to explain to a degree'd FCC engineer exactly why
> a UHF transmitter that used klystrons for amnplifiers, alway had a
> backgound audio buzz. At the moment this was taking place, the station
> was crippled as we'd had a circuit breaker failure, single phasing and
> stopping the cooling water pump, which in turn destroyed the klystron
> used as a visual amplifier (one circuit breaker boom as the building
> went dark when the tube filled with steam, byby $120,000 USD), so just
> to stay on the air, I had moved a weak & about used up klystron from the
> aural cabinet to the visual cabinet, and tee connected the aural drive
> into the visual drive.
>
> When the engineer came in the door, one of the first things he had
> noticed when he monitored the station from about 15 miles away the
> previous evening, was that we were a UHF, but didn't have that annoying
> background buzz in the sound.  So I had to explain it.
>
> What we were observing was that by combining the two carrier signals into
> one tube, meant that both signals were being treated equally to the
> phenomenon they had called incidental carrier phase modulation, and its
> created in the amplitude modulated signal because the 4 foot long
> electron beam is traveling at a speed where speed vs mass is beginning
> to make itself measureable. Said simply, the tube amplifies the signal
> by nominally 30db, by introducing an electrical field across the input
> cavities gap that alternately speeds up, or slows down, an electron
> traverseing that gap with a 20 kilovolt induced speed. 4 feet and  3
> more cavities later, those electrons are now bunched up, the ones in
> front slowing to fall into the bunch, and the ones behind being pushed
> to catch up with the bunch. That induces, because the beam is something
> north of 5 amps, a considerable amount of power in the last cavity which
> can be coupled back out and sent to the antenna, typically about 30 kw.
>
> However, because this beam of electrons is traveling fast enough for
> relativity to come into play, the energy applied to speed the beam up
> encounters an electron with higher mass as it accelerates, whereas the
> energy applied to slow it encounters an electron with lower mass, so the
> deceleration is fractionally greater.  IOW, its not perfectly
> symetrical, the net effect being that the average speed of the beam is
> instantaneous power level dependent, the tube being effectively,
> physically longer, with a longer transit time as the power level rises.
> This is efffectively a frequency modulation, and an unwanted effect.
>
> Some circuits, once the cause of the phenom was known, were designed to
> predistort this by intruducing an opposing FM and cancel it, but by then
> the heyday of the klysron amplifier was coming to an end because of its
> horrible efficiency, that 30 kw of output came at a cost of a few hairs
> over 100kw in the beam supply, making a UHF transmitter the local power
> companies largest customer by a fairly wide margin. That tramsitter used
> nearly 200 kw for every hour it was on the air, and multi-thousand
> dollar power bills were getting the bean counters attention.
>
> But when both signals, visual and aural, are subjected to the same
> effect, AND the sound detection is based on the FM of the 4.5 megahertz
> difference, it cancels out in the receiver. Later, while still operating
> crippled, I made some aural signal to noise measurements, finding truely
> amazing figures of nearly 80 db with video still applied, where when
> operating with 2 klystrons as intended, it was hard put to make a bit
> over 50 db.  It was such a problem that the FCC allowed us to make those
> measurements with the baseband video cable unplugged when doing a proof
> of performance, required for license renewal every 5 years back in those
> days.
>
> So in that scenario, I have first hand knowledge about relativity despite
> my offical 8th grade education.

Gene, your massive and varied experiences trump my formal education any day.

>Photons not having a mass but can exert
> a push isn't something this 81 yo wet ram can quite figure out.  In my
> mind, when the ball bounces, its mass exerts a push on the wall it was
> bounced off of.  For a photon to do that, requires it have a mass,
> however miniscule it might be, possibly just the mass of the light
> energy its carrying.  Can that be quantified to a known value, probably
> color dependent?