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 it had been understood in terminology that is obsolete now, a non-zero 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. 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? > <https://en.wikipedia.org/wiki/Mass#Mass_in_relativity> > <https://en.wikipedia.org/wiki/Mass_in_special_relativity#Relativistic >_mass> > > F'up2 sci.physics.relativity > > -- > PointedEars > > Twitter: @PointedEars2 > Please do not cc me. / Bitte keine Kopien per E-Mail. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> -- https://mail.python.org/mailman/listinfo/python-list
