Quote:
Originally Posted by bgilbert
. G'day Ray
. With respect, I think you have missed the point, I’m trying to demonstrate a principle that can be adapted to any frequency. The “Photo Electric Effect” is considered a crucial stumbling block for classical theory, I’m basically proposing that metals could have the equivalent of a “High Pass Filter”(HPF) in their surface. The simplest HPF is a hollow open ended cylinder.
. Photon counting is a misnomer, photo-multiplier tubes (PMT) do not exclusively count photons, they count noise and “photons”, and there is no one for one correlation between signal and out put pulses or Feynman’s clicks.
. I am one of those extremely rare individuals, that does not believe in photons.
Cheers Barry
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Hi Barry.
As I understand it, classical theory makes some completely wrong predictions about photoelectricity as follows:
1.
all radiation is capable of producing photoelectrons. In experiments, there is a radiation cutoff frequency for a given material, below which there are
absolutely no photoelectrons regardless of radiation intensity. Wrong prediction.
2.
as the frequency increases, the number of photoelectrons will increase. In experiments, as the frequency increases, the
energy of the photoelectrons increases, not their numbers. Wrong prediction.
3.
as the intensity increases for a given frequency, photoelectron energies increase. In experiments, as the intensity increases, the
number of photoelectrons increases, but they have the
same energy. Wrong prediction.
4.
there will be a delay between the start of illumination and the production of photoelectrons. Experimentally,
there is no consistent delay. Wrong prediction.
ie, classical theory fails (spectacularly) to predict experimental results when dealing with photoelectricity - which is why Einstein wrote his well known paper... Your proposal above that metals may somehow incorporate a high pass filter could possibly get around point 1. but will not change the other wrong predictions. Since classical theory gets it wrong when dealing with emission and detection of light, it makes sense for us astronomers to use photon concepts when thinking about sources and detectors.
As for "believing" in photons, the question becomes what to use instead - many alternative (mathematically purer) approaches have been proposed over the years, but nothing yet seems to have supplanted the photon. At the most pragmatic level, "photons are what photodetectors detect" (not sure where I read that). I had personal experience of the reality of photons as detectable entities when designing a photon counting system for a UV spectrometer (40 years ago). It was clear as day, when looking the irregular stream of consistent pulses in the scope output, that the RbTe photocathode of the pm tube was responding to a random stream of discrete packets of light when the intensity was low. Call them what you will and maybe the "light particle" idea is a bit simplistic, but the reality of photodetection can be described very accurately as the detection of quanta of light energy. There is also a vast array of published research on the nature of photons, including work on how they can be applied as individual entities - even to the extent of showing experimentally what the shape of the wavefunction is - photons are here to stay.
It is also equally true that light can behave like a continuous electromagnetic wave when it passes through an interference filter or an optical system etc. My understanding is that the wave-particle duality concept is simply a way of framing the demonstrably real behaviours of light in different circumstances - in a way that makes some sort of sense to humans. The basic problem is that light often behaves counter to our intuition and commonsense.
Cheers Ray