Wave Particle Duality

[TravisM]

I've started this thread because of two previous threads howard2 has started on the photon and the electron. I think, since both particles mentioned exhibit this behavior, among others, it would be nice to contain the discussion here. Perhaps a Q&A thread could be in order.

I'd like to post two more messages of mine here that I feel are relevant but haven't been responded to.

[TravisM]

Yes, but an electron is not a photon. An electron creates its own magnetic field at 90deg to the axis as it moves. Please correct me if I'm wrong. A photon doesn't. [snip...]

In physics, the photon (from Greek φως "phos", meaning light) is the quantum of the electromagnetic field, for instance light.

My Emphasis.

[TravisM]

(This post and its original wording can be found here.)

This is the setup.

There is a photon emitter in the bottom left hand corner. There are two half silvered mirrors (the blue ones,) and two regular mirrors. There are two photon detectors in the upper right hand corner. If all path lengths are equal, the top detector will never register a photon. In fact 100% of the photons will be detected by the detector on the top right.
This experiment has been done with path lengths up to several meters long.

If either path is blocked, there's a 50% chance either detector will register. But, given the 'decision' of both paths, photons will not enter the top detector.

What do you make of it?

[TravisM]

There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe that there ever was such a time. There might have been a time when only one man did because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in one way or another, certainly more than twelve. On the other hand I think I can safely say that nobody understands quantum mechanics.

I think this captures what's going on here very nicely.

[Relmuis]

There is another difference between photon and electron, I think.

An electron is associated with a De Broglie wave, which obeys the Schrödinger Equation. But a photon is associated with an electromagnetic wave, which obeys the Maxwell Equations. Both kinds of wave interfere with themselves, and cause interference patterns in a double slit experiment. But wouldn't these patterns be different? Wouldn't there be a way to see, from the pattern itself, whether it had been made by photons or electrons?

[TravisM]

While I'm not sure about the diferentiation by viewing the patterns, but I think the pattern has to do with the quantum wavelength of the particles, the nature of the slit, and the distance to the screen.
But, it's clear that all matter has this duality.

[Sandoval]

If either path is blocked, there's a 50% chance either detector will register. But, given the 'decision' of both paths, photons will not enter the top detector.

Correction: if either path is blocked, photons will not be detected at all 50% of the time, and will be detected at either detector the other 50% of the time (25% for each detector).