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Old 09-03-2010, 07:07 PM
Location: Westwood, MA
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Originally Posted by Lux Hauler View Post
So if one photon were emitted from the source and we were able to track its movement would it or would it not move along a sinusoidal path? And also if we were to look straight down on the photon with it moving directly away from us, what dictates the rotational orientation of it's path?
The answer is mostly no.

The uncertainty principle complicates everything on this small scale, and limits the precision to which you can know the position and momentum of a particle. Specifically, the produce of the minimum uncertainty in position dx and the minimum uncertainty in momentum dp must be less than a constant, very small value (dp * dx <= hbar/2). What this means in practice is that you can't really know exactly how the photon travels from the source to the place that it's absorbed.

It's a macroscopic (i.e. not quantum) intuition that makes you think that there is some specific path that the photon takes. I know it seems like the photon has to travel in a specific path, but repeated experiments have shown this is not the case. In fact, the best method for calculating what particles do when they travel from point A to point B is to calculate the effect of every possible trajectory and add up behavior of each possible path. Some of those paths are sinusoidal (all the fraction is vanishingly small)

Richard Feynman does a much better job of explaining all this in his book QED: The Strange Theory of Light and Matter. It's a nontechnical (i.e. not much math) book on the subject that is worth checking out from the library if you're interested. Feynman is probably the best there ever was at explaining physics, so definitely worth looking at.
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Old 09-04-2010, 10:20 AM
Location: Maryland not Murlin
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Originally Posted by Werone View Post
From what I understand, and please correct me if I am wrong, but the trajetory of a single electron is "particle like" and that is why we can direct it at a phosphorescent material on a screen. Both the electron and the photon present the duality behavior, and that is that they have both behaviors, like a particle and a wave.

I know that a laser is a stream of photons, and a photon is the smallest unit of electromagnetic radiation, we can emit single photons, like particles, and have them behave like any particle having mass, aiming it at a target. This to me says that the particle moves in a straight line, but the "Color" or spectrum/wavelength of the particle is also measurable, and that to me is that it is behaving like a wave.
Particles travel in a straight line until they encounter an object that alters their path (usually other particles). I'm using particles generically, here, mind you. Some particles can travel in a 'spiraling' motion depending on the number of electrons and their ring of orbit. Basically, making them lopsided.

Now, as for waves, the particles do not actually move in a wave. The 'wave' is just how humans interpret the strength of energy. The wave has to do with how much energy the particle, atom, molecule, etc. is emitting-and how fast it is moving. Look at it like this:

You have a line of cars on the highway and it is bumper to bumper traffic. One car moves forward, then stops. The car behind moves forward, then stops. Repeat ad naseum. If you were to go up some distance and look down on the row of cars, you would see the illusion of continual motion, of waves-much like if you dropped a pebble into a pond and ripples occur.

The faster the cars move forward and stop, the faster the waves (or ripples, if you like) appear to moving...and in a higher frequency. So, how fast the driver can maneuver the car forward when the space opens up, the more 'energy' the wave has.

Aside from that, the OP is beyond my understanding...maybe.
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Old 09-04-2010, 11:19 AM
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K luv, the particles in question, Photons, have mass and inertia therefore behave in ways we have come to expect. Gravity and mass define the movement of that particle.

A wave has a measurable wavelength, and a photon therefore has a measurable wavelength even in its smallest unity, the photon. You can measure the photons wavelength using refraction. I have read of experiments where they will use "out of phase" lasers or photons to slow and even stop photons ( 0 Kelvin).
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