On Oct 14, 2010, at 2:31 PM, Tim Gruene wrote: > I would like to understand how the notion of a photon being scattered from all > electrons in the crystal lattice explains the observation that radiation > damage > is localised to the size of the beam so that we can move the crystal along and > shoot a different location.
Modify it to all points in the lattice bathed in the beam. > > The double slit paradox is actually not a paradox, I agree with that, but for different reasons than what follows ... > and a single photon is not scattered by both slits: if you reduce the light > intensity so that you really > detect single photons, you observe that each photon decides on exactly one > slit > that it goes through. Really? Why do you get interference fringes then? You need two (or more) slits to create the interference pattern, and the location of the subsidiary maxima in the interference pattern do not change with the intensity of the light source. If you dim it to the point where one photon per second emerges, and you wait long enough, you still get the identical interference pattern. You do not observe single-slit diffraction. However, if you put your used chewing gum in one of the slits, the pattern changes to that of a single-slit experiment. > It is only the sum of many photons that create the typical > pattering of the double slit experiment. No. That is false. That would give you the scalar sum of two intensity peaks with no interference patterns. You have to add the amplitudes with phases, not the intensities, to get the interference pattern. > The photon knows it is both wave and particle, but depending on the experiment > we carry out we observe only one of the two phenomena, but never both. That's > also the idea behing Schroedinger's cat. Schrödinger actually developed the cat gedanken-experiment to illustrate that the conventional (Copenhagen) interpretation leads to absurd conclusions. But it sounds like you are talking about the Heisenberg "uncertainty principle" or scatter relation. Sure, you can observe both, or we couldn't count photons in individual diffraction spots (which is what we do when we measure their intensities). The scatter relation simply means you can't measure both simultaneously to arbitrary precision.
