Diffraction and Re: uploadind (sic)

Wed, 2 Sep 1998 23:44:06 EDT

To obtain a structure from a pattern of photons that make it through a piece of matter is esentially a diffraction problem. The trade-offs in wavelengths of the radiation affect resolution (in space and time) and the amount of information recoverable. This trade-off is similar to the quantum uncertianty of time and energy , position and momentum (Heisenburg). Spatial precision necessary can be argued, depending on assumptions to be 1e-5 meters to 1e-10 meter scale (neuron structure -->protein structure -->atom locatons). So this means probably shorter wavelengths than IR. High intensities or very energetic photons have the upper limitation also Heisenburg like, of perturbing the system that they are trying to probe (thermal effects to breaking of molecular bonds).

X-rays currently do very large proteins. The structures are deconvoluted and can be simulated, the analogous goal of uploading. For them, the computational requirements are absolutly state of the art. In the mid 80s, my advisor did x-ray photoelectron diffraction experiments. He simulated the real structures, and the diffraction patterns of two dimensonal crystal surfaces. He ran his code on the fastest Cray available.


John Clark wrote...
>When most photons that make up an image enter milk they are refracted
>off the many fat globules in solution, if any photons come out the other side
>of the milk container they have been bounced around so much that the
>information on where they originated is hopelessly scrambled, all you would
see is a diffuse glow, not an image. However, a few very lucky photons, perhaps one in a billion trillion, perhaps less, can make it through the milk without interacting with anything. Because these rare photons don't get bounced around but take a shorter direct path, they are the first photons to emerge from the milk. If you only looked at those early photons and ignored
>the much more numerous later ones, you could see an image and not just a
>general glow.