X-Message-Number: 3290 From: Brian Wowk <> Date: Tue, 18 Oct 94 17:25:21 CDT Subject: SCI.CRYONICS.Uploading,etc. Yvan Bozzonett: (deleted) > A superficial reader could ask: who is right? Brian or me? The > answer is both: Brian solution applies to imaging by X-ray > absorbtion, my one by X-ray phase shift. Well, there is no > perfect system and even with a holographic setting, some > photons will be lost by absorbtion, producing > some irradiation, but this is only a residual effect with low > doses. The holographic system you propose for low-dose tissue imaging would work-- but only for small tissue samples and soft x-ray energies of ~1keV where coherent Rayleigh scattering (no energy absorption) dominates. To penetrate the depths of an intact brain, x-ray engeries on the order of 100keV are required. At this energy, inelastic photoelectric absorption and Compton scattering dominate over all other interactions. A large portion of the x-ray energy would be lost to ionization within the brain. Any intensity of incident x-rays sufficient to encode 10^18 bits of information on a photographic plate (even if by phase effects) would necessarily cause ~10^18 ionization events within the brain. There is no way around this. > May be some readers know about the Aspect's experiment on > quantum Bell's inequalities. To reduce everything at some lines, > quantum mechanics predicts than, when a photon, in a > correlated pair or set, is perturbed, the other feels the effect > instantaneously. Practical experiments strongly > suggest this is indeed the way real world applies physics. (details on Yvan's novel imaging scheme deleted.) I am familiar with Aspect's experiment, Bell's inequalites, the EPR paradox and all that stuff. I also know that there is no measurement that can be made on a correlated particle that will tell you anything at all about what interactations its conjugate has undergone some distance away. Remember that in the Stern- Gerlach experiment, there is no way to determine the orientation of a polarization or spin analyzer from a measurement made at the other analyzer. If it were otherwise, causality would be violated! > In July 86 or 87, on the cover of the scientific magazine Nature > there was the picture of a cell produced by high gradient MRI > with many details down to micron or less. Yes, MRI microscopy is an established field. It works by using rf coils that are hundreds of times smaller than the coil required to image an intact brain. Such small coils only receive noise from their immediate neighborhood instead of the entire brain (the brain being a million times larger, giving a million times more noise). In theory you could image an intact brain with micron resolution using MRI-- if you used nanomachines to strategically position thousands of tiny rf coils with microscopic preamplifiers and (multiplexed?) connecting wires throughout the brain. Instead of connecting wires you could use on-site nanocomputers to acquire and process signal data. However, as you can see once again, we are now many decades into the future. --- Brian Wowk Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3290