mes (10/23/82)
This is a call to interested and/or knowledgeable peo- ple who might have some ideas about the possible uses of photoreversible pigments in logical devices such as memory. (If that looks complicated, see the explanation). Comments, information, and other assistance regarding this pipe-dream will be appreciated. Explanation In plants, evolution has already produced a pigment capable of reverting from one absorption form to another in what are known as phytochromes. These compounds are essen- tially proteins with an attached light-absorbing chromato- phore portion. Red light causes the phytochrome (Pr) to convert to the Pfr form, which is capable of reconverting to the Pr upon absorbing far-red light. There are several problems with using this as a logical device, (Aside from the obvious engineering difficulties) however: 1) It is impossible to avoid a racemic mixture. 2) Although Pr to Pfr takes about < 10E-12 seconds, Pfr to Pr takes more than 1 second. 3) Phytochrome is unstable, and will eventually revert to one form. Therefore, another related (possibly) compound must be sought after. What nature took millions of years to do, man should be able to accomplish in a few. There are some possibilities that photon circuitry would be able to explore or exploit, given the proper logi- cal devices, photomultipliers, pathways, etc.: 1) Propogation speed approaching c (in vacuum) than electrons in current circuitry, allowing more i.p.s. 2) New twists in a) pattern recognition b) holographic memory c) signal (dx) processing d) image processing 3) Simultaneous pathway use by polarized signals, regardless of direction. 4) ? It should be understood that the two contributors of this article are not giants in the fields of physics or organic chemistry; nor do they yet have the time necessary to explore this subject until certain degree (M.S. Biology and M.S. Computer Science) obligations are met. History has shown that fresh ideas produced at the right time and place can go far, so, have fun.