X-Message-Number: 13661 Date: Fri, 28 Apr 2000 21:19:06 -0700 (PDT) From: Driven FromThePack <> Subject: Radiation damage to frozen brains Last time this subject was discussed on Cryonet, I believe Brian Wowk calculated that storage time was limited to perhaps 5000 or 10000 years because of radiation damage. However, a poster on the Extropian mailing list has stated that 500 years is a likely limit due to radiation damage from C-14 isotopes from *within* the patient himself. Any comment? Here are the relevant posts: The limits on cryonic storage are much less than those discussed (quoted below). Robert Freitas has done a paper on this and the draft version placed limits of 500-1000 years cryonic suspension before endoradiation would become a significant factor. Currently the paper is being reworked to take into account radiation from the carbon in the histones, so those limits may be revised downward. Counter to that is the possibility of syn-genome replacement based on the methods of genome fragment reassembly (pioneered by TIGR). As I've stated before, and I'll state again, the limits on cryonic reanimation would appear to be fundamentally based on the question of whether or not the freezing process causes loss of positional information that could prevent 3D-reassembly. Given the size of synaptic and cellular structures, I strongly doubt that to be the case. These are hundreds of thousands to tens-of-millions of atoms in size. They are only going to match up in unique places. Only if you unfreeze the brain and let it decay away into a molecular soup have you lost that >From: "Robert J. Bradbury" <> >Reply-To: >To: >Subject: CRYONICS: Limits to storage [was: Where to look for the >answers...] >Date: Thu, 27 Apr 2000 14:21:27 -0700 (PDT) > > >The limits on cryonic storage are much less than those discussed >(quoted below). Robert Freitas has done a paper on this and >the draft version placed limits of 500-1000 years cryonic >suspension before endoradiation would become a significant >factor As I've stated before, and I'll state again, the limits on cryonic reanimation would appear to be fundamentally based on the question of whether or not the freezing process causes loss of positional information that could prevent 3D-reassembly. Given the size of synaptic and cellular structures, I strongly doubt that to be the case. These are hundreds of thousands to tens-of-millions of atoms in size. They are only going to match up in unique places. Only if you unfreeze the brain and let it decay away into a molecular soup have you lost that information. Mike: Thanks, Robert. I had not considered the fact that unstable isotopes within the frozen body would slowly damage surrounding cells. Is carbon-14 believed to be the main culprit? Regarding loss of positional information, you indicate that ice damage should not be an insurrmountable problem because of the small size of synaptic and cellular structures which should match up uniquely. But are these truly unique? Or are there merely very many permutations? Perhaps like snowflakes, there are huge numbers of different configurations, but there is still some duplication because of the still larger number of instances. __________________________________________________ Do You Yahoo!? Talk to your friends online and get email alerts with Yahoo! Messenger. http://im.yahoo.com/ Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13661