X-Message-Number: 9828 Date: Sun, 31 May 1998 21:47:35 -0400 From: Thomas Donaldson <> Subject: more re Ralph Merkle's posting Hi everyone! In response to Bob's defense, I have gotten another copy of Ralph Merkle's posting and reread it. I believe I should clarify my objections, of which the main one still stands. On rereading this posting, I note that the main advantage of "advanced technology" will be that it will allow us to locate every atom and molecule in the damaged brain. My objection to this claim is simple: the main structures which cause our memories do not exist at the level of atoms or molecules. They are very likely to be the connectivity of our neurons, which is not something that the location of atoms and molecules in a damaged brain will tell us. Please understand: this is not in itself an argument against nanotechnology of any kind. But no amount of information about where atoms and molecules may be will tell us about such higher level structures. We need to look for them particularly, and in doing so we must look for objects and structures much larger than atoms or molecules. After rereading Ralph's posting, I do feel happier about his arguments that comparatively little movement will occur, and even against turbulence. I must add, however, that neither observation really requires much knowledge of physics, and the simple argument that "brain tissue" will be viscous is not, logically, enough. The problem is that "brain tissue" consists of many different structures, each of which will respond differently to fluid motion. Some may well encounter turbulence while many others do not. However the micrographs I have seen strongly suggest that neither turbulence nor long-distance motion (ie. motion enough that the original structure cannot be seen, IF we had that motion and no other changes) play much of a role, if any. Other events happening during freezing, such as accumulation of salts, can still do plenty of damage. And on both movement and turbulence, I will point out that, again, knowledge of the location of atoms and molecules will tell us nothing about either. We need to look at structures on a larger scale, and that is exactly what Ralph is doing when he discusses these issues. And here is an example of just why I say that locations of atoms and molecules will tell us very little, if anything: consider a sand castle of the kind people make on beaches. Every grain of sand that makes it up, for the sake of argument, is identical to every other. And if waves come and destroy that sand castle, we may well be able to locate every grain that made it up in the flat expanse of sand that results --- but that location will tell us nothing about the original structure of the sand castle, not even that it once existed. But note something else, too: suppose we catch that sand castle while the waves have eroded it but not destroyed it. We can then rebuild it, since we will see how it was put together despite the erosion. And even more interesting, when we do that rebuilding we need not bother at all to use the original sand grains, we only need more sand. Those higher level structures do survive, though damaged. Every micrograph I've seen of brains after cryopreservation tell me that. And it is those higher level structures that we should pay close attention to in any attempt at revival. Best and long long life to all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=9828