Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!cs.utexas.edu!rutgers!aramis.rutgers.edu!athos.rutgers.edu!nanotech From: rod@venera.isi.edu (Rodney Doyle Van Meter III) Newsgroups: sci.nanotech Subject: Re: Utility Fog Message-ID: Date: 21 Aug 89 22:07:19 GMT Sender: nanotech@athos.rutgers.edu Organization: Information Sciences Institute, Univ. of So. California Lines: 53 Approved: nanotech@aramis.rutgers.edu A quibble and a question: Re: hitting a brick wall at 100mph Let's use "immovable object" so people don't start getting pedantic about breaking through. In a standard size car, you don't want to hit it head on at anything above 35mph. There's basically no way to prevent brain damage at anything above that speed. Even if you decellerate uniformly from the moment your car touches and finish when your head reaches the wall, your brain will slosh against your brain case, almost certainly causing brain damage and reaching real jelly stage by 70 mph (4 times the kinetic energy). This from friends of mine who make airbag sensors for cars, so they're familiar with this stuff. Of course, even most head on collisions don't really have the dynamics of hitting immovable objects, usually the cars end up spinning and skidding around for a while. I think even nanomachines will have a tough time changing this fact of life, though you never know. Questions: Where does the energy come from to power this Utility Fog, where does its waste heat go, and what is the maximum density of this stuff? Also, if it's to be a fog, where do raw materials come from, or does the fog itself not grow (all premade)? When do we get nanomachines that can help with our pollution (particularly air pollution) problems? Seems to me we should be on the verge of producing microbes that are airborne and quite happy on a diet of nitrogen and sulphur compounds, simply by virtue of the strain we're already putting on the system. -=-Rod [This is a good quibble, see dmocsny's letter. However, I would like to note that a certain amount of the "brain sloshing" damage in collisions comes from the braincase's *rotation* as the head whips around. This mode of damage at least would be reduced. Purely guessing now, I would suggest that a good structural material for Fog assemblers might be silicon nitride, primarily since these are two extremely abundant elements. Energy is a subject of considerable interest, which has been discussed here before (and will again, I'm sure). My favorite scheme involves replacing grass with a nanoengineered replacement that stores and transmits solar energy (but still looks like grass). Power could be transmitted to anywhere it's needed by dynamically created pathways trough the Fog. --JoSH]