josh@aramis.rutgers.edu (06/30/89)
"I can imagine a "black goo" that ate tire rubber and used the mechanical energy of the periodic compressions as the tires roll. It could easily spread by falling off and lying around on road surfaces to wait for the next car." --from an addendum I tacked onto a message last January. Suppose someone invented a nanobug to devour the millions of tons of used tires that form an increasing disposal problem in this country. Now suppose the bug were a little more capable than we thought, and was able to live in the "wild" and flourish on tires still on the cars. We would not be in immediate mortal peril, nor would the ecosphere begin to slump down into a living, crawling tapioca pudding. However, we might be in a jam until we had an alternative to tires--which would almost certainly require the application of more nanotechnology. Suppose instead, we tried to invent a "hunter-killer" nanobug which would rid us of this troublesome infestation. It would have to be self-reproducing just to keep up, and would have to "live off the land" to be present in sufficient quantity to keep the original bug down. In short, if this stuff gets out of control, we lose a lot more than tires. Of course, if the stuff that got loose in the first place were more voracious, we might not have a choice. Thus, although I can't assign a probability, there seems a solid chance that after several decades of accidents, intentional attacks, counterattacks to both, and so forth, the planet will be covered with microscopic gadgets trying to eat everything in sight and reproducing as fast as they can. Surprise! The planet is already covered with microscopic gadgets trying to eat everything in sight and reproducing as fast as they can. They are called bacteria, amoebae, paramecium, etc: the entire panoply of unicellular life. So maybe there isn't so much new under the sun after all. Indeed, unicellular life evolves quite fast in response to particular threats--we may find that some of our "gray goo" is being held down by regular ordinary green slime! On the other hand, it is reasonable to suppose that there will be nanobugs suitable for consuming most common materials which promise a return in energy for the eating. This includes most metals, wood, plastic, natural and artificial fibers, asphalt, rubber, etc. Kindly notice that the naturally-occuring materials are generally already susceptible to such attack from naturally-occuring micro- organisms. It has been too short a time for organisms to evolve to live off the artificial materials named above, but it would have happened anyway--nanotech will merely accelerate the process. Construction and manufacturing will have to move to materials that are not reservoirs of usable energy--brick, stone, ceramics, glass, silicon-based plastics. Metals can still be used, they'll just have to be a lot more protected than they are now. The other option is "living materials." Animals and plants are currently good food for microbes--just watch what happens to a dead body. They have internal defense systems that hold an advantage over the microbes while the organism is alive, which can be summarized by saying it's "their turf" and they outnumber the potential foe therein. The same general principles can be followed for a nanotech material: It is a system which maintains its own internal repair and protection nanogadgets, and which consumes energy and possibly materials to supply them. Just like a plant or animal, if it "dies" we would expect it to "rot" from ubiquitous but invisible grey goo gadgets. Most existing objects--the entire inventory of our civilization-- must be considered "dead" in this sense and thus like to disappear within the next century. Naturally living things present a more interesting problem. How likely are a living organism's defenses to be able to handle nanobugs? Plants, particularly trees, are higher in raw energy content than animals (this sounds backwards to the dietary mindset, but try burning a log and a leg and see what happens. We just don't eat the good part, ie the resin-impregnated heartwood!). Furthermore, the animals have a much faster-moving and adaptive immune system. Thus, other things being equal, the plants may be in a bit more danger. It may behoove us to start designing nanoplants to take over the critical duties of plants in the biosphere to forestall a drastic shortage of oxygen (not to mention a severe greenhouse effect!). This is not to say that nanomachines designed specifically to attack animal biology wouldn't go through them like a knife through butter. However, this is a more specific attack, and more specific defenses would be used (such a nanobug would be a "disease" rather than a "rot"; we would be using specifically targetted "antinanotics" rather than general protective mechanisms.) So, willy-nilly, we may find ourselves a century hence living in a largely artificial world. Perhaps we should start designing it now. --JoSH
bane@mimsy.UUCP (John R. Bane) (07/04/89)
In article <Jun.29.22.44.58.1989.29638@athos.rutgers.edu>, josh@aramis.rutgers.edu writes: > > "I can imagine a "black goo" that ate tire rubber and used the mechanical > energy of the periodic compressions as the tires roll. It could easily > spread by falling off and lying around on road surfaces to wait for the > next car." > --from an addendum I tacked onto a message last January. > > Suppose someone invented a nanobug to devour the millions of tons of > used tires that form an increasing disposal problem in this country. > Now suppose the bug were a little more capable than we thought, and > was able to live in the "wild" and flourish on tires still on the > cars. > I don't have a reference handy, but I remember reading that bacteria that eat tire rubber exist in the wild already. Their existance was first deduced by scientists who noted the abscence of piles of tire dust on the sides of the highways. Cars in the US go about 10K miles a year, and their tires last about 50K miles; this means each car deposits about 4/5 of the tread of one tire on the roads each year. If nothing could break this stuff down in a reasonable amount of time, the roads would be thick with it real fast. As it turns out, something does break it down; there are bacteria that live on tire dust. Anybody with a Science News index near their workstation want to look this up? Maybe evolution isn't as slow as we've been assuming... ;-) -- ARPAnet: bane@mimsy.umd.edu UUCP:...umcp-cs!bane