Nanotech assemblers that can make copies of themselves out of almost anything. One week you have a lovely blue-green M-class planet to disport yourself on, the next a great big homogeneous blob of virulent grey nanites hanging there in space.
Nanotech assemblers made the green of the lovely blue-green M-class planet. A cell is a nanite. Let's try to understand, cooperate and enhance nature as technology moves to the molecular level. Then we can have benign blue green nanites, instead of virulent grey nanites.
Actually, no, cells aren't nanites. They're microscopic bags of protoplasm, not nanoscopic robot factories. Apart from the great difference in scale, there's a real difference in style too; organic cells do their work by osmotically filtering big membranes full of molecules that tend, statistically, to produce what's desired; nanobots are little pick-and-place robots, tiny self-reproducing precision tools that can tear through a cell like a sawmill through a rainforest.
[See NanotechDoubts for a response.]
I guess I define nanotechnology differently than some. I view it as ANY technology on the nanoscale. Cells may be on a different scale than nanobots, but the molecules within them are on the nanoscale. We could create nanobots that use brute force to make the changes we desire. But we could also develop a deep understanding of the mechanisms already in place. Based on that understanding, we could make enhancements. -- CayteLindner
"Nanotechnology" is indeed ambiguous. You can buy nanotech molecular sieves today, but they have nothing to do with GreyGoo. MolecularNanoTechnology is where the GreyGoo problem lives, and regrettably it's not clear that either brute force or deep understanding of existing mechanisms afford us any help in solving it.
Why? The problem is much like the present encroachment of human industry on the ecosphere. We have deep understanding of existing ecosphere. We have brute force aplenty. But species are going extinct at a rate 10,000 times (yes, you read that right, 1,000,000 percent) the rate they were going extinct a few thousand years ago [http://www.ejnet.org/rachel/rehw441.htm]. Fossil record shows the present extinctions are happening faster than extinctions occurred during death of dinosaurs.
In short, we humans are GreyGoo, or at least we act like it when given a chance. Nanotech only gives us a quicker and more thorough way to do it. Not certain there is a way out of this when we as a race show all the good sense of yeast in a vat of grapes. It'd be nice to think that before we get nanotech we'll develop some means to control it. But we've never done that with any technology before, so it seems unlikely that we'll start in a hurry ...
The big deal with GreyGoo is twofold:
See, a StoneSociety would solve this potential problem.
No, not by a long shot. A StoneSociety is just a legislative mechanism, a way of coming up with policies, and an untried one at that. A StoneSociety made out of GreyGoo will employ the policy of GreyGoo - assimilate everything you can. It remains to be demonstrated that even BlueGoo could control GreyGoo - and if it can't, then consensual mechanisms within either Goo are irrelevant.
Perhaps the first assemblers will simply punctuate the equilibrium that exists in the earthly ecosphere at the moment. GreyGoo wipes out a few billion years of evolution, then takes a few billion years to evolve itself. Not exactly a user-friendly technology, but then what is? On the other hand, being machine-style rather than organic-style devices, perhaps assemblers don't evolve no matter how long you give them.
But maybe the GodGoo will save us.
I'd guess RainbowGoo :)
Some of these ideas are dramatized in NealStephenson's TheDiamondAge, which is the best SF take on nanotechnology I know of. The technology can build anything we want. What should we build? -- DaveHarris
I find it hard to believe we're talking about this here. This subject has been hammered pretty flat on the Usenet chat groups. Essentially, it is a question of mass. If you have more grey goo than blue goo then the grey goo wins. Oh, by the way -- nobody has yet determined what it takes to build a von Neumann machine on a nanoscopic scale. Perhaps we will need to have goo factories that are considerably larger than the nanites themselves.
Only in the beginning. The GreyGoo scenario is about nano-assemblers which know how to take apart any nearby matter and put it back together into more copies of themselves. It only takes one such nano-assembler released into the wild, for it to reproduce at an exponential rate and turn the entire planet into GreyGoo in a very short time (IIRC it would take less than 6 days).
A paper co-authored by EricDrexler and described at http://ej.iop.org/EJ/news/-topic=763 (full paper: http://www.iop.org/EJ/abstract/0957-4484/15/8/001/ ) says GreyGoo is probably not going to be a problem.
In a similar statement a big software producer said, Viruses pose no problem because we don't need them. It's highly improbable that a program runs wild and infects lots of computers on the internet ;-)
The ForesightInstitute considers this and other nanotech-related problems.