Eric Drexler, the man who made nanotechnology synonymous with 'grey goo', now says there is no need for self-replicating machines at all. So the world is in no danger of being mined indiscriminately for all its carbon, and we can all breath a sign of relief.

Phew.

Now, however, he says runaway replication could only be the result of deliberate engineering, not something that happened by accident. And anyway, we can't build them with the technology available to us at the moment.

In a new paper, published in the Institute of Physics journal Nanotechnology, Drexler and co-author Chris Phoenix, argue that discussion of grey goo is distracting from serious debate on the subject.

The authors argue that self-replication is unnecessary. Like Asimov's vision of a robotic future, the vision of self replication is based on lots of self contained, highly complex units being used to carry out tasks. In reality, we use robots as components, arms in car factories and so on. It will be the same on the nano scale, with all the machines being tools, not able to operate autonomously.

However, we cannot rest easy. Far more serious, according to Phoenix, is the possibility that someone could deliberately abuse the technology.

"[There is] the possibility that a large-scale and convenient manufacturing capacity could be used to make powerful non-replicating weapons in unprecedented quantity, leading to an arms race or war. Policy investigation into the effects of molecular nanotechnology should consider deliberate abuse as a primary concern, and runaway replication as a more distant issue," he said.

Don't you all feel better? ®

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