Feb. 6, 2004 -- There is a growing mantra in the nanotech community that molecular nanotechnology (MNT) and its precursors will clean up the toxic mess left by older technologies, then produce clean energy and materials to replace them.
Yet each time that I suggest building such features into nanotechnology from the start, the reply is: "We've got other things to worry about such as how to build the darn assembler and keep it militarily secured, and besides that it might be hard to achieve such perfection with early versions."
This is disturbingly reminiscent of "nuclear power will give us clean limitless energy, and don't worry, we'll deal with the byproducts later because we'll have the tools by then."
However, we can avoid such risks from the start by using "self-regulating assembly" and "disassembly."
Self-regulating assembly means built-in controls that limit replication rates of molecular assemblers. Surprisingly, there is virtually no talk of such newly discovered processes that occur naturally.
For example, "nanobacteria" are organisms less than a micron wide that already achieve this Holy Grail. They have a very slow replication rate -- a "limiting" factor that stops them from turning everything into gray goo despite their prevalence in the environment.
One genus found in human disease has an ingenious way of self-cloaking with a calcium phosphate shell. This disguise led medical researchers to misidentify the organism as a lifeless deposit in heart and other diseases. Such a shell is also a formidable defense against drugs, radiation and heat used in treatments.
How does this link with MNT research? Scientists have been looking for ways to build self-regulation into assemblers. Nanobacteria warrant study because they approximate the envisaged size of some assemblers and replicate in days instead of minutes or hours. This sets them apart from most viruses and regular bacteria.
Then we come to disassembly -- a concept well known among nanotechnologists. There are many ways to "disassemble" something.
One is with an assembler working in reverse to take something apart element by element, molecule by molecule, or chemical by chemical into components that can be discarded or reused. Present-day manufacturers do this on a primitive scale with some old cars, but that is only a rough analogy.
Next there is biodegradability: incorporating a chemical trigger that makes a material degrade via measurable pathways into harmless components that nature can reuse. This is done now with biodegradable packaging.
Finally, there is rapid oxidation, i.e. incineration, which today is largely an ecological disaster. Oxidation is a treacherous area because the tendency might be to say, "We can just burn everything cleanly." But it's not that easy. Energy balances and atmospheric/oceanic heating also must be considered. But with pure MNT materials this might be achieved cleanly if done right.
We have many disassembly options. I argue that it is possible and necessary to incorporate them into a "Law of Disassembly" that says every MNT product must be disassemblable by at least one such pathway.
Why can't this discussion wait? Here's why: Primitive non-MNT nanotechnologies are already creating products that cannot yet be disassembled in such pathways. Complex coatings and integrated nanomaterials that are hard to take apart are being manufactured now, albeit in smaller quantities that so far have negligible impacts. We can't blindly continue to say that someday we'll know how to decommission them.
Most nanotechnologists whom I talk to say that disassembly is a great idea but not practical in the near future. Is this expediency instead of careful thought?
In my experience managing scientists, I have seen that natural disassembly happens all the time via chemical synthesis, biodegradation, and combustion. It is a rule, not an exception. Moreover, the concept of disassembly in the wet chemistry that is basic to nanotechnology is well known and often referenced, so such capacities are not limited to nature.
If we don't consider such options now, then we may build assemblers that are fundamentally defective from environmental and military security viewpoints.
Would such a "Law of Disassembly" stick a green albatross around the neck of MNT researchers?
On the contrary, it may be the key to our future security. But if the message is misinterpreted as a green pinko socialistic back-door ploy to kill new technology, then it won't get off the ground. And we'll have a mess. So it has to be properly presented. That means serious research and careful presentation.
This does not mean putting a moratorium on MNT research, as some environmentalists have suggested. It means accelerating research into molecular assembly and disassembly.
Organizations such as the Center for Responsible Nanotechnology are well positioned to put this forward, because self-regulating systems and disassembly have enormous ethical and military implications. There are many practical examples today of natural as well as synthetic disassembly to study.
The Law of Disassembly is a challenge that I put to nanotechnology developers and to the community that funds and regulates them.