Nanotechnology refers to the engineering of functional systems at the molecular scale. There are thousands of nanotechnology products, including components in such diverse items as tennis balls, beer bottles, flak vests, power drills, and home pregnancy tests. In all these instances, nanotechnology allows manufacturers to design the precise, optimal product when the specific arrangement of molecules may not exist in nature, or may be impossible to construct with conventional engineering.

Like any technology, there is potential for harm through error or intent. But while there are what could be called “nano-weapons,” these are all conventional weapons that incorporate nanoscale material in some way. It does not refer to a swarm of tiny robots who escape from a 1950s SciFi flick and rummage about in our bodies subcutaneously.

Still, there are concerns with how nanotechnology could be used, with some opponents more measured than others. There have even been two unsuccessful attempts on the lives of nanotechnology researchers in the last decade by eco-anarchists.

Among those who are not failed assassins, there are some more legitimate worries, such as the resultant tiny particles perhaps being hazardous to the respiratory system in the same way that asbestos is. This is a reasonable concern, but any new material can be unexpectedly hazardous, so the potential problems of  nanotechnology are not unique to this particular scientific advancement.

What stokes most of the fear is the notion of self-replicating nanobots being the catalyst for an impending doomsday. In this scenario, the exponential growth of these machines require them to devour Earth’s materials along the way.

Eric Drexler’s book Engines of Creation first raised the possibility of this occurrence. He coined the term “grey goo” to describe the proverbial living mass of nanobots. He proffered a scenario whereby a runaway reaction produces more grey goo than the entire mass Earth in less than two days. However, this idea assumes the continued availability of both raw materials and a fuel source for these created critters.

Brian Dunning at Skeptoid noted that these nanoscale machines would have to do their construction by selecting and placing one atom at a time. Besides being hampered by this laborious process, these hypothetical nanobots would also have substantial power needs and would generate tremendous heat waste. And, Dunning continued, “Unless they were in an environment consisting solely of carbon and hydrogen atoms, nanobots would quickly become mired in a swamp of useless, unwanted molecules. Their ability to spread physically is likely always going to be confined to a very specific given resource.”

And as machines, they are reliant on outside help. Our most advanced commercial airliner would be of no value without fuel and pilots, and it would eventually break down without preventive maintenance, spare parts, and safety inspections. Similarly, nanobots would fail without a support network. They also must still be given instructions from an external computer, and this lack of autonomy is a built-in safety measure against any grey goo apocalypse.