 that engineering cannot improve on biology. This may be true for complex problems, but not for the relatively simple tasks that are tackled by engineering.
Perhaps because of the opposition of these scientists, not many people are working on molecular manufacturing in the lab; most of the work has been theoretical study, which is easier to do without funding. For now, it remains a controversial theory. But after more than a decade, no one has managed to find a real problem with the theory, and evidence is accumulating in favor of it. Some predicted phenomena, such as exceptionally low friction in certain cases, have now been observed. A single atom has been mechanically removed from a crystal and put back in the same place. Although these were not intended as demonstrations of molecular manufacturing theory, they indicate that at least some of the predictions are valid.
Separating science from science fiction, and alarmism from serious policy concerns, will not be an easy task. Most nanotechnology researchers have not paid enough attention to molecular manufacturing to be able to give informed commentary. The section on "Molecular Manufacturing Myths" lists some of the common misconceptions about molecular manufacturing.
According to its proponents, molecular manufacturing could be revolutionary. Because chemistry is very precise and repeatable, the manufacturing operations should be reliable enough to allow complete automation. Because the chemical steps are simple, a single fabricator could build a wide variety of products by changing the control program. Furthermore, machines built this way could have very precise features. This is a good thing, because building with molecules would be quite slow, and small machines can be built more quickly. In fact, if the calculations are right, a complete nanoscale manufacturing system could build a complete copy of itself in a few hours-and this remains true if many small manufacturing systems are combined into one large one, so that even human-scale factories and products can be built quite rapidly. Finally, it appears that the materials produced by the manufacturing system may be extremely high-performance, allowing products to be far more compact and powerful. The section on "Risks and Benefits of Molecular Manufacturing" discusses some implications of the technology.
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Exponential general-purpose molecular manufacturing -- thatís a mouthful, but what does it mean? Letís take the phrase apart to see why it is so important.
MANUFACTURING: The ability to make products, in this case ranging from clothing, to electronics, to medical devices, to books, to building materials, and much more.
MOLECULAR manufacturing: The automated building of products from the bottom up, molecule by molecule, with atomic precision. This will make products that are extremely lightweight, flexible, durable, and potentially very Ďsmartí.
GENERAL-PURPOSE molecular manufacturing: A manufacturing technology that will find many applications across many segments of society. Its extreme flexibility, precision, high capacity, and low cost will cause rapid adoption almost everywhere, and therefore will have disruptive effects in many industries.
EXPONENTIAL general-purpose molecular manufacturing: The word exponential refers to the rapid pace -- probably unprecedented -- at which this technology may be deployed. A compact automated molecular manufacturing system will be able to make more manufacturing systems. Weíre talking about factories that can build duplicate factories -- and probably do it in less than a single day. The math is simple: if one factory makes two, and two factories make four, then within ten days you could have one thousand factories, in ten more days a million factories, and ten days after that a billion factories. Within the span of just a few weeks, in theory, every household in the world could have one of their own, to make most of the products they need, at just the cost of raw materials.
Exponential general-purpose molecular manufacturing means a manufacturing system capable 