RobertBradbury writes "The Univ. of Michigan has announced the ability to do nanoscale milling (down to 20nm) using ultra-short laser pulses. Interestingly according to the abstract they aren't exactly sure how it works. This is a new approach to top-down nanotechnology (lithography is also top-down and is currently pushing towards 70nm). In contrast biotechnology, mechanosynthesis and complex chemical methods can be considered bottom-up methods. From a size scale perspective 20nm is slightly smaller than a ribosome and roughly the diameter of Eric's nanomanipulator arm described in Nanosystems (Figure 13.11). So a top-down milling machine methodology might allow the production of a scaled-up nanomanipulator arm which in turn could be used to produce increasingly smaller versions of itself."