Editorial in Nature:
For the last two decades of the twentieth century, a cold war rumbled on between the laboratories of physicists in Moscow and in the West over the quality of sapphire. The Russian scientists claimed to have measured the rate of decay of the material’s resonance — a signal of its quality — with what researchers elsewhere considered impossible precision. The stakes were high: sapphire mirrors were being considered for use in a new generation of laser interferometer gravitational-wave detectors. But were they up to the task? Labs in the United States and United Kingdom could not reproduce the Moscow findings. The discrepancy fuelled mistrust and antagonism. At the turn of the millennium, the mystery was solved. Measuring the quality of sapphire, it turns out, is as much art as science. The Moscow scientists were expert experimenters, but this expertise was not transferred through the methods sections of their academic papers. The fine fibres used to suspend the sapphire cylinders under investigation were greased with “the presence of a fatty film”, one of their translated papers pointed out. Less explicit was the source of the grease. Only after years of struggling with various lubricants did the Western researchers realize that one member of the Russian group would sometimes run the thread across the bridge of his nose or behind his ear. With the right amount of human ‘flossing’ (and the right human), the Western scientists managed to get similar results.
The thread greasing is an example of tacit knowledge: know-how that can be passed on only through direct contact, and not by written or verbal instruction. How to ride a bicycle is a classic case. How to make an atomic bomb is a less-well-known example: all the instructions to build a nuclear weapon may be there on the Internet, but the ‘been there, done that’ personal experience is not. Indeed, security analysts have suggested that the lack of active testing and consequent erosion of nuclear-weapon tacit knowledge is leading to the “uninvention” of the bomb, and reduced credibility of the nuclear deterrent. In a paper published this month in the journal Science and Public Policy, researchers in the United Kingdom suggest that a reverse process is under way when it comes to biology and biological weapons (J. Revill and C. Jefferson Sci. Public Policy 41, 597–610; 2014). Access to tacit knowledge in the life sciences is not dwindling but proliferating, argue James Revill and Catherine Jefferson. As secrets are shared, chiefly through advances in information and communications technology, tacit knowledge becomes explicit and barriers are demolished.