Fig. 4.

Published estimates of the speed of light. The light gray boxes that start in 1930 are the recommended values from the particle physics group that presumably include an effort to consider uncertainty arising from systematic error (40). Note that for over two decades the reported confidence intervals on these recommended values did not include the present best-measured value. Henrion and Fischhoff (40), from which this figure is combined and redrawn, report that the same overconfidence is observed in the recommended values of a number of other physical constants.