Abstract
As a fellow target for crank letters, I feel a lot of sympathy for Robert Crease (May p14) and his quandary about how best to deal with them. Like him, I routinely use the CAPITAL LETTERS test to decide whether to read the letter or turn it into a maximally compacted Calabi-Yau manifold, suitable for ballistic deposition. However, there are some cranks out there who cunningly restrict the use of upper case to proper nouns and the beginnings of sentences. In such cases, one can apply the "Barmy accuracy test" and look for quantities quoted to vast numbers of decimals – a reliable diagnostic of crankdom, unless the writer is claiming a disproof of quantum electrodynamics, that is.