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As John Barrow says, when a theory in physics gives infinite answers something is usually thought to be wrong with it ("The battle that just rages on and on", August 12). When classical physics gave infinities in the theory of black body radiation, the classical theory was abandoned and quantum mechanics was developed. It is odd that when quantum electrodynamics produced infinities, "renormalisation" procedures were devised to save it.

Alex Chablo
Manchester