From Ken Appleby, Ledbury, Herefordshire, UK
Robin Asby misunderstands the essential difference between quantum and classical. In a quantum equivalent of his observation that his cat is sleeping in one of a number of possible places when he gets home, the quantum “cat” is in none of the locations until he observes it (or all of them, depending on which interpretation of quantum mechanics you choose) and the actual location is chosen randomly at the point of measurement (Letters, 11 November).
Swap the cat for an electron and this kind of experimental result, true randomness at the point of measurement, is readily observed. At the quantum scale, reality is just different. There really is a divide between “the world of the very small” and “our everyday world”.
