The above discussion may seem to imply that physical science laboratories should all be much alike. In practice, they vary greatly. Some, such as the Bell Telephone Laboratories in the United States, and the Cavendish Laboratory in Cambridge in the United Kingdom, acquired great reputations for the novelty and originality of their achievements. This may largely have been self-generated. Once an establishment has acquired a high reputation, it often tends to make it higher still. As in any sort of institution, high-class laboratories attract high-class scientists, and gain still more as a result. And yet an experiment in physical science does not depend on the experimenter. Possibly because of some personal theory he is exploring, such an experimenter may set up and try out a highly unusual original experiment and observe its outcome with care. A good example is the cavity magnetron, invented at the U.K. Birmingham University 66in 1942 by the physicists John Randall and Harry Boot. This highly original device could generate watts of power at gigahertz frequencies. It was invented during the Second World War, and transformed radar: it became the RAF’s most cherished secret. It did not depend in the least on the mental state of Randall and Boot. Indeed, had the design been published, it would have been very easy to copy. Any experiment in physical science, however ingenious and unusual, is published in due course; the whole idea is that it can then be copied and verified by another worker. That worker may have an entirely different state of mind to the inventor, and perhaps could never have invented the design himself or herself. My feeling is that some prompting from the unconscious mind of the inventor stimulates the new conscious idea. In Chapters 16 to 18 of this book, I imagine experiments in which the unknown world outside our diving bell can be explored without employing a human mind as part of the equipment.