MODELS AND MODELLING, LIFE AND LIVING - MUSINGS OF A MATH TEACHER IN A LETTER TO OLD FRIENDS

摘要

It is now thirty-six years since my year at Goddard - almost the entire span of the working life of a UK academic. It is good to see that you found the energy and enthusiasm to work on well past the normal UK retirement age of sixty-five, but then there is no "ageism" in the USA. Mind you, Prime Minister Blair is talking about raising this to seventy! Scientifically, 1969/70 was an exciting and productive year for me, and was a valuable addition to my CV when I came to look for a new job in my homeland a few years later. But the most valuable things to come from that time are friendships that have endured. However my relationship with atomic physics came to an end more or less in 1980. So what have I been up to for the last twenty-five years or so? Dick, you undoubtedly remember our 1970 paper on a "Simplified Model for Positronium-Helium Scattering" [1], because you mentioned in your talk on Few-body Positron Theory and the Three H's at John Humberston's retirement in 2003 that we had been "caught out" [2] at last and that a better result had been obtained. But what I want to draw attention to now is not the physics, but the word "model". This was the first time I had used the word in my scientific work, it was almost the first time I had seen it used in a scientific context, and it was to play a very big part in my subsequent thinking and teaching. In 1970 we used a "model" potential because we could not solve the problem with the "real" potential from the full Hamiltonian for the system.