ÁñÁ«ÊÓƵ

Harry Collins describes one of his eureka moments as the only time in his career when "I have run out into the corridor whooping (fully clothed, I should add)". His excitement was generated by managing "to construct a 'toy' interferometer out of a laser pointer, bits of broken shaving mirror and chipboard - but that was of no interest to anyone except me" ("It's there - or is it?", 25 February).

I worked on the same corridor in Cardiff University's Glamorgan Building at the time, and wish to state that his account is inaccurate in two importantly trivial respects. First, it was balsa, not chipboard. Second, I was very interested and impressed. But perhaps that would not make such a good story?

Stephen Gorard, School of Education, University of Birmingham.