Charles Kao is known internationally as the 'father of fibre optics'. I knew him in the 1980s when he was already a distinguished scientist in ITT, and I was a new recruit to ITT's UK R&D Lab, STL in Harlow. At that time I was researching the upcoming field of Artificial Intelligence - Charles took a keen interest in new scientific areas and arranged a meeting at Yale with a leading AI researcher, Drew McDermott.
As we drove to the university, Charles had to stop for gas. I should explain that Charles is typically asiatic in his appearance and slight build, and additionally has an unassuming personal style ... outside intellectual debate. The gas attendant stopped by and with casual racism said dismissively 'What's it to be, Wong'? Something inside me gulped at how this guy was treating one of the smartest and most accomplished people in the world. Charles of course took it all in his stride.
My research was in models of the modal logic of intention and belief. The structure of these models is that they represent all the ways the world could be, based on what you belief and want. There is a rough analogy with the many-worlds interpretation of quantum mechanics (it is no more than that, pace David Deutsch, The Fabric of Reality) and I made the mistake of saying so to Charles. He looked at me quizzically, and asked me a question about non-commutative operators in Hilbert Space.
I literally stood there, without any idea how to respond: I had never taken a course in QM. Charles waited a moment, and then strolled away, leaving me feeling about one inch tall.