John Polkinghorne’s Erdös Number

John Polkinghorne is a neighbour of my parents and, very tenuously, a relative.

He was active in Cambridge around the time of events in The Theory of Everything, and knew many of the people in it, including Hawking himself. Since getting to the cinema is a little hard for him now, a few months ago my parents invited John over to watch the DVD and eat Sunday lunch. I attended too, as chief video operator (!).

It was really fun, and interesting to hear John’s insights into the film and the people it featured.

The previous time I had spoken to John at a meal I had brought up Paul Erdös because I knew John had met Erdös, from an anecdote in John’s autobiography. Erdös was in Cambridge to receive an honorary degree and John was one of the people helping him. Erdös was expected downstairs by 9:30am but hadn’t appeared yet. John went to investigate and found him in his room still not quite ready. He asked John if he thought he should wear a tie, and John said that yes, he probably ought to, but this posed a problem because Erdös had never tied one before and didn’t know how! John had only tied his own ties so doing so on someone else was counterintuitive as everything would be mirrored. I guess you’ll have to read the autobiography to find out how the story ended.

Anyway…I was pretty sure that John was aware of the concept of Erdös numbers, but didn’t know his own. So I decided to find out what his Erdös number is. This proved quite difficult and I got in touch with Jerrold Grossman from The Erdös Number Project to help. He passed me on to Chris Fields, who was able to give me a chain of 5 co-authors. I did the googling to determine exactly which papers these were and made the following information sheet.

John Polkinghorne's Erdos Number

Click the image to enlarge.

I gave the sheet to John on the Sunday we watched The Theory of Everything, and he was really pleased with it. John indeed hadn’t known his own Erdös number! He even said “That’s jolly clever of you Jim to find that out”, which gave me cause for a wry smile.