h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

"How many of them had you met?" [Hoovooloo9]

None. I was thinking of the "you" in the subject line as hypothetical. If a population is small enough, everyone can get to know everyone else. I don't know if the Jewish population in Prague was that small, but if it was, someone might have known everyone on the list. I would doubt that that someone would still be alive, though.

There is something called the Dunbars Number, which refers to the largest group in which it is possible for everyone to know everyone else. This number is roughly 148, sometimes rounded off to 150.

https://en.wikipedia.org/wiki/Dunbar's_number

Sorry,

http://en.wikipedia.org/wiki/Dunbar's_number

Seems like exactly the kind of thing there should be a Guide entry about...

That's a good idea. I had the idea in the back of mind after reading a book that mentioned it, but I couldn't remember the name of it.

This bit is especially Hitch-hikerish: "Dunbar explained it informally as "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.""