Humans are the only animal to have these weird little tufts of hair above their eyes. I find the question of why this is to be a surprisingly interesting one, worthy of a long and rambling post about human evolution.
A little while ago I read Leonard Susskind’s book The Black Hole War (subtitle: My Battle with Stephen Hawking to make the World Safe For Quantum Mechanics). It’s an interesting and mostly quite readable popular science book about the black hole information paradox. Susskind thinks that information isn’t destroyed when stuff falls into a black hole, and his book is about why.
The first part of the book has some useful thought experiments about black holes, some of which I’ll take you through below. After that it starts to talk about string theory, whereupon it becomes as utterly incomprehensible as any other book on the subject.
However, I think Susskind makes an important logical error just before he turns to string theory. I think that if you correct this error then it leads to a much more elegant resolution of the information paradox — one that doesn’t require the use of string theory. I won’t get as far as talking about that in this post, but I will point out the error I think Susskind makes, and show how resolving it leads to a simpler explanation of what happens when something passes an event horizon.