I’m a regular reader of the xkcd web-comic and sometimes read the what if section which answer more or less absurd questions with physical explanations. The book what if, from that section.

While the question asked are often whimsical, for instance: what happens if everybody points their laser beam to the moon, the question are hard science, and very often hard-core, people must be warned: the book contains a large amount of things dissolving into high energy plasma.