Part of the Twenty Books in Twenty Days series.
The concept is right there in the title: Serious scientific answers to absurd hypothetical questions. Is it possible to use a machine gun to create a jet pack? How many Lego bricks would it take to build a bridge from London to New York? How high can a human throw things?
In that sense, “What if?” [affiliate link] is another one of those “backwards” choices. The book itself is only ten years old but I think my love of taking absurd questions seriously goes back much further. I do it often when my kids ask silly questions, but Munroe is able to do it with a lot more scientific and mathematical rigour. I love the concept, and it’s executed pretty much perfectly.