From Negative Numbers to a World War!
Steven Strogatz’s The Joy of x is a “guided tour” from “an adult perspective” to “math’s most compelling and far-reaching ideas”. Each chapter is short (“bite-size”), and the book can be read in any order. Let’s look at one topic from the book: negative numbers. From early in life, most of us get the “use” of negative numbers. “Minus 1” meaning the basement is self-evident. Or it can mean debt (money owed). But there’s one aspect that doesn’t make intuitive sense to most people: “The most unsettling thing is that a negative times a negative is a positive.” And of course, as adults, we tend to ask “if these abstractions have any parallels in the real world”. Strogatz gives a fascinating example. Say, you have 3 entities (people, companies, countries, whatever). A solid line designates the connected entities are friends, a dashed line conveys they are enemies. Take 2 such possible arrangements: Social scientists refer to such triangles that denote rel...