Why the familiar equal sign isnt just a marker of sameness but a gateway into mathsand humanitysmost profound questions
Math is famous for its equations: 1 + 1 = 2, a2 + b2 = c2, or y = mx + b. Much of the time it can seem like thats all mathematics is: following steps to show that whats on one side of an equation is the same as whats on the other.
In Unequal, Eugenia Cheng shows thats just part of the story, and the boring part to boot. Mathematics isnt about showing how numbers and symbols are the same. It isnt even just about numbers and symbols at all, but a world of shapes, symmetries, logical ideas, and more. And in that world, the boundary between things being equal and unequal is a gray area, or perhaps a rainbow of beautiful, vibrant, subtly nuanced color.
As Unequal shows, once you go over that rainbow, almost everything can be considered equal and unequal at the same time, whether its shapes (seen from the right perspective, a circle is the same as an ellipse), words (synonyms), or peopleeven numbers! It all depends on what features we care about. And its up to us what we do about it. Thats because mathematics isnt a series of rules, facts, or answers. Its an invitation to a more powerful way of thinking.
