The book Flatland: A Romance of Many Dimensions by Edwin A. Abbott explores the concept of physical dimensions through characters who encounter higher-dimensional beings. The protagonist, “A. Square,” ...

Mathematicians say knots cannot exist in four-dimensional space because the extra dimension allows a rope to move around itself and untangle, revealing surprising insights into geometry and topology.

Here’s what you’ll learn when you read this story: Theoretical physicists believe math shows the possibilities of a fourth dimension, but there’s no actual evidence—yet. Albert Einstein believed space ...