Philosophy
The Philosophy of Space and Time and the Debate Over Substantivalism
Quick fact
The debate over substantivalism and relationism was famously illustrated by Newton's bucket argument and Leibniz's shift argument, and it remains unresolved even after Einstein's general relativity, which made spacetime itself a dynamical entity.
Why this is interesting
Is space a real thing—a grand container that exists even if it were empty—or is it just a convenient way to talk about the distances between objects? This question has haunted philosophers and physicists for centuries.