On a crisp fall New England day during my junior year of college, I was walking past a subway entrance when a math problem caught my eye. A man was standing near a few brainteasers he had scribbled on ...

Category theory, K theory and homological algebra are interrelated branches of mathematics that comprise a powerful conceptual framework for studying structures and their interconnections. Category ...

Emily Riehl thinks hard about objects that don't exist in the material world yet mysteriously seem to underlie many things that do. These objects have no concrete existence of their own, but they do ...

Carlo Rovelli discusses his research on time and his view that it should not appear in the quantum theory of gravity. Robert Hazen and Michael Wong discuss their bold proposal for a new law of nature, ...