In the mid-19th century, Bernhard Riemann conceived of a new way to think about mathematical spaces, providing the foundation for modern geometry and physics.

The International Space Station marks a quarter-century of continuous occupancy this weekend, boasting a guest list of nearly 300 — mostly professional astronauts but also the occasional space tourist ...

Whenever someone talks about black holes, they almost always talk about the event horizon and the singularity. After all, that's what defines a black hole, right? Well, it depends on what you mean by ...