The universe comes with a built‑in speed cap, a hard limit that shapes everything from how stars shine to how cause and ...

An artist’s illustration of a lightsail powered by a radio beam (red) generated on the surface of a planet. Credit: M. Weiss/CfA An artist’s illustration of a lightsail powered by a radio beam (red) ...

Relativistic physics imposes one of the most frustrating limitations predicted by science. It tells us that an inescapable speed limit exists in the universe: we can't go faster than the speed of ...

The Sagnac effect, first observed over a century ago, remains central to our understanding of relativistic kinematics and the operational definitions of simultaneity. Fundamentally, this effect arises ...