The universe comes with a built‑in speed cap, a hard limit that shapes everything from how stars shine to how cause and effect unfold. That limit is usually described as the speed of light, yet the ...

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 ...

When an object moves extremely fast – close to the speed of light – certain basic assumptions that we take for granted no longer apply. This is the central consequence of Albert Einstein's special ...