The hyperdrive from Star Wars appears to depict an ultra-relativistic motion through space, extremely close to the speed of light. Under the laws of relativity, you neither reach nor exceed the speed ...

Some say that the reason you can't travel faster than light is that your mass will increase as your speed approaches light speed – so, regardless of how much energy your star drive can generate, you ...

Everyone knows that relativity plays hell with time, and that it can do a number on space, but what about mass? Why do objects get more or less mass depending on their relative speed? We’re going to ...

A spacecraft traveling at 99 percent the speed of light toward Alpha Centauri would cross 4.3 light-years in what feels like months to its crew, while decades tick by on Earth. That asymmetry is not ...

I've been trying to explain quantum physics, forces, relativity, and space-time to my kid and we had a question that I'm finding difficult to find a solid answer to. Background you can skip if you ...

The general theory of relativity is a remarkably successful model for gravity. However, many of the best tests for it don’t push its limits: they measure phenomena where gravity is relatively weak.