The speed of light is constant, or so textbooks say. But some scientists are exploring the possibility that this cosmic speed limit changes, a consequence of the nature of the vacuum of space. The ...

Albert Einstein might be known for a great many things, but even the layman might be familiar with at least one thing: E = mc 2, the formula for mass-energy equivalence. However, a critical part of ...

On one hand, the speed of light is just a number: 299,792,458 meters per second. And on the other, it’s one of the most important constants that appears in nature and defines the relationship of ...