Doubly special relativity

Doubly special relativity (DSR) is a type of theory that explains how the laws of physics may be different at very high speeds or very small sizes. In DSR, the speed of light (the fastest thing in the universe) is a special speed that never changes, no matter how fast something is going. DSR also says that the Planck length (the smallest measurable size) is a special size that never changes, no matter how small something is.