Doubly special relativity

Doubly special relativity (DSR) – also called deformed special relativity – is a modified theory of special relativity in which there is not only an observer-independent maximum velocity (the speed of light), but also an observer-independent maximum energy scale (the Planck energy) and/or a minimum length scale (the Planck length). This contrasts with other Lorentz-violating theories, such as the Standard-Model Extension, where Lorentz invariance is instead broken by the presence of a preferred frame.

Source: Wikipedia — Doubly special relativity (CC BY-SA 4.0)