Theory of relativity

The theory of relativity refers to two connected theories in physics developed by Albert Einstein: special relativity (1905) and general relativity (1915). Together they transformed the understanding of space, time and gravity.

Special relativity

Special relativity applies to objects moving at constant speed and is based on two postulates: the laws of physics are the same for all non-accelerating observers, and the speed of light is constant. It leads to effects such as time dilation and the famous equation E = mc².

General relativity

General relativity extends the idea to gravity, describing it not as a force but as the curving of spacetime by mass and energy. It predicted phenomena such as the bending of light by gravity and black holes.

Impact

Relativity underpins modern physics and technologies such as the Global Positioning System.

Frequently asked questions

Who developed the theory of relativity?

Albert Einstein.

What is E = mc²?

The relation showing that energy and mass are equivalent, from special relativity.