Special relativity
Theory · 1905, Switzerland and Germany · Physics, stage 2: Map the theories
Special relativity starts from two assumptions: the laws of physics are the same in every inertial frame, and the speed of light in vacuum is the same for every observer. Einstein published it in 1905 while working at the patent office in Bern, and everything else follows from those two statements by argument rather than by new experiment. Moving clocks run slow, moving objects are shortened along the direction of motion, simultaneity depends on the observer, and mass and energy are the same quantity in different units. Minkowski recast the theory in 1908 as geometry on four-dimensional spacetime, which is the form used ever since. The theory applies where gravity can be ignored.
What it claims
- The laws of physics take the same form in every inertial frame.
- The speed of light in vacuum is the same for all observers, whatever their motion.
- Time intervals and lengths depend on the frame in which they are measured.
- Mass and energy are the same quantity, related by a factor of the speed of light squared.
Key ideas
People
Sources
- Special relativity English Wikipedia
- Special relativity Britannica
- Einstein's Philosophy of Science Stanford Encyclopedia of Philosophy
