CENTENARIO

The theory built on the insights of Einstein’s first theory of relativity, the “special theory”, one of a trio of breakthroughs that made his reputation in 1905. That theory dramatically abandoned the time-honoured description of the world in terms of absolute space and time in favour of a four dimensional space-time (three spatial dimensions, one temporal one). In this new space-time observers moving at different speeds got different answers when measuring lengths and durations; for example, a clock moving quickly with respect to a stationary observer would tell the time more slowly than one sitting still. The only thing that remained fixed was the speed of light, c, which all observers had to agree on (and which also got a starring role in the signature equation with which the theory related matter to energy, E=mc²).