Spark of Genius

ALBERT EINSTEIN never learned to drive. He thought it too complicated and in any case he preferred walking. What he did not know—indeed, what no one knew until now—is that most cars would not work without the intervention of one of his most famous discoveries, the special theory of relativity.

Special relativity deals with physical extremes. It governs the behaviour of subatomic particles zipping around powerful accelerators at close to the speed of light and its equations foresaw the conversion of mass into energy in nuclear bombs. A paper in Physical Review Letters, however, reports a more prosaic application. According to the calculations of Pekka Pyykko of the California South University and his colleagues, the familiar lead-acid battery that sits under a car’s bonnet and provides the oomph to get the engine turning owes its ability to do so to special relativity.