The recent finding by an international team of astronomers that the fine-structure constant has increased over time may support the idea that the universe has extra dimensions.
In the movie The Meaning of Life, the Monty Python team reminds us that we live in “an amazing and expanding universe”. Ever since the startling evidence for cosmic expansion was discovered in the 1920s, physicists have considered the possibility that the so-called constants of nature – such as the charge on the electron and the gravitational constant – are not constant and may, in fact, vary with time.
In the late 1960s, George Gamow suggested that the charge on the electron, e, may vary rather than gravity. More precisely, he considered a variation in the fine-structure constant, a = e2/h-bar c, where h-bar is the Planck constant divided by 2 pi and c is the speed of light. The fine-structure constant is the gauge-coupling constant in quantum electrodynamics and determines the relative strength of the electromagnetic force. In essence, a can be considered a dimensionless measure of the charge on the electron.
Observational tests of the time variation of physical constants have been an idle curiosity of a handful of individuals, including myself, over the last few decades. Now a recent measurement by a team led by John Webb of the University of New South Wales in Sydney has thrust such studies into the spotlight. Webb and co-workers claim to have detected a significant variation in the fine-structure constant over time (J K Webb et al. 2001 Phys. Rev. Lett. 87 091301).
In the October issue of Physics World, Chris L Carilli of the National Radio Astronomy Observatory, Socorro, USA, explores the implications of the surprising discovery.
