Australian scientists are calling into question one of our most important scientific theories — Einstein's calculation of the speed of light, the famous E=MC² equation.
Theoretical physicist Professor Paul Davies, based at Macquarie University, has uncovered evidence that, rather than being one of the constants of the universe, the speed of light has actually slowed down over time.
"The laws of nature contain certain numbers known as physical consonants," said Davies. "One assumes that these are god-given fixed numbers. The fact that one of these appears to be varying with time isn't supposed to happen."
The speed of light is currently measured at roughly 300,000 kilometres a second.
"If the speed of light varies, potentially it could have been anything 12-15 billion years ago when the Big Bang occurred. The speed of light could have been infinite at that time, which would explain a lot about our current universe," said Davies.
If Davies' theory is correct, it could resolve many puzzles of the universe, such as why distant parts of it are the same temperature.
This is not the first time one of these 'constant' figures had been called into question. Earlier this year University of New South Wales astronomer John Webb discovered that the fine structure content, or alpha, of the quasar light was about a millionth smaller than the accepted value of 1/137. This calculation shows that alpha is therefore not a constant number throughout the universe.