Was Einstein wrong?
The speed of light has slowed down since the Big Bang, a team of Sydney researchers has conjectured. If true, the findings rock the very foundations of some of our most sacred scientific laws. The discovery was made by Paul Davies from Macquarie University and Tamara Davis and Charles Lineweaver from University of New South Wales.
Based on measurements of light that has travelled for 10 to 12 billion years to reach Earth from massive stellar objects called quasars, the scientists argue that light speed, which clocks 300,000 kilometres a second, has been slowing down over time. They have proposed several reasons for this, including the possibility that the structure of the vacuum in space has changed. When light travels through a medium other than a vacuum, such as a glass of water, it slows down. If the vacuum of space is changing uniformly across the universe, just as the universe is expanding uniformly, it could affect the speed of light by slowing it, they say.
So, do the findings mean that the great cosmological constant should now be consigned to the dusty annals of history? Not necessarily, say the scientists. It just means Einstein's theory based on the speed light being constant might no longer be the last word on the subject. This discovery implies that faster-than-light travel, which is prohibited by the law of relativity, may one day be possible. "It also affects other branches of physics like thermodynamic and quantum physics,' says Davies.
However, the new theory has some detractors. Don Melrose, head of the school of physics at the University of Sydney, has expressed doubts, saying the raw data from the quasar light was probably wrong. According to physicist David Blair from the University of Western Australia, more research on quasars is needed to confirm the observed effects.