Scientists are finally whispering the unthinkable question – did Einstein get his sums wrong?
Albert Einstein was not the first scientist to put a number on the speed of light in a vacuum, but he was the first to develop his theory of relativity to explain why.
Einstein theorised that the speed of light was a universal constant and always had been so since the dawn of time.
The theory altered the way scientists thought about gravity, space and time.
Einstein suggested nothing could travel faster than light and for his theory to work, the speed of light should remain a constant number.
Since Einstein introduced his theory, every test and measurement has resulted in the same constant for the speed of light.
Speed of light may be variable
But one brave scientist at Imperial College, London, dared to think that Einstein may be wrong.
Joao Magueijo spoke out when considering how to solve the horizon problem.
The problem is that the universe would have had to reach a uniform temperature for light to cover the entire area.
Scientists constructed inflation as a solution. The solution says the temperature evened before the universe started expanding and then rapidly expanded.
A lot of scientists have doubts about the explanation because they cannot explain why inflation started and stopped again.
Magueijo suggests that light has travelled at different speeds since the Big Bang.
If the speed was faster or slower, he reckons, then Einstein would be wrong.
To try and prove his point, Magueijo has developed a test.
He argues that galaxies and other structures in the universe evolved from tiny fluctuations in the early universe and that these fluctuations are held in the cosmic microwave – the oldest light in the universe.
Reading these fluctuations and some fancy maths would will show the speed of light at the time and comparing this to the spectral index of light travelling at Einstein’s measured speed would show whether light has travelled faster or slower at any time.
“The theory has produced a testable prediction. If observations do find this number to be accurate, it could lead to a modification of Einstein’s theory of gravity,” said Magueijo.
“The idea that the speed of light could be variable was radical when first proposed, but with a numerical prediction, it becomes something physicists can actually test. If true, it would mean that the laws of nature were not always the same as they are today.”