The speed of light is one of the few constants that we can really rely on - it’s 299,792,458 m/s if you’re curious. What if it turns out that it isn’t constant, that in fact the speed of light has changed?
Scientists have developed a test which they hope will prove that in the first moments after the big bang, light was moving a lot, lot faster.
Professors João Magueijo and Niayesh Afshordi believe that if they can prove this to be true then it could fundamentally change the way we view the universe and would ultimately prove one of Einstein’s most significant theories to be untrue.
So how do you test a theory that effectively breaks one of our most assured equations?
What the pair are doing is looking at the structures in our universe, galaxies for example. They were all created in the early stages of the big bang and all have varying densities.
These fluctuations in density have effectively left a trail of breadcrumbs hidden with the cosmic microwave background - otherwise known as the static noise when you can’t find a channel.
The breadcrumbs do also have an official term known as the spectral index. The hope, for Magueijo and Afshordi, is that these fluctuations were in fact caused by light travelling at different speeds, something that will show up in the spectral index.
Magueijo explains just how significant this could actually be, “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.”
What’s really interesting about this test however is that it could hopefully solve one of the biggest problems we currently have with light speed.
You see taking into account the size and age of the universe, even at its current speed, light shouldn’t have reached as far as it has.
Hayley Dunning at Imperial College has a wonderful analogy that should put that into better context.
“To heat up a room evenly, the warm air from radiators at either end has to travel across the room and mix fully. The problem for the universe is that the ‘room’ – the observed size of the universe – appears to be too large for this to have happened in the time since it was formed.”
So in essence, the universe really shouldn’t be this ‘warm’.
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