The speed of light has not always been a constant, says a theory, and the scientists who back this new hypothesis can now actually test its validity. Their paper has recently been published in Physical Review.
Einstein might have been wrong— the speed of light is possibly not a constant, says a team of scientists who have finally come up with a hypothesis that can be tested.
We’ve been hearing it all our lives:
“The speed of light is a constant.”
“The speed of light does not change no matter what.”
“The speed just does not vary.”
Physicists articulated this law with such confidence, given that Einstein, one of the world’s greatest geniuses, came up with it, with substantiation and all. Furthermore, scientists have built up from this, and consequently, many other laws and theories are based on the speed of light being a constant. Well, guess what—it might not be that true.
According to Einstein’s theory, the speed of light remains unchanged in under any given circumstance, and this has allegedly always been the case. The plot twist is that this might not have “always been the case”. The scientists behind the revolutionary statement suggest that the speed of light might have been of a greater value during the early days of the universe. This theory of theirs can now allegedly be tested with a model they came up with, says Professor João Magueijo from Imperial College London, one of the first scientists to contradict Einstein in this regard.
Professor Magueijo and like-minded scientists say that a varying speed of light characterising the early universe might have affected structures like galaxies back then. The latter would have been formed from fluctuations in density which would have originated from a changing speed of light. These early fluctuations can be traced back as they have left their “spectral index” mark on the cosmic microwave background. The team now propose an exact figure featuring on this spectral index by using a new model: 0.96478. The current estimate describing the cosmic microwave background is at 0.968.
“The theory, which we first proposed in the late-1990s, has now reached a maturity point—it has produced a testable prediction. If observations in the near future do find this number to be accurate, it could lead to a modification of Einstein’s theory of gravity,” says Professor 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.”
The theory of the varying speed of light can help solve the “horizon problem”. The latter goes as follows: the universe seems to be homogeneous throughout, and this can only be possible if all of its regions were once able to influence one other, but this is problematic if the speed of light was a constant because that would mean light could not have reached the outermost limits of the universe to balance the energy in the amount of time that has elapsed, that is, the apparent size of the universe is not congruous with the age of the universe. On the other hand, a changing speed of light, with a greater value during the early days of the universe, would have made it possible for the edges of the universe to have been connected while the universe underwent expansion. Then, with the change in the universe’s density, the speed of light would have dropped in magnitude.
There goes one of your most important theories, Einstein!