Way back, Albert Einstein had suggested that light travels at a steady pace. But this theory is being challenged by two scientists with their own theory that the speed of light may be variable.
Most physicists measured the speed of light but Albert Einstein and by his relativity theory, people found out why light has such pace., repeated Quartz in a Sunday report. It was also mentioned that as per Einstein, nothing can travel faster than light, as it would cause the violation of laws of physics which is why he brought up the idea of the speed of light not being variable but stable throughout.
No one seriously challenged Einstein and the idea that light always travels at the constant speed, since the theory of relativity was given. Joao Magueijo, In 1998, started raising a question, whether Einstein was precise with his theory or his ideas about light's speed had some flaws in them. He speculated that debunking of Einstein's theory may be required to solve the physics conundrum which is also known as "horizon problem".
Inflation generally explains the horizon problem, it means that after Big Bang, the temperature of the universe had become more steady, but before it quickly and substantially expanded. But, as the scientists are annoyed by the inflation's why and how, the reason it stopped, many questions about inflation serving as a valid answer to the conundrum.
This is when Maqueijo started wondering whether this speed is variable or not, he was looking for the alternate way of solving the horizon problem. But, it's only that in its earnest, his alternate theory is now being tested, according to The Guardian.
In the research, the proposed hypothesis suggests that when the universe was young, the gravity and light were moving at the same speed. If the photons moved faster than the gravity then the universe would have been allowed to expand in its entirety and helped t reach balance, uniform temperature.
