One of greatest scientists ever, Albert Einstien stated a theory nearly a century ago that speed of light is constant in the same medium. The speed of light is maximum in vaccum and nothing can move faster than the speed of light. However, a group of scientists is now challenging the Einstien’s famous theory and will test its validity soon.

Several scientists have tested the speed of light with their own method  and found it to be constant in vaccum — 299,792,458 meters per second. However, such precise calculations took place after 1970s when researchers got their hands on highly sensitive instruments.

Einstien stated that nothing can move faster than light as it would break the fundamental laws of physics. In addition, the speed of light as a constant allowed his theory of relativity to work. His theory has stood for over a century and scientists community have accepted it.

However, a team of scientists from the Imperial College of London stepped down and raised questions over the theory back in 1998. Since then they have been working to prove that the speed of light is not constant.

Team lead Joao Magueijo proposed that to solve one of the biggest physics problems, called the “horizon problem,” we might have to challenge the idea that the speed of light is constant. The problem states that the universe reached a uniform temperature long before energy-carrying photons travelling at constant speed could have had the time to reach all corners of the expanding universe.

The most common explanation for such anomaly is inflation which says that after the Big Bang, the temperature spread out equally even before the universe started expanding. However, many scientists are sceptical about the theory of inflation because no one could explain why inflation started and how it stopped.

Magueijo started looking for an alternative solution to the inflation and found that the problem could be solved if speed of light is not constant. He is about to test his theory and will come with a testable hypothesis. He will publish his study in the journal Physical Review. If he succeeds and then it will break the base of modern physics and Einstien’s theory of relativity.

Magueijo’s theory states that photons and gravity travel at different speeds. At the beginning, when Universe started expanding, photons were moving faster than the gravity which helped them reach every corner of the universe and maintain temperature equilibrium.

The testable hypothesis of Maguejio can be checked using cosmic microwave background (CMB) radiation, which is a fossilized impression of the early universe that we can measure even today. Through CMB, physicists will be able to measure the change of speed of light and speed of gravity with respect to the changing temperature of the universe.

“The theory, which we first proposed in the late-1990s, has now reached a maturity point — it has produced a testable prediction,” said Mr. Magueijo.

“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,” he said.

According to the values predicted by Maguejio, the value of spectral index is 0.96478 which is fairly close to the values obtained through CMB, 0.968. If these values mismatch while testing the theory then Maguejio’s theory is wrong and if they match then it would be a disaster for Physics. It would change the way we have been looking towards our universe since past one century.

“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,” Magueijo said.

“If true, it would mean that the laws of nature were not always the same as they are today,” he said.

The research appeared in the journal Physical Review D.

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Kanishk Singh, co-founder, and editor-in-chief at The TeCake, has forayed in the Science and Space for over five years, he enjoys his stint as an editor of several local magazines. He has written several editorials and high-level documentations.

#### Around the World

• Yashgee Y’Assmen

It is quantum mechanics at work, shows up instantly elsewhere……. just magical………………..

I am glad, they were all wrong……. so I failed in exams………… But now I know……. There existed no Einstein, just Frankenstein in the jars….. resonating in time…………

• Xinhang Shen

There is no surprise that the speed of light is not constant because the entire relativity theory has been disproved both theoretically and experimentally (see “Challenge to the special theory of relativity” March 1, 2016 Physics Essays). The most obvious evidence is the absolute time shown by the universally synchronized clocks on the GPS satellites which move at high velocities relative to each other while special relativity claims that time is relative and can never be synchronized on clocks moving with relative velocities.

• shobhit bansal

Those synchronised clocks adjust for the relative velocities and accelerations.
Go read any basic physics book, of any school.

• Xinhang Shen

Just like many other people, you really don’t understand special relativity. The core of special relativity is that time is relative and can never be synchronized on clocks moving with relative velocities. That is, no matter how you correct, the clocks just can’t be synchronized. If a clock can be corrected relative to all inertial reference frames, then the correction is the same in all the reference frames and the correction is absolute, independent from reference frames. The clocks on the GPS satellites are perfectly synchronized not only relative to the ground clocks but also relative to each other. Therefore, all so called relativistic corrections are just misinterpretations of errors caused by various known and unknown factors.

• sam

what can b said abt an article on science which get the name of the scientist wrong ?

“Einstien”
really!!

• Anirudh Kumar Satsangi

Good news.