Scientists have found an evidence that the mystifying "dark energy' may not exist at all.

A study conducted by researchers at Oxford found out that the universe is continuously expanding at a constant rate and not an accelerated rate, which possibly suggests that there is no such thing as dark energy.

Space.com defines dark energy as "a mysterious quantity that makes up, along with dark matter, most of the mass of the universe." The term came from the theory that there is some strange kind of energy-fluid that filled space and creates cosmic acceleration as the universe ages.

According to Space Daily, this theory was further fueled when three astronomers analyzed Type Ia supernovae - the spectacular thermonuclear explosion of dying stars - picked up by the Hubble space telescope and large ground-based telescopes and concluded that the universe is expanding at an accelerating pace. Their study conducted in the 1990s was awarded the Nobel Prize in Physics five years ago.

Until now, that is what remains to be the most popular and accepted theory about our Universe. The team lead by Professor Subir Sarkar of Oxford University's Department of Physics looked into a much larger dataset to counter the widely accepted theory.

Science Alert says that the team applied different analytical models to the 740 Type Ia supernovae that have been identified so far.

"We analysed the latest catalogue of 740 Type Ia supernovae -- over 10 times bigger than the original samples on which the discovery claim was based -- and found that the evidence for accelerated expansion is, at most, what physicists call '3 sigma'," Sarkar said.

"This is far short of the '5 sigma' standard required to claim a discovery of fundamental significance."

The team also said that the techniques used by the 1900s team are too obsolete as it was devised in the 1930s and cannot account for the already growing database set.

Since other evidence, such as faint afterglow of the Big Bang, that support the theory of dark energy was based on the 1930s framework, the researchers are also suggesting that these are flawed.

The research has been published in Scientific Reports.