Pune couple part of team that debunked Hawking's theory

A Pune-based couple who was part of an international team has debunked a popular theory — proposed by none other than Stephen Hawking five decades ago — about the mysterious ‘dark matter’.

Astrophysicist-duo Surhud More and Anupreeta More, from the Inter University Centre for Astronomy and Astrophysics (IUCAA) collaborated with scientists from the US and Japan to question the famous Hawking theory, which says that black holes formed very early in the universe could have formed dark matter.

Dark matter is a hypothetical form of matter, that is supposed to be responsible for 85% mass of the universe. However, it remains hypothetical because all attempts to detect dark matter particles through experiments have failed so far.

For their experiments, the researchers from IUCAA, University of Tokyo, Princeton University and Osaka University looked at Andromeda a spiral galaxy which is the closest neighbour of the Milky Way with Subaru telescope at Hawaii on a November night four years ago.

They used a technique called gravitational lensing to look for primordial black holes — with a mass window of 0.001 to 10 times the mass of the Moon — in the space between Milky Way and Andromeda.

If Hawking’s theory was right, the team should have stumbled upon nearly 1,000 observations that are consistent with primordial black holes. But at the end of a seven-hour search with one of the world’s finest telescopes, they found only one such candidate.

Way back in 1971, Hawking showed primordial black holes — made up of ordinary matter and formed within few seconds of the Big Bang — could be a strong choice as dark matter candidates.

Such primordial black holes are distinctly different from the black holes arising from a giant star in its dying stage.

The primordial black holes can have a wide range of masses, ranging from as low as billionth of a gram to thousands of times that of the solar mass.

Now, the entire theory is in question after the recent findings.

“Our research demonstrated that primordial black holes can’t be dark matter candidates. The theorists have to find out an alternate theory,” Surhud told DH. The findings have been reported in the Nature Astronomy journal on Monday.

“The study disfavours (or questions) Hawking’s hypothesis about early universe black holes. The results have now confirmed that primordial black holes with masses similar or less massive than the moon can’t contribute more than a percent of all dark matter,” Surhud said.