Stephen Hawking's Dark Matter Theory Weakened by Powerful Telescope

Powerful telescopes snaps night sky and find little evidence that dark matter is made up of ancient tiny black holes.
Jessica Miley

One of Stephen Hawking's key theories about black holes just got a little weaker thanks to a super powerful telescope.

In the 1970s Hawking and some of his colleagues theorized that the big bang might have created lots of small black holes, each about the size of a proton that exerts a huge gravitational pull on other objects in the universe.

This theory helps explain the idea of 'dark matter' - or the phenomena that causes all objects in our universe to rotate, move or orbit under the influence of invisible forces.


Masahiro Takada and his team at the Kavli Institute for the Physics and Mathematics of the Universe in Japan used The Hyper Suprime-Cam (HSC) digital camera on the Subaru telescope in Hawaii to search for these mysterious primordial black holes and to see if Hawking was correct. The results of their search have been published in the journal Nature Astronomy. 

Hard to photograph 

Black holes are objects dense with matter that have such strong gravitational pulls that not even light can not get out of them. They are so hard to find for this reason - light cannot escape from them - therefore they emit no light.

While supermassive black holes like the one that was recently photographed by the Event Horizon Telescope do have a ring of fiery gases, smaller holes are almost invisible.

Primordial black holes are even harder to find due to their tiny size.

Super cam takes a photo of the entire galaxy

To hunt down black hole scientists must scan the universe looking for evidence of where light bends which indicates the close proximity of a black hole. This phenomenon is known as 'microlensing'.

Telescopes look for microlensing events by taking photographs of stars many times over a period of time. If a black hole passes in front of that star, the star will flash due to the distorted light.

The quicker the flash the smaller the black hole. Hyper Suprime-Cam (HSC) digital camera on the Subaru telescope in Hawaii is able to take a photograph of the closest galaxy to our own, the entire Andromeda galaxy in one shot.

Takada and his team took 200 pictures of the Andromeda galaxy over a seven-hour period on a clear night then compared the images looking for flashes. 

The theory has some holes

The results showed just one instance of microlensing. If Hawking's theory was right and that primordial black holes make up a large amount of dark matter the research team says they should have seen approximately 1,000 microlensing signals.

"Microlensing is the gold standard for detecting black holes or ruling them out," said Simeon Bird, a black- hole physicist at the University of California — Riverside, who was not involved in the work.

"This work rules out primordial black holes as dark matter in a range of masses where the previous constraints were not as strong nor as robust as this new one. It's a very nice result."

Hawking's theory isn’t totally blown out of the water though. Takada and his team believe that it's possible the primordial black holes are so tiny, they can’t be found using this method.

The one flash they did find is also an exciting validation that primordial black holes do exist.

The research team will continue their study looking for further evidence of these ancient tiny black holes.

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