The Colliding Black Holes that Shouldn’t Exist

Ever since the beginning of human life on Earth, the history of our universe’s creation — nearly 14 billion years ago — has plagued the minds of philosophers and astronomers. 

The world of astrophysics and cosmology, the study of the history of our universe and its physical composition, was thought to have been conquered until Albert Einstein introduced the theory of relativity. The famous scientist’s theory opened doors that scientists never even thought existed and built the foundations of modern-day quantum mechanics. 

A computer-generated image of a black hole|Photo Courtesy of NASA

Quantum mechanics ties spacetime, the mathematical model of a four-dimensional manifold composed of three-dimensional space and one-dimensional time, and gravity together in a single theory, allowing for a more composite and integrated understanding of the universe’s physical functions and adherence to physical laws. This new branch of astrophysics led scientists around the world, like British theoretical physicist Stephen Hawking, to first theorize the presence of something that can deform, or bend, spacetime by having a gravitational pull so strong that not even light can escape its grasp. These pits of nothingness are commonly known as black holes. 

Although black holes are notorious for being unventured territory in theoretical physics, there are still some theories scientists believe to be concrete. Some of these certainties included the process of their formation: when a star — with a standard of about 300 solar masses, or 300 times the mass of our sun — collapses onto itself, it can form a highly concentrated pocket of energy which may lead to the development of a black hole. 

Formation of a black hole|Photo courtesy of Invention Sky

However, recent observation of the collision of two black holes proved these seemingly faultless theories wrong. The merging seemed relatively standard until physicists took a gander at the masses of the colliding black holes. According to theoretical calculations, this occurrence was thought to be impossible because the black holes involved shouldn’t exist. 

Schwarzschild’s radius describing the form of black holes|Photo courtesy of

In a New York Times interview, University of Chicago theorist and team member of Caltech’s Laser Interferometer Gravitational-Wave Observatory, Daniel Holtz said that the immensely massive collision left a dent in the world of theoretical physicists.

“The first LIGO/Virgo detection that’s truly surprising. All the other binary systems that we’ve detected fit reasonably well within expectations,” Holz said. “But the black holes in this event aren’t supposed to exist!”

Astrophysicists agreed that the minimum mass required for a star to turn into a black hole is 300 solar masses. This standard was completely defied by the collided black holes, as both of them had masses below 100.

The collision happened at an unfathomably large distance of 17 billion light-years away — as determined by cosmological calculations that took into account the expansion of our universe —which means the light created from the collision took 17 billion years to reach Earth. This event involved a black hole 85 times the mass of our sun and another even smaller black hole with a mass 66 times that of our sun; both are under the standard of 300, making their formations fundamentally impossible. 

The gravitational waves of colliding black holes|Photo courtesy of

Stars that are 60 to 130 times the mass of our Sun form a pair-instability supernova. Although they go out with a bang, they never usually become black holes, as the heat that occurs during the compression of the star is so powerful that all of the ejected material that would have been used to create a black hole is destroyed. 

In an effort to explain this seemingly impossible event, scientists have theorized that these black holes might have both been a product of previous collisions of other black holes. Another explanation is that they are primordial, or formed at or right after the big bang. The period of time just after the big bang didn’t adhere to the present-day laws of physics, making it possible for such mathematically impossible black holes to form. If they are primordial, their impossible masses wouldn’t have been considered impossible at the time of their formation. 

Nothing is certain for the time being, but nothing really ever is in theoretical physics. By proving scientists wrong, it introduced a new and exciting branch of physics defining intermediate-mass black holes.

Inflationary theory model|Photo courtesy of

“A discovery like this is simultaneously disheartening and exhilarating,” Holz said. “On the one hand, one of our cherished beliefs has been proven wrong. On the other hand, here’s something new and unexpected, and now the race is on to try to figure out what is going on.”

 As the old saying goes, when life gives you an impossible collision of two potentially primordial black holes, you make a new branch of theoretical physics!

Written by Roaa Alkhawaja

Co-Editor in Chief and Senior, Ro'aa Alkhawaja, loves herself a good week of reading, baking, tea-drinking, and eating more Nutella sandwiches than should be humanly possible.

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