As predicted by Einstein’s general theory of relativity, scientists from Cardiff University have discovered a bizarre twisting motion in the orbits of two merging black holes.

Professor Mark Hannam, Dr. Charlie Hoy, and Dr. Jonathan Thompson’s work, which was published in Nature, notes that this is the first evidence of the precession effect—where the twisting is 10 billion times quicker than in previous observations—being observed in black holes.

Early in 2020, the Advanced LIGO and Virgo detectors detected gravitational waves that led to the discovery of the binary black hole system.

One of the black holes is 40 times bigger than our Sun and is probably the one that spins the fastest that gravitational waves have found.

And unlike what had been seen before, the quickly spinning black hole warped space and time so much that the entire orbit of the binary moved back and forth.

Einstein’s theory of general relativity is the only one that can explain this kind of precession. The collision of two black holes, the most severe physical event we can witness, provides evidence for its existence.

“We’ve always thought that binary black holes can do this,” says Professor Mark Hannam of Cardiff University’s Gravity Exploration Institute. “We have been hoping to spot an example ever since the first gravitational wave detections. We had to wait for five years and over 80 separate detections, but finally we have one!”

Precession can also be seen in more everyday phenomena, such as the swaying of a spinning top, which may wobble once every few seconds. Precession in general relativity, however, typically has such a weak influence that it is undetectable. In the case of binary pulsars, which are neutron stars that orbit each other, the fastest precession was measured to take over 75 years. The black-hole binary that was the subject of this study, also known as GW200129 (from the date it was discovered, January 29, 2020), precesses many times per second, a phenomenon that is 10 billion times more powerful than anything previously detected.

“It’s a very tricky effect to identify,” adds Dr. Jonathan Thompson. 

“Gravitational waves are extremely weak and to detect them requires the most sensitive measurement apparatus in history. The precession is an even weaker effect buried inside the already weak signal, so we had to do a careful analysis to uncover it.”

Einstein made the first prediction of gravitational waves in 1916. They were first directly identified in 2015 by the Advanced LIGO sensors from the merger of two black holes, a ground-breaking discovery that earned them the 2017 Nobel Prize.

With a network comprising the Advanced LIGO, Virgo, and KAGRA detectors functioning in the US, Europe, and Japan, gravitational wave astronomy is currently one of the most active fields of science. All over 80 detections so far have been of black holes or neutron star mergers.

When this study was being conducted, Dr. Charlie Hoy, who is currently at the University of Portsmouth, was a researcher at Cardiff University.

He adds: “So far most black holes we’ve found with gravitational waves have been spinning fairly slowly. The larger black hole in this binary, which was about 40 times more massive than the Sun, was spinning almost as fast as physically possible. Our current models of how binaries form suggest this one was extremely rare, maybe a one-in-a-thousand event. Or it could be a sign that our models need to change.”

The international network of detectors for gravitational waves is being updated right now, and its next search of the universe will begin in 2023. They will undoubtedly discover hundreds of additional black hole collisions, and this will inform scientists whether or not GW200129 was an anomaly, or if the cosmos is much crazier than we believed.

Image Credit: Getty

You were reading: Discovery Of “Wobbling Black Hole” Could Be A Rare One-in-1000 Event