2023-10-27 06:00:07
A duo of black holes doesn’t always end in cataclysmic merger, new research shows. This discovery challenges the common belief that two black holes in close orbit are destined to become one.
Schematic of gravitational waves generated by two black holes orbiting each other.
The study reveals that it is theoretically possible for two black holes to remain a fixed distance apart. This phenomenon is explained by the expansion of the Universe, compensating their mutual gravitational attraction.
Óscar Dias, a physicist at the University of Southampton, indicates that from a distance, these black holes could look like one. According to him, it would be difficult to determine whether it is one or two black holes. The research team published its results in the journal Physical Review Letters on September 25.
The researchers pointed out a logical inconsistency in one theorem and a limiting assumption in another. Contrary to popular belief, two black holes could be delicately balanced by the expansion due to the cosmological constant (The cosmological constant is a parameter added by Einstein in February 1917…).
The expansion of the Universe plays a crucial role in keeping two black holes at a fixed distance. This expansion is propelled by dark energy, which causes an acceleration in the distance of cosmic objects. In the case of the black holes in question, this expansion force counterbalances their mutual gravitational attraction.
Simply put, while gravity seeks to pull the two black holes closer together, the expansion of the Universe exerts an opposing pressure on them. distant. If these two forces are perfectly balanced, black holes can stay at a constant distance from each other. It is an unstable balance, similar to a pen resting on its tip: any minor change can disrupt this balance.
The rotation of black holes could add a new dimension to this delicate balance. A rotating black hole has what is called an “angular momentum” (In physics, angular momentum or angular momentum is the magnitude physics which plays a…)”, which influences surrounding objects in addition to gravity. If two black holes rotate in opposite directions, their angular momentum could, in theory, contribute to balancing their gravitational attraction.
This mechanism has not yet been demonstrated, but it offers an interesting avenue of research. The rotation could make the balance between the two black holes more stable, increasing the likelihood that such pairs exist in the Universe.
Jorge Santos, co-author of the study and professor of theoretical physics at the University of Cambridge, suggests that this theory could also apply to more complex systems, such as configurations with three or four black holes.
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