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Scientists have found a way to create black holes without the mysterious singularities where physics breaks down. Using pure gravity rather than exotic matter, their new model challenges previous theories and brings us closer to understanding the true nature of space-time. The breakthrough not only simplifies the conditions for black holes to form, but also aligns with the fundamental laws of thermodynamics. The research opens the door to new astrophysical applications and could ultimately reveal how the universe prevents singularities from forming.
Black holes without singularities
Black holes, as described in Albert Einstein's theory of general relativity, are thought to contain singularities - points where the laws of physics no longer apply. Understanding how these singularities can be resolved within the framework of quantum gravity remains one of the biggest challenges in theoretical physics. Now, researchers from the Institute for Space Sciences of the University of Barcelona (ICCUB) have made a groundbreaking discovery. They have demonstrated for the first time that black holes can form solely through gravitational effects, without requiring exotic matter - an ingredient that some previous models have relied on.
Published in Physics Letters B, this finding opens up new insights into the quantum nature of gravity and could change our understanding of the true structure of space-time.
Exotics are no longer needed
Term exotic matter refers to a type of matter that has unusual properties not found in ordinary matter. It often has negative energy density, produces gravitational repulsive effects, and can violate certain energy conditions in general relativity. Exotic matter is largely theoretical and has not been observed in nature, but is used in models to investigate concepts such as wormholes, faster-than-light travel, and the resolution of black hole singularities.
A new study mathematically demonstrates that an infinite series of higher-order gravitational corrections can eliminate these singularities and lead to so-called regular black holes.
Pure gravity and ordinary black holes
Unlike previous models that required exotic matter, this new study shows that pure gravity—without additional matter fields—can generate regular black holes without singularities. This discovery represents a significant departure from previous theories and simplifies the conditions required for regular black holes.
"The beauty of our design is that it is based only on modifications of Einstein's equations, naturally predicted by quantum gravity. No other components are required," says researcher Pablo A. Cano from the Department of Quantum Physics and Astrophysics, Faculty of Physics and ICCUB.
The theories developed by the ICCUB team are applicable to any space-time dimension greater than or equal to five. “The reason for considering higher dimensions of space-time is purely technical,” says Kano, “because it allows us to reduce the mathematical complexity of the problem.” However, the researchers say that “the same conclusions should apply to our four-dimensional space-time.”
Unraveling the mystery of singularities
"Most scientists agree that the singularities of general relativity must be finally resolved, although we know very little about how this process can be achieved. Our work provides the first mechanism to achieve this in a reliable way, albeit under certain assumptions about symmetry," explains Robi Hennigar (UB and ICCUB). "It is not yet clear how nature prevents the formation of singularities in the Universe, but we hope that our model will help us better understand this process," says the expert.
Thermodynamics and Astrophysics
The study also examines the thermodynamic properties of these regular black holes and shows that they obey the first law of thermodynamics. The theories developed provide a solid framework for understanding the thermodynamics of black holes in a completely universal and unambiguous way. This consistency adds credibility and potential applicability to the findings. The researchers plan to extend their work to four-dimensional space-time and explore the implications of their findings in different astrophysical scenarios. They also aim to investigate the stability and possible signatures of observations of these regular black holes.
"These theories not only predict black holes without singularities, but also allow us to understand how these objects form and what is the fate of the matter that falls into the black hole. We are already working on these questions and expect to get really exciting results," Kano concludes.
