A quantum solution for black holes

The two families of physics They have not spoken for 100 years. Einstein’s general relativity describes with centenary precision The large-scale universe: how the planets, stars and galaxies deform the space-time fabric. On the other hand, quantum mechanics explains the strange and tiny world of subatomic particles.

Both theories form the pillars of modern science, but are fundamentally incompatible. Unifying them in a single theory of “quantum severity” is, for decades, The Holy Grail of Physics. New research suggests that the key to achieving this could be hidden in the heart of the more enigmatic objects of the universe: Black holes.

The impassable wall of physics. The problem is simple and the time incredibly complex. Quantum mechanics has managed to explain three of the four fundamental forces of nature: electromagnetism, strong nuclear force and weak nuclear force. Gravity, however, resists him. General relativity, our best theory of gravity, falls apart in the most extreme environments of the universe, precisely where quantum effects should be crucial.

The clearest example of this rupture is the singularities, the theoretically infinite density points that are found In the center of black holes. For physicists, an infinity in an equation is an alarm signal that indicates that the theory has reached its limit. “We believe that general relativity only works on large or ‘macroscopic’ scales, but that in very short distances, or microscopic scales, it must be replaced by a quantum theory of gravity,” He explained to Space.com Theoretical physicist Xavier Calmet, author of a new study published in Europhysics Letters.

A new recipe for black holes. Until now, string theory was the main candidate for this unification, in the absence of experimental verification. But Calmet and his team have adopted a different and surprisingly effective approach. Instead of a complete and finished quantum theory, they have used what is known as the “effective action of Vilkovisky-Dewitt” to calculate universal quantum corrections that should be applied to Einstein’s equations, regardless of the underlying theory.

When applying these corrections, the team discovered something fascinating: in addition to black holes that arise from general relativity, there must also be holes born from “quantum solutions.” And it is not simple adjustments to the black holes we already knew. “They are completely new black holes that exist in a world of quantum gravity,” explains Calmet. New theoretical objects that emerge from the same mathematics, but with a quantum “flavor.”

What all this means. Einstein’s relativity works great for huge things such as planets and galaxies (a continuous world); and quantum mechanics, for the tiny, like atoms (a world to jump). When it comes to explaining black holes, relativity predicts a singularity, an infinite density point that, in practice, tells us that the theory does not work anymore.

What these physicists have done is to use a mathematical “patch” to add the basic quantum rules to relativity. This patch is the action of Vilkovisky-Dewittdeveloped by physicists Georgy Vilkovisky and Bryce Dewitt. In doing so, they not only fixed the “error”, but discovered that the new rules allow the existence of a completely new type of black hole, one that simply could not exist according to Einstein’s old rules.

Can we ever see them? The study details how these solutions can be built near the events horizon, the border from which nothing can escape the black hole. Although these quantum solutions are theoretically different, distinguishing them from their classic counterparts is, for now, an almost impossible task. The most significant differences manifest very close to the horizon of events, a region that we cannot observe directly.

“The astrophysical black holes that we are observing well could be described with our new solutions instead of those of general relativity,” Callmet concludes. “As both theories match great distances, it will be difficult to propose evidence capable of differentiating between the two types of solutions.”

The theory shows that it is possible that There are black holes within a frame of quantum gravity. But the secrets of quantum gravity remain fiercely saved by these cosmic titans: the response to the greatest enigma of modern physics is not in a particle accelerator, but quietly orbiting in the darkness of space.

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