Spacetime quantum fabric: tangled black holes

Quantum particles can be connected through the wormhole of space-time

A hundred years ago, after Einstein developed the general theory of relativity, physicists are still unable to deal with perhaps one of the most difficult incompatibility problems in the universe. Einstein described the landscape of space-time like a picture of Salvador Dali - smooth, seamless, without gaps, geometric. But quantum particles that fill the space are more like the creation of Georges-Pierre Seurat - a point, discrete, described by probabilities. The basics of these two descriptions are contradictory. However, the new idea suggests that the quantum correlations of different points of the impressionist paintings create not only Dali’s landscapes, but also the canvas on which they are painted - as well as the three-dimensional space around them. Einstein, as is often the case with him, is at the center of all this, still turning our theories upside down.



A description of the new idea, ER = EPR, is like initials carved on a tree. This is a combination of two ideas proposed by Einstein in 1935. One is the Einstein-Podolsky-Rosen (EPR) paradox , a “frightening long-range action” between two elementary particles (spooky action at a distance). The second is the connection of two black holes through a wormhole (Einstein-Rosen Bridge, ER). At the time these ideas were born, there was no connection between them.



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Paradox EPR even hit the pages of newspapers



But what if we accept that these two ideas are manifestations of the same thing? Then this connection will be the basis of all space-time. Quantum entanglement, which so bothered Einstein, will be a manifestation of spatial connections that crosslink space, as Leonard Saskind, a physicist at Stanford University and one of the authors of the idea, says. Without such connections, the space would break up into “atoms,” according to Juan Maldacena, a physicist at the Princeton Institute for Advanced Study, a co-author of the idea. “In other words, a solid and reliable structure of space-time is possible only due to invisible entanglements,” he says. Moreover, the ER = EPR hypothesis may shed light on the relationship between gravity and quantum mechanics.



Of course, not everyone likes this idea (and, in the opinion of Saskind, it should not - it is still in its infancy). Joe Polchinski, a researcher at the University of California at Santa Barbara, is careful about his grades, but he is interested: “I don’t know where this is going, but it looks interesting enough.”

Black Hole Wars

The road leading to ER = EPR itself is like a Möbius strip, turning into itself and resembling Escher’s drawings.



You can start with quantum entanglement. If two particles are entangled, they turn into two parts of one whole. What happens to one happens to another, regardless of the distance between them.





Juan Maldacena



Maldacena explains this with the example of a pair of gloves: if you find the right one, you immediately know that the other one will be left. There is nothing frightening about it. But in quantum mechanics, both gloves at once are left and right (and all intermediate variants) until you make observations on one of them. What is even stranger - the left glove does not become left until you find the right glove - and at that moment they both acquire their properties.



Entanglement is closely related to the discovery by Stephen Hawking of 1974 of the fact that black holes evaporate. In space, constantly appear pairs of virtual particles of matter and antimatter. Hawking realized that if one particle falls into a black hole, and the other escapes from it, the hole will emit radiation. After a sufficient amount of time, the hole will disappear, which raises the question of information disappearing along with it.



But the laws of the quantum world prohibit the destruction of information. Therefore, the question arises - will the information that has fallen into a black hole be simply encrypted, or will it really disappear? Disputes about this led to the so-called. "Wars of black holes".



In the end, Saskind realized that all the information that fell into the hole falls into the trap of its two-dimensional event horizon. And everything is stored in it, as if a three-dimensional image in a hologram. It is as if the bits of information needed to recreate your home and all its contents could be placed on its walls. Information is not lost - it is encrypted and stored outside access.



After continuing to work on the idea, Saskind and Maldacena began to use the holographic principle, not only to understand black holes, but also any part of the space that can be described by its boundaries. Over the past ten years, the insane idea that space is a hologram has evolved into an ordinary, physicist tool used everywhere, from cosmology to superdense matter. “One of those events happening with scientific ideas is that they go from a crazy idea to a good idea, and then to a working tool,” says Suskind. It has become a routine. ”





Leonard Saskind



The holographic principle was related to what happens at the boundaries of objects, including the black hole event horizon. The question remains - what is happening inside. Since no information can leave the insides of the event horizon, the laws of physics prohibit direct checks of the insides of a black hole.



Then in 2012, the physicists Almhayri, Marolf, Polchinski and Sally - all from Santa Barbara, came to such a strange conclusion that one could say - wait a minute. We do not know anything.



T.N. the work of AMPS (according to the authors' initials) says that black holes may not have any viscera at all, since the “wall of fire” on the horizon of events will destroy everything that it tries to reveal their secrets.

Measuring a wall of fire

The essence of the work is as follows: if the black hole event horizon is a smooth and ordinary place, as predicted by TO (the authors call this condition “without drama”), particles ejected from a black hole must be entangled with particles falling into the hole. But in order not to lose information, particles flying out of a hole must also be entangled with those that have already left the hole long ago and are now scattered somewhere throughout Hawking’s radiation. So, we have too many entanglements.



Entanglement cannot exist between three particles simultaneously - only for each pair of particles. “Polygamousness” is impossible in the quantum world, which means that a smooth and extended space-time cannot exist in the “vent” of a black hole. The breakdown of entanglement on the horizon means that there is some kind of space boundary - a wall of fire.



Stephen Schenker, a physicist from Stanford, called the work of AMPS "trigger". Physicists love these paradoxes - they provide fertile ground for discovery.



Saskind and Maldassen immediately seized upon the idea. They worked on their intricacies and wormholes, inspired by the work of Mark Van Raamsdon, a physicist from the University of British Columbia in Vancouver. He made an important thought experiment, suggesting that entanglement and space-time are strongly interconnected.



“Once,” says Saskind, “Juan sent me a mysterious message containing the equation ER = EPR. I immediately understood what he meant, and we began to discuss the idea. ”



They presented their thoughts in the 2013 work “Cold horizons of entangled black holes”, describing the confusion that the authors of AMPS overlooked - the one that binds space together. AMPS suggested that parts of the space inside and outside the event horizon are independent. But Saskind and Maldasena believe that particles from either side of the border can be connected through a wormhole, and this can resolve the paradox. The picture from the work, some jokingly called "octopus" - many wormholes come from the insides of a black hole to Hawking radiation from the outside.







In other words, there is no need to invent intricacies that create strangeness on the smooth surface of the black hole vents. The particles inside it will be directly connected to the particles outside, which have long gone away. No need to cross the horizon. Internal and external particles are one, as explained Maldacena. The octopus combines the insides of a black hole with particles from the Hawking radiation cloud.

Holes in the hole

While there is no certainty that ER = EPR will solve the problem of the fire wall. John Presquil, a physicist at Caltech, recalls that physicists sometimes rely on their nose to “sniff out” promising theories. And at the first "nose" the theory of ER = EPR "may smell fresh and pleasant, but it still needs to ripen on the shelf."



Nevertheless, Schenker argues that the correspondence between the entanglement of particles and the geometry of a smoothly curved space-time is a big deal. This allowed him and his colleague from the Institute of Advanced Researchers to work with the complex problems of quantum chaos in such a way that, as Schenker says, “this simple geometry was understandable even to me.”



ER = EPR does not describe any part of any space or any confusion. She comes to a special entanglement and special wormholes. Marolf, who recently published a work describing wormholes with more than two ends, believes that physicists are aware of these limitations. ER = EPR works in special cases, but AMPS claims that the wall of fire is a much broader task.



Marolf and others worry that ER = EPR will change the standard quantum mechanics. “There is a feeling that only Lenny and Juan understand this thing,” says Marolf. But, all the same, we are working in an interesting time for science. ”



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