Physics

Theoretical physicists develop method to model the central theory of quantum gravity in the lab

Illustration of the theory used to model quantum gravity: The lattice simulates a curved space-time. Near the boundary, the lattice becomes denser due to the curvature. Interacting electrical signals in the bulk (yellow, red, and blue lines) simulate the gravitational dynamics. The dynamics in the bulk and at the outer boundary correspond to each other. They are consistent with the AdS/CFT correspondence. Credit: Erdmenger/JMU, Böttcher/Alberta

For physicists, gravity is no longer a mystery. At least, over large distances. Thanks to science, we can calculate the orbits of planets, predict the tides and launch rockets into space with precision. But the theoretical description of gravity reaches its limits at the level of the smallest particles, the so-called quantum level.

“To explain the Big Bang or the interior of black holes, we need to understand the quantum properties of gravity,” explains Professor Johanna Erdmenger, Chair of the Department of Theoretical Physics III at the University of Würzburg (JMU) in Bavaria, Germany.

“At very high energies, the classical laws of gravity do not hold. Our goal is therefore to contribute to the development of a new theory that can explain gravity at all scales, including the quantum level.”

Central theory of quantum gravity

The AdS/CFT correspondence, which is central to quantum gravity theory, plays a key role in the development of the new model: it shows that a complex theory of gravity in a higher-dimensional space can be described by a simpler quantum theory at the boundary of that space.

AdS stands for anti-de Sitter, a special type of space-time that curves inwards like a hyperbola. CFT stands for Conformal Field Theory, which describes quantum physical systems whose properties are the same across all spatial distances.

“It sounds very complicated at first, but it’s easy to explain,” Erdmenger says. “The AdS/CFT correspondence allows us to understand difficult gravitational processes, such as those that exist in the quantum world, using a simpler mathematical model. At its heart is a curved space-time, which can be thought of as a funnel.”

“This correspondence shows that the quantum mechanics at the edge of the funnel must correspond to more complex mechanics inside. This is similar to the hologram on a banknote, which produces a three-dimensional image despite being itself two-dimensional.”

Proof of concept for achieving gravitational dynamics in the laboratory

Erdmenger and his team developed a way to experimentally test a previously unconfirmed prediction of the AdS/CFT correspondence by using a branched electrical circuit to mimic curved space-time: the electrical signals at each branch of the circuit correspond to the gravitational dynamics seen at different points in space-time.

The research was published in the journal Physical Review Letters.

The team’s theoretical calculations show that in the proposed circuit, the dynamics at the edges of the mimicked spacetime also correspond to the dynamics in its interior, and thus the central predictions of the AdS/CFT correspondence can be fulfilled by the circuit.

As a next step, the Würzburg team is now planning to put the experimental setup described in the study into practical use, which could lead to major advances in gravity research as well as technological innovations.

“Our circuit also opens up new technological applications,” explains Erdmenger. “Based on quantum techniques, it bundles and stabilizes the signals by simulating the curvature of space, which hopefully allows the transmission of electrical signals with reduced losses. This would be a breakthrough, for example, for signal transmission in neural networks used in artificial intelligence.”

Further information: Santanu Dey et al., “Simulations of holographic conformal field theory on hyperbolic lattices,” Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.133.061603. On arXiv: DOI: 10.48550/arxiv.2404.03062

Courtesy of Julius Maximilian University of Würzburg

Citation: Theoretical Physicists Develop Method to Model Central Theory of Quantum Gravity in the Lab (September 16, 2024) Retrieved September 17, 2024 from https://phys.org/news/2024-09-theoretical-physicists-method-central-theory.html

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