Researchers find quantum gravity has no symmetry

June 19, 2019

A new study by a pair of researchers in the US and Japan has found that, when gravity is combined with quantum mechanics, symmetry is not possible.

"Many physicists believe that there must a beautiful set of laws in Nature and that one way to quantify the beauty is by symmetry. Some of the symmetries may be hidden in our world, but they should manifest themselves if we look at Nature at a more fundamental level. We showed that this expectation is wrong once we take into account the gravity," said Hirosi Ooguri, Director of the Kavli Institute for the Physics and Mathematics of the Universe, and one of the paper authors.

There are four kinds of fundamental forces in Nature: electromagnetism, strong force, weak force, and gravity. Of the four, the gravity is the only one still unexplainable at the quantum level. Researchers believe the holographic principle is an important hint to combine the gravity and quantum mechanics successfully.

A hologram makes three-dimensional images pop out from a two-dimensional screen. Similarly, the holographic principle allows physicists to study gravitational systems by projecting them on a boundary that surrounds the entire Universe. The AdS/CFT (anti-de Sitter/conformal field theory) correspondence, developed in the late 1990s by Juan Maldacena, has been particularly useful because it gives a precise mathematical definition of the holographic principle.

In the paper published on May 17, Ooguri and Daniel Harlow, Assistant Professor at Massachusetts Institute of Technology, proved that symmetry is not possible in a gravitational theory if it obeys the holographic principle.

Previous work by Harlow and others had found a precise mathematical analogy between the holographic principle and quantum error correcting codes, which protects information in a quantum computer. In the new paper, Ooguri and Harlow showed such quantum error correcting codes are not compatible with any symmetry, meaning that symmetry would not be possible in quantum gravity.

Their result has several important consequences. In particular, it predicts that the protons are stable against decaying into other elementary particles, and that magnetic monopoles exist.

Details of their study were published in Physical Review Letters on May 17 and selected for Editor's Suggestion "due to its particular importance, innovation, and broad appeal."

Kavli Institute for the Physics and Mathematics of the Universe

Related Quantum Mechanics Articles from Brightsurf:

Theoreticians show which quantum systems are suitable for quantum simulations
A joint research group led by Prof. Jens Eisert of Freie Universit├Ąt Berlin and Helmholtz-Zentrum Berlin (HZB) has shown a way to simulate the quantum physical properties of complex solid state systems.

A new interpretation of quantum mechanics suggests reality does not depend on the measurer
For 100 years scientists have disagreed on how to interpret quantum mechanics.

New evidence for quantum fluctuations near a quantum critical point in a superconductor
A study has found evidence for quantum fluctuations near a quantum critical point in a superconductor.

Simulating quantum 'time travel' disproves butterfly effect in quantum realm
Using a quantum computer to simulate time travel, researchers have demonstrated that, in the quantum realm, there is no 'butterfly effect.' In the research, information--qubits, or quantum bits--'time travel' into the simulated past.

Orbital engineering of quantum confinement in high-Al-content AlGaN quantum well
Recently, professor Kang's group focus on the limitation of quantum confine band offset model, the hole states delocalization in high-Al-content AlGaN quantum well are understood in terms of orbital intercoupling.

A Metal-like Quantum Gas: A pathbreaking platform for quantum simulation
Coherent and ultrafast laser excitation creates an exotic matter phase with spatially overlapping electronic wave-functions under nanometric control in an artificial micro-crystal of ultracold atoms.

Fluid mechanics mystery solved
An environmental engineering professor has solved a decades-old mystery regarding the behavior of fluids, a field of study with widespread medical, industrial and environmental applications.

Quantum leap: Photon discovery is a major step toward at-scale quantum technologies
A team of physicists at the University of Bristol has developed the first integrated photon source with the potential to deliver large-scale quantum photonics.

USTC realizes the first quantum-entangling-measurements-enhanced quantum orienteering
Researchers enhanced the performance of quantum orienteering with entangling measurements via photonic quantum walks.

A convex-optimization-based quantum process tomography method for reconstructing quantum channels
Researchers from SJTU have developed a convex-optimization-based quantum process tomography method for reconstructing quantum channels, and have shown the validity to seawater channels and general channels, enabling a more precise and robust estimation of the elements of the process matrix with less demands on preliminary resources.

Read More: Quantum Mechanics News and Quantum Mechanics Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to