This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Recent research shows that gravity and quantum information are deeply connected and that the shape of spacetime can be traced back to the way information is stored in quantum fields. Einstein's theory of general relativity describes gravity as the curvature of space and time caused by matter and energy.
Quantum theory, on the other hand, describes the microscopic world. Uniting the two is one of the biggest open problems in physics. In 1995, the physicist Ted Jacobson showed that Einstein's equations can be derived from thermodynamics, the physics of heat and entropy, much like the laws governing a gas emerge from the motion of its molecules.
This suggested that gravity might not be fundamental but could emerge from something deeper. In their research, published in the journal Physical Review Letters, the authors reconstruct the thermodynamic derivation of general relativity through sophisticated mathematical methods that connect quantum information to spacetime geometry. However, the paper and extensive conversations with the authors suggest that their research could provide new clues about the origin of gravity, a tentative conclusion they reach through their use of quantum relative entropy.
The authors build on the idea that space and gravity may not be fundamental features of nature but may instead emerge from the quantum world. Rather than relying on the classical notion of entropy, they employ quantum relative entropy, a precise mathematical measure from quantum information theory that quantifies how distinguishable two quantum states are. "We show that this quantity, evaluated at a horizon—a boundary in spacetime beyond which no information can be received—equals the energy flowing across that horizon," explained Dr.
Albert Much, assistant professor of quantum field theory and general relativity and coauthor of the study. "Combined with the well-established relation between entropy and the area of horizons, as illustrated by Bekenstein and Hawking, this leads directly to the equations that describe how quantum matter curves spacetime." Relative entropy measures how well two quantum states can be told apart. Imagine the surface of the sea, which is never perfectly still.
Its constant rippling is like the quantum vacuum, the state we call empty space. Now imagine a wave passing across this surface. Relative entropy tells us how well one can distinguish that wave from the rippling background.
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