ScienceNot yet confirmed elsewhere1 publisher2 min readPublished
Physicists say quantum relative entropy at a horizon yields Einstein's equations
Authors of a Physical Review Letters paper say they derive Einstein's equations from quantum relative entropy evaluated at a horizon. Their stated gain is mathematical rigor, since the ingredients were already known.
The Scientist · Science desk
What happened
- Ted Jacobson showed in 1995 that Einstein's equations can be derived from thermodynamics, the physics of heat and entropy.
- The new paper swaps classical entropy for quantum relative entropy, a measure from quantum information theory of how distinguishable two quantum states are.
- Coauthor Albert Much says relative entropy at a horizon "equals the energy flowing across that horizon" and, with the Bekenstein-Hawking entropy-area relation, "leads directly to the equations that describe how quantum matter curves spacetime."
- Coauthor Philipp Dorau of Leipzig University says the findings suggest quantum field theory in curved spacetime hints at a more fundamental relation, with local spacetime curvature tied to quantum information.
Why it matters
- contradiction The account's opening says the research shows gravity and quantum information are deeply connected, but it later calls the authors' conclusion about gravity's origin tentative and their fundamental ingredients already known.
- constraint Quantum field theory in curved spacetime is often seen as a first step toward quantum gravity, so the result leaves the larger problem of uniting relativity and quantum theory open.
- exposure The authors rest the paper's significance on the genuine novelty of their proof, so a gap in that proof would remove most of what they say is new.
Relative entropy is easiest to picture on water. The account offers this image: the surface of the sea is never perfectly still, and its constant rippling is like the quantum vacuum, the state we call empty space [20]. Now picture a wave passing across it. Relative entropy tells how well one can distinguish that wave from the rippling background [20]. The horizon matters because it is a boundary in spacetime beyond which no information can be received [17].
The swap addresses a looseness the authors see in the older argument. For decades the link between entropy and gravity relied on analogies with classical thermodynamics [10], and the researchers say the relationship was often presented through physical intuition and suggestive arguments [4]. Albert Much, an assistant professor of quantum field theory and general relativity [7], said: "Our derivation uses mathematically rigorous and well-defined quantities, replacing earlier heuristic arguments," [5]
What comes out is the quantum-corrected form of the equations. "The equations of gravity, in their quantum-corrected form, can be obtained from quantum information," Much said [21]. He words the larger inference with a "may". The derivation, he said, "supports the view that spacetime and gravity may emerge from more fundamental quantum information, a key clue in the search for a theory of quantum gravity." [18]
In our view the defensible reading is the authors' own: a tighter proof of a link that was already known [3], offered as a clue about quantum gravity [18]. A derivation has no sample and no control to inspect. Its test is whether other physicists can follow each step. The account quotes only coauthors Much and Dorau [13], and it reports no assessment of the proof from physicists outside the group.
What to watch
- Whether physicists outside the author group publish checks or extensions of the proof; the phys.org account reports none.
- Whether anyone identifies an observation that could separate this information-based picture of gravity from the standard one.
- The full paper text, for the assumptions the proof makes about the quantum states and horizons it covers.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence35
- Adoption
- Insufficient
- Hype gap+20
- Incentives50
- Confidence45
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The study is published in Physical Review Letters, and its authors reconstruct the thermodynamic derivation of general relativity through mathematical methods that connect quantum information to spacetime geometry.
- [2]
In 1995 the physicist Ted Jacobson showed that Einstein's equations can be derived from thermodynamics, the physics of heat and entropy.
- [3]
The authors acknowledge that the fundamental ingredients of the deep connection between information and gravity were already known.
- [4]
The researchers emphasize that the relationship between information and gravity was often presented in terms of physical intuition and suggestive arguments, not a fully rigorous mathematical framework with precise derivations and proofs.
- [5]
Much said: "Our derivation uses mathematically rigorous and well-defined quantities, replacing earlier heuristic arguments,"
- [6]
According to the account, the paper and extensive conversations with the authors suggest the research could provide new clues about the origin of gravity, a tentative conclusion the authors reach through their use of quantum relative entropy.
- [7]
Albert Much is an assistant professor of quantum field theory and general relativity and a coauthor of the study.
- [8]
Quantum field theory in curved spacetime describes quantum matter in a gravitational background and is often seen as a first step toward quantum gravity.
- [9]
Uniting general relativity and quantum theory is one of the biggest open problems in physics.
- [10]
For decades, the connection between entropy and gravity relied on analogies with classical thermodynamics.
- [11]
The phys.org account opens by saying recent research shows that gravity and quantum information are deeply connected and that the shape of spacetime can be traced back to how information is stored in quantum fields.
- [12]
The authors argue that the significance of their findings rests on the genuine novelty of their proof.
- [13]
The only people quoted in the phys.org account are coauthors Albert Much and Philipp Dorau.
- [14]
Instead of the classical notion of entropy, the authors employ quantum relative entropy, a measure from quantum information theory that quantifies how distinguishable two quantum states are.
- [15]
Albert Much said that relative entropy, evaluated at a horizon, "equals the energy flowing across that horizon".
- [16]
Much said that, combined with the well-established relation between entropy and the area of horizons illustrated by Bekenstein and Hawking, this "leads directly to the equations that describe how quantum matter curves spacetime."
- [17]
A horizon is a boundary in spacetime beyond which no information can be received.
- [18]
Much said: "This supports the view that spacetime and gravity may emerge from more fundamental quantum information, a key clue in the search for a theory of quantum gravity."
- [19]
Coauthor Philipp Dorau, a theoretical physicist at the Institute for Theoretical Physics at Leipzig University, says the findings suggest that quantum field theory in curved spacetime hints at a more fundamental relation: local spacetime curvature is tied to quantum information.
- [20]
The account pictures the quantum vacuum as the surface of the sea, which is never perfectly still; relative entropy tells how well one can distinguish a passing wave from the rippling background.
- [21]
Much said: "The equations of gravity, in their quantum-corrected form, can be obtained from quantum information,"
Sources
1 independent publisher whose own reporting we read for this story.
- phys.orgGravity and quantum information linked through a derivation of Einstein's equations
1 article · October 12, 2026
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