- Two quantum models produce Newtonian gravity from entropy alone.
- Gravity may be disorder pushing masses together, not a fundamental pull.
- The models reproduce Newton but cannot yet recover Einstein's relativity.
Daniel Carney has spent his career thinking about a result that should not exist. Black holes have temperature. They radiate heat. A phenomenon defined by the most extreme gravitational collapse in nature behaves, somehow, like a thermodynamic system.
"I've been mystified by this result for my entire adult life," says Carney, a theoretical physicist at Lawrence Berkeley National Laboratory.
The mystery led him toward an old and unsettling question: could gravity, the force that holds galaxies together, be an illusion produced by entropy? The idea, known as entropic gravity, has circulated in theoretical physics for decades – but nobody had built a working microscopic model.
Now Carney and four colleagues have done something about it. In a paper published in Physical Review X in August 2025, they built two microscopic quantum models in which gravitational attraction emerges not from a fundamental force but from entropy. The tendency of any system to drift toward maximum disorder.
In their models, gravity is not pulling. The universe's disorder is pushing.
Three centuries of pulling
Isaac Newton published his law of universal gravitation in 1687. Two masses attract each other in proportion to their sizes and in inverse proportion to the square of the distance between them. The mathematics worked beautifully.
The mechanism remained a mystery. Newton himself called it "so great an absurdity" that action at a distance needed explaining.
Einstein replaced Newton's invisible rope with curved spacetime. Mass tells space how to bend; space tells mass how to move. Both frameworks treat gravity as something fundamental, built into the fabric of reality.
What is entropic gravity?
The idea that gravity is not a fundamental force but an emergent effect, arising from the statistical tendency of physical systems to maximize their entropy (disorder). Just as gas molecules spread to fill a room without any force pushing them, gravitational attraction could be a macroscopic consequence of microscopic disorder seeking its maximum.
A different tradition asks whether gravity might be neither a force nor a curvature, but a statistical consequence. In 1995, theoretical physicist Ted Jacobson at the University of Maryland derived Einstein's equations of general relativity from thermodynamic principles alone.
Fifteen years later, Erik Verlinde at the University of Amsterdam argued that gravity is entirely entropic. A by-product of information and disorder.
The physics community was intrigued. Then sceptical. The arguments were elegant but abstract, operating at the level of thermodynamic reasoning without specifying what microscopic system could produce such behaviour.
Two toy universes made of qubits
Carney's contribution is making the idea concrete. His team constructed two models from qubits, the basic units of quantum information.
In the first, qubits sit in a crystalline grid and align in the presence of massive objects, creating small pockets of order. In the second, qubits lack fixed positions but carry energy capacities that depend on how far apart objects are.
Key figure
2
The number of independent microscopic quantum models that reproduce Newtonian gravity from entropy alone, presented in a single paper.
In both cases, the same thing happens. The system's drive to maximize total entropy nudges ordered regions closer together. The result looks precisely like Newtonian gravitational attraction.
No fundamental force required.
"There's some kind of gas or some thermal system out there that we can't see directly," Carney says.
Where Jacobson and Verlinde worked from the top down, starting with thermodynamic equations and deriving gravitational ones, Carney's group works from the bottom up. They specify microscopic components and let gravity emerge.
The distinction matters. Top-down arguments show that gravity and thermodynamics share mathematical structure. Bottom-up models suggest that structure might reflect physical reality.
Newton, yes. Einstein, not yet
The models have limits, and Carney is characteristically candid about them. "It actually seems to require a peculiar engineered-looking interaction to get this to work," he says. The qubit interactions need precise tuning to reproduce gravitational behaviour.
That tuning could signal hidden structure. It could also simply mean the models are too simple.
More significantly, they reproduce Newton but not Einstein. The gravitational attraction that emerges is Newtonian, valid for weak fields and low speeds. General relativity, with its curved spacetime, gravitational waves, and black holes, remains out of reach.
Mark Van Raamsdonk, a theoretical physicist at the University of British Columbia, has pointed out that the models do not capture key features of general relativity. The absence of gravitational force during free fall, a hallmark of Einstein's equivalence principle, is missing entirely.
For entropic gravity to graduate from curiosity to contender, it would need to recover Einstein's full theory.
I've been mystified by this result for my entire adult life.
Daniel Carney, Lawrence Berkeley National Laboratory
The weak-field test
Separately, Ginestra Bianconi at Queen Mary University of London published a framework in Physical Review D in March 2025 that derives gravitational effects from quantum relative entropy. Her approach treats the spacetime metric itself as a quantum operator.
It hints at connections to dark matter. A very different direction from Carney's, but rooted in the same conviction: gravity and information are entangled at some fundamental level.
Verlinde, whose 2010 paper started much of this conversation, sees the path forward in observation rather than theory. "You have to go to very weak fields, because then these fluctuations might become observable," he says.
In strong gravitational environments, any entropic signal would be drowned out by conventional physics. In the quietest gravitational environments, such as the outer edges of galaxy clusters, the statistical noise that entropic models predict could become detectable.
The textbooks still describe gravity as a fundamental force. Carney's qubit models will not change that tomorrow. But other groups are now designing experiments to test whether entropic signatures appear in precisely those weak-field regimes where Verlinde says to look.
The question is no longer purely theoretical - and it connects to related proposals that treat gravity as an emergent byproduct of deeper computational or informational principles. If the signatures are there, three centuries of asking what gravity is may give way to a stranger question: whether gravity is a thing at all.
That question could carry some real weight.
Sources
- Primary Research: On the Quantum Mechanics of Entropic Forces (Carney et al., Physical Review X, 2025)
- Additional Context:
- Is Gravity Just Entropy Rising? Long-Shot Idea Gets Another Look (Quanta Magazine)
- Gravity from entropy: A radical new approach (Phys.org)
Fact Check: Claim-by-Claim Verification Verified
The article accurately summarizes Carney et al.'s 2025 Physical Review X paper and historical context of entropic gravity, with correct names, dates, affiliations, and limitations.
Commentary
- Article simplifies qubit models (grid vs. non-local) but captures essence without errors; dramatic phrasing like "push not pull" is acceptable for popular science.
- Quotes from Carney align with Quanta article; no misattributions found.
Sources used for verification
Academic/Peer-reviewed:
- On the Quantum Mechanics of Entropic Forces - APS.org
- On the quantum mechanics of entropic forces - arXiv.org
- Thermodynamics of Spacetime: The Einstein equation of state? - arXiv.org
- On the Origin of Gravity and the Laws of Newton - arXiv.org
Other reliable sources:
- Is Gravity Just Entropy Rising? Long-Shot Idea Gets Another Look - Quantamagazine.org
- Gravity from entropy: A radical new approach - Phys.org
- Daniel Carney - lbl.gov
Fact-checked by Perplexity Sonar Pro on 2026-03-09
