Ginestra Bianconi, a professor of applied mathematics at Queen Mary University of London, has published a study that says gravity comes from entropy. The work, called 'Gravity from Entropy,' appeared in Physical Review D. It aims to connect quantum mechanics, which explains tiny particles, with general relativity, Einstein's idea of gravity as curved space. This long search for a single theory of physics might see progress here.
Background
Physicists have tried for years to blend two big ideas. Quantum mechanics works for small things like atoms and light. It says particles can act like waves and exist in many states at once. General relativity handles big things like planets and stars. It sees gravity as bends in space caused by mass.
The two do not mix well. Quantum mechanics needs math that breaks down at huge scales, like black holes. General relativity ignores the fuzzy rules of the small world. Many have chased quantum gravity, a theory that fits both. String theory and loop quantum gravity tried but hit roadblocks. No full answer has stuck.
Bianconi's approach uses entropy. Entropy measures disorder or how spread out information is. In quantum terms, relative entropy compares states of systems. She treats space's shape, or metric, as a quantum tool that changes states. This lets entropy link space bends to matter.
Her idea builds on past work. Erik Verlinde said gravity might come from entropy in 2010. Others linked information to black holes. Bianconi goes further by making math that matches known gravity at everyday levels.
Key Details
The core of the theory is an entropic action. This is a number that shows the gap between space's shape and the shape matter creates. To minimize this gap, space curves in ways that look like gravity.
How the Math Works
Bianconi writes space's metric as a quantum operator. Matter fields, like those for particles, interact with it. Quantum relative entropy measures their mismatch. The theory changes Einstein's equations slightly. At low energy and small curves, they match the old ones exactly.
A new piece called the G-field appears. It is like a helper that balances the equations. The G-field acts as a multiplier in the math setup. It has size and direction, like a vector field.
The theory predicts a small positive cosmological constant. This is the push that makes the universe expand faster. Observations show this push exists, but past theories guessed wrong sizes. Bianconi's matches real data better.
"This work proposes that quantum gravity has an entropic origin and suggests that the G-field might be a candidate for dark matter," said Professor Ginestra Bianconi. "Additionally, the emergent cosmological constant predicted by our model could help resolve the discrepancy between theoretical predictions and experimental observations of the universe's expansion."
Tests so far look good in simple cases. The equations recover Newton's gravity law for weak fields. They also fit how light bends near the sun.
Dark matter fits in too. This unseen stuff holds galaxies together. Its pull acts like extra mass. The G-field might provide that pull without new particles.
What This Means
If the theory holds, gravity is not basic. It comes from how quantum information arranges itself. Space does not just bend; it seeks order through entropy.
Quantum gravity would follow. Black holes, big bang starts, and tiny space bits could use the same rules. No need for extra dimensions or spins like in other ideas.
Dark matter gets a fresh look. Labs hunt particles like WIMPs or axions but find none. The G-field offers a gravity-based answer. It might explain why galaxies spin fast without flying apart.
The cosmological constant puzzle shrinks. Why the universe speeds up has bugged experts. This theory gives a natural small value from quantum effects.
Wider effects touch daily physics. Particle colliders like the LHC test high energies. If G-fields show up, it backs the idea. Space probes measure expansion to check the constant.
Other fields might borrow the math. Quantum computers deal with entropy daily. Linking it to gravity could speed designs.
Challenges remain. The theory needs full checks against data. High-curve cases, like neutron stars, must match. Experts will test if it beats rivals.
Bianconi plans more work. She wants to compute black hole traits and early universe heat. Partners in quantum info might run simulations.
This step joins a line of entropy-gravity tries. Each adds pieces. If it pans out, physics textbooks change. Gravity becomes an outcome of disorder's drive to balance.
Researchers watch close. Conferences buzz with talks. Young physicists see paths in info theory. The hunt for one big theory rolls on, with entropy now in play.
