Physics
Why the world remembers which way time runs.
The microscopic laws of physics are very nearly time-reversal symmetric — run them backwards and they remain valid — yet the world around us is full of irreversibility. The resolution is entropy and information. This programme covers thermodynamic reversibility, the arrow of time, Maxwell's demon, and Landauer's principle, which ties physical reversibility directly to computation.
Latest news
A universal recipe for extracting work without knowing the state
A 2026 result builds a single state-independent quantum process that still extracts work equal to the free energy of an unknown state, near the reversible bound.
PhysicsReal memory cells reveal a thermodynamic limit stricter than Landauer’s
Single-electron-resolved measurements on silicon DRAM showed bit erasure never reaches the Landauer bound, exposing a tighter, practically relevant limit on erasure energetics.
PhysicsA single-qubit engine amplifies microwaves using only quantum measurement
A superconducting qubit acts as a quantum Maxwell demon, turning the backaction energy of repeated measurements into amplified microwave pulses with no hot thermal source.
Explore
Principles →
Reversible processes, Loschmidt's paradox, Landauer's principle and Maxwell's demon.
Thermodynamics →
Reversibility, the second law, the Carnot benchmark and the fluctuation theorems.
Information →
Landauer's principle, Maxwell's demon and the physics of information.
Research →
The people and venues behind the thermodynamics of information.
Key ideas
Thermodynamic reversibility
A reversible process is a quasi-static, entropy-conserving idealisation. Real processes have finite rates, friction and heat flow across finite temperature differences, so they produce entropy: ΔStotal > 0, with equality only in the reversible limit.
Microscopic reversibility & Loschmidt's paradox
The microscopic equations of motion are time-reversal symmetric, yet macroscopic behaviour is not. This tension — Loschmidt's paradox — is resolved statistically: from a low-entropy start, evolution toward higher-entropy macrostates is overwhelmingly probable.
Landauer's principle
Erasing one bit of information must dissipate at least kT ln 2 of heat. Physical reversibility and computation are tied together: information is physical.