Erasing a single bit of information isn't free. In 1961, Rolf Landauer showed that at room temperature, it takes at least about 3 zeptojoules of energy — a tiny but nonzero amount. This limit was considered as ironclad as the conservation of energy.
But what if you could give the system a little nudge? Physicists took a microscopic resonator, a tiny vibrating plate, and placed it in a virtual potential well created by a laser. The well had two stable positions, like a ball in a dimpled cup with two hollows. The bit was stored by which hollow the ball sat in. Erasing meant making the ball always roll into the same hollow, regardless of where it started.
The key trick was hysteresis. This is when a system remembers its history: the force that returns the ball to the center depends on where it came from. Like a door that closes with different effort depending on whether you pushed it in or out. By tuning the hysteresis, the scientists created a non-equilibrium state with an effective temperature below room temperature. In this state, erasing a bit cost 20% less than Landauer's limit.
This doesn't break physics; it sidesteps it. Landauer's limit holds for equilibrium, but here the system is kept away from it. The practical benefit is in creating more energy-efficient information-processing devices, where every bit counts.
Landauer's principle links information and energy: erasing a bit inevitably turns some energy into heat. It's a bridge between information theory and thermodynamics.
In Greg Egan's novel "Permutation City," digital copies of people exist in a simulation where the laws of thermodynamics can be rewritten — experiments like this blur the line between information and physical reality.