Szilard's engine

Szilard's engine is a thought experiment in thermodynamics illustrating how information affects energy. It involves a sterile box with a single particle of gas and a dividing wall. A hypothetical intelligent being (an "agent") can observe which side the particle is on and insert a piston accordingly. By doing this, the agent can extract work—like lifting a weight—without violating physical laws. The engine shows that acquiring and using information about a system’s state can be converted into usable energy, highlighting the deep connection between information, measurement, and thermodynamic work.