James Prescott Joule

Joule is famous for experiments showing the mechanical equivalent of heat, including a paddle-wheel apparatus that warmed water through mechanical work. These 1840s experiments helped establish that heat is a form of energy rather than a fluid substance.

The joule is the SI unit of energy, named for James Prescott Joule because of his work on heat, work, and energy conservation. One joule is the energy transferred when a force of one newton moves an object one meter.

Joule's measurements supported the idea that energy is conserved while changing form. His work helped make the first law of thermodynamics scientifically persuasive in the nineteenth century.

Yes, Joule collaborated with William Thomson, later Lord Kelvin, on the Joule-Thomson effect. That effect describes how a gas temperature can change when it expands without external work, a principle used in refrigeration.