Knowra Perpetual motion Perpetual motion Perpetual motion is motion that continues indefinitely without an external energy supply. A perpetual-motion machine is an impossible device claimed to run forever while producing net work.
Conservation of energy : The physical principle that energy cannot be created or destroyed, only transferred or transformed. A machine cannot deliver energy indefinitely without an equivalent source.
Bhāskara's wheel : A proposed self-turning wheel with mercury-filled containers arranged around its rim. Its shifting mercury was meant to keep one side heavier, but the cycle cannot yield net rotation.
Newton's first law : The law stating that an object maintains its velocity unless acted on by a net external force. Ideal motion can persist without ongoing energy input, but it does not thereby produce unlimited work.
Patent : A government-granted, time-limited right to exclude others from making, using, or selling an invention. Some patent systems require a credible working demonstration, making perpetual-motion claims difficult to patent.
First law of thermodynamics : The thermodynamic statement of energy conservation for systems exchanging heat and work. It rules out a machine that produces work without drawing energy from somewhere.
Cox's timepiece : An eighteenth-century clock designed to draw energy from changes in atmospheric pressure or temperature. It appeared self-running because it harvested small environmental energy inputs.
Superconducting persistent current : An electric current that can circulate for a very long time in a superconducting loop with negligible resistance. It is persistent motion in a near-lossless system, not a source of net work.
United States Patent and Trademark Office : The United States federal agency that examines patent applications and registers trademarks. Since 1911, it has required working models for applications claiming perpetual-motion machines.
Second law of thermodynamics : The thermodynamic law that constrains entropy and limits the conversion of heat into work. It rules out cyclic machines that turn all ambient heat into useful work.
Bessler's wheel : A self-rotating wheel demonstrated by Johann Bessler in the early eighteenth century, whose mechanism was never independently verified. Its demonstrations fueled a celebrated claim of perpetual motion without establishing a workable machine.
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