Why can a perpetual motion machine never be built?

A perpetual motion machine is designed to operate indefinitely without an external energy source, effectively creating energy out of nothing. The reason such a machine can never be built is fundamentally tied to the principles of physics, particularly the laws of thermodynamics.

The first law of thermodynamics states that energy cannot be created or destroyed in an isolated system, which implies that a perpetual motion machine, claiming to create energy or continue working indefinitely without an energy input, would inherently contradict this principle. The second law of thermodynamics introduces the concept of entropy, which states that energy systems tend to move toward a state of disorder and that energy transformations are never 100% efficient. Therefore, energy must be continually supplied to maintain motion, making perpetual motion machines impossible.

While considerations about cost, elasticity, and energy may contribute to the practical limitations in creating such machines, they do not address the fundamental physical impossibility governed by thermodynamic laws.