Perpetual motion refers to a hypothetical concept of a machine that can operate indefinitely without an external energy source. According to the laws of thermodynamics, specifically the first and second laws, perpetual motion machines are considered impossible. These laws state that energy cannot be created or destroyed (conservation of energy) and that in any energy transfer or conversion, some energy is always lost as heat (entropy increases). These fundamental principles place limitations on the efficiency and operation of any physical system.
While people have proposed various designs for perpetual motion machines throughout history, none have been successfully created that operate as intended. Many of these proposals violate the laws of thermodynamics or rely on unproven principles. In essence, perpetual motion machines are often seen as a scientific impossibility or a hoax.
It's worth noting that there are devices that can operate for a long time or seemingly indefinitely without an apparent energy source. However, these systems either rely on energy from an external source that is not immediately apparent (e.g., solar-powered devices) or are designed to extract energy from their surroundings (e.g., some low-power electronic devices that scavenge energy from ambient sources).
In conclusion, while the concept of perpetual motion has intrigued inventors and scientists for centuries, current scientific understanding suggests that it is not possible to create a machine that operates perpetually without an external energy source.