Definition

Noun: 1. A hypothetical state of motion that continues forever without any external source of energy: This concept describes a machine or system that, once set in motion, would operate indefinitely and perform useful work without requiring any additional energy input. It is considered impossible to achieve in practice due to energy losses from forces like friction and air resistance.

Usage

The term "perpetual motion" is primarily used in scientific, engineering, and philosophical discussions to describe an idealized, impossible concept. It is often used attributively (as an adjective) in phrases like "perpetual motion machine."

Examples

• Noun:
  • The idea of perpetual motion has fascinated inventors for centuries.
  • The device claimed to achieve perpetual motion, but it was quickly debunked by physicists.
  • His theory violated the laws of thermodynamics, making it a classic case of seeking perpetual motion.

Advanced Usage

• "Perpetual motion machine": The most common usage, referring to a hypothetical device that would produce perpetual motion. Often abbreviated as PMM.
  • The patent office rejects all applications for perpetual motion machines on principle.
• Used metaphorically to describe relentless, continuous activity.
  • The news cycle is a perpetual motion machine of information. (Note: This is a figurative, not scientific, use.)

Variants and Related Words

• Perpetual motion machine (n): The specific device hypothesized to exhibit perpetual motion.

Synonyms

• Impossible machine (in a literal, scientific context)
• Idealized motion (in a theoretical context)

Antonyms

• Entropy
• Energy dissipation
• Friction

Related Idioms and Phrases

• "A perpetual motion machine": Often used figuratively to describe a person, system, or process that seems to operate with constant, tireless energy.
  • With three jobs and night classes, she was like a perpetual motion machine.

Noun

1. motion that continues indefinitely without any external source of energy; impossible in practice because of friction