absolute zero

Temperature at which a thermodynamic system (see thermodynamics) has the lowest energy, 0 kelvin (K). It corresponds to -459.67°F (-273.15°C) and is the lowest possible temperature theoretically achievable by a system. A gas at constant pressure contracts as the temperature is decreased. A perfect gas would reach zero volume at absolute zero. However, a real gas condenses to a liquid or a solid at a temperature higher than absolute zero. At absolute zero, the system's molecular energy is minimal and none is available for transfer to other systems. The Kelvin temperature scale has absolute zero as its zero point, and its fundamental unit is the kelvin.

Find more information on absolute zero. Upgrade to Britannica Online for more on absolute zero.