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Why is absolute zero impossible to attain in practice?

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Engraved portrait of Rudolf Julius Emanuel Clausius, a bearded man in formal attire with sideburns, facing forward. — thermodynamics Rudolf Clausius (1822 - 1888) is considered one of the central founders of the science of thermodynamics.

In thermodynamics, absolute zero is defined as the temperature at which a system reaches its lowest possible energy state, specifically −273.15 °C or −459.67 °F.12

The impossibility of attaining this temperature in practice is a consequence of the third law of thermodynamics. This law states that as a system’s temperature approaches absolute zero, the entropy of an isolated system approaches a constant value. In practical terms, this means that as you attempt to cool a system further toward absolute zero, the process of extracting the remaining energy becomes increasingly difficult.3

While scientists have achieved temperatures as low as 9.7 picokelvin, reaching absolute zero remains physically unattainable because no mechanism exists to remove the final increments of energy from a system. Furthermore, even at this limit, molecules do not cease motion entirely; they continue to vibrate with zero-point energy.231