How does the third law of thermodynamics relate entropy to absolute zero?

The third law of thermodynamics establishes a fundamental relationship between entropy and absolute zero. It states that the entropy of a closed system approaches a constant value as the system's temperature approaches absolute zero (−273.15 °C, or −459.67 °F).12

In practical terms, this theorem implies that it is impossible to reach absolute zero. As a system nears this temperature, extracting further energy becomes increasingly difficult. While modern science has achieved temperatures within a fraction of a degree above absolute zero, the state of absolute zero itself remains unattainable.12

This law, formulated by Walther Nernst, provides essential insights into the behavior of matter at extreme low temperatures, reinforcing the principles of quantum mechanics regarding the specific heats of solids.2