On the other hand, absolute zero refers to the complete absence of thermal energy. It is the lowest temperature that matter can possibly reach, where molecular motion stops completely. According to the Kelvin scale, which is based on absolute zero, absolute zero is defined as 0 Kelvin.
The main difference between the zero grade on the Celsius scale and absolute zero is the reference point. The zero grade on the Celsius scale is a relative measure based on the properties of water on Earth while absolute zero is a fundamental physical constant.
