What is absolute zero in degrees Celsius?

Absolute zero is the theoretical temperature at which a substance has minimum thermal energy, and the motion of its atoms virtually comes to a stop. In the Celsius scale, this temperature is defined as -273.15 degrees Celsius, which is rounded to -273 degrees for simplicity in many contexts. At absolute zero, the entropy of a perfect crystal approaches zero according to the third law of thermodynamics.

The other temperature values do not correspond to absolute zero. For instance, 0 degrees Celsius is the freezing point of water, while 100 degrees Celsius is the boiling point of water under standard atmospheric conditions. 273 degrees Celsius is a significant temperature as it corresponds to 0 degrees Kelvin, but it is not the correct definition of absolute zero in Celsius. Thus, the correct understanding aligns with -273 degrees Celsius as the definition of absolute zero.