Here's why:
* Absolute Zero: Absolute zero is the theoretical temperature at which all molecular motion ceases. This temperature is -273.15 degrees Celsius (or 0 Kelvin).
* Thermal Energy: Even at 0 degrees Celsius, molecules still possess a certain amount of thermal energy, which manifests as vibration and other forms of motion.
* Quantum Mechanics: According to quantum mechanics, even at absolute zero, there is a minimum amount of energy that molecules can possess. This is known as the zero-point energy.
In summary: Molecular motion does not completely stop at 0 degrees Celsius. It simply slows down significantly. Absolute zero is the only temperature at which molecular motion is theoretically considered to be at a minimum.
