Answer:
Because something at absolute zero would have no kinetic energy, and atoms can never stop vibrating.
Step-by-step explanation:
If something were to reach absolute zero, that means that the particles would reach a position were we are able to detect precisely their velocity and position in the atom.
This cannot be possible because it would violate Heisenberg's Uncertainty Principle, which in brief states that we can measure the velocity of electron but we would be uncertain about the position and vice versa. We cannot predict both velocity and position accurately.