I've found similar threads like this, but with no clear answer. I understand that the specific heat capacity of a substance increases with temperature, because the vibrational nodes and rotational movements of the atoms are quantized (I assume that the increase is because the energy is distributed evenly over all degrees of freedom?).
What I don't understand is why the heat capacity goes to zero as temperature goes to zero. This comes out of the mathematics, sure - but what is the physical explanation here? If the translational movements are not quantized (or temperature-dependent, rather), what is explanation?
I hope my question makes sense.