Why does an oscillatory system have a lower bound in energy?

[fricke]

Thermodynamics question:

Why does the internal energy have a lower bound?

I tried to explain it using postulates, but cannot get the connection between the postulates. Please do explain it briefly. Thank you.

 

[ehild]

An oscillatory system has got a lower bound. It can not be explained in the frames of Classical Physics, but comes out from Quantum Mechanics. The lowest energy of an oscillator vibrating with frequency f is hf/2, called the zero-point energy of the oscillator.