exchemist
Valued Senior Member
Indeed.Welcome to the realm of QM. With macroscopic systems, there is always some energy leakage ( even orbiting planets, failing anything else would eventually spiral into their stars due to energy loss via gravitational wave radiation.)
However, when you get down to the level of atoms, things aren't as simple. Instead of being able to slowly "leak" energy, energy loss or gain can only be done in discrete units that are significant compared to the atom's total energy.
For example: Classically, if you consider an atom as a nucleus with an electron orbiting around it, then the electron is a charge undergoing constant acceleration. This should lead to it radiating EMR, losing energy and spiraling in towards the nucleus. Given the orbital period of the typical electron, which determines the frequency of the radiation and its energy, no atom should last more than a fraction of a second before all the electrons had fallen into the nucleus. This of course is not the case. This is because Quantum mechanics limits how electrons can lose energy to discrete units. If we assign this a value of 1, we can compare this to the energy it should radiate in one orbit, which would produce 1 wavelength or one unit of EMR, it turns out that this is less than 1, Since this is smaller than the energy unit the electron must lose energy by, it lose energy by radiation.
Now of course, QM has moved beyond the electron orbiting the nucleus model, but the same basic principle holds, Atoms can only "fall apart" if they lose energy, but they can only lose energy in "chunks" of a minimum size, and there is no process in an undisturbed (non-radioactive) atom that can emit energy "chunks" that large. A stable isotope is expected to remain stable indefinitely. It doesn't require any outside influence to hold together.
Just to amplify the point, there is no state below the "ground state" of any system. The ground state is a QM concept for the state with the least energy that the system in question is allowed to have. This is the "zero point" energy of that system. For example, in the hydrogen atom, the electron in the 1s orbital is in the ground state. No lower energy levels exist.