The Non-Unique Vacuum

In terms of tunneling and so on, maybe you could give us a classical picture. Can you describe that kind of idea? Yeah, before we jump into that, let me perhaps give you an example that may be more familiar to us in the context of thermal physics. Even at zero temperature, quantum mechanics has a way of giving rise to processes like that where a system that is not in its preferred state can actually sort of tunnel quantum mechanically by nucleating new states.