@mattbrowne “Order gets replaced by randomness.” That’s entropy, not energy.
The picture of the vacuum coming out of quantum field theory is that virtual particles pop in and out of existence on short time scales. It’s as it they can loan mass-energy from the universe for a very short period of time but then they have to pay it back.
How this squares with Noether’s theorem? I don’t know.
Virtual particles do produce some effects on real matter (ex: g-2). There is only one instance I know of when virtual particles could be “promoted” to real ones and that’s close to the event horizon of a black hole (see: Hawking radiation). Note that even in this case, the net effect is not “free energy”. The energy radiated away is compensated by the loss of mass from the black hole.