I believe the Nature article on the universe being created from a vacuum fluctuation relates to the Heisenburg principle. An energy fluctuation is allowed if the time is short, ie Delta E times Delta t < h. [Or is it more strictly h/2 pi ??!, it has been a long time since QM class !]. Guth et al argue that the temporary energy fluctuation was then caught in a false vacuum and stabilized so it could not revert back to zero.
Further, in the early days of thermodynamics it was postulated that the energy of the universe is a constant. And thermo teaches that only changes in energy can be measured, so an arbitrary reference state can be chosen, so that constant is zero, or any other quantity for that matter.
-Jay
[First born, INTJ ;-} ]