Energy required to create electron positon pair

[emanaly]

I have read in a book by Jonathan Allday (Quarks, Leptons and
the Big Bang, Institute of Physics Publishing
Bristol and Philadelphia), the following
The positron electron pair which are materialized out of the vacuum are being created by the energy stored in the vacuum(zero point energy) and the energy returned again when the pair disappear.

My Question is :Is his explanation about the energy which creates electron positron pair being provided from the energy stored in the vacuum right?

 

[chroot]

Quantum mechanics predicts a (sort of) uncertainy principle between energy and time. (Even though time is technically not an observable.) This means that a system can have quite large fluctuations in total energy, as long as those fluctuations are short-lived.

- Warren

 

[Demystifier]

As time is not an operator, in principle energy can be measured with an arbitrary precision during an arbitrarily short time. The intuitive picture of particles created for a short time owing to the Heisenberg uncertainty relations is never used in actual calculations. In my opinion, such an intuitive picture is completely misleading.

Furthermore, the vacuum is an eigenstate of the operator of the number of particles. Therefore, the number of particles does NOT fluctuate in the vacuum. What fluctuates is the field energy, but electron-positron pairs cannot be created in the true vacuum, not even for a short time.