Quantum vacuum fluctuations are facts in the real world - they were a fundamental prediction of Quantum Mechanics revealed in several processes. The spectrum of quantum fluctuations is a neat mathematical formulation that embodies this concept. It serves as a pivotal point between the very large (cosmological scale) and the very small (subatomic scale). No cosmological model that aspires to describe the real world can have the luxury of ignoring this fundamental reality.

If it's not going to be me then who? Your wife?? Better me than somebody else...

I got as far as looking up equation 37 in http://soi.blogspot.ca/2014/04/the-essential-quantum-field-theory.htmlThen I got confused as to why you substituted k for p.

It's just basic math - I can always replace A in an equation by B. Now, it is the general practice to use p for the momentum of a particle. But waves can also have momentum, and the general practice is to use k. It's a general practice, not a law written into stones.