Please take a look at this statement that in Volovik's presentation gives the SuperFluid a Variable Volume , a statement that implies the SuperFluid ( quantum vacuum as Volovik labels it ) can be streched or shrunk ( something that is opposite to the UPN description of the Universe SuperFluid ) :

[link to arxiv.org]


" ... Let us consider a large portion of such vacuum liquid under external pressure P [21].

The volume V of quantum vacuum is variable, but its total “charge” Q(t) ≡ R d3r q(r, t)
must be conserved, dQ/dt = 0 ... " .


... and why "charge" is under quotations ? Are there more than one interpretations of "charge" for This particular case , and if so , why not use the appropriate one instead of quotations ?

But more importantly regarding Volovik's interpretation , if the foundation of the Universe , the SuperFluid or quantum vacuum as per Volovik , that can increase or decrease its volume as per Volovik , what New space it could occupy when its volume increases ?? And when it shrinks , what space does it leave behind ??
Those questions are fundamental because the SuperFluid makes the Universe hence there is nothing ' else ' there to leave behind or occupy !
Are the Empirical ( experimental ) formulas used by Volovik not 100 % true ??

You will not find those conundrums in the UPN !

See the logic steps that tells us what we are , an Analog , uncompressible , non-granular , extreme low viscosity SuperFluid in motion :

[link to UPNtheory.WordPress.com] , Quantum/Relativity shocking !