Are you saying that the outside void i.e the nothing is absolute zero? This might be semantics but just to clarify that prescribing a property i.e. temperature on "nothingness" makes no sense to me.
WELL, ALTHOUGH IT IS TRUE WE HAVE NO CONCEPT OF WHAT THE "TEMPERATURE" MIGHT BE WHERE THERE IS, BY DEFINITION, NO SPACE-TIME SCALAR, AT SUCH A "NULL" INTERFACE CONFRONTING AN ENERGETIC QUANTA MEASURED AS 10 to the 18th GIGA EV's, BUT IT DOESN'T MATTER SINCE AT THAT REACTIVE INTERFACE, THE "TEMPERATURE" MIGHT BE THOUSANDS OR EVEN HUNDREDS OF THOUSANDS OF DEGREES, BUT THE RELATIVE EFFECT WOULD BE THE SAME.
I still am wary of using the terms nothingness or void for what is outside this universe. I stand by my statement that there is no outside thus no void thus no thermal content.
WELL, THERE IS EITHER SOMETHING (WHICH WE CANNOT NAME) OR AT THE VERY LEAST A BOUNDARY WHICH NOW LIES AT THE MARGIN OF OUR CURRENT UNIVERSE. WHATEVER OUR CONCEPT OF "IT" IS, IS IRRELEVANT AND PROBABLY ALWAYS WILL BE. IT'S WHAT LIKELY TOOK PLACE AT THE INTERFACE THAT WAS (AND MAY STILL BE) IMPORTANT.
Also in regards to your explanation of Onsager Reciprocal Relations in the universe I agree this explains the temperature gradients in the early cosmos which eventually spread out to form galaxies, etc in the universe. However, if we say the universe originated from an infinite density singularity then this singularity would by definition have to be homogeneousness would it not? That is this singularity would have to be uniform in its energy composition because singularity implies a finited mass compressed into 0 space. If this is true how would it form these pressure differentials in 0 space?
ONCE INFLATION BEGAN, THERE WOULD BE NO "ZERO SPACE" AND ONCE THE SINGULARITY BEGAN REACTING (INFLATING) AT THE INTERFACE, MORPHING TO PROGRESSIVE ENTROPY WOULD COMMENCE. THUS ENORMOUS ENERGY ADMIXED IN CHAOS WITH FOCAL HARMONICS GUIDED BY NON-EQUILIBRIUM THERMODYNAMICS WOULD INEVITABLY PROGRESS TO "THE BITS AND PIECES" (STRINGS AND MEMBRANE "COMPONENTS") OF PRIMORDIAL MATTER. ALL THAT IS THEN NEEDED IS TIME -- ALSO FIRMLY ESTABLISHED FROM THIS POINT ON -- TO ALLOW THE SUPERSYMETRIC MATTER-ANTIMATTER ANIHILATIONS TO TAKE PLACE AND NEUTRINO EVOLUTIONS TO RELATIVISTIC MATTER. ANOTHER 300,000,000 YEARS (OR SO) AND THE FORCES NOW SEPARATED AND THEIR DOMAINS WELL ESTABLISHED. EVENTUALLY YOU HAVE PROTONS WHICH HAVE ACQUIRED ELECTRONS TO FORM THE PROTONIC MATERIAL FOR THE FIRST STARS AND THE REST OF THE STORY IS PRETTY WELL DETERMINED.