Posted: Aug 04, 2010 9:24 am
by twistor59
AMR wrote:
twistor59 wrote: What I was getting at is that we currently have no way of deriving the vacuum energy from fundamental particle physics. . . . The Casimir effect tells us nothing about the absolute value of vacuum energy density. It only points to differences in vacuum energy density with and without the plates.The only way to estimate VED is currently phenomenological - measure the cosmic expansion and compute the VED responsible for it.

OK, then the answer to your original question, as you must know, would obviously be the subject of much debate. The inflation era lambda driving expansion implies a much greater force than we see today, so is the cosmological constant mutable and why would it adjust to save our universe from re-collapse, inhomogeneity, or cold dispersal?

The reason I raised it was that in a previous post

AMR wrote:
The 1st Law of Thermodynamics states that energy can neither be created or destroyed; but clearly as the universe expands the vacuum energy increases, and what's more the more more it expands with time the faster it will expand. The expansion rate is accelerating with time, this clearly indicates more energy is being added to our universe system. There are only two possibilities here as I see things 1. energy is being created out of the growing vacuum of space or 2. energy is being added to the universe from outside; and I mean outside the universe as a whole itself, not just outside the observable part of our universe (which given the recent discovery of "Dark Flow" must be far greater than the total mass/energy of what is visible out to a ~13 billion light-year radius).

Explain the difference between "closed" and "isolated" universes with respect to the 1st Law of Thermodynamics.

you alluded to energy of the vacuum. I merely wanted to point out that the relationship between the cosmological constant and the vacuum energy is completely unknown at the moment, so there is no reason to be forced to consider an input of energy from "outside the universe" (whatever that may mean).