More Inflation - the Inflaverse

There seem to be at least two ways of viewing inflation.  There is the inflationary epoch, which I talked about in the imaginatively titled post Inflation, and then there is eternal inflation.  In the first, you have our universe beginning shortly before the Big Bang (for reasons unknown) and, in the second, you have what I call the inflaverse, which is a greater universe in which inflation goes on forever for the most part and our universe (“the universe”) condenses out of it due to some mechanism.  We’d not be the only universe, so this is a form of multiverse theory (or rather the multiverse is an apparently unavoidable consequence of the model).  So you would have the multiverse consisting of a multitude of universes that are totally disconnected (sorry MCU fans) immersed in an eternally inflating inflaverse.

 

A mechanism by which our universe could condense out of the inflaverse was raised in Does Inflation have a Homogeneity Problem?  An event of vacuum decay (or collapse) could lead to a bubble of spacetime that is not inflating but instead is expanding out at the speed of light.

 

Note that the time of the inflaverse would not be the same as the time of the universes that it spawns.  It would be reasonable to think of universal time as orthogonal to inflaversal time, in which case we could find ourselves in a situation in which the bubble of spacetime that expands out from the vacuum decay event would expand in both a positive and negative direction (with those assignments being arbitrary).

 

To remain flat (so that the density equals the critical density), the twin universes would accrue mass-energy at a rate equivalent to one unit of Planck mass per unit of Planck time, divided equally between the two.  Or as modified by periods of deceleration and/or acceleration (since the mass-energy density is related to the Hubble radius).

 

In the following posts, I am not going to consider the inflaverse version of inflation in the first fraction of a second of our universe.  I’m going to assume that however it happened, at the beginning of the radiation-dominated era the conditions are such that either could have happened immediately prior.