Image 1 Caption: A cartoon of the growth of an inflation region with representative numbers.
The inflation region includes observable universe.
Features:
The false-vacuum universe is probably a rather bland place where there is NOT much structure. It is usually assume that general relativity and the cosmological principle applies to the false-vacuum universe in which case it may be expansion or contraction.
However, sufficiently large quantum fluctuations will lift the region over the energy threshold. So the false-vacuum universe is NOT completely stable.
Note quantum fluctuations are a fundamental feature of quantum mechanics and are NOT specfic to any particular quantum field theory.
The essential idea is that the energy becomes (perhaps NOT directly) photons, leptons, quarks, and probably dark matter particles.
The particles are created with kinetic energy which drives a super rapid expansion of the inflation region. The super rapid expansion is the inflation itself and it's duration is the inflation era which is though to be ∼ 10**(-32) s to ∼ 10**(-36) s after the time of the Big Bang singularity---which very probably did NOT happen, but is just the time zero of the Friedmann-equation (FE) models that the inflation tracks into as the inflation era ends.
For a slightly longer explication of the decay from the false-vacuum state, see Cosmology file: inflation_false_vacuum_decay.html.
Well, there are various suggested values, but for the cartoon yours truly chose expansion by a factor ∼ 10**60 which seems to be a typical value.
Particular inflation theories will give specific expansion factors and specific durations for the inflation era
So, in fact, it is a like pure cosmological constant growth (such as in the de Sitter universe), but with a much larger EFFECTIVE cosmological constant than is used to account for the accelerated expansion of the universe of the modern observable universe in the Λ-CDM model.
Of course, yours truly is NOT arguing that unbelievability is a proof of truth.
Outside it may be Hamlet's "nutshell.'' See the figure below local link / general link: hamlet_edwin_booth.html).
If this is literally true, stuff from outside could fall into our pocket universe, but CANNOT get out---but where it would arrive and how would it appear and what would it be?
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In fact, there may be NO boundaries on the inside. The pocket universes could be some kind of black hole universes: i.e., they are the insides black holes.
Stuff from outside can fall in, but nothing can get out. But where does stuff appear on the inside?
If PHYSICAL CONDITIONS do vary, then they must be set randomly from some distribution.
The PHYSICAL CONDITIONS of our pocket universe are then what they are by the anthropic principle: fine-tuned enough for life as we know it, but NOT overly fined-tuned. Our pocket universe is thus a fine-tuned universe: i.e., fine-tuned for life as we know it.
Most pocket universe might lifeless and rather boring.
Thus, eternal inflation with randomly set PHYSICAL CONDITIONS passes one significant falsification test: PHYSICAL CONDITIONS we observe are
NOT overly fine-tuned for life as we know it.
This may be the only falsification test it passes---but it is a significant falsification test.
UNDER CONSTRUCTION BELOW