## Wednesday, September 26, 2012

### uncertainty and inflation

all fields associated with elementary particles fluctuate on the time scale $\Delta t$ by energies $\Delta E$ which can be estimated to be $>\hbar / \Delta t$ according to the uncertainty principle. Why isn't then the inflation field generating inflationary epochs every time (i.e. nowadays too!) if it acquires enough energy by statistical fluctuation?

#### 1 comment:

1. This is a very good question, since if universes are easy to produce from nothing''
via quantum cosmology, why are they not being
produced copiously all around us still ?

In the space around us today the (gravitational) pressure due to any mass-energy is positive, or effectively zero. Whereas an inflationary field is a negative pressure: therefore any fluctuation of
an inflaton field within it is rapidly suppressed by the outside positive pressure rapidly extinguishing it -like lighting a match
under water.

If you force an even bigger fluctuation to happen anyway, as in the universe in a lab'' work of Guth and others then the inflationary universe is forced to disconnect from our universe and now expand into some complety different region of nothing'' whereas to an observer left behind in our universe it appears that only an (evaporating) black hole was produced.

But to get back to the more fundamental question
:how do we know that nothing'' can actually allow inflationary expansion to expand within it? i.e that there is actually no water to follow the above analogy - a deep issue for quantum cosmology.