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.