ABSTRACT

We show that the inclusion of backreaction of massive long wavelengths imposes dynamical constraints on the allowed phase space of initial conditions for inflation. Only high energy inflation is stable against collapse from the gravitational instability of massive perturbations. The backreaction term in the Wheeler-DeWitt equation, for the wavefunction of the universe propagating on the landscape background, originates from the self-gravity of massive moduli degrees of freedom and metric perturbations and leads to a Master equation.

We present arguments to lend support to the conjecture that the initial conditions problem can not be meaningfully addressed by thermostatistics where gravitational degrees of freedom are concerned. The choice of the initial conditions for the universe in the phase space and the emergence of an arrow of time have to be treated as a dynamic selection

"This puzzle is one of the most challenging and important mysteries of nature," says Mersini-Houghton. "Big Bang cosmology relies heavily on the assumption that our universe started with high energy inflation. Energy is inversely proportional to entropy. The probability for creating a universe varies exponentially with entropy. So low entropy implies an exponentially small probability for creating the universe."

If we just look at the probabilities, continues Mersini-Houghton, the big, cold universe of today may be more likely to originate by ‘popping out of nothing’ – or, in physics-speak, through a ‘nucleating process’ – than from a onetime- only Big Bang. If so, Mersini-Houghton suggests that "pop-up" nuclei, originating from seeming nothingness, would probably give rise to more than one universe, all of which would exist inside an impossibly large "Multiverse."

In this view, a multitude of “starter universes” having locally low entropy could be bubbling up all the time, as long as the entropy of the larger system as a whole – the Multiverse – increases. Some of the starter universes may last long enough to eventually become “survivor universes,” as Mersini-Houghton calls them, prevailing against the "fighting tendencies" between gravitational collapse and repulsive vacuum energy: As gravity tries to force matter into an infinitely small point, vacuum energy tries to stretch the starter universe to infinite size.

So, according to Mersini-Houghton, in the vastness of the Multiverse, only the highest-energy starter universes would be able to overcome gravity, expanding long enough for stars to ignite, planets to congeal and intelligent life to invent cars. Realms with lower energy, on the other hand, would not survive the
stresses, dying off. In this scenario, then, only a high-energy origin – no matter how unlikely – would produce a universe such as ours.