Inflation without a beginning: A Null boundary proposal

@article{Aguirre2003InflationWA,
  title={Inflation without a beginning: A Null boundary proposal},
  author={Anthony Aguirre and Steven Gratton},
  journal={Physical Review D},
  year={2003},
  volume={67},
  pages={083515}
}
We develop our recent suggestion that inflation may be made past eternal, so that there is no initial cosmological singularity or "beginning of time". Inflation with multiple vacua generically approaches a steady-state statistical distribution of regions at these vacua, and our model follows directly from making this distribution hold at all times. We find that this corresponds (at the semi-classical level) to particularly simple cosmological boundary conditions on an infinite null surface near… 

Figures from this paper

Arrows of time and the beginning of the universe

I examine two cosmological scenarios in which the thermodynamic arrow of time points in opposite directions in the asymptotic past and future. The first scenario, suggested by Aguirre and Gratton,

The most probable size of the Universe

Unitary Evolution and Cosmological Fine-Tuning

Inflationary cosmology attempts to provide a natural explanation for the flatness and homogeneity of the observable universe. In the context of reversible (unitary) evolution, this goal is difficult

Initial conditions for bubble universes

The ''bubble universes'' of Coleman and De Luccia play a crucial role in string cosmology. Since our own Universe is supposed to be of this kind, bubble cosmology should supply definite answers to

The eternal sunshine of the spotless mind

We extend the worldline measure for pocket formation in eternal inflation to allow for time-ordered bubble formation. Such a time-ordering is equivalent to imposing a preferred time-slicing on the

Does inflation provide natural initial conditions for the universe

If our universe underwent inflation, its entropy during the inflationary phase was substantially lower than it is today. Because a low-entropy state is less likely to be chosen randomly than a

Eternal inflation and its implications

I summarize the arguments that strongly suggest that our universe is the product of inflation. The mechanisms that lead to eternal inflation in both new and chaotic models are described. Although the

Singularities in and Stability of Ooguri-Vafa-Verlinde Cosmologies

Ooguri, Vafa, and Verlinde have recently proposed an approach to string cosmology which is based on the idea that cosmological string moduli should be selected by a Hartle-Hawking wave function. They

Eternal Inflation, past and future

Cosmological inflation, if it occurred, radically alters the picture of the `big bang', which would merely point to reheating at the end of inflation. Moreover, this reheating may be only local, so

CPT-Symmetric Universe.

TLDR
The Universe after the big bang is the CPT image of the Universe before it, both classically and quantum mechanically, providing a new interpretation of the cosmological baryon asymmetry, as well as a remarkably economical explanation for thecosmological dark matter.
...

References

SHOWING 1-10 OF 49 REFERENCES

Essay: An Alternative to Inflation

Inflationary models are generally credited with explaining the large scale homogeneity, isotropy, and flatness of our universe as well as accounting for the origin of structure (i.e., the deviations

Why does inflation start at the top of the hill

We show why the universe started in an unstable de Sitter state. The quantum origin of our universe implies one must take a ``top down'' approach to the problem of initial conditions in cosmology, in

Steady state eternal inflation

Since the advent of inflation, several theorems have been proven suggesting that although inflation can (and generically does) continue eternally into the future, it cannot be extended eternally into

Inflationary universe: A possible solution to the horizon and flatness problems

The standard model of hot big-bang cosmology requires initial conditions which are problematic in two ways: (1) The early universe is assumed to be highly homogeneous, in spite of the fact that

Tall tales from de Sitter space I: Renormalization group flows

We study solutions of Einstein gravity coupled to a positive cosmological constant and matter which are asymptotically de Sitter and homogeneous. Regarded as perturbations of de Sitter space, a

Recycling universe

If the effective cosmological constant is non-zero, our observable universe may enter a stage of exponential expansion. In such case, regions of it may tunnel back to the false vacuum of an inflaton

Nonperturbative amplification of inhomogeneities in a self-reproducing universe.

TLDR
The distribution of energy density in a stationary self-reproducing inflationary universe is investigated to demonstrate that nonperturbative effects in quantum cosmology, at least in principle, may have significant observational consequences, including an apparent violation of the Copernican principle.

Creation of open universes from de Sitter space

Hawking1,2 has shown that event horizons produce thermal radiation. I propose here a new cosmological model which has an early event horizon and in which the observed3 cosmic microwave background

Inflationary spacetimes are not past-complete

Many inflating spacetimes are likely to violate the weak energy condition, a key assumption of singularity theorems. Here we offer a simple kinematical argument, requiring no energy condition, that a