Did the Universe have a beginning?

  title={Did the Universe have a beginning?},
  journal={Physical review. D, Particles and fields},
  volume={46 6},
  • Vilenkin
  • Published 15 September 1992
  • Philosophy, Physics
  • Physical review. D, Particles and fields
It is argued that eternal inflation'' must have a beginning in time. Conditions are formulated for a spacetime to describe an eternally inflating universe without a beginning, and it is shown that these conditions cannot be satisfied. A rigorous proof is given for a two-dimensional spacetime, and a plausibility argument for four dimensions. 

A-Temporal Universe

In scientific experiments we observe irreversible material change.. Physical time exists only as a stream of this change. Newton's time is only a concept through which one experiences irreversible

Is the History of our Universe Finite?

  • M. Chan
  • Physics
    Theology and Science
  • 2019
ABSTRACT Modern cosmology indicates that our universe has a finite age. However, it is not understood whether the initial state before the Big Bang is finite in history or not. In this article, I

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

Quantum instability of the emergent universe

We perform a semi-classical analysis of the Emergent Universe scenario for inflation. Fixing the background, and taking the inflaton to be homogenous, we cast the inflaton’s evolution as a

Inflation without a beginning: A Null boundary proposal

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

Eternal Universe

We discuss cosmological models for an eternal universe. Physical observables show no singularity from the infinite past to the infinite future. While the universe is evolving, there is no beginning

Is Eternal Inflation Past-Eternal? And What if It Is?

As a result of discussions with Bousso and Vilenkin I want to return to the question of whether the multiverse is past-eternal or if there was a beginning. Not surprisingly, given three people, there

A Bang into Nowhere Comments on the Universe Expansion Theory

The notion of a first ever moment of Time is selfcontradictory: In lacking a moment before it, it lacks a lower barrier, so there is no stopping it from—inconsistently— receding further and further

In What Sense Is the Early Universe Fine-Tuned?

It is commonplace in discussions of modern cosmology to assert that the early universe began in a special state. Conventionally, cosmologists characterize this fine-tuning in terms of the horizon



Eternal inflation and the initial singularity.

It is shown that a physically reasonable spacetime that is eternally inflating to the future must possess an initial singularity.


The big bang theory of cosmology - the idea that the universe originated in a single cataclysmic explosion between ten and twenty billion years ago - has become the foundation stone not only of

Toward the application of a metric size function in galactic evolution and cosmology

We have measured the metric size function eta(r) defined by Petrosian on a limited sample of luminous distant galaxies, up to a redshift of 1.175. Although our investigation has a preliminary

The physical universe : the interface between cosmology, astrophysics and particle physics : proceedings of the XII Autumn School of Physics held at Lisbon, Portugal, 1-5 October 1990

Meant as a review for students of astrophysics and particle physics, this book contains a selection of survey articles and seminar reports on "high energy cosmology". Included are contributions on

The discovery of a type Ia supernova at a redshift of 0.31

OBSERVATIONS indicate that nearby supernova of type Ia have similar peak brightnesses, with a spread of less than 0.3 mag (ref. 1), so that they can potentially be used as 'standard candles' to

On the cosmological significance of the apparent deficit of small interplanetary scintillation sources

The deficit of scintillating sources with small angular sizes, revealed by interplanetary scintillation (IPS) surveys, has led to suggestions that the universe is closed. More recent developments in

Quantum Theory of Gravity. I. The Canonical Theory

Following an historical introduction, the conventional canonical formulation of general relativity theory is presented. The canonical Lagrangian is expressed in terms of the extrinsic and intrinsic

The Redshift-Distance and Velocity-Distance Laws

The distinction between Hubble's linear redshift-distance z(L) law and the linear velocity-distance V(L) law that emerged later is discussed, using first the expanding space paradigm and then the

Early type galaxies, dark halos, and gravitational lensing statistics

We present calculations of the expected statistics of gravitational lensing of quasars in the Hubble Space Telescope snapshot survey. We first model early-type (elliptical and S0) galaxies using

A possible local counterpart to the excess population of faint blue galaxies

OBSERVATIONS have revealed a population of faint blue galaxies1–5 at intermediate redshifts (z≈0.4). These galaxies are present in significant excess relative to what is expected based on