Is Our Universe Natural?

Abstract

It goes without saying that we are stuck with the universe we have. Nevertheless, we would like to go beyond simply describing our observed universe, and try to understand why it is that way rather than some other way. Physicists and cosmologists have been exploring increasingly ambitious ideas that attempt to explain why certain features of our universe aren't as surprising as they might first appear.

Invited review for Nature, 11 pages

References in corpus (18)

• Dimensionless constants, cosmology and other dark matters
• What does inflation really predict?
• Probabilities in the inflationary multiverse
• Baby Universes in String Theory
• Things Fall Apart: Topology Change from Winding Tachyons
• Spontaneous Inflation and the Origin of the Arrow of Time
• The Tachyon at the End of the Universe
• Anthropic prediction for Lambda and the Q catastrophe
• Branches of the Landscape
• Density Perturbations and the Cosmological Constant from Inflationary Landscapes
• Dynamics and instability of false vacuum bubbles
• Two Tunnels to Inflation
• Anthropic Distribution for Cosmological Constant and Primordial Density Perturbations
• Why the Universe Started from a Low Entropy State
• Islands in the Lambda-sea: An alternative cosmological model
• Scientific alternatives to the anthropic principle
• On making predictions in a multiverse: conundrums, dangers, and coincidences
• Supersplit Supersymmetry

Cited by in corpus (21)

• The Mathematical Universe
• The Degree of Fine-Tuning in our Universe -- and Others
• Vacuum Energy: Myths and Reality
• PREdicted the Higgs Mass
• Two Notions of Naturalness
• Arrows of time and the beginning of the universe
• Implications for the Cosmological Landscape: Can Thermal Inputs from a Prior Universe Account for Relic Graviton Production?
• Arrow of Time in String Theory
• The Halo Spin Transition as a Probe of Dark Energy
• Supersymmetric Majorana Quantum Cosmologies
• Astrophysics in 2006
• Complex Action Support from Coincidences of Couplings
• A possible cosmological application of some thermodynamic properties of the black body radiation in $n-$dimensional Euclidean spaces
• Constraints on Vacuum Energy from Structure Formation and Nucleosynthesis
• CPTM symmetry, closed time paths and cosmological constant problem in the formalism of extended manifold
• Boundary Effects in Local Inflation and Spectrum of Density Perturbations
• Comparative Quantum Cosmology: Causality, Singularity, and Boundary Conditions
• Seeking a Game in which the standard model Group shall Win
• Time, Uncertainty and Non-Locality in Quantum Cosmology
• On the Carroll-Chen Model
• Influence from Future, Arguments