Predictions from Quantum Cosmology

Abstract

After reviewing the general ideas of quantum cosmology (Wheeler-DeWitt equation, boundary conditions, interpretation of $\psi$), I discuss how these ideas can be tested observationally. Observational predictions differ for different choices of boundary conditions. With tunneling boundary conditions, $\psi$ favors initial states that lead to inflation, while with Hartle-Hawking boundary conditions it does not. This difficulty of the Hartle-Hawking wave function becomes particularly severe if the role of `inflatons' is played by the moduli fields of superstring theories. In models where the constants of Nature can take more than one set of values, $\psi$ can also determine the probability distribution for the constants. This can be done with the aid of the `principle of mediocrity' which asserts that we are a `typical' civilization in the ensemble of universes described by $\psi$. The resulting distribution favors inflation with a very flat potential, thermalization and baryogenesis at electroweak scale, a non-negligible cosmological constant, and density fluctuations seeded either by topological defects, or by quantum fluctuations in models like hybrid inflation (as long as these features are consistent with the allowed values of the constants).

final version of Erice lectures; some corrections regarding predictions for the origin of density fluctuations and for the cosmological constant; 23 pages; 3 figures can be faxed on request

References in corpus (6)

• Predictions from Quantum Cosmology
• Eternal inflation and the initial singularity
• Monopoles as Big as a Universe
• Quantum scale of inflation and particle physics of the early universe
• Making Predictions in Eternally Inflating Universe
• Chaotic Coupling Constants

Cited by in corpus (15)

• Why is the CMB fluctuation level 10^{-5}?
• Operator ordering and consistency of the wavefunction of the Universe
• What can the observation of nonzero curvature tell us?
• Dark energy equation of state and anthropic selection
• One Hundred Years of the Cosmological Constant: from 'Superfluous Stunt' to Dark Energy
• The distribution of Omega_k from the scale-factor cutoff measure
• Measures on Mixing Angles
• Resonant structure of space-time of early universe
• Multiverse Predictions for Habitability: Fraction of Planets that Develop Life
• Hadronic production and decays of Charginos and Neutralinos in Split Supersymmetry
• Phenomenology of the CAH+ measure
• A fully quantum method of determination of penetrability and reflection coefficients in quantum FRW model with radiation
• Volume Weighting the Measure of the Universe from Classical Slow-Roll Expansion
• Spectra of conditionalization and typicality in the multiverse
• A brief history of the multiverse