Shortcomings in the Understanding of Why Cosmological Perturbations Look Classical

Abstract

There is a persistent state of confusion regarding the account of the quantum origin of the seeds of cosmological structure during inflation. In fact, a recent article (C. Kiefer & D. Polarski, ArXiv: 0810.0087 [astro-ph]) addresses the question "Why do the Cosmological Perturbations look Classical?" and offers an answer based on unitary quantum mechanics (i.e., without reference to the projection postulate) relying on the decoherence type of analysis. The argument is, thus, implicitly assuming that decoherence offers a satisfactory solution to the measurement problem in quantum mechanics. We will review here, why do we, together with various other researchers in the field, consider that this is not the case, in general, and particularly not at all in the situation at hand. In fact, as has been previously discussed (A. Perez, H. Sahlmann, and D. Sudarsky, CQG 23, 2317, (2006);[arXiv: gr-qc/0508100]), we will argue that the cosmological situation is one where the measurement problem of quantum mechanics appears in a particular exacerbated form, and that, it is this, even sharper conondrum, the one that should be addressed when dealing with the inflationary account of the origin of the seeds of cosmic structure in the early universe.

New version: In press in International Journal of Modern Physics D

References in corpus (10)

• Gravitation and quantummechanical localization of macroobjects
• The Classical Universes of the No-Boundary Quantum State
• Inflationary Perturbations: the Cosmological Schwinger Effect
• Realistic clocks, universal decoherence and the black hole information paradox
• Spin-Squeezing and Light Entanglement in Coherent Population Trapping
• The No-Boundary Measure in the Regime of Eternal Inflation
• Quantum Physics and Human Language
• Generalizing Quantum Mechanics for Quantum Spacetime
• The Seeds of Cosmic structure as a door to New Physics
• Fundamental decoherence from relational time in discrete quantum gravity: Galilean covariance

Cited by in corpus (88)

• Encyclopaedia Inflationaris
• Quantum Discord of Cosmic Inflation: Can we Show that CMB Anisotropies are of Quantum-Mechanical Origin?
• Cosmological Inflation and the Quantum Measurement Problem
• CSL Wave Function Collapse Model as a Mechanism for the Emergence of Cosmological Asymmetries in Inflation
• Inflation after Planck: Judgment Day
• Implications of stochastic effects for primordial black hole production in ultra-slow-roll inflation
• Obstructions to Bell CMB Experiments
• Benefits of Objective Collapse Models for Cosmology and Quantum Gravity
• Observational constraints on quantum decoherence during inflation
• Quantum-to-classical transition of primordial cosmological perturbations in de Broglie--Bohm quantum theory
• A manifestly covariant theory of multifield stochastic inflation in phase space: solving the discretisation ambiguity in stochastic inflation
• A cosmic shadow on CSL
• Towards a formal description of the collapse approach to the inflationary origin of the seeds of cosmic structure
• Compatibility of Planck and BICEP2 in the Light of Inflation
• Black Holes: Eliminating Information or Illuminating New Physics?
• Cosmological constraints on non-standard inflationary quantum collapse models
• Quantum origin of the primordial fluctuation spectrum and its statistics
• Impact of dynamical collapse models on inflationary cosmology
• The slow roll condition and the amplitude of the primordial spectrum of cosmic fluctuations: Contrasts and similarities of standard account and the "collapse scheme"
• Constraining chameleon field driven warm inflation with Planck 2018 data
• Decoherence in an Interacting Quantum Field Theory: The Vacuum Case
• Real-space entanglement in the Cosmic Microwave Background
• On the choice of the collapse operator in cosmological Continuous Spontaneous Localisation (CSL) theories
• Critical review of prevailing explanations for the emergence of classicality in cosmology
• Cosmic decoherence: primordial power spectra and non-Gaussianities
• Relativistic collapse dynamics and black hole information loss
• Less Decoherence and More Coherence in Quantum Gravity, Inflationary Cosmology and Elsewhere
• Boson stars and their relatives in semiclassical gravity
• Multiple quantum collapse of the inflaton field and its implications on the birth of cosmic structure
• Comparing quantumness criteria
• The collapse of the wave function in the joint metric-matter quantization for inflation
• The Quantum State of Inflationary Perturbations
• Black Holes: Information Loss But No Paradox
• Emergence of inflationary perturbations in the CSL model
• Generally covariant dynamical reduction models and the Hadamard condition
• Does inflation squeeze cosmological perturbations?
• On the Consistency of the Consistent Histories Approach to Quantum Mechanics
• In-in formalism for the entropy of quantum fields in curved spacetimes
• Reassessing the link between B-modes and inflation
• Expectation of primordial gravity waves generated during inflation
• Discussions about the landscape of possibilities for treatments of cosmic inflation involving continuous spontaneous localization models
• Quantum-to-classical transition of primordial cosmological perturbations in de Broglie-Bohm quantum theory: the bouncing scenario
• Real-space quantum-to-classical transition of time dependent background fluctuations
• A Non-static Quantum inspired Spacetime in $f(R)$ Gravity: Gravity's Rainbow
• Origin of structure: Statistical characterization of the primordial density fluctuations and the collapse of the wave function
• Constraining quantum collapse inflationary models with CMB data
• Smooth coarse-graining and colored noise dynamics in stochastic inflation
• Primordial gravitational waves and the collapse of the wave function
• Open Quantum System Approach to the Gravitational Decoherence of Spin-1/2 Particles
• Constraining quantum collapse inflationary models with current data: The semiclassical approach
• Losing stuff down a black hole
• Superhorizon entanglement from inflationary particle production
• Inflation including collapse of the wave function: The quasi-de Sitter case
• Finding origins of CMB anomalies in the inflationary quantum fluctuations
• Inhomogeneities from quantum collapse scheme without inflation
• Primordial Stochastic Gravitational Wave Background Anisotropies: in-in Formalization and Applications
• Classicalization of Quantum Fluctuations at the Planck Scale in the R_h=ct Universe
• Semiclassical Self Consistent Treatment of the Emergence of Seeds of Cosmic Structure. The second order construction
• Eternal inflation and the quantum birth of cosmic structure
• Stochastic inflation and primordial black holes
• Quasi-matter bounce and inflation in the light of the CSL model
• A (not so?) novel explanation for the very special initial state of the universe
• Generation of inflationary perturbations in the continuous spontaneous localization model: The second order power spectrum
• Inflationary gravitational waves in collapse scheme models
• A note on the semiclassicality of cosmological perturbations
• Quantum collapse as source of the seeds of cosmic structure during the radiation era
• Novel Possibility of Nonstandard Statistics in the Inflationary Spectrum of Primordial Inhomogeneities
• Enlightening the CSL model landscape in inflation
• The effect of quantum decoherence on inflationary gravitational waves
• Collapse of the wavefunction, the information paradox and backreaction
• Trans-Planckian Philosophy of Cosmology
• Novel vacuum conditions in inflationary collapse models
• Revisiting Higgs inflation in the context of collapse theories
• Emergent universe revisited through the CSL theory
• Emergent universe: tensor perturbations within the CSL framework
• Observational constraints on inflationary potentials within the quantum collapse framework
• Regularization of Single Field Inflation Models
• Revisiting astrophysical bounds on continuous spontaneous localization models
• Does a Quantum Particle Know its Own Energy?
• A simple gravitational self-decoherence model
• Towards a unitary formulation of quantum field theory in curved spacetime: the case of de Sitter spacetime
• Observational constraints on the second-order primordial power spectrum: Exploring a Continuous Spontaneous Localization inspired inflationary model
• Physical observers, $T$-vacuum and Unruh like effect in the radiation dominated early universe
• Stochastic gravitational wave from graviton bremsstrahlung in inflaton decay into massive spin 3/2 particles
• Preheating and gravitational waves in large-field hilltop inflation
• On the Quantum-to-Classical Transition of Primordial Perturbations
• Constraining tachyonic inflationary β-exponential model with Continuous Spontaneous Localization collapse scheme
• Unified meta-theory of information, consciousness, time and the classical-quantum universe