Quantum mechanics from cosmic fluctuations

Anonymous

Jérôme Martin

According to the theory of cosmic inflation, the large scale structures observed in our Universe (galaxies, clusters of galaxies, Cosmic Background Microwave—CMB—anisotropy…) are of quantum mechanical origin. They are nothing but vacuum fluctuations, stretched to cosmological scales by the cosmic expansion and amplified by gravitational instability. At the end of inflation, these perturbations are placed in a two-mode squeezed state with the strongest squeezing ever produced in Nature (much larger than anything that can be made in the laboratory on Earth). This article studies whether astrophysical observations could unambiguously reveal this quantum origin by borrowing ideas from quantum information theory. It is argued that some of the tools needed to carry out this task have been discussed long ago by J. Bell in a, so far, largely unrecognized contribution. A detailled study of his paper and of the criticisms that have been put forward against his work is presented. Although J. Bell could not have realized it when he wrote his letter since the quantum state of cosmological perturbations was not yet fully characterized at that time, it is also shown that Cosmology and cosmic inflation represent the most interesting frameworks to apply the concepts he investigated. This confirms that cosmic inflation is not only a successful paradigm to understand the early Universe. It is also the only situation in Physics where one crucially needs General Relativity and Quantum Mechanics to derive the predictions of a theory and, where, at the same time, we have high-accuracy data to test these predictions, making inflation a playground of utmost importance to discuss foundational issues in Quantum Mechanics.

J. S. Bell

J. S. Bell

Masahiro Morikawa

We explore consistent application of quantum mechanics to the objects in the Universe and in laboratories. The measurement dynamics in quantum mechanics is modeled as a physical process of spontaneous symmetry breaking (SSB) which is described by the generalized effective action method. A violation of the Bell inequality is observed in this model and the generation of the density fluctuations in the early Universe is described as the SSB process of the spatially translational symmetry.

Masahiro Morikawa

We explore consistent application of quantum mechanics to the objects in the Universe and in laboratories. The measurement dynamics in quantum mechanics is modeled as a physical process of spontaneous symmetry breaking (SSB) which is described by the generalized effective action method. A violation of the Bell inequality is observed in this model and the generation of the density fluctuations in the early Universe is described as the SSB process of the spatially translational symmetry.