scholarly journals The case for a Casimir cosmology

2020 ◽  
Vol 378 (2177) ◽  
pp. 20190229 ◽  
Author(s):  
Ulf Leonhardt
Keyword(s):  
New York ◽  
Cosmological Constant ◽  
Casimir Effect ◽  
Quantum Field ◽  
Vacuum Fluctuations ◽  
Correct Order ◽  
Dielectric Media ◽  
Analogue Gravity ◽  
Lifshitz Theory ◽  
Order Of Magnitude

The cosmological constant, also known as dark energy, was believed to be caused by vacuum fluctuations, but naive calculations give results in stark disagreement with fact. In the Casimir effect, vacuum fluctuations cause forces in dielectric media, which is very well described by Lifshitz theory. Recently, using the analogy between geometries and media, a cosmological constant of the correct order of magnitude was calculated with Lifshitz theory (Leonhardt 2019 Ann. Phys. ( New York ) 411 , 167973. ( doi:10.1016/j.aop.2019.167973 )). This paper discusses the empirical evidence and the ideas behind the Lifshitz theory of the cosmological constant without requiring prior knowledge of cosmology and quantum field theory. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

scholarly journals How to hide a cosmological constant

2019 ◽  
Vol 28 (14) ◽  
pp. 1943004 ◽  
Author(s):  
Steven Carlip
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Cosmological Constant ◽  
Planck Scale ◽  
Quantum Field ◽  
Vacuum Fluctuations ◽  
And Topology ◽  
Spacetime Foam

Naive calculations in quantum field theory suggest that vacuum fluctuations should induce an enormous cosmological constant. What if these estimates are right? I argue that even a huge cosmological constant might be hidden in Planck-scale fluctuations of geometry and topology — what Wheeler called “spacetime foam” — while remaining virtually invisible macroscopically.

Cosmological constant

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Accelerated Expansion ◽  
Vacuum Fluctuations ◽  
Present Epoch ◽  
Modify Gravity ◽  
Expansion Of The Universe ◽  
The Universe

The contribution of vacuum fluctuations to the cosmological constant is reconsidered studying the dependence on the used regularisation scheme. Then alternative explanations for the observed accelerated expansion of the universe in the present epoch are introduced which either modify gravity or add a new component of matter, dubbed dark energy. The chapter closes with some comments on attempts to quantise gravity.

scholarly journals Thermal Casimir effect with general boundary conditions

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
J. M. Muñoz-Castañeda ◽  
L. Santamaría-Sanz ◽  
M. Donaire ◽  
M. Tello-Fraile
Keyword(s):  
Boundary Conditions ◽  
Vacuum Energy ◽  
Casimir Effect ◽  
Quantum Field ◽  
Quantum Vacuum ◽  
Parallel Plates ◽  
Casimir Forces ◽  
Thermal Correction ◽  
Frequency Independent ◽  
Scalar Quantum

Abstract In this paper we study the system of a scalar quantum field confined between two plane, isotropic, and homogeneous parallel plates at thermal equilibrium. We represent the plates by the most general lossless and frequency-independent boundary conditions that satisfy the conditions of isotropy and homogeneity and are compatible with the unitarity of the quantum field theory. Under these conditions we compute the thermal correction to the quantum vacuum energy as a function of the temperature and the parameters encoding the boundary condition. The latter enables us to obtain similar results for the pressure between plates and the quantum thermal correction to the entropy. We find out that our system is thermodynamically stable for any boundary conditions, and we identify a critical temperature below which certain boundary conditions yield attractive, repulsive, and null Casimir forces.

Heuristic determination of the cosmological constant

2021 ◽  
pp. 2150114
Author(s):  
Manuel Urueña Palomo ◽  
Fernando Pérez Lara
Keyword(s):  
Field Theory ◽  
Energy Density ◽  
Cosmological Constant ◽  
Accelerated Expansion ◽  
Fundamental Constants ◽  
Quantum Field ◽  
Brute Force ◽  
Expansion Of The Universe ◽  
The Universe

The vacuum catastrophe results from the disagreement between the theoretical value of the energy density of the vacuum in quantum field theory and the estimated one observed in cosmology. In a similar attempt in which the ultraviolet catastrophe was solved, we search for the value of the cosmological constant by brute-force through computation. We explore combinations of the fundamental constants in physics performing a dimensional analysis, in search of an equation resulting in the measured energy density of the vacuum or cosmological constant that is assumed to cause the accelerated expansion of the universe.

scholarly journals ON THE QUANTUM THEORY OF MASSLESS SPIN-3/2 FIELD IN MINKOWSKI SPACETIME

2006 ◽  
Vol 03 (07) ◽  
pp. 1303-1312 ◽  
Author(s):  
WEIGANG QIU ◽  
FEI SUN ◽  
HONGBAO ZHANG
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Theory ◽  
Casimir Effect ◽  
Minkowski Spacetime ◽  
Quantum Field ◽  
Explicit Result ◽  
Massless Spin ◽  
The Many ◽  
The One

From the modern viewpoint and by the geometric method, this paper provides a concise foundation for the quantum theory of massless spin-3/2 field in Minkowski spacetime, which includes both the one-particle's quantum mechanics and the many-particle's quantum field theory. The explicit result presented here is useful for the investigation of spin-3/2 field in various circumstances such as supergravity, twistor programme, Casimir effect, and quantum inequality.

A First-Principles Method of Determining Van Der Waals Forces in a Dissipative Media

2012 ◽  
Author(s):  
Yi Zheng ◽  
Arvind Narayanaswamy
Keyword(s):  
Stress Tensor ◽  
First Principles ◽  
Van Der Waals ◽  
Maxwell Stress ◽  
Quantum Field ◽  
Maxwell Stress Tensor ◽  
Lifshitz Theory ◽  
Dissipative Media ◽  
Dissipative Material ◽  
Vdw Force

Lifshitz theory of van der Waals (vdW) force and energy is strictly valid when the location at which the stress tensor is calculated is in vacuum. Generalization of Lifshitz theory to the case when the stress tensor is to be calculated in a dissipative material, as opposed to vacuum, is a surprisingly difficult undertaking because there is no expression for the electromagnetic stress tensor in dissipative materials. Here, we derive the expression for vdW force in planar dissipative media by calculating the Maxwell stress tensor in a fictious layer of vacuum, that is eventually made to vanish, introduced in the structure, without employing the complicated quantum field theoretic method proposed by Dzyaloshinskii, Lifshitz, and Pitaevskii. Even though this work has proven to be a corroboration of Dzyaloshinskii et al., it has thrown new light on our understanding of vdW forces and suggests that it should be possible to achieve the similar result for objects with arbitrary shapes.

Casimir effect and the uncertainty principle

2018 ◽  
Vol 33 (24) ◽  
pp. 1850140 ◽  
Author(s):  
Jaume Giné
Keyword(s):  
Uncertainty Principle ◽  
Casimir Effect ◽  
Vacuum Fluctuations

The Casimir effect is one of the observable consequences of the vacuum fluctuations. The Casimir effect manifests itself as a force between two uncharged conductive plates in a vacuum placed a few nanometers apart. In this work, we try to deduce the Casimir effect directly from the uncertainty principle.

scholarly journals NEGATIVE ENERGY DENSITIES IN QUANTUM FIELD THEORY

2010 ◽  
Vol 25 (11) ◽  
pp. 2355-2363 ◽  
Author(s):  
L. H. FORD
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Energy Density ◽  
Negative Energy ◽  
Mean Value ◽  
Quantum Field ◽  
Two Dimensional ◽  
Vacuum Fluctuations ◽  
Negative Energy Density ◽  
Dimensional Spacetime

Quantum field theory allows for the suppression of vacuum fluctuations, leading to sub-vacuum phenomena. One of these is the appearance of local negative energy density. Selected aspects of negative energy will be reviewed, including the quantum inequalities which limit its magnitude and duration. However, these inequalities allow the possibility that negative energy and related effects might be observable. Some recent proposals for experiments to search for sub-vacuum phenomena will be discussed. Fluctuations of the energy density around its mean value will also be considered, and some recent results on a probability distribution for the energy density in two dimensional spacetime are summarized.

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