The Cosmological Constant (original) (raw)

1995

A diverse set of observations now compellingly suggest that Universe possesses a nonzero cosmological constant. In the context of quantum-field theory a cosmological constant corresponds to the energy density of the vacuum, and the wanted value for the cosmological constant corresponds to a very tiny vacuum energy density. We discuss future observational tests for a cosmological constant as well as the fundamental theoretical challenges-and opportunities-that this poses for particle physics and for extending our understanding of the evolution of the Universe back to the earliest moments.

1 an Issue to the Cosmological Constant Problem

2015

On geometrical grounds, the cosmological constant problem turns out to be an artifact due to the unfounded link of this fundamental constant to vacuum energy density of quantum fluctuations.

A resolution of the cosmological constant problem

The standard calculation of vacuum energy or zero point energy is in strong disagreement with observation. We suggest that this discrepancy is caused by the incomplete quantization of standard field theory. The vacuum energy calculation for fermions shows an unacceptable asymmetry between particles and anti-particles, which has to be corrected by an additional quantization step that reverses the order of the anti-particle operators. Boson fields can be handled similarly, but have to be expanded first in terms of bilinear fermion operators. After the full quantization the vacuum energy vanishes. This does not violate the Casimir effect as this can be explained without reference to the vacuum energy, as Jaffe has demonstrated elsewhere.

A Solution to the cosmological constant problem

Arxiv preprint astro-ph/9606071, 1996

According to general relativity, the present analysis shows on geometrical grounds that the cosmological constant problem is an artifact due to the unfounded link of this fundamental constant to vacuum energy density of quantum fluctuations.

The cosmological constant problem

Astronomical observations indicate that the cosmological constant is many orders of magnitude smaller than estimated in modern theories of elementary particles. After a brief review of the history of this problem, five different approaches to its solution are described.

An Issue to the Cosmological Constant Problem

Gravitation and Astrophysics - On the Occasion of the 90th Year of General Relativity - Proceedings of the VII Asia-Pacific International Conference, 2007

On a physical description and origin of the cosmological constant

Classical and Quantum Gravity

In this paper we use and extend the results present in [1, 2, 3, 4] and in particular in [4] to obtain a statistical description of the cosmological constant in a cosmological de Sitter universe in terms of massless excitations with Planckian effects. First of all, we show that at a classical level, the cosmological constant Λ > 0 can be obtained only for T → 0. Similarly to the black hole case, when quantum effects are taken into account, a representation for Λ is possible in terms of massless excitations, provided that quantum corrections to the Misner-Sharp mass are considered. Moreover, thanks to quantum fluctuations, an effective cosmological constant arises depending on the physical scale under consideration, thus representing a possible solution to the cosmological constant problem without introducing a quintessence field. The smalness of the actual value for Λ can be due to the existence of a quantum decoherence scale above the Planck length such that the spacetime evolves as a pure de Sitter universe with a small averaged cosmological constant frozen in the lowest energy state.

One hundred years of the cosmological constant: from superfluous stunt to dark energy

The European Physical Journal H, 2018

We present a centennial review of the history of the term known as the cosmological constant. First introduced to the general theory of relativity by Einstein in 1917 in order to describe a universe that was assumed to be static, the term fell from favour in the wake of the discovery of the expanding universe, only to make a dramatic return in recent times. We consider historical and philosophical aspects of the cosmological constant over four main epochs; (i) the use of the term in static cosmologies (both Newtonian and relativistic): (ii) the marginal-ization of the term following the discovery of cosmic expansion: (iii) the use of the term to address specific cosmic puzzles such as the timespan of expansion, the formation of galaxies and the redshifts of the quasars: (iv) the re-emergence of the term in today's Λ-CDM cosmology. We find that the cosmological constant was never truly banished from theoretical models of the universe, but was marginalized by astronomers for reaso...

The Demystification of the Mystery of the Cosmological Constant

The article proposes a mechanism to eliminate the difference between the experimental values of the cosmological constant and its theoretical predictions made within the framework of the theory of elementary particles based on the concept of the neutron cluster (complex). It is shown that the quantum vacuum is unstable with respect to the formation of giant fluctuations in the density of particles (clusters) formed as a result of the birth of virtual pairs. The reverse annihilation of pairs does not occur due to the divergence of the components of the pair under the action of tidal forces in the inhomogeneous gravitational field created by the particles themselves. This resembles the mechanism underlying the evaporation of black holes. The formation of a cluster is described by the example of neutrons. As it was shown earlier in the author's works, the neutron cluster can be considered the initial stage of the formation of a neutron star. This concept made it possible to reconcile the predictions obtained within the frameworks of elementary particle theory, cosmology, and traditional quantum mechanics. The result obtained is fundamental both for cosmology and for the theory of elementary particles.

The Cosmological Constant (original) (raw)

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