Is the Decaying Vacuum Model a Complete Description of Cosmic Expansion?

  • Thread starter Thread starter wolram
  • Start date Start date
  • Tags Tags
    Model Vacuum
AI Thread Summary
The Decaying Vacuum Model proposes a cosmological scenario that evolves from an initial de Sitter stage through radiation, matter, and dark energy epochs, avoiding initial singularities and addressing the horizon problem. It introduces a running vacuum energy density that varies as a power series of the Hubble rate, leading to a smooth transition from inflation to the radiation epoch. The model suggests a graceful exit into a slow accelerated expansion characterized by a dynamic vacuum energy. While it closely resembles the standard ΛCDM model, it claims to provide a more comprehensive account of cosmic evolution. The discussion highlights skepticism about its novelty, viewing it more as an interesting curve-fitting approach than a groundbreaking model.
wolram
Gold Member
Dearly Missed
Messages
4,410
Reaction score
555
What do you guys think of this new model?


[4] arXiv:1209.2802 [pdf, ps, other]
Expansion History with Decaying Vacuum: A Complete Cosmological ScenJ. A. S. Lima, S. Basilakos, Joan So
Comments: LaTeX, 11 pages and one figure
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
We propose a novel cosmological scenario with the space-time emerging from a pure initial de Sitter stage and subsequently evolving into the radiation, matter and dark energy dominated epochs, thereby avoiding the initial singularity and providing a complete description of the expansion history and a natural solution to the horizon problem. The model is based on a running vacuum energy density which evolves as a power series of the Hubble rate: \rho_{\Lambda}(H). The transit from the inflation into the standard radiation epoch is universal, giving a clue for a successful description of the graceful exit. The Universe is finally driven into the present slow accelerated expansion, characterized by a residual (but dynamical) vacuum energy: \rho_{\Lambda}(H)=c_0+c_2H^2. While the resulting late time cosmic history is very close to the concordance \Lambda CDM model, the new unified framework embodies a more complete past cosmic evolution than the standard cosmology
 
Space news on Phys.org
It doesn't seem to be a new model so much as "curve fitting" but it looks like interesting and useful curve fitting.
 
https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
The formal paper is here. The Rutgers University news has published a story about an image being closely examined at their New Brunswick campus. Here is an excerpt: Computer modeling of the gravitational lens by Keeton and Eid showed that the four visible foreground galaxies causing the gravitational bending couldn’t explain the details of the five-image pattern. Only with the addition of a large, invisible mass, in this case, a dark matter halo, could the model match the observations...
Why was the Hubble constant assumed to be decreasing and slowing down (decelerating) the expansion rate of the Universe, while at the same time Dark Energy is presumably accelerating the expansion? And to thicken the plot. recent news from NASA indicates that the Hubble constant is now increasing. Can you clarify this enigma? Also., if the Hubble constant eventually decreases, why is there a lower limit to its value?
Back
Top