Is Dark Energy a Macroscopic Effect of Quantum Gravity?
A new paper by Leonid Marochnik, Daniel Usikov, and Grigory Vereshkov suggests that dark energy maybe be the third macroscopic quantum effect, after superfluidity and superconductivity. Dark energy is a theoretical form of energy that causes the rate of expansion of the Universe to speed up. In terms of total mass-energy present in the Universe, it is thought to account for up to 74% of it.
Current models that attempt to explain dark energy include Lambda-CDM (Cold Dark Matter) and Quintessence. Lambda-CDM includes a cosmological constant that describes this dark energy as a vacuum energy that fills fills all space. It is called the standard model of cosmology, as it is the most widely accepted model. Quintessence, on the other hand, explains dark energy as a scalar field with density and equation of state that varies throughout spacetime. Neither, however, have been proven to a satisfactory degree of validity. Also, neither can explain exactly why dark energy exists.
Marochnik, Usikov, and Vereshkov dub their theory “Lambda-GCDM” where the added G stand for gravity. Gravity is incorporated into the existing Lambda-CDM model by interpolating exact solutions of one-loop quantum gravity. Loop quantum gravity is a proposed theory that attempts to reconcile quantum mechanis with general relativity.
While their 92-page paper covers many possibilities and makes many points, they clearly express the view that their calculations point towards dark energy consisting of a “graviton-ghost condensate,” and that “a graviton-ghost condensate played a measurably significant part in shaping global cosmological dynamics.” Identifying this component of dark matter is critical, they say, and could be accomplished by exploring the area of possible transition in differing red-shifts. This is the point at which any graviton-ghost condensate would change from it’s pre-asympotitc state to its asymptotic state. More on this later, once I learn exactly what it entails…
They are able to show that their model is consistent with existing observational data on dark energy extracted from the Hubble diagram for supernovae SNIa. They also argue that their model has several advantages over Lambda-CDM. However, they concluded by saying the next step in determining their theory’s viability will be to conduct numerical experiments with the BBGKY(Born, Bogoliubov, Green, Kirkwood, and Yvon) chain, taking into account non-relativistic matter. This modification and expansion of currently accepted models could be a great step forward, depending on peer reviews of it.
Actual paper in sources below.
Sources:
Marochnik L, Usikov D, Vereshkov G. Graviton, Ghost and instanton condensation on horizon scale of the Universe. Dark energy as Macroscopic Effect of Quantum Gravity. Arxiv.org Nov 27, 2008
http://www.astronomytoday.com/cosmology/quintessence.html/
This entry was posted on Tuesday, December 2nd, 2008 at 6:43 pm and is filed under Astrophysics, Quantum Physics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
