Quintessence (physics)


Quintessence (physics)

__NOTOC__In physics, quintessence is a hypothetical form of dark energy postulated as an explanation of observations of an accelerating universe.

calar field

Quintessence is a scalar field which has an equation of state (relating its pressure "p""q" and density ho"q") of "p""q" = "w" ho"q", where "w" is equal to the equation of state of the energy component dominating the universe (i.e. equal to 1/3 during radiation domination and 0 during matter domination) until "w" undergoes a transition to less than -1/3 which initiates the accelerated expansion of the universe. Quintessence is dynamic, and generally has a density and equation of state that varies through time and space. By contrast, a cosmological constant is static, with a fixed energy density and "w" = −1.

Tracker behavior

Many models of quintessence have a "tracker" behavior, which partly solves the cosmological constant problem. In these models, the quintessence field has a density which closely tracks (but is less than) the radiation density until matter-radiation equality, which triggers quintessence to start having characteristics similar to dark energy, eventually dominating the universe. This naturally sets the low scale of the dark energy.

Phantom energy

Some special cases of quintessence are phantom energy, in which w < −1, and k-essence (short for kinetic quintessence) which has a non-standard form of kinetic energy.

Terminology

The name comes from the Classical elements of the ancient Greeks, where a pure "fifth element," (known as "quinta essentia" in Latin) the aether, was thought to fill the Universe beyond Earth.

External links

* [http://www.astro.uni-bonn.de/~webiaef/outreach/posters/darkenergy/ Dark Energy dominates the Universe] (outreach poster from University of Bonn)
* [http://www.astro.uni-bonn.de/~kilbinge/de/index.shtml/ Dark Energy dominates the Universe]
* [http://www.astronomytoday.com/cosmology/quintessence.html/ Quintessence Accelerating the Universe]
* [http://physicsworld.com/cws/article/print/402 Quintessence]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Quintessence — The Transformers characters are spelled Quintessons. Quintessence, literally fifth essence (from Latin quinta essentia ), can refer : * Aether (classical element), the fifth classical element after earth, fire, water and air * Quintessence… …   Wikipedia

  • List of unsolved problems in physics — This is a list of some of the major unsolved problems in physics. Some of these problems are theoretical, meaning that existing theories seem incapable of explaining a certain observed phenomenon or experimental result. The others are… …   Wikipedia

  • Aristotelian physics — The Greek philosopher Aristotle (384 BC – 322 BC) developed many theories on the nature of physics that are completely different from what are now understood as the laws of physics. These involved what Aristotle described as the four elements, as …   Wikipedia

  • Dark energy — Not to be confused with dark matter, dark fluid, or dark flow. Physical cosmology …   Wikipedia

  • Alternatives to general relativity — are physical theories that attempt to describe the phenomena of gravitation in competition to Einstein s theory of general relativity.There have been many different attempts at constructing an ideal theory of gravity. These attempts can be split… …   Wikipedia

  • Dark matter — Not to be confused with antimatter, dark energy, dark fluid or dark flow. For other uses, see Dark Matter (disambiguation) …   Wikipedia

  • Cosmological constant — Physical cosmology Universe · Big Bang …   Wikipedia

  • Paul Steinhardt — Infobox Scientist box width = 300px name = Paul J. Steinhardt image width = 250px caption = At the 2008 World Science Festival in New York City birth date = birth place = death date = death place = residence = U.S. citizenship = nationality =… …   Wikipedia

  • Christof Wetterich — Born 1952 Freiburg, Germany Fields …   Wikipedia

  • Cosmology — The Hubble Ultra Deep Field. Every speck of light in this image is an entire galaxy. This is just a small region of a Universe which could contain as many as 200 billion galaxies. Cosmology is the discipline that deals with the nature of the… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.