Inflationary epoch

Inflationary epoch

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In physical cosmology
Physical cosmology
Physical cosmology, as a branch of astronomy, is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. For most of human history, it was a branch of metaphysics and religion...

 the inflationary epoch was the period in the evolution of the early universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

 when, according to inflation theory, the universe underwent an extremely rapid exponential expansion
Metric expansion of space
The metric expansion of space is the increase of distance between distant parts of the universe with time. It is an intrinsic expansion—that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space...

. This rapid expansion increased the linear dimensions of the early universe by a factor of at least 1026 (and possibly a much larger factor), and so increased its volume by a factor of at least 1078.

The expansion is thought to have been triggered by the phase transition
Phase transition
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.A phase of a thermodynamic system and the states of matter have uniform physical properties....

 that marked the end of the preceding grand unification epoch
Grand unification epoch
In physical cosmology, assuming that nature is described by a Grand unification theory, the grand unification epoch was the period in the evolution of the early universe following the Planck epoch, starting at about 10−43 seconds after the Big Bang, in which the temperature of the universe was...

 at approximately 10−36 seconds after the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

. One of the theoretical products of this phase transition was a scalar field
Scalar field
In mathematics and physics, a scalar field associates a scalar value to every point in a space. The scalar may either be a mathematical number, or a physical quantity. Scalar fields are required to be coordinate-independent, meaning that any two observers using the same units will agree on the...

 called the inflaton
The inflaton is the generic name of the hypothetical and hitherto unidentified scalar field that may be responsible for the hypothetical inflation in the very early universe...

 field. As this field settled into its lowest energy state throughout the universe, it generated a repulsive force that led to a rapid expansion of the fabric of space-time. This expansion explains various properties of the current universe that are difficult to account for without such an inflationary epoch.

It is not known exactly when the inflationary epoch ended, but it is thought to have been between 10−33 and 10−32 seconds after the Big Bang. The rapid expansion of space meant that elementary particles remaining from the grand unification epoch were now distributed very thinly across the universe. However, the huge potential energy of the inflation field was released at the end of the inflationary epoch, repopulating the universe with a dense, hot mixture of quarks, anti-quarks and gluons
Quark-gluon plasma
A quark–gluon plasma or quark soup is a phase of quantum chromodynamics which exists at extremely high temperature and/or density. This phase consists of asymptotically free quarks and gluons, which are several of the basic building blocks of matter...

 as it entered the electroweak epoch
Electroweak epoch
In physical cosmology the electroweak epoch was the period in the evolution of the early universe when the temperature of the universe was high enough to merge electromagnetism and the weak interaction into a single electroweak interaction . The electroweak epoch began when the strong force...


External links

  • Inflation for Beginners by John Gribbin
    John Gribbin
    John R. Gribbin is a British science writer and a visiting Fellow in astronomy at the University of Sussex.- Biography :John Gribbin graduated with his bachelor's degree in physics from the University of Sussex in 1966. Gribbin then earned his master of science degree in astronomy in 1967, also...