Electroweak Era

lan Guth, now a Professor at MIT, proposed an Inflation addition to the Big Bang Standard Model in 1981. As shown in the chart at the left produced by Guth himself, the universe went through an expansionary phase that was faster than the speed of light. (Space-time is not limited by the speed of light, only objects "within" space-time are.) In this brief interval of Inflation, the "observable" universe expanded by a factor of about 10^70 (1 followed by 70 zeros) from being unimaginably smaller than a subatomic particle to about the size of a grapefruit. That is the equivalent of going from about the size of a grape to the current size of the observable universe in the blink of an eye - awesome!

Note that Inflationary theory does not say anything about the "whole" universe, only the observable universe. The Inflationary model does not make any statement about the whole universe which could in fact be infinite. See paper on Inflation by Alan Guth. Inflation ends when the inflation field decays into ordinary particles in a process called "reheating", at which point the ordinary Big Bang expansion begins.

What caused Inflation to happen? Cosmologists are not sure of this and several theories exist. Guth proposed that the super cooling initiated a anti-gravitational field which then caused a violent growth spurt. There were some side issues with Guth's proposal and Andrei Linde of Stanford suggested "New Inflation" which could have various triggers, among them a random fluctuation of the initial field. There are several other theories floating about including one from Paul Steinhardt of Princeton. Steinhardt has championed an alternative to Inflation, in which the universe begins from a collision between a pair of universes known in string theory as "branes", short for membranes (see Branes in string theory sister page).

The important cosmological feature added by Guth is the rapid expansion of the very early universe which then blends in very smoothly with the standard Big Bang theory. Inflation solves the three issues with the initial theory (see theBig Bang Page.) and has now been incorporated as part of the standard Big Bang Theory. The recent WMAP satellite measurements are very consistent with the Guth type inflation models providing the first soft evidence for Inflation. (See the WMAP section under Early CMB Maps on the Microwave page.)

To Inflation purists, the Big Bang never really took place. Inflation was the start of the universe as we know it and all particles, stars, galaxies, etc. came about as a result of Inflation. There was no Big Bang explosion per se.  Top

Reheating (10^-35 to About 10^-10 Of A Second)

Inflation was a period of super cooled expansion and the temperature dropped by a factor of 100,000 or so and continued to be cool during this phase. When Inflation ended the temperature returned to the pre-Inflationary temperature, back up by a factor of 100,000. This period is called "Reheating".

The huge potential energy of the inflation field suddenly decayed and filled the universe with elementary particles and radiation similar to water vapor in the atmosphere condensing into water droplets forming a cloud. Because the fundamental driving principles of Inflation are not known, this process is not well understood.

During Reheating, the elementary particles - photons, gluons, and quarks - were formed, but in a dense plasma state. Quarks and anti-quarks began to annihilate each other. However for reasons not yet understood, the mutual destruction of quarks and anti-quarks ended with a surplus of quarks. Because of this discrepancy, i.e. a surplus of quarks (matter), all galaxies, stars, planets, and human beings exist today.

Also, the three additional fundamental forces - the Electro-magnetic Force, the Strong Nuclear Force, and the Weak Nuclear Force - formed and then separated during this time according to the Grand Unified Theory. The universe, as we now know it, had evolved. The laws of physics and the four forces of nature began to apply. The fundamental particles had mass, but the temperature of the universe is still too high to allow quarks to bind together to form neutrons and protons. Reheating ended at about 10^-10th of a second.