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Cosmic inflation is the process of extreme accelerated expansion of the universe during its first few moments. According to the standard inflationary model (proposed in 1981 by Alan Guth, Andrei Linde, Paul Steinhardt, and Andy Albrecht) the nascent universe passed through a phase of exponential expansion prior to the more gradual Big Bang expansion. During this time, the energy density of the universe was dominated by a cosmological constant-type of vacuum energy that later decayed to produce the matter and radiation that fill the universe today. This expansion is responsible for the continuing Hubble expansion of the universe, its present huge size, its relative homogeneity and isotropy, and its spatial flatness. Inflation also explains the origin of the large-scale structure of the cosmos. The quantum fluctuations of the inflation field produced the ripples in space-time, which are thought to be the primordial seeds of the galaxy formation. More Information What is the Inflation Theory? WMAP site _____________________________________________________________________________________ Inflation is one of the most popular methods known for generating an isotropic and homogeneous universe. The basic idea is that the universe, which is expanding now with some time dependent scale factor a(t), starts expanding faster and faster. Expansion means that the scale factor changes with time, d a(t)/dt is nonzero. For inflation, this change in the scale factor changes with time as well, that is, the scale factor accelerates: d2 a(t)/ d t2 > 0 . The effect of this is to dilute away all the inhomogeneities in space, such as monopoles predicted by many high energy theories (one of the early motivations), or any other sort of fluctuations. The number density of particles goes to zero, since space is expanding so fast. Read more from Joanne Cohn.
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