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A graphical representation of the expansion of the universe from the Big Bang to the present day, with the inflationary epoch represented as the dramatic expansion seen on the left. This visualization shows only a section of the universe; the empty space outside the diagram should not be taken to represent empty space outside the universe ...
In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the very early universe.Following the inflationary period, the universe continued to expand, but at a slower rate.
The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago. [ 8 ] [ notes 1 ] Within the framework of general relativity , an accelerated expansion can be accounted for by a positive value of the cosmological constant Λ , equivalent to the presence of ...
If dark energy—represented by the cosmological constant, a constant energy density filling space homogeneously, [3] or scalar fields, such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space—accelerates the expansion of the universe, then the space between clusters of galaxies will grow at an ...
This expansion explains various properties of the current universe that are difficult to account for without such an inflationary epoch. Most inflationary models propose a scalar field called the inflaton field, with properties necessary for having (at least) two vacuum states.
Timeline of the expansion of the universe, where space, including hypothetical non-observable portions of the universe, is represented at each time by the circular sections. On the left, the dramatic expansion occurs in the inflationary epoch ; and at the center, the expansion accelerates (artist's concept; neither time nor size are to scale).
The nature of both dark energy and dark matter is unknown. Dark matter, a mysterious form of matter that has not yet been identified, accounts for 26.8% of the cosmic contents. Dark energy, which is the energy of empty space and is causing the expansion of the universe to accelerate, accounts for the remaining 68.3% of the contents. [8] [97] [98]
In physical cosmology, the Big Rip is a hypothetical cosmological model concerning the ultimate fate of the universe, in which the matter of the universe, from stars and galaxies to atoms and subatomic particles, and even spacetime itself, is progressively torn apart by the expansion of the universe at a certain time in the future, until distances between particles will infinitely increase.