In astronomy, the explosive event that marked the origin of the universe as we know it. At the time of the Big Bang, the entire universe was squeezed into a hot, superdense state. The Big Bang explosion threw this compact material outwards, producing the expanding universe seen today.
From Astronomy Encyclopedia Remnant radiation from the creation of the Universe. Early cosmologists predicted theoretically that the Universe originally began as a singularity that expanded into a small, hot ‘soup’ of radiation and elementary particles.
From Atlas of the Universe Before we can make any attempt to trace the history of the universe, we must look carefully at the situation we find today. As we have seen, each group of galaxies is receding from each other group, so that the entire universe is expanding.
From Collins Dictionary of Astronomy
Galaxies must have condensed out of the gases expanding from the Big Bang, beginning at a time when the average density of the Universe was roughly the same as the current mean density of a galaxy.
From Collins Dictionary of Astronomy Extremely weak wavelike disturbances that were predicted by Einstein's general theory of relativity. They represent the radiation associated with the gravitational force, and are produced when massive bodies are accelerated or otherwise disturbed.
Life history of a star, beginning with its condensation out of the interstellar gas (see interstellar matter) and ending, sometimes catastrophically, when the star has exhausted its nuclear fuel or can no longer adjust itself to a stable configuration.
From The Hutchinson unabridged encyclopedia with atlas and weather guide
In physics and cosmology, a mathematical theory developed in the 1980s to explain the properties of elementary particles and the forces between them (in particular, gravity and the nuclear forces) in a way that combines relativity and quantum theory.
From Science in the Early Twentieth Century: An Encyclopedia Astrophysics is a branch of astronomy that deals primarily with dynamic relationships and physical structures. It came to prominence before the twentieth century and was substantially helped by the development of new technology.
From Collins Dictionary of Astronomy A short period of very rapid expansion of the Universe postulated to occur very soon after the big bang. The hypothesis of inflation in the early Universe solves a number of cosmological problems.
From Astronomy Encyclopedia Planet not associated with our Solar System. The existence of other worlds, especially inhabited ones, has been the subject of debate since ancient times. In the 20th century, stars with irregular proper motions were suspected of having planetary companions; BARNARD'S STAR was a famous candidate.
From Collins Dictionary of Astronomy Two mathematical expressions derived by Jan Oort that describe the effects of differential galactic rotation on the radial velocities (vr) and tangential velocities (vt) of stars at an average distance r from the Sun.
From Astronomy Encyclopedia Radius that a body must exceed if light from its surface is to reach an outside observer. If an object collapses below this radius, its escape velocity rises to above the speed of light and the object becomes a black hole.