universe

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All of space and its contents, the study of which is called cosmology. The universe is thought to be between 10 billion and 20 billion years old, and is mostly empty space, dotted with galaxies for as far as telescopes can see. These galaxies are moving further apart as the universe expands. Current theories that attempt to explain how the universe came into being and evolved are all versions of the Big Bang theory of an expanding universe originating in a single explosive event creating hydrogen and helium gases.

The most distant detected galaxies and quasars lie 10 billion light years or more from Earth. Apart from those galaxies within the Local Group, all the galaxies we see display red shifts in their spectra, indicating that they are moving away from us. The further we look into space, the greater are the observed red shifts, which implies that the more distant galaxies are receding at ever greater speeds.

This observation led to the theory of an expanding universe, first proposed in 1929 by US astronomer Edwin Hubble, and to Hubble's law, which states that the speed with which one galaxy moves away from another is proportional to its distance from it. Current data suggest that the galaxies are moving apart at a rate of 65–75 kps/40–47 mps for every million parsecs of distance (one parsec equals 3.26 light years, or 3.08 × 10¹³ km). Recent discoveries suggest that the speed of recession is accelerating rather than slowing.

White was added to the flag to identify Bahrain as a friendly state. Red was the traditional colour of the Kharijite Sect. In 2002 the number of serrations were reduced to five, possibly representing the five pillars of Islam. Effective date: 19 August 1972. >>