Universe

Universe

The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The observable universe is about 93 billion light years in diameter. The size of the entire Universe is unknown.

Definition

The Universe is defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term Universe may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world, or nature.

Chronology and the Big Bang

The chronology of the Universe describes the history and future of the Universe according to Big Bang cosmology, the prevailing scientific model of how the Universe developed over time from the Planck epoch, using the cosmological time parameter of comoving coordinates.

Observable universe and beyond

The observable universe is a spherical region of the Universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion.

Multiverse hypothesis

The multiverse is a hypothetical group of multiple universes. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them.

See also

• Big Bang
• Cosmology
• Multiverse
• Observable universe
• Planck epoch

References

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External links

• NASA - What is the Universe?
• The Expanding Universe: From the Big Bang to Today

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