Big Bang

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The Big Bang is the name that scientists use for the most common theory of the universe,[1][2][3] from the very early stages to the present day.[4][5][6]

The Big Bang theory is that the universe has not always existed. It states that the early universe was hot and dense. As time passed the universe expanded, cooled, and became less dense. The Big Bang theory can explain why the universe looks the way it does. It explains why distant galaxies are moving away from us, and why the speed that they move away from us is proportional to distance. It explains why most of the visible universe is made of hydrogen and helium. It explains why there is a cosmic microwave background.[7]

Working backwards suggests that there would have been a time when temperatures and density were infinite.[8] Scientists are undecided whether this means the universe began from a singularity, or that current knowledge is insufficient to describe the universe at that time. Detailed measurements of the expansion rate of the universe tell us that the Big Bang happened at around 13.8 billion years ago. This is the age of the universe,

Early ideas of the Bang suggested a "cosmic egg ". Modern models say the whole early universe was hot and dense, and so there is no "centre" to the universe. Nor is there any place where the Big Bang happened, Instead the Big Bang was everywhere.[9][10] The expansion of the universe is the expansion of the spacetime and not the motion of atoms through space.

Graphical timeline of the universe[change | change source]

Many things happened in the first second of the universe's life:

Cosmic microwave background radiationTimeline of the Big Bang#Matter domination: 70,000 yearsTimeline of the Big Bang#Recombination: 240,000-310,000 yearsBig Bang nucleosynthesisInflationary epochPlanck timeTimeline of the Big Bang#Dark AgesPhoton epochLepton epochHadron epochQuark epochElectroweak epochGrand unification epochThe Five Ages of the UniverseReionizationGraphical timeline of the Stelliferous EraBig BangPlanck epoch

References[change | change source]

  1. Overbye, Dennis (20 February 2017). "Cosmos Controversy: The Universe Is Expanding, but How Fast?". The New York Times. Retrieved 21 February 2017.
  2. Kurki-Suonio, Hannu (2018). "Cosmology I" (PDF). University of Helsinki. p. 9-10. Retrieved 30 January 2019.
  3. Kornreich, Dave (27 June 2015). "Can we find the place where the Big Bang happened? (Intermediate)". Ask an Astronomer, Cornell University. Retrieved 20 October 2018.
  4. Silk, Joseph (2009). Horizons of Cosmology. Templeton Press]]. p. 208.
  5. Singh, Simon (2005). Big Bang: The Origin of the Universe. Harper Perennial. p. 560.
  6. Wollack, Edward J. (10 December 2010). "Cosmology: The Study of the Universe". Universe 101: Big Bang Theory. NASA. Archived from the original on 14 May 2011. Retrieved 2017-04-15. The second section discusses the classic tests of the Big Bang theory that make it so compelling as the likely valid description of our universe.
  7. Wright E.L. 2009. What is the evidence for the Big Bang?. Frequently Asked Questions in Cosmology. UCLA, Division of Astronomy and Astrophysics. [1]
  8. Hawking, S. W.; Ellis, G. F. R. (1973). The Large-Scale Structure of Space-Time. Cambridge University Press. ISBN 978-0-521-20016-5.
  9. Kurki-Suonio, Hannu (2018). "Cosmology I" (PDF). University of Helsinki. p. 9-10. Retrieved 30 January 2019.
  10. Kornreich, Dave (27 June 2015). "Can we find the place where the Big Bang happened? (Intermediate)". Ask an Astronomer, Cornell University. Retrieved 20 October 2018.

More reading[change | change source]

  • Caleb, Weedon (2005). Big Bang: the most important scientific discovery of all time and why you need to know about it. Harper Perennial. ISBN 9780007152520.