Universe size

The size of the universe is unknown.
The diameter of the (where "observable" refers to the universe that can theoretically be observed since the light coming from that area has had time to reach us since the ) is estimated to be about 93 billion lightyears (about 29 billion s or about \(8.8 \times 10^{23}\) kilometers).I. Bars and J. Terning (2009) Extra Dimensions in Space and Time Springer Science & Business Media p.27 As nothing can exceed the speed of light, some nonastronomers and laymen assume that the observable universe is actually 13.8 billion light-years in size, as this is the scientifically hypothesized age of the universe in years. The curvature of the universe makes it much larger than this.Edward L. Wright (2006) Why the Light Travel Time Distance should not be used in Press Releases Update 2013-08-02. Retrieved 2023-09-15.
The size of the observable universe is determined by how far light can travel given the total elapsed time since the Big Bang. There are most likely galaxies outside the observable universe that cannot be seen yet because they are too far away for their light to have traveled to Earth, and no conceivable technology by modern means can change that.
The diameter of the actual universe is unknown. One source estimates that the whole universe is at least 250 times larger (3,450 billion light-years) than the observable universe,Vanessa Janek Universe Could be 250 Times Bigger Than What is Observable Universe Today. 2011-02-08. whereas other sources give lower bounds of \(10^{10^{10^{122}}}\) times.D. N. Page (2007) Susskind's challenge to the Hartle–Hawking no-boundary proposal and possible resolutions Journal of Cosmology and Astroparticle Physics JCAP01(2007)004. Preprint
Linde and Vanchurin (2010) estimated possible number of universes in the as \(10^{10^{10^7}}\).A. Linde and V. Vanchurin. (2010) How many universes are in the multiverse? Phys. Rev. D 81, 083525. Preprint.
If the universe's geometry is flat (i.e. it has zero curvature), it will be infinite in size. NASA confirmed with (WMAP) that the universe is flat with only a 0.4% margin of error as of 2013.NASA. Will the Universe expand forever? WMAP's Universe. 2014-01-24.
For the size of the universe in time, although is agreed on among scientists to some degree, the cannot be predicted with certain, and there are several scenarios depending on various undetermined factors. There are some predictions on .
== Sources ==
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