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  2. Observable universe - Wikipedia

    en.wikipedia.org/wiki/Observable_universe

    According to the theory of cosmic inflation initially introduced by Alan Guth and D. Kazanas, [23] if it is assumed that inflation began about 10 −37 seconds after the Big Bang and that the pre-inflation size of the universe was approximately equal to the speed of light times its age, that would suggest that at present the entire universe's ...

  3. Universe - Wikipedia

    en.wikipedia.org/wiki/Universe

    Because humans cannot observe space beyond the edge of the observable universe, it is unknown whether the size of the universe in its totality is finite or infinite. [3] [57] [58] Estimates suggest that the whole universe, if finite, must be more than 250 times larger than a Hubble sphere. [59]

  4. Shape of the universe - Wikipedia

    en.wikipedia.org/wiki/Shape_of_the_universe

    Hence, it is unclear whether the observable universe matches the entire universe or is significantly smaller, though it is generally accepted that the universe is larger than the observable universe. The universe may be compact in some dimensions and not in others, similar to how a cuboid [citation needed] is longer in one dimension than the ...

  5. Cosmology - Wikipedia

    en.wikipedia.org/wiki/Cosmology

    Physical cosmology was shaped through both mathematics and observation in an analysis of the whole universe. The universe is generally understood to have begun with the Big Bang, followed almost instantaneously by cosmic inflation, an expansion of space from which the universe is thought to have emerged 13.799 ± 0.021 billion years ago. [8]

  6. Outer space - Wikipedia

    en.wikipedia.org/wiki/Outer_space

    The size of the whole universe is unknown, and it might be infinite in extent. [20] According to the Big Bang theory, the very early universe was an extremely hot and dense state about 13.8 billion years ago [ 21 ] which rapidly expanded .

  7. List of largest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_largest_stars

    A variable yellow hypergiant whose size varied from around 680 R ☉ in 1950–1970 to 910 R ☉ in 1977, and later decreased to 390 R ☉ in the 1990s. [77] V382 Carinae (x Carinae) 485 ± 56 [78] L/T eff: A yellow hypergiant, one of the rarest types of stars. V838 Monocerotis: 464 [79] L/T eff

  8. Planck units - Wikipedia

    en.wikipedia.org/wiki/Planck_units

    One example is represented by the conditions in the first 10 −43 seconds of our universe after the Big Bang, approximately 13.8 billion years ago. The four universal constants that, by definition, have a numeric value 1 when expressed in these units are: c, the speed of light in vacuum, G, the gravitational constant, ħ, the reduced Planck ...

  9. Hubble volume - Wikipedia

    en.wikipedia.org/wiki/Hubble_volume

    Visualization of the whole observable universe.The inner blue ring indicates the approximate size of the Hubble volume. In cosmology, a Hubble volume (named for the astronomer Edwin Hubble) or Hubble sphere, Hubble bubble, subluminal sphere, causal sphere and sphere of causality is a spherical region of the observable universe surrounding an observer beyond which objects recede from that ...