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  2. Chronology of computation of π - Wikipedia

    en.wikipedia.org/wiki/Chronology_of_computation...

    3.125: 1 Between 1 BC and AD 5: Liu Xin [7] [11] [12] Unknown method giving a figure for a jialiang which implies a value for π ≈ 162 ⁄ (√ 50 +0.095) 2. 3.1547... 1 AD 130: Zhang Heng (Book of the Later Han) [2] √ 10 = 3.162277... 736 ⁄ 232: 3.1622... 1 150: Ptolemy [2] 377 ⁄ 120: 3.141666... 3: 250: Wang Fan [2] 142 ⁄ 45: 3 ...

  3. Shape of the universe - Wikipedia

    en.wikipedia.org/wiki/Shape_of_the_universe

    The most familiar is the aforementioned 3-torus universe. In the absence of dark energy, ... " π 39 (Pi and the size of the Universe)". Numberphile. Brady Haran.

  4. Pi - Wikipedia

    en.wikipedia.org/wiki/Pi

    The number π (/ p aɪ /; spelled out as "pi") is a mathematical constant, approximately equal to 3.14159, that is the ratio of a circle's circumference to its diameter.It appears in many formulae across mathematics and physics, and some of these formulae are commonly used for defining π, to avoid relying on the definition of the length of a curve.

  5. Approximations of π - Wikipedia

    en.wikipedia.org/wiki/Approximations_of_π

    He also suggested that 3.14 was a good enough approximation for practical purposes. He has also frequently been credited with a later and more accurate result, π ≈ 3927 ⁄ 1250 = 3.1416 (accuracy 2·10 −6), although some scholars instead believe that this is due to the later (5th-century) Chinese mathematician Zu Chongzhi. [17]

  6. Friedmann equations - Wikipedia

    en.wikipedia.org/wiki/Friedmann_equations

    k = +1, 0 or −1 depending on whether the shape of the universe is a closed 3-sphere, flat (Euclidean space) or an open 3-hyperboloid, respectively. [4] If k = +1, then a is the radius of curvature of the universe. If k = 0, then a may be fixed to any arbitrary positive number at one particular time.

  7. List of formulae involving π - Wikipedia

    en.wikipedia.org/wiki/List_of_formulae_involving_π

    where H is the hypervolume of a 3-sphere and r is the radius. S V = 2 π 2 r 3 {\displaystyle SV=2\pi ^{2}r^{3}} where SV is the surface volume of a 3-sphere and r is the radius.

  8. Friedmann–Lemaître–Robertson–Walker metric - Wikipedia

    en.wikipedia.org/wiki/Friedmann–Lemaître...

    The Friedmann–Lemaître–Robertson–Walker metric (FLRW; / ˈ f r iː d m ə n l ə ˈ m ɛ t r ə ... /) is a metric that describes a homogeneous, isotropic, expanding (or otherwise, contracting) universe that is path-connected, but not necessarily simply connected.

  9. Planck units - Wikipedia

    en.wikipedia.org/wiki/Planck_units

    Table 3: Today's universe in Planck units Property of present-day observable universe Approximate number of Planck units Equivalents Age: 8.08 × 10 60 t P: 4.35 × 10 17 s or 1.38 × 10 10 years Diameter: 5.4 × 10 61 l P: 8.7 × 10 26 m or 9.2 × 10 10 light-years: Mass: approx. 10 60 m P: 3 × 10 52 kg or 1.5 × 10 22 solar masses (only ...