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The observable universe is thus a sphere with a diameter of about 28.5 gigaparsecs [27] (93 billion light-years or 8.8 × 10 26 m). [28] Assuming that space is roughly flat (in the sense of being a Euclidean space ), this size corresponds to a comoving volume of about 1.22 × 10 4 Gpc 3 ( 4.22 × 10 5 Gly 3 or 3.57 × 10 80 m 3 ).
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]
120 μm – the geometric mean of the Planck length and the diameter of the observable universe: √ 8.8 × 10 26 m × 1.6 × 10 −35 m; 120 μm – diameter of a human ovum; 170 μm – length of the largest mammalian sperm cell (rat) [103] 170 μm – length of the largest sperm cell in nature, belonging to the Drosophila bifurca fruit fly ...
A finite universe is a bounded metric space, where there is some distance d such that all points are within distance d of each other. The smallest such d is called the diameter of the universe, in which case the universe has a well-defined "volume" or "scale".
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 ...
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 ...
The astronomical unit is typically used for stellar system scale distances, such as the size of a protostellar disk or the heliocentric distance of an asteroid, whereas other units are used for other distances in astronomy. The astronomical unit is too small to be convenient for interstellar distances, where the parsec and light-year are widely ...
Neither time nor size are to scale. 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.