An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 2 Search : de Sitter Universe
de Sitter Universe
  گیتی ِ دوسیتر   
giti-ye de Sitter

Fr.: Univers de de Sitter   

A solution to → Einstein's field equations of → general relativity which contains no ordinary matter (ΩM = 0) or radiation (ΩR = 0), is → Euclidean (k = 0), but has a → cosmological constantΛ > 0). The Universe expands exponentially forever. This solution was the first model expanding of → expanding Universe. See also → empty Universe, → Milne Universe.

After the Dutch mathematician and physicist Willem de Sitter (1872-1934) who worked out the model in 1917; → universe.

Einstein-de Sitter Universe
  گیتی ِ اینشتین-دو سیتر   
giti-ye Einstein-de Sitter

Fr.: Univers Einstein-de Sitter   

The → Friedmann-Lemaitre model of → expanding Universe that only contains matter and in which space is → EuclideanM > 0, ΩR = 0, ΩΛ = 0, k = 0). The Universe will expand at a decreasing rate for ever.

Einstein; de Sitter, after the Dutch mathematician and physicist Willem de Sitter (1872-1934) who worked out the model in 1917; → Universe.