Space exploration began with the launch of Sputnik and Astrophysics was born as the application of physics to the phenomena observed by Astronomy, which etymologically means laws of the stars.
There are 2759 entries in this glossary.| Term | Definition |
|---|---|
| De Sitter Universe |
A model of the expanding universe proposed in 1917 in which there is no matter or radiation. This unrealistic hypothesis is historically important because it established the idea that the universe might be expanding rather than static.
See also: Einstein-de Sitter universe.
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