An amateur story of space
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Euclid created mathematical 2-D space
Euclidean space is a scene where the Earth events take place
Euclidean math space is an absolute and rigid, nothing can change it
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In 1908 Minkowski mathematically showed that Einstein's
SR theory would be more beautiful if to use 4-D.
Most important, the 4-D is as flat as 2-D, only one (2-D) is used
as Earth scene and another (4-D) is used as a Cosmic scene.
And from Cosmic view the Earth's scene is looked as the 3-D.
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During 1830 - 1854 Lobachevsky, János Bolyai and Riemann separately
and independently had an idea, maybe, some ''hidden force'' can change
the Euclidean 2-D. And they created non-Euclidean geometry.
Many years this mathematical idea was considered as an abstract idea
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But in 1915 Einstein by using Riemann geometry
(plus using ''hidden matter'' -- mass and energy)
showed that the Riemann geometry can have practical profit.
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The Earth ''empty'' space (air) is filled with different molecules
The Cosmic ''empty'' space (vacuum) is filled with different ''virtual particles''
Both spaces are real.
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