| open universe | has geometry of space negative curvature |  |
| has definition Big Bang model that was formulated by Friedmann and Lemaitre which has a negative curvature, like a saddle-shaped surface, in which case the universe is infinite, open, and will expand forever. This space is unbounded. | |
| has definition Any model of the Universe which does not contain enough matter to halt its expansion. | |
| has definition A homogeneous, isotropic Universe is said to be temporally open if gravity is not strong enough to eventually reverse the expansion, so the universe goes on expanding forever. It is said to be spatially open if it curves the opposite way from a closed universe, so that triangles would contain less than 180°, the circumference of a circle would be more than π times the diameter, and the volume would be infinite. If Einstein's Cosmological Constant is zero, as is frequently assumed, then a universe which is temporally open is also spatially open, and vice versa. | |
| has definition Cosmological model in which the universe continues to expand forever; its space-time geometry is hyperbolic, or "open". | |
| is a kind of big bang | |
| big bang | has synonym Friedmann-Lemaitre universe | |
| has antonym big crunch | |
| cosmology theory | has domain cosmology | |
| theory | has validity correct or incorrect with caveats | |
| has author or reasearch group | |
| has date or a range of dates for which the theory was active | |
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