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Einstein's static universe, aka the Einstein universe or the Einstein static eternal universe, is a relativistic model of the universe proposed by Albert Einstein in 1917. [ 1 ] [ 2 ] Shortly after completing the general theory of relativity , Einstein applied his new theory of gravity to the universe as a whole.
The growing block universe, or the growing block view, is a theory of time arguing that the past and present both exist, and the future as yet does not. The present is an objective property, to be compared with a moving spotlight. By the passage of time more of the world comes into being; therefore, the block universe is said to be growing.
A cyclic model (or oscillating model) is any of several cosmological models in which the universe follows infinite, or indefinite, self-sustaining cycles. For example, the oscillating universe theory briefly considered by Albert Einstein in 1930 theorized a universe following an eternal series of oscillations, each beginning with a Big Bang and ending with a Big Crunch; in the interim, the ...
Einstein's static universe is closed (i.e. has hyperspherical topology and positive spatial curvature), and contains uniform dust and a positive cosmological constant with value precisely = /, where is Newtonian gravitational constant, is the energy density of the matter in the universe and is the speed of light.
Some philosophers appeal to a specific theory that is "timeless" in a more radical sense than the rest of physics, the theory of quantum gravity. This theory is used, for instance, in Julian Barbour's theory of timelessness. [20] On the other hand, George Ellis argues that time is absent in cosmological theories because of the details they ...
General relativity is a theory of gravitation developed by Einstein in the years 1907–1915. The development of general relativity began with the equivalence principle , under which the states of accelerated motion and being at rest in a gravitational field (for example, when standing on the surface of the Earth) are physically identical.
When studying and formulating Albert Einstein's theory of general relativity, various mathematical structures and techniques are utilized. The main tools used in this geometrical theory of gravitation are tensor fields defined on a Lorentzian manifold representing spacetime. This article is a general description of the mathematics of general ...
where the variables refer to Friedmann–Einstein universe, where is defined in the equations, is the speed of light, is the scale factor, is the radius of the universe (measured in light years) and its maximal value, is the mean density of matter, is time and the age of the universe (last line, measured in years), and is the Einstein's gravitational constant.