Cecile G. Tamura
The Einstein–de Sitter universe
In 1917, both Einstein and de Sitter proposed a new interpretation of the universe as a whole: the structure of the universe could be described in terms of relativistic field equations.
Their contributions marked the beginning of the modern scientific comprehension of the origin and evolution of the universe.
The Einstein-DeSitter model is a matter-dominated Friedmann model with zero curvature (k = 0).
This model corresponds to a Minkowski universe (zero curvature), in which the universe will continue to expand forever with just the right amount of energy to escape to infinity.
It is analogous to launching a rocket. If the rocket is given insufficient energy, it will be pulled back by the Earth.
However, if its energy exceeds a certain critical velocity (escape velocity), it will continue into space with ever-increasing speed.
If it has exactly the escape velocity, it will proceed to escape the Earth with a velocity going to zero as the rocket approaches spatial infinity.
The Einstein-DeSitter model corresponds to the universe having exactly the right escape velocity provided by the Big-Bang to escape the pull of gravity due to the matter in the universe.
Image © Wide World Photos, New York.
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