Closed Model

Definition

A closed model, in the context of cosmology, refers to a model of the universe that is finite in size and closed in on itself, with the total mass and energy of the universe being finite and contained within a closed spatial geometry. This model suggests that the universe has a beginning and an end, and that its overall structure and evolution can be described by a specific set of physical laws and parameters.

5 Must Know Facts For Your Next Test

1. The closed model of the universe is one of the possible solutions to the Einstein field equations of general relativity, which describe the evolution and structure of the universe.
2. In a closed model, the total mass and energy of the universe are finite, and the overall geometry of space-time is positively curved, meaning that the universe has a finite volume and is closed in on itself, like the surface of a sphere.
3. The closed model predicts that the universe will eventually reach a maximum size and then begin to contract, ultimately leading to a Big Crunch, where the universe collapses back in on itself and ends in a state of infinite density and temperature.
4. The closed model was one of the earliest cosmological models proposed, but it has been largely superseded by the currently favored Lambda-CDM model, which describes an open, accelerating universe.
5. Observational evidence, such as measurements of the cosmic microwave background radiation and the large-scale structure of the universe, strongly suggests that the universe is spatially flat or very close to flat, which is more consistent with an open or flat model than a closed model.

Review Questions

• Explain the key features of a closed model of the universe.
  • In a closed model, the universe is finite in size and has a positively curved spatial geometry, meaning that it is closed in on itself, like the surface of a sphere. The total mass and energy of the universe are finite and contained within this closed spatial volume. The closed model predicts that the universe will eventually reach a maximum size and then begin to contract, ultimately leading to a Big Crunch, where the universe collapses back in on itself and ends in a state of infinite density and temperature.
• Describe how the closed model differs from the open model of the universe.
  • The key difference between the closed model and the open model is the overall geometry and structure of the universe. In the closed model, the universe has a positively curved spatial geometry and a finite volume, whereas in the open model, the universe is infinite in size and has a flat or negatively curved spatial geometry. The closed model predicts a cyclical evolution with a Big Crunch, while the open model suggests a continuous, ever-expanding universe.
• Evaluate the current observational evidence for or against the closed model of the universe.
  • The observational evidence, particularly measurements of the cosmic microwave background radiation and the large-scale structure of the universe, strongly suggests that the universe is spatially flat or very close to flat, which is more consistent with an open or flat model than a closed model. The closed model has largely been superseded by the currently favored Lambda-CDM model, which describes an open, accelerating universe. While the closed model was one of the earliest cosmological models proposed, the available data and our current understanding of the universe's evolution and structure do not support the closed model as the most accurate representation of the universe.

Related terms

Open Model: An open model of the universe is one in which the universe is infinite in size and has a flat or negatively curved spatial geometry, with the total mass and energy being infinite or at least unbounded.

Curvature: The curvature of space-time, as described by the general theory of relativity, determines the overall geometry and structure of the universe, which can be either positively curved (closed), negatively curved (open), or flat.

Big Crunch: In a closed model of the universe, the Big Crunch is the hypothetical future state where the expansion of the universe reverses and the universe collapses back in on itself, eventually reaching a state of infinite density and temperature.