Cosmological constant

Definition

The cosmological constant, denoted by $\Lambda$, is a term in Einstein's field equations of general relativity that represents the energy density of empty space, or dark energy. It was originally introduced by Einstein to achieve a static universe but is now associated with the accelerating expansion of the universe.

5 Must Know Facts For Your Next Test

1. The cosmological constant was introduced by Albert Einstein in 1917.
2. $\Lambda$ is associated with dark energy and the accelerating expansion of the universe.
3. Observations of distant supernovae provided evidence for a positive $\Lambda$.
4. A positive value for the cosmological constant implies a repulsive force counteracting gravity on large scales.
5. $\Lambda$ has units of inverse square seconds ($s^{-2}$) in natural units.

Review Questions

• What role does the cosmological constant play in Einstein's field equations?
• How did observations of distant supernovae influence our understanding of $\Lambda$?
• What does a positive value for the cosmological constant imply about the fate of the universe?

Related terms

Dark Energy: A form of energy that permeates all of space and tends to accelerate the expansion of the universe.

General Relativity: Einstein's theory describing gravity as a geometric property of space and time.

$H_0$ (Hubble Constant): The rate at which the universe is expanding, measured in kilometers per second per megaparsec.