Dark energy

Definition

Dark energy is a mysterious form of energy that makes up about 68% of the universe and is responsible for its accelerated expansion. Its exact nature remains unknown, but it is a crucial component in cosmological models.

5 Must Know Facts For Your Next Test

1. Dark energy was first proposed in the late 1990s to explain observations of an accelerating universe.
2. It is distinct from dark matter, which interacts with gravity but not electromagnetic radiation.
3. The leading theory suggests dark energy could be associated with the cosmological constant (Λ) introduced by Einstein.
4. Evidence for dark energy comes from supernovae measurements, cosmic microwave background data, and large-scale structure observations.
5. Understanding dark energy is one of the major challenges in modern astrophysics and cosmology, influencing theories about the fate of the universe.

Review Questions

• What percentage of the universe's total energy density is made up by dark energy?
• How was dark energy initially discovered?
• What are some observational methods used to infer the existence of dark energy?

Related terms

Dark Matter: A type of matter thought to account for approximately 27% of the mass and energy in the observable universe, it does not emit or interact with electromagnetic radiation.

Cosmological Constant (Λ): A term introduced by Einstein in his equations of General Relativity, often associated with dark energy as a constant energy density filling space homogeneously.

Accelerated Expansion: The observation that galaxies are moving away from each other at an increasing rate, attributed to the influence of dark energy.