Astronomy & Space Science · AST-761
The Cosmological Constant: Foundations
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Overview
Core model: The Cosmological Constant
The cosmological constant, written Λ, is the simplest dark-energy term in Einstein's equations. It behaves like an energy density intrinsic to empty space that remains constant as the universe expands and has equation-of-state parameter w = -1.
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References & evidence
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- 01DESI DR2 Results GuideOpen source ↗
DESI Collaboration
- 02The Big Bang — SummaryOpen source ↗
OpenStax Astronomy 2e · Mar 9, 2022
View claim-by-claim traceability3 verified claims
The cosmological constant, written Λ, is the simplest dark-energy term in Einstein's equations.
supported · checked Sep 22, 2026A constant vacuum-like energy density has negative pressure in general relativity.
supported · checked Sep 22, 2026A constant-Λ model fits a wide combination of CMB, supernova, BAO, and large-scale-structure data remarkably well.
supported · checked Sep 22, 2026