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A capital Greek lambda, the energy of empty space.
Also known as: Cosmological constant, Dark energy density, Capital lambda in cosmology, Vacuum energy term
Lambda is a constant energy density of the vacuum, added to the field equations. Einstein put it in to hold the universe static, removed it when expansion was found, and it returned in 1998 when supernova measurements showed the expansion is accelerating.
Denotes the cosmological constant, a uniform energy density of the vacuum appearing in the Einstein field equations.
Contexts: Laboratory
Was introduced by Einstein for a static universe, abandoned after the discovery of expansion, and reinstated after 1998 measurements of accelerating expansion.
Contexts: Laboratory
Has an observed value some 120 orders of magnitude below the naive quantum field theory estimate, which is an unexplained discrepancy rather than a solved problem.
Contexts: Laboratory
A capital Greek lambda, two straight strokes meeting at an apex like a triangle without a base.