2005/10/19 by Xavier Calmet, X Calmet · 1 citation
Physics and Astronomy · #Advanced Mathematical Theories and Applications #Cosmological constant #Cosmology and Gravitation Theories #Noncommutative algebraic geometry #Noncommutative and Quantum Gravity Theories #Noncommutative geometry #Noncommutative quantum field theory #Planck energy #Quantum differential calculus #Spacetime #Unimodular matrix #astro-ph #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1209/0295-5075/77/19002
published as Europhys.Lett.77:19902,2007 · 7 pages
arxiv created 2005/10/19 · openalex publication_date 2007/01/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We show that the cosmological constant appears as an integration constant if nature is described by a canonical noncommutative spacetime. It is thus an arbitrary parameter unrelated to the action and thus to vacuum fluctuations. The noncommutative algebra restricts general coordinate transformations to four-volume–preserving noncommutative coordinate transformations. The noncommutative gravitational action is thus a unimodular noncommutative gravity. We show that spacetime noncommutativity provides a very natural justification to a unimodular gravity solution to the cosmological problem. We obtain the right order of magnitude for the critical energy density of the universe if we assume that the scale for spacetime noncommutativity is the Planck scale.