Recognition: unknown
Cosmological Constant - the Weight of the Vacuum
read the original abstract
Recent cosmological observations suggest the existence of a positive cosmological constant $\Lambda$ with the magnitude $\Lambda(G\hbar/c^3) \approx 10^{-123}$. This review discusses several aspects of the cosmological constant both from the cosmological (sections 1-6) and field theoretical (sections 7-11) perspectives. The first section introduces the key issues related to cosmological constant and provides a brief historical overview. This is followed by a summary of the kinematics and dynamics of the standard Friedmann model of the universe paying special attention to features involving the cosmological constant. Section 3 reviews the observational evidence for cosmological constant, especially the supernova results, constraints from the age of the universe and a few others. Theoretical models (quintessence, tachyonic scalar field, ...) with evolving cosmological `constant' are described from different perspectives in the next section. Constraints on dark energy from structure formation and from CMBR anisotropies are discussed in the next two sections. The latter part of the review (sections 7-11) concentrates on more conceptual and fundamental aspects of the cosmological constant. Section 7 provides some alternative interpretations of the cosmological constant which could have a bearing on the possible solution to the problem. Several relaxation mechanisms have been suggested in the literature to reduce the cosmological constant to the currently observed value and some of these attempts are described in section 8. Next section gives a brief description of the geometrical structure of the de Sitter spacetime and the thermodynamics of the de Sitter universe is taken up in section 10. The last section deals with the role of string theory in the cosmological constant problem.
This paper has not been read by Pith yet.
Forward citations
Cited by 7 Pith papers
-
Perturbation Dynamics and Structure Formation in Extended Proca-Nuevo Gravity
Extended Proca-Nuevo gravity modifies the background expansion via a vector field algebraic constraint but leaves the matter growth equation identical to general relativity.
-
Observational constraints on nonlocal black holes via gravitational lensing
Nonlocal black holes remain consistent with general relativity at the 1.13-sigma level after joint lensing and quasinormal-mode constraints.
-
Dynamical system analysis of the cosmological phases in Palatini $k$-essence gravity
Dynamical systems analysis of a Palatini k-essence model identifies fixed points for quasi-de-Sitter epochs, scaling solutions, and quintessence phases connected by heteroclinic orbits in flat FLRW cosmology.
-
Testing $\Lambda$CDM with ANN-Reconstructed Expansion History from Cosmic Chronometers
The ANN-reconstructed Hubble parameter H(z) from cosmic chronometers aligns with Lambda CDM predictions within uncertainties.
-
How Complex is Dark Energy? A Bayesian Analysis of CPL Extensions with Recent DESI BAO Measurements
Bayesian evidence from DESI BAO plus CMB and SN data favors the standard CPL evolving dark energy model over both simpler constant-w and more complex higher-order extensions.
-
Observational tests of \texorpdfstring{$\Lambda(t)$}{Lambda(t)} cosmology in light of DESI DR2
MCMC constraints on two Lambda(t) models with DESI DR2, CC, and Pantheon+ data yield H0 ~72.5-73 km/s/Mpc, Omega_m0 near standard values in joint fits, and n~0.3 indicating mild deviation from LambdaCDM.
-
A Survey through Conformal Time
This pedagogical survey clarifies how conformal time governs geodesics and curvature in different eras of a flat FRW universe and provides a general affine-parameter formalism.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.