Spatial curvature
Definition: The constant-curvature contribution to FLRW spatial geometry, parameterized by Omega_k.
Why it matters here: It is required to answer Which parts of the distance-redshift curve reveal new physics? and to distinguish direct observation from cosmological inference.
Relationships: Read it with Equation-of-state parameter, the model \(E^2(z)=Omega_m(1+z)^3+Omega_k(1+z)^2+Omega_DE(1+z)^{3(1+w)}\), and the evidence statement Pantheon+ and DES published w summaries are listed with their exact analysis labels; they are not combined here.
Boundary or common confusion: A constant-w extension is not a generic reconstruction of dark energy; priors, curvature, neutrinos, and early-time assumptions matter.
Equation-of-state parameter
Definition: The pressure-to-density ratio w used to characterize a dark-energy component.
Why it matters here: It is required to answer Which parts of the distance-redshift curve reveal new physics? and to distinguish direct observation from cosmological inference.
Relationships: Read it with Evolving dark energy, the model \(E^2(z)=Omega_m(1+z)^3+Omega_k(1+z)^2+Omega_DE(1+z)^{3(1+w)}\), and the evidence statement Pantheon+ and DES published w summaries are listed with their exact analysis labels; they are not combined here.
Boundary or common confusion: A constant-w extension is not a generic reconstruction of dark energy; priors, curvature, neutrinos, and early-time assumptions matter.
Evolving dark energy
Definition: A model in which w changes with epoch rather than remaining constant.
Why it matters here: It is required to answer Which parts of the distance-redshift curve reveal new physics? and to distinguish direct observation from cosmological inference.
Relationships: Read it with Expansion history, the model \(E^2(z)=Omega_m(1+z)^3+Omega_k(1+z)^2+Omega_DE(1+z)^{3(1+w)}\), and the evidence statement Pantheon+ and DES published w summaries are listed with their exact analysis labels; they are not combined here.
Boundary or common confusion: A constant-w extension is not a generic reconstruction of dark energy; priors, curvature, neutrinos, and early-time assumptions matter.
Expansion history
Definition: The redshift dependence of H(z) implied by the cosmic energy budget and gravity model.
Why it matters here: It is required to answer Which parts of the distance-redshift curve reveal new physics? and to distinguish direct observation from cosmological inference.
Relationships: Read it with Geometric degeneracy, the model \(E^2(z)=Omega_m(1+z)^3+Omega_k(1+z)^2+Omega_DE(1+z)^{3(1+w)}\), and the evidence statement Pantheon+ and DES published w summaries are listed with their exact analysis labels; they are not combined here.
Boundary or common confusion: A constant-w extension is not a generic reconstruction of dark energy; priors, curvature, neutrinos, and early-time assumptions matter.
Geometric degeneracy
Definition: Different parameter combinations that preserve nearly the same distance or angular observable.
Why it matters here: It is required to answer Which parts of the distance-redshift curve reveal new physics? and to distinguish direct observation from cosmological inference.
Relationships: Read it with Spatial curvature, the model \(E^2(z)=Omega_m(1+z)^3+Omega_k(1+z)^2+Omega_DE(1+z)^{3(1+w)}\), and the evidence statement Pantheon+ and DES published w summaries are listed with their exact analysis labels; they are not combined here.
Boundary or common confusion: A constant-w extension is not a generic reconstruction of dark energy; priors, curvature, neutrinos, and early-time assumptions matter.