Cosmology Foundations

Overview

Expansion relations in quantsmind.cosmology (expansion.py): Hubble velocities, scale-factor/redshift conversion, Hubble distance and time, relativistic Doppler shift, and component density scalings.

Purpose

Let users connect redshift, scale factor, and cosmic scales with transparent low-redshift math.

Concept

Linear Hubble law plus exact relations (a = 1/(1+z), matter ∝ (1+z)³, radiation ∝ (1+z)⁴, Λ constant); the luminosity distance is explicitly a low-z approximation.

API

hubble_velocity(), scale_factor(), redshift_from_scale(), hubble_distance_mpc(), hubble_time_gyr(), doppler_redshift(), density_scaling(), lookback_time_gyr(), luminosity_distance_linear_mpc().

Input / Processing / Output

Input: Mpc distances, redshifts, H0. Processing: closed forms. Output: km/s, scale factors, Mpc, Gyr, dimensionless ratios.

Example

python examples/cosmology/hubble_flow.py walks a z = 0.1 galaxy through velocity, scale, distance, and the 13.97 Gyr Hubble time.

Limitations

No integrated distances, no perturbation theory, no CMB physics; H0 defaults to 70 km/s/Mpc for examples, not a measurement claim.