Astronomy
Hubble law
Explore a 3D galaxy survey, measure spectral shifts and build a Hubble diagram. Test peculiar velocities, distance errors and the choice of observer.
What happens
Synthetic low-redshift survey. The map, distances and spectra use the same epoch. Expansion uses a constant H, not ΛCDM, and freezes when you measure. Peculiar velocities are snapshot perturbations, not integrated orbits. Galaxy glyphs are enlarged and keep their size. Auto-fit uses five noisy, identified line centroids; manual z has no calibrated uncertainty. Positive lognormal distance noise has central 68% bars. Through-origin OLS ignores these distance errors and correlated observer motion: its slope is descriptive and RMS is not an H₀ confidence interval. Changing the generator clears the survey; changing sample or distance calibration preserves it.
Equations used in the module
Equations v_ij = H₀ d_ij + (u_j − u_i)·n z ≈ v/c, λ_obs = λ₀ (1 + z) z_fit = Σ λ₀(λ_measured − λ₀) / Σ λ₀² H_fit = Σ d_measured (cz_measured) / Σ d_measured² a(t) = exp(H₀ t)
