Redshift ↔ Velocity/Distance implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-065

Effect

Computation or source lookup only

Input and validation requirements

The distance calculation is undefined when the user selects H0=0, and the specification provides no explicit high-redshift branch or threshold even though v=cz is only a low-z approximation. Wavelength-field reversal also produces a materially different signed result.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "z": 0.01,
    "H0_km_s_Mpc": 67.4,
    "c_km_s": 299792.458
  },
  "expected_outputs": {
    "velocity_km_s": 2997.92458,
    "distance_Mpc": 44.47959317
  },
  "working": "v = cz = 299792.458 km/s × 0.01 = 2997.92458 km/s. d = v/H0 = 2997.92458 km/s ÷ 67.4 km/s/Mpc = 44.47959317 Mpc."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json