Does Every Redshift Mean an Object Is Receding?

If the same spectral line appears at a longer wavelength, which equation belongs to motion, gravity, or cosmic expansion?

Measure z first, then choose a physical model before translating the shift into velocity, compactness, scale factor, or distance.

One spectral wave passes through scenes of radial motion, light escaping a compact star, and galaxies separating in an expanding cosmic web. — Vastward conceptual reconstruction. The three scenes distinguish physical mechanisms; the wave spacing is illustrative rather than a measured data trace.

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