What law formally quantifies the direct proportionality between a galaxy's recessional velocity and its distance from an observer?

Answer

Hubble’s Law

Hubble’s Law establishes that the speed at which a galaxy recedes is directly proportional to how far away it is from the observer, and the constant of proportionality is the Hubble Constant.

What law formally quantifies the direct proportionality between a galaxy's recessional velocity and its distance from an observer?

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