If the redshift parameter ($z$) of a distant object is $z=1$, what does this signify about the expansion since the light was emitted?

Answer

The universe has expanded by a factor of two.

A redshift parameter of $z=1$ specifically correlates with the universe having expanded by a factor of two since the photon began its journey from the distant source.

If the redshift parameter ($z$) of a distant object is $z=1$, what does this signify about the expansion since the light was emitted?

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