# negative redshifts

03 May 2012Would negative cosmological redshifts (aka blueshifts) be useful to describe events in the future evolution of the Universe? if yes, whatâ€™d be the largest (most negative) redshift which can be defined in a sensible way?

The most negative blue-shift is not \(-\infty\)! Looking at the relation \(a = 1/(1+z)\) between scale-factor \(a\) and redshift \(z\) implies that \(z\rightarrow -1\) for \(a\rightarrow\infty\).