First words of the abstract: > In the redshift range 100<(1+z)<137, ... z is the letter often used for redshift, https://en.wikipedia.org/wiki/Redshift https:

First words of the abstract: > In the redshift range 100<(1+z)<137, ... z is the letter often used for redshift, https://en.wikipedia.org/wiki/Redshift https://en.wikipedia.org/wiki/Redshift, a stand-in for cosmological time that's easy to extract experimentally (as compared to an actual time). (1+z) is essentially the ratio by which the universe is bigger today than it was when the physics being observed happened.