The distance-duality relation expresses a mathematical equation describing how large a galaxy appears compared to how bright it is. This article uses exploding stars called supernovae to derive the distances to galaxies and compares these distances to their angular scale, thus testing the distance-duality relation. The results of this study can help astronomers better study far-off galaxies.

 

http://www.raa-journal.org/raa/index.php/raa/article/view/769