“Resolving, for the first time, multiple images of a strongly lensed standard candle supernova is a major breakthrough," Professor Goobar said in a statement. "We can measure the light-focusing power of gravity more accurately than ever before, and probe physical scales that may have seemed out of reach until now."
If our worry is the important constants of the cosmos, then the discovery of a lensed type Ia supernova has a lot more importance than just another distance measurement. When massive objects – like galaxies or black holes – bend space-time, they can magnify and distort light, but they don’t act like a common magnifying glass.
The foreground lensing galaxy is not perfectly symmetric, so the path that each photon takes will be slightly different. Some may be longer, some may be shorter. This means that the four images are different snapshots of the supernova at slightly different moments. By studying the differences in the four images, astronomers can learn a lot about the possible changes in the cosmological parameters.
Graphic of how the four images came to form. ALMA (ESO/NRAO/NAOJ), L. Calçada (ESO), Y. Hezaveh et al., edited and modified by Joel Johansson