Test #5: Supernova lightcurves
Type Ia supernova lightcurves have a characteristic shape and rate of decline. If the universe were expanding, supernova lightcurves in high redshift galaxies would be stretched out in time due to the rapid recession of the parent galaxy. In a static universe, no such stretching would occur. The best case so far is for a supernova in a redshift z = 0.31 galaxy seen only after the explosion reached its maximum brightness and begun its decline. Model-dependent assumptions about the time and intensity of the maximum brightness must be made. The observations can then be fit with an expanding universe model.9 But expansion is not required for a good fit to the observations because the light maximum was not seen, so static models work too. The results of this test are therefore presently ambiguous. In 1993, another supernova was seen in a galaxy at redshift z = 0.43. Details of an analysis of those observations are eagerly awaited.