Tolman surface brightness test

Adding these effects together, the surface brightness in a simple expanding universe (flat geometry and uniform expansion over the range of redshifts observed) should decrease with the fourth power of 1+z.

One of the earliest and most comprehensive studies was published in 1996, as observational requirements limited the practicality of the test till then.

[2] However, therein, the authors note that: "The results of any Tolman SB test where galaxies must be corrected to a standard condition will involve some dependence on the assumed cosmology, but as will be described below, for the redshifts of interest here, the effect of cosmology is quite small compared to the predicted difference between the expansion and tired-light models.

"A later paper that reviewed this one removed their assumed expansion cosmology for calculating SB, to make for a fair test, and found that the 1996 results, once the correction was made, did not rule out a static universe.

[3][5] The predicted difference between static and expansion diverges dramatically towards higher redshifts, however, accounting for galaxy evolution becomes increasingly uncertain.