In principle, the redshift will continue to increase until the gravitational potential drops to zero, which means an infinite distance, since

*1/r*^{2} will never go to zero for any finite value of

*r*. In practice, and in our case of light climbing out of the Earth, once the light passes through the surface, and the mass behind it now remains essentially constant, the increase in gravitational redshift with distance will be too small to measure. So we can treat the gravitational redshift as unchanging beyond the surface and make no significant error as a result, as long as we are far from the surface. This is the case, for instance, for observing the gravitational redshift of sunlight due to the Sun's gravity (i.e.,

Lopresto, Chapman & Sturgis, 1980. Lopresto tells me this is still the most precise measure of solar gravitational redshift, but it is only good enough to show that the correct theory of gravity must be metric, and not good enough to show that general relativity in particular is that metric theory).