(Phys.org)—Physicists have performed a test designed to investigate the effects of the expansion of the universe—hoping to answer questions such as “does the expansion of the universe affect laboratory experiments?”, “might this expansion change the lengths of solid objects and the time measured by atomic clocks differently, in violation of Einstein’s equivalence principle?”, and “does spacetime have a foam-like structure that slightly changes the speed of photons over time?”, an idea that could shed light on the connection between general relativity and quantum gravity.