Reply to: Atom gravimeters and the gravitational redshift

TL;DR

This paper defends the validity of atom gravimeter experiments in testing gravitational redshift, arguing that they are equivalent to classical tests and that previous critiques based on questionable physics laws are invalid.

Contribution

The authors reaffirm the validity of atom interferometry redshift tests and clarify their equivalence to classical gravitational redshift experiments.

Findings

Atom gravimeters are valid for redshift testing.

Redshift experiments and atom interferometry are fundamentally equivalent.

Previous critiques based on certain physics laws are challenged.

Abstract

We stand by our result [H. Mueller et al., Nature 463, 926-929 (2010)]. The comment [P. Wolf et al., Nature 467, E1 (2010)] revisits an interesting issue that has been known for decades, the relationship between test of the universality of free fall and redshift experiments. However, it arrives at its conclusions by applying the laws of physics that are questioned by redshift experiments; this precludes the existence of measurable signals. Since this issue applies to all classical redshift tests as well as atom interferometry redshift tests, these experiments are equivalent in all aspects in question.