Atomic clocks are arguably the most accurate scientific instruments ever built. Modern clocks are astonishing timepieces guaranteed to keep time within a second over the age of the Universe.  The cosmological applications of atomic clocks so far have been limited to searches of the uniform-in-time drift of fundamental constants. We point out that a transient in time change of fundamental constants (translating into clocks being sped up or slowed down) can be induced by dark matter objects that have large spatial extent, and are built from light non-Standard Model fields. The stability of this type of dark matter can be dictated by the topological reasons. We argue that correlated networks of atomic clocks, such as atomic clocks onboard satellites of the GPS constellation, can be used as a powerful tool to search for the topological defect dark matter. In other words, we envision using GPS as a 50,000 km-aperture dark-matter detector. Similar arguments apply to terrestrial networks of atomic clocks.

 Details: A. Derevianko and M. Pospelov, Nature Phys. 10, 933 (2014)