. "An interferometer was a device that could be used to measure gravitational waves. It was used by the Urbankans and Trakenites, though the Urbankan interferometer could be used in the time-curve circuits of a TARDIS. (PROSE: Four to Doomsday) File:TechnologyStub.png"@en . . "An interferometer was a device that could be used to measure gravitational waves. It was used by the Urbankans and Trakenites, though the Urbankan interferometer could be used in the time-curve circuits of a TARDIS. (PROSE: Four to Doomsday) File:TechnologyStub.png"@en . "Interferometer"@en .