The One-Way Linear Effect, a first order optical effect

In the One-Way Linear Effect, the round-trip time interval [Formula: see text] taken by light to propagate around a moving linear closed contour, is measured by a device. If the contour changes velocity by Δv, the round-trip interval [Formula: see text] turns out to depend on the device position [Formula: see text] and Δv. The variation [Formula: see text] , related to [Formula: see text] , is experimentally observable by means of standard interferometry, ring laser techniques, or high precision time-delay detectors of light pulses. Being sensitive to velocity variations, if experimentally confirmed the One-Way Linear Effect may have relevant applications in inertial guidance systems and related areas. Furthermore, the One-Way Linear Effect can be used to confirm Lorentz invariance by testing relative simultaneity versus absolute simultaneity.