A Differential Dual-Interferometer Test of History-Dependent Space

Interferometric measurements in space normally assume that the propagation medium ismemoryless: phase and polarization depend only on instantaneous geometry and boundaryconditions. We propose a dual-interferometer experiment in space designed to test thisassumption directly. Two nearly identical interferometric arms share common hardwareand timing but experience different photon-illumination histories. By alternatelyconditioning one arm with elevated photon flux while holding the other as a control, andthen probing both with weak signals, the experiment searches for hysteresis or relaxation inphase and polarization that depends on prior illumination. Differential subtraction cancelslaser, clock, and platform noise, isolating any history-dependent response of thepropagation path itself.