The Free-orbit Experiment with Laser Interferometry X-Rays (FELIX) belongs to a category of experiments exploring whether macroscopic systems can be in superposition states. It was originally proposed by the physicist Roger Penrose in his 2004 book, " The Road to Reality " specifically to prove whether unconventional decoherence processes such as gravitationally induced decoherence or spontaneous wave-function collapse of a quantum system occur.