The time-dependent Schrödinger equation and wave function collapse (or reduction) separately determine the time evolution of quantum systems. Since the 1980s, objective collapse theories have become relevant candidates for unifying quantum time evolutions. One of the most intriguing of such theories is the Diósi-Penrose model. Its central hypothesis is that gravity causes the quantum superposition to collapse. When two quantum superposed states are spatially separated, two spacetime distortions associated with each state should co-exist. However, according to Penrose, 9 such a superposition of distortions is unstable and spontaneously collapses the wave function.