However, observing it in a system like iron vacancy superposition at room temperature would still be challenging because decoherence (toward the crystal structure) would select the position basis and suppress any sign of quantum interference in a much shorter time scale. When the superposition displacement increases, the gravitational self-energy saturates corresponding to the minimum collapse time, C,min. This quantity is plotted in Figure for a homogeneous carbon atom distribution, which, although artificial, can be taken as representative of the mean mass and width in organic matter. These values were obtained with (8) in the saturation regime (R → ∞). r  is computed with (C.10) for a number density of 7.5×10 28 m -3 , typical for coal. As expected, the collapse time is tiny for a macroscopic system, of the order of 10 -27 s for a 1 kg mass. It increases to 10 -7 s for 10 -11 kg, the mass of a pollen grain. However, it is somewhat surprising that it is highly long for isolated mesoscopic systems like a virus (10 6 s) or a protein (10 11 s).