A second problem, also arising in Penrose's proposal, is the origin of the Born rule. To solve the measurement problem, a mere explanation why a wave-function collapses to, e.g., a dot on a screen is not enough. A good model for the collapse process also has to explain why the dot appears on different positions of the screen with probabilities that are determined by the absolute-value squared of the wave-function. Although it might be possible that a model based on Penrose's idea could provide such an explanation, there is no evident way how the Born rule could arise naturally from it.