In QM, experiments show us that entangled particle spin probabilities vary non-linearly with the angle between detectors (even if those detectors are far apart).

This means that either: 1) locality is broken.. state is somehow transmitted faster than the speed of light between particles. 2) realism is broken.. god plays dice with the universe

But there's also a 3rd, which is: the choice of detector angle is not an independent variable (a necessary assumption for Bell's inequalities to hold).. instead the state of the universe is pre-determined and the experimenter's choice of detector angle is known beforehand so there is no need for spooky action at a distance. This isn't a very popular explanation since it provides no reason as to why we don't see this weird lack of independence elsewhere.