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The generalised or "folk" version of Murphy's Law, fully named "Finagle's Law of Dynamic Negatives" and usually rendered "Anything that can go wrong, will". One variant favoured among hackers is "The perversity of the Universe tends toward a maximum".
The label "Finagle's Law" was popularised by SF author Larry Niven in several stories depicting a frontier culture of asteroid miners; this "Belter" culture professed a religion and/or running joke involving the worship of the dread god Finagle and his mad prophet Murphy.