> On the other hand, if the many-worlds interpretation of quantum mechanics is correct, the explanation for why there has been no vacuum decay yet despite many high-energy particle collisions changes entirely. In this case, the corresponding collisions did trigger the vacuum decay, and we're not observing it simply because every such event excludes any observers in its causal (light-cone) future - and there are always worlds exactly identical to such a world in everything except the decay event and its future cone. More generally, the same applies to any set of future light-cones - that is,…