 Some of the researchers who seek to decide the continuum hypothesis think that it is true; others think that it is false. But there are also many set theorists and philosophers of mathematics who believe that the continuum hypothesis not just undecidable in ZFC but absolutely undecidable, i.e. that it is neither provable (in the informal sense of the word) nor disprovable (in the informal sense of the word) because it is neither true nor false. If the mathematical universe is a set theoretic multiverse, for instance, then there are equally models that make the continuum hypothesis true and equally good models that make it false, and there is no more to be said (Hamkins, 2015).