Nietzsche scholars and some major continental philosophers (Deleuze) take the idea of eternal recurrence seriously. Why?
Modern science (especially chaos theory) showed that the notion of eternal recurrence is pure nonsense. Even in a simple gas system with several particles, tiny atomic deviations can lead to humongous changes in the long term (aka the butterfly effect). It it absolutely ridiculous to hypothesize that the whole world, and each human being can be replicated 100% ad infinitum. The chance of that is 0%.
Is Nietzschean notion of the eternal return anything more than poetic nonsense?