Do absolutely closed universes exist?

It is hypothesized that universes closed in the framework of classical mechanics are not absolutely closed in the case of the existence in nature of a certain limiting length l(min). This would mean that a universe cannot arise 'from nothing'. In particular, it is suggested that the final state of a black hole of the second kind must be stable and have a mass of the order of the maximon mass. Maximons could play the role of the 'missing mass' in astrophysics.