  We study some collective phenomena that may happen in a multiverse scenario.
First, it is posed an interaction scheme between universes whose evolution is
dominated by a cosmological constant. As a result of the interaction, the value
of the cosmological constant of one of the universes becomes very close to zero
at the expense of an increasing value of the cosmological constant of the
partner universe. Second, we found normal modes for a 'chain' of interacting
universes. The energy spectrum of the multiverse, being this taken as a
collective system, splits into a large number of levels, some of which
correspond to a value of the cosmological constant very close to zero. We
finally point out that the multiverse may be much more than the mere sum of its
parts.
