  The information conservation principle is probed for classically isolated
systems, like the Hubble sphere and black holes, for which the rise of
entanglement entropy across their horizons is expected. We accept the analogy
of Landauer's principle that entanglement information should introduce some
negative potential energy, which corresponds to the positive energy of
measurements that destroy this quantum behavior. We estimated these
dark-energy-like contributions and found that they can explain the dark energy
of the Universe and also are able to resolve the observed superluminal motion
and redshift controversies for black holes.
