  We show that an unification of quantum mechanics and general relativity
implies that there is a fundamental length in Nature in the sense that no
operational procedure would be able to measure distances shorter than the
Planck length. Furthermore we give an explicit realization of an old proposal
by Anderson and Finkelstein who argued that a fundamental length in nature
implies unimodular gravity. Finally, using hand waving arguments we show that a
minimal length might be related to the cosmological constant which, if this
scenario is realized, is time dependent.
