  The relevance of the Planck scale to a theory of quantum gravity has become a
worryingly little examined assumption that goes unchallenged in the majority of
research in this area. However, in all scientific honesty, the significance of
Planck's natural units in a future physical theory of spacetime is only a
plausible, yet by no means certain, assumption. The purpose of this article is
to clearly separate fact from belief in this connection.
