  "Doubly-special relativity" (DSR), the idea of a Planck-scale Minkowski limit
that is still a relativistic theory, but with both the Planck scale and the
speed-of-light scale as nontrivial relativistic invariants, was proposed
(gr-qc/0012051) as a physics intuition for several scenarios which may arise in
the study of the quantum-gravity problem, but most DSR studies focused
exclusively on the search of formalisms for the description of a specific
example of such a Minkowski limit. A novel contribution to the DSR physics
intuition came from a recent paper by Smolin (hep-th/0501091) suggesting that
the emergence of the Planck scale as a second nontrivial relativistic invariant
might be inevitable in quantum gravity, relying only on some rather robust
expectations concerning the semiclassical approximation of quantum gravity. I
here attempt to strengthen Smolin's argument by observing that an analysis of
some independently-proposed Planck-scale particle-localization limits, such as
the "Generalized Uncertainty Principle" often attributed to string theory in
the literature, also suggests that the emergence of a DSR Minkowski limit might
be inevitable. I discuss a possible link between this observation and recent
results on logarithmic corrections to the entropy-area black-hole formula, and
I observe that both the analysis here reported and Smolin's analysis appear to
suggest that the examples of DSR Minkowski limits for which a formalism has
been sought in the literature might not be sufficiently general. I also stress
that, as we now contemplate the hypothesis of a DSR Minkowski limit, there is
an additional challenge for those in the quantum-gravity community attributing
to the Planck length the role of "fundamental length scale".
