  Preconception-free analyses of the inclusive invariant transverse-momentum
distribution data taken from the measurements of Au+Au collisions at
$\sqrt{s_{NN}}=130$ GeV and $\sqrt{s_{NN}}=200$ GeV have been performed. It is
observed that the distributions exhibit for $p_{T}\geq 2$ GeV/c remarkably good
power-law behavior ($p_{T}$-scaling) with general regularities. This power-law
behavior leads us in particular to recognize that the concept of centrality,
albeit its simple appearance, is rather complex; its underlying geometrical
structure has to be understood in terms of fractal dimensions. Experimental
evidences and theoretical arguments are given which show that the observed
striking features are mainly due to geometry and self-organized criticality. A
simple model is proposed which approximately reproduces the above-mentioned
data for the ``suppression'' without any adjustable parameter. Further
heavy-ion collision experiments are suggested.
