  We show that in the Randall-Sundrum model the Casimir energy of bulk gauge
fields (or any of their supersymmetric relatives) has contributions that depend
logarithmically on the radion. These contributions satisfactorily stabilize the
radion, generating a large hierarchy of scales without fine-tuning. The
logarithmic behaviour can be understood, in a 4D holographic description, as
the running of gauge couplings with the infrared cut-off scale.
