  Black holes are interesting astrophysical objects that have been studied as
systems sensitive to quantum gravitational data. The accelerated geometry in
the exterior of extremal black holes can induce large center-of-mass energies
between particles with particular momenta at the horizon. This is known as the
Ba\~nados-Silk-West (BSW) effect. For point particles, the BSW effect requires
tuning to have the collision coincide with the horizon. However, this tuning is
relaxed for string-theoretic objects. String scattering amplitudes are large in
the Regge limit, occurring at large center-of-mass energies and shallow
scattering angles, parametrically surpassing quantum field theoretic
amplitudes. In this limit, longitudinal string spreading is induced between
strings with a large difference in light-cone momenta, and this spread can be
used to 'detune' the BSW effect. With this in mind, quantum gravitational data,
as described by string theory, may play an important role in near horizon
dynamics of extremal Kerr black holes. Further, though it may be hard to
realize astrophysically, this system acts as a natural particle accelerator for
probing the nature of small-scale physics at Planckian energies.
