  Causality on the gravity side of the AdS/CFT correspondence restricts motion
on the moduli space of the N=4 super Yang Mills theory by imposing a speed
limit on how fast the scalar field may roll. This effect can be traced to
higher derivative operators arising from integrating out light degrees of
freedom near the origin. In the strong coupling limit of the theory, the
dynamics is well approximated by the Dirac-Born-Infeld Lagrangian for a probe
D3-brane moving toward the horizon of the AdS Poincare patch, combined with an
estimate of the (ultimately suppressed) rate of particle and string production
in the system. We analyze the motion of a rolling scalar field explicitly in
the strong coupling regime of the field theory, and extend the analysis to
cosmological systems obtained by coupling this type of field theory to four
dimensional gravity. This leads to a mechanism for slow roll inflation for a
massive scalar at subPlanckian VEV without need for a flat potential (realizing
a version of k-inflation in a microphysical framework). It also leads to a
variety of novel FRW cosmologies, some of which are related to those obtained
with tachyon matter.
