  We investigate open string theory on backreacting D3-branes using a spacetime
approach. We study in detail the half-BPS supergravity solutions describing
open strings ending on D3-branes, in the near horizon of the D3-branes. We
recover quantitatively several non-trivial features of open string physics
including the appearance of D3-brane spikes, the polarization of fundamental
strings into D5-branes, and the Hanany-Witten effect. Finally we detail the
computation of the gravitational potential between two open strings, and
contrast it with the holographic computation of Wilson lines. We argue that the
D-brane backreaction has a large influence on the low-energy gravity, which may
lead to experimental tests for string theory brane-world scenarios.
