  The sensitivity of the SKA enables a number of tests of theories of gravity.
A Galactic Census of pulsars will discover most of the active pulsars in the
Galaxy beamed toward us. In this census will almost certainly be pulsar-black
hole binaries as well as pulsars orbiting the super-massive black hole in the
Galactic centre. These systems are unique in their capability to probe the
ultra-strong field limit of relativistic gravity. These measurements can be
used to test the Cosmic Censorship Conjecture and the No-Hair theorem.
  The large number of millisecond pulsars discovered with the SKA will also
provide a dense array of precision clocks on the sky. These clocks will act as
the multiple arms of a huge gravitational wave detector, which can be used to
detect and measure the stochastic cosmological gravitational wave background
that is expected from a number of sources.
