Long-wavelength gravitational waves and cosmic acceleration
  Strong long-scale gravitational waves can explain cosmic acceleration within
the context of general relativity without resorting to the assumption of exotic
forms of matter such as quintessence. The existence of these gravitational
waves in sufficient strength to cause observed acceleration can be compatible
with the cosmic microwave background under reasonable physical circumstances.
An instance of the Bianchi IX cosmology is demonstrated which also explains the
alignment of low-order multipoles observed in the CMB. The model requires a
closed cosmology but is otherwise not strongly constrained. Recommendations are
made for further observations to verify and better constrain the model.
