Linearized Gravitational Waves in Nonlocal General Relativity
  We investigate gravitational radiation in the linear approximation within the
framework of the recent nonlocal generalization of Einstein's theory of
gravitation. In this theory, nonlocality can simulate dark matter; in fact, in
the Newtonian regime, we recover the phenomenological Tohline-Kuhn approach to
modified gravity. To account for the observational data regarding the rotation
curves of spiral galaxies, nonlocality is associated with a characteristic
length scale of order \lambda_0 = 10 kpc. It follows that in nonlocal gravity,
the treatment of extremely low-frequency (~ 10^{-12} Hz) gravitational waves
with wavelengths of order \lambda_0 would be quite different than in general
relativity. However, for radiation of frequency > 10^{-8} Hz, which is the
frequency range that is the focus of current observational searches, the
corresponding wavelengths are very small compared to \lambda_0. We find that in
this frequency regime the nonlocal deviations from general relativity
essentially average out and can be safely neglected in practice.
