A possible target of gravitational wave detection experiments is a stochastic background of gravitational waves. The detection of such a background would have a profound impact on early universe cosmology and on high-energy physics, opening up a new window and exploring very early times in the evolution of the universe, and correspondingly high energies, that will never be accessible by other means. The emission of gravitational waves from a large number of unresolved astrophysical sources can create a stochastic background of gravitational waves. For instance, sufficiently massive stars, at the final stage of their evolution, collapse to form a black hole or a neutron star. In this explosive supernova event gravitational waves are liberated. Also, in rapidly rotating neutron stars there is a whole class of instabilities driven by the emission of gravitational waves.
A stochastic gravitational wave background is also of theoretical interest. Given its stochastic nature, a coincidence of gravitational waves at a particular point could create stress-energy densities sufficient to produce an event horizon. This would produce a relativistic explanation of nonlocal effects.