It seems by this paper that there are more black holes than expected, so what is the expected density of black holes in the nearby universe? arXiv:1606.04996 (cross-list from gr-qc) [pdf, other] Constraining modified theories of gravity with gravitational wave stochastic background Andrea Maselli, Stefania Marassi, Valeria Ferrari, Kostas Kokkotas, Raffaella Schneider Comments: 5 pages, 4 figures Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE) The direct discovery of gravitational waves has finally opened a new observational window on our Universe, suggesting that the population of coalescing binary black holes is larger than previously expected. These sources produce an unresolved background of gravitational waves, potentially observables by ground-based interferometers. In this paper we investigate how modified theories of gravity, modeled using the ppE formalism, affect the expected signal, and analyze the detectability of the resulting stochastic background by current and future ground-based interferometers. We find the constraints that AdLIGO would be able to set on modified theories, showing that they may significantly improve the current bounds obtained from astrophysical observations of binary pulsars.