The recent LIGO detection of gravitational waves from merging black holes with tens of solar masses has confirmed that distortions in the fabric of space-time can be observed and measured . Researchers from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) have spent the past decade searching for low-frequency gravitational waves emitted by black hole binaries with masses many millions of times larger than those seen by LIGO.
 LIGO is the Laser Interferometer Gravitational-Wave Observatory (https://www.ligo.caltech.edu)
 National Science Foundation (http://www.nsf.gov)
NANOGrav press officer
NRAO Public Information Officer