LIGO/VIRGO collaboration has announced 4 confirmed detection of gravitational wave (GW) signals
from the merging binary black holes. This opens a new window in the astronomy: gravitational wave astrophysics.
There are three major efforts to search for GWs: LIGO-VIRGO detectors operating in the frequency range
between few Hz and kHz, LISA - space based detector which will be launched in 2034 and is sensitive
in the milli-Hertz band, PTA (Pulsar Timing Array) - uses the monitoring of millisecond (stable) pulsars
to detect GWs in the nano-Hertz band.