  With his seminal and pioneering work on the stability of the Schwarzschild
black hole and its interaction with gravitational radiation, Vishu had opened a
new window on black hole astrophysics. One of the interesting results that soon
followed was that "a black hole has no hair", it is entirely specified by the
three parameters, mass, spin and charge, and nothing more. The discovery of
gravitational waves in 2016 produced by merger of two black holes, and observed
by the Ligo-Virgo collaboration, carried the definitive signature of
quasi-normal modes, the phenomenon of black hole ringdown, exactly what Vishu
had predicted in his 1970 Nature paper~(See Isaacson's commentary) 46 years
ago. This was the crowning glory.
