Lincoln and Stuver argue that in the coalescing binary black hole system detected by LIGO with gravitational waves, GW150914, “[r]adiation carried away energy, but not angular momentum.”1 That is not the case; gravitational waves carried both energy and angular momentum. In the quadrupole approximation, for circularly orbiting masses m1 and m2 at a separation R, the power carried by gravitational waves P and the rate at which angular momentum is carried by gravitational waves L̇ are given by2 

P=325G4c5m12m22(m1+m2)R5

and

L˙=325G7/2c5m12m22m1+m2R7/2,

where G is Newton’s constant and c is the speed of light in vacuum.

Another interesting point made in...

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