[jraines]

the extra mass is converted into energy in the form of gravitational waves (maybe other forms too idk but this is part of it)

[maxbond]

Entire solar masses being lost to gravitational waves, like the voltage drop across a resistor, is a humbling prospect.

[bot403]

I'll underscore your awe by reminding you those solar masses disappeared in only 1 tenth of a second - the length of the gravitational wave signal.

[Bluestein]

Dang

[nine_k]

I suppose nothing but gravitational waves can escape the even horizon — or, rather, gravitational waves are born near / around it, because the black holes bend the space enormously.

OTOH whatever else may be outside the black holes near the merger and count towards their mass for astronomical purposes, such as accretion discs, should be much lighter weight than what's inside the event horizon.

[ars]

Gravitational waves also can not escape. Those waves carry energy, and it's actually energy that can't escape.

The waves are actually made just to the outside of the event horizon.