How fast can a black hole spin?
If any object made of regular matter spins too fast -- it breaks apart.
But a black hole might not be able to break apart -- and its maximum spin rate is really unknown.
Theorists usual model rapidly rotating black holes with the
Kerr solution to Einstein's
General Theory of Relativity, which predicts several
Perhaps its most easily testable prediction, though, is that matter entering a
maximally rotating black hole should be last seen
orbiting at near the speed of light, as seen from far away.
This prediction was tested recently by NASA's
NuSTAR and ESA's
satellites by observing the supermassive black hole at the center of
spiral galaxy NGC 1365.
The near light-speed limit was
confirmed by measuring the heating and
spectral line broadening
of nuclear emissions at the inner edge of the surrounding
Pictured above is an artist's illustration depicting an accretion disk of normal matter swirling around a black hole, with a
jet emanating from the top.
Since matter randomly falling
into the black hol|