https://phys.org/news/2020-12-black-holes-gain-powers-fast.html
extract:
Many modified relativity theories have an extra parameter not seen in the standard theory. Known as a massless scalar field, it allows Einstein's model to connect with quantum theory in a way that isn't contradictory. In this new work, the team looked at how such a scalar field connects to the rotation of a black hole. They found that at low spins, a modified black hole is indistinguishable from the standard model, but at high rotations, the scalar field allows a black hole to have extra features. In other words, in these alternative models, rapidly rotating black holes can have hair.
As the authors point out, future gravitational wave observatories should be able to use rapidly rotating black holes to determine whether an alternative to general relativity is valid.
Einstein's theory of general relativity has passed every observational challenge so far.......more at link.....
the paper:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.231101
Spin-Induced Black Hole Spontaneous Scalarization:
ABSTRACT:
We study scalar fields in a black hole background and show that, when the scalar is suitably coupled to curvature, rapid rotation can induce a tachyonic instability. This instability, which is the hallmark of spontaneous scalarization in the linearized regime, is expected to be quenched by nonlinearities and endow the black hole with scalar hair. Hence, our results demonstrate the existence of a broad class of theories that share the same stationary black hole solutions with general relativity at low spins, but which exhibit black hole hair at sufficiently high spins (a/M≳0.5). This result has clear implications for tests of general relativity and the nature of black holes with gravitational and electromagnetic observations.
extract:
Many modified relativity theories have an extra parameter not seen in the standard theory. Known as a massless scalar field, it allows Einstein's model to connect with quantum theory in a way that isn't contradictory. In this new work, the team looked at how such a scalar field connects to the rotation of a black hole. They found that at low spins, a modified black hole is indistinguishable from the standard model, but at high rotations, the scalar field allows a black hole to have extra features. In other words, in these alternative models, rapidly rotating black holes can have hair.
As the authors point out, future gravitational wave observatories should be able to use rapidly rotating black holes to determine whether an alternative to general relativity is valid.
Einstein's theory of general relativity has passed every observational challenge so far.......more at link.....
the paper:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.231101
Spin-Induced Black Hole Spontaneous Scalarization:
ABSTRACT:
We study scalar fields in a black hole background and show that, when the scalar is suitably coupled to curvature, rapid rotation can induce a tachyonic instability. This instability, which is the hallmark of spontaneous scalarization in the linearized regime, is expected to be quenched by nonlinearities and endow the black hole with scalar hair. Hence, our results demonstrate the existence of a broad class of theories that share the same stationary black hole solutions with general relativity at low spins, but which exhibit black hole hair at sufficiently high spins (a/M≳0.5). This result has clear implications for tests of general relativity and the nature of black holes with gravitational and electromagnetic observations.
People are capable of reading the article old friend.....Who has ever denied that GR one day will be surpassed...not invalidated...surpassed...just as GR surpassed Newtonian, but I wouldn't expect you to understand old friend!!