Black Hole Challenge To Einstein's Theory

Black Hole Challenge To Einstein's Theory

That in turn would have consequences for dark matter, the mysterious gravitational force evoked to explain why galaxies don’t just spiral apart, and dark energy (the cosmological constant described by Einstein as his “greatest blunder”), which is thought to be behind the gravity-defying expansion of the universe.
“This is off the edge of the map,” theoretical astrophysicist Avery Broderick, a member of the research team, told Forbes.com. “General relativity works on Earth and on solar-system scales, but on a galactic scale, maybe not, and on the scale of a black hole, we just don’t know.”
The discovery is to be announced at a conference next week (10 to 14 November) at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, on the Event Horizon Telescope (EHT) project, the world’s largest millimetre-wavelength radiotelescope.
The EHT − which is composed of dishes in Hawaii, Arizona and California and will soon be expanded to include three more sites, including the South Pole, making it far more powerful − is our highest-resolution planet-sized telescope, designed to show scientists what’s happening on the black hole’s event horizon − in effect its surface.

PIRSA - Perimeter Institute Recorded Seminar Archive

Abstract:

Quantum-gravity effects as noise for gravity-wave detectorsI discuss a mechanism that can allow Planck scale effects to manifest themselves as a source of lof-frequency noise for interferometers.  The mechanism requires a discrete formulation of dynamics at the Planck scale.
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Dancing in the Dark: Images of Quantum Black Holes
There have recently been a number of rather surprising suggestions that the quantum nature of black holes is manifested on macroscopic scales.  This raises the question of just what the image of such an object should look like.  The answer is more than simply academic; with the advent of the Event Horizon Telescope (EHT), a millimetre-wave very long baseline array, it is now possible to probe a handful of supermassive black holes with angular resolutions sufficient to image their horizons.  I will discuss what we might expect to see, and how in the near future we will begin to empirically probe the existence of black hole quantum states with horizon scale curvature deviations from general relativity.
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The Irritating Persistence of HorizonsIn some approaches to quantum gravity Lorentz invariance is modified. Without Lorentz invariance one can theoretically see behind the usual Killing horizon of a black hole if, for example, one allowed for superluminal propagation. This in turn raises the possibility that one could in principle probe the singularity and the quantum gravity regime. We discuss how Lorentz violating black hole solutions in Einstein-aether theory unfortunately possess another causal boundary behind the Killing horizon that is impenetrable to any superluminal mode. We also detail progress in determining the laws of black hole mechanics and the radiation spectrum from these so-called "universal horizons". Our results suggest that even if superluminal dispersion at high frequencies did exist in nature, singularities and their associated quantum gravity resolutions may very well remain locked behind horizons.