General Relativity has successfully passed all experimental tests, including the spectacular recent detection of gravitational waves by LIGO, a century after their prediction. Yet Einstein’s classical theory remains unreconciled to quantum theory.
Quantum theory and gravity come into closest contact in two areas also at the forefront of observational cosmology and astrophysics, namely in the physics of the accelerating universe and of gravitational collapse to a ‘black hole.’ The paradoxes that beset both arise only when quantum vacuum fluctuations in gravitation are considered.
Taken at face value, present observations imply that some 72% of the energy in the universe is attributable to the energy of the vacuum itself, with a negative pressure p = - ρ. Elucidating the nature and dynamics of this vacuum dark energy and the cosmological ‘constant’ is widely recognized as the most pressing problem of cosmology and fundamental physics today.
The final state of gravitational collapse is the second circumstance where quantum vacuum fluctuations in gravity again come into play. As in cosmology, difficulties appear at this interface, for example in the ‘information paradox’ posed by the enormous Bekenstein-Hawking entropy supposedly associated with a black hole. The resolution of these and related paradoxes and the true nature of the interior of a ‘black hole’ remain very much open questions.
In the next few years we are poised to realize an enormous increase in observational information about the Universe’s Large Scale Structure, as well as potentially direct evidence for or against black hole horizons in tests of strong field gravity. The SDSS-BOSS baryon acoustic oscillation survey, the Atacama Cosmology Telescope, numerous weak lensing surveys, and the Dark Energy Survey will greatly expand our knowledge of structure in the Universe. Imaging and X-ray spectroscopic observations of accreting black holes with current and future instruments will lead to the first direct test of the ‘no-hair’ theorem of spinning black holes. LIGO is expected to provide evidence of many more detections of gravitational waves from compact sources that will test GR in the strong-field and near horizon limit. The Event Horizon Telescope is closing in on the first images of the near horizon region of the supermassive object Sgr A* in the center of the Galaxy. As in cosmology, we are entering an era when a fundamental conundrum at the heart of reconciling quantum physics with Einstein’s theory will become illuminated at long last by observational data.
This intensive two week program at the MITP seeks to bring a select group of theoretical physicists with expertise in Quantum Field Theory and General Relativity, together with observational cosmologists and astrophysicists, in order to develop new approaches to these longstanding problems in the Quantum Vacuum and Gravitation Theory, with the goal of confronting viable theoretical ideas to the wealth of observational data that is now becoming available.
Specific Topics to be considered are:
Trace Anomaly Induced Effective Action and Dynamics
Non-ideal Cosmological Fluids and Bulk Viscosity
Spatially Inhomogeneous Cosmology
Dynamical Vacuum Energy
Primordial Non-Gaussianity and Large Scale Structure
Anomalies in the CMB and Hubble expansion
Quantum Effects at ‘Black Hole’ Horizons and Interiors
Gravitational Waves
Strong Field Astrophysical Tests of General Relativity
The Scientific Program will be posted shortly.
The Distinguished Participants in the Program include: