The universe on the largest scales is controlled by gravity. Quantum fluctuations of the gravitational vacuum directly influence its behavior, even on the largest scales: they accelerate the cosmic expansion today, and created perturbations during early cosmic inflation that led to all large scale structure, including cosmic background anisotropy on the largest angular scales. This talk will review some difficulties with the current theory of these phenomena, and suggest that they might be resolved with a theory of gravity that accounts for causal coherence of quantum states.

Web-link: Professor Craig Hogan, University of Chicago

Brief Bio: Craig Hogan's theoretical work has encompassed many areas of astrophysical cosmology: the origin of the elements, cosmic phase transitions and defects, magnetic fields, background radiation, cosmic reionization, gravitational lensing, cosmic structure and dark matter, global cosmological parameters, and gravitational waves. Hogan's recent scientific papers can be found on the preprint ArXiv. His current work is developing a theory of a proposed new phenomenon, which he calls "holographic noise", a fundamental, universal uncertainty in the fabric of spacetime, due to a fundamental bandwidth of reality at the Planck frequency, 10⁴⁴ bits per second. With colleagues at Fermilab, the University of Chicago, and other institutions, he is developing an experiment, the Fermilab Holometer, to measure this effect.