Experimental Probes of Quantum Geometry

In this seminar, I will describe the Holometer, an experiment currently under construction at Fermilab to study gravitational microphysics at the Planck scale 10^-33 cm.     Black hole thermodynamics already provides some clues to what form this microphysics might take.  The Bekenstein-Hawking entropy formula suggests that all information in our universe may be stored holographically on 2-dimensional surfaces rather than in 3-dimensional volumes.  Even more startling to our world-view is the notion this formula implies, that the universe has a bandwidth limit of 1 bit per Planck area.  Philosophical issues aside, the universal bandwidth limit may produce diffractive effects which become observable when the diffraction is allowed to grow over macroscopic distances to magnify the intrinsic Planck-scale resolution of space-time.  The Holometer is a Michelson interferometer-based device optimized to detect the resulting characteristic position noise spectrum of objects apparently at rest in space, but in reality suffering a constantly growing position jitter due to the fundamental inability of nature to specify object positions with greater precision.  The instrument's relatively small 40 meter size, compared to that of large gravitational wave detectors, allows flexibility of reconfiguration to probe detailed properties of the predicted holographic noise.