Ultrasound in Regular and Irregular Bodies, Random Matrix Theory and classical elastic waves

Richard Weaver (r-weaver@uiuc.edu), Physics, UIUC

We review laboratory work comparing ultrasonic responses in generic elastic bodies to predictions from Random Matrix Theory. Measurements of level statistics and quantum fidelity are found to conform remarkably well to RMT even in bodies whose ray dynamics one might have considered pseudo integrable or even regular. We also find that return probabilities, related to the distribution of decay rates of excited nuclei, conform well to RMT, although a more naive Porter-Thomas-like model does almost as well.