Lawrence A. Crum
Appl. Phys. Lab., 1013 NE 40th Street, Univ. of Washington, Seattle, WA 98105
Because of the technical area of physical acoustics represents the center of Lindsay's Wheel of Acoustics, this area is often the origin of many research topics that eventually find application in other committees, and even other disciplines. Thus, ``hot'' topics in physical acoustics can be defined as anything done by physical acousticians, especially if they involve bubbles! However, for the benefit of those from outside this area who want to learn something about this exciting committee, a number of topics that are currently of major interest will be discussed briefly and a few selected topics of particular interest to the presenter will be discussed in more detail. In particular, it will be shown how a few specific topics being developed by physical acousticians have direct relevance to problems of more general interest to our society. For example, advances in the important new area of sonochemistry await progress in the fundamental understanding of sonoluminescence; advances in the new ventures of medical ultrasound, such as extracorporeal shock wave lithotripsy and ultrasonic surgery, await a more complete understanding of acoustic cavitation and nonlinear acoustics; the utilization of containerless processing of exotic materials in space awaits developments in acoustic levitation and an understanding of the surface-oscillation characteristics of liquid drops. These and similar topics will be discussed in some detail.