Honors Theses
Date of Award
2008
Document Type
Undergraduate Thesis
Department
Physics and Astronomy
First Advisor
Joel Mobley
Relational Format
Dissertation/Thesis
Abstract
In this project acoustic waves were employed to measure dispersion properties of two suspensions of polymer microspheres that were believed to support superluminal group velocities. Broadband ultrasonic pulses were first used to study a suspension of microspheres with a mean diameter of 160 microns. The validity of the data was verified using Kramers-Kronig relations, and the attenuation, phase, and group velocity spectra During the second phase of the project a pulse consisting of broadband and narrowband components were propagated through the same 160 micron sample. The data are depicted in the Results section. Phase II studied several different bandwidths for each center frequency of the narrowband portion of the pulse. Finally, for Phase 111 the 160 micron suspension was replaced with a 100 micron suspension. A different range of center frequencies and bandwidths were employed for the narrowband portion of the pulse. As in Phase II the pulses contained both broadband and narrowband components. At each phase of the project attenuation, pha.se velocity, and group velocity were all examined and compared. Superluminal (i.e., faster than light) group velocities were calculated for certain frequency bands in each suspension. Although the group velocity was found to exceed the speed of light, relativity were published (Mobley, 2007a). was not violated.
Recommended Citation
Heithaus, Robert Evans, "Abnormal Group Velocities of Ultrasonic Pulses in Aqueous Suspensions of Polymer Microspheres" (2008). Honors Theses. 2346.
https://egrove.olemiss.edu/hon_thesis/2346
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