Download 美国华盛顿大学Prof. Lawrence A. Crum学术讲座通知

美国华盛顿大学 Prof. Lawrence A. Crum
学术讲座通知
2014-09-11 16:40:36
讲座时间：
9 月 17 日
讲座地点：
教二北楼
讲座人：
9:30-12:00
308 室
Lawrence A. Crum
讲座内容：
1.
Sonofusion: Star in a Jar?
Abstract: When a sound wave of moderate intensity is propagated through
water, light emissions can be observed. This conversion of sound energy into
light energy is called Sonoluminescence (SL) and represents an energy
amplification per molecule of over eleven orders of magnitude. The discovery
in our laboratory (J. Acoust. Soc. Am. 91, 3166-3183 (1992) that a single,
stable gas bubble, acoustically levitated in a liquid, can emit optical
emissions each cycle for an unlimited period of time stimulated considerable
interest in this topic. Presumably, the oscillations of the bubble cause the
gas in the interior to be heated to incandescent temperatures during the
compression portion of the cycle. Because the lifetime of the optical pulse
can be on the order of 50 picoseconds, it is likely that some rather unusual
physics is occurring. One explanation for the short pulse length is that a
shock wave is created in the gas which is then elevated to high temperatures
by inertial confinement. If shock waves are the mechanism for SL emission,
then optimization of the process has been speculated to lead to extraordinary
physics, including thermonuclear fusion. Recent reports from Taleyarkhan, et
al. (Science, vol. 295, 1868-1873, 2002; Phys Rev Lett. 2006 Jan
27;96(3):034301.) have even provided evidence for the nuclear emissions that
should be associated with this phenomenon. Since this mechanism (thermonuclear
fusion) is the energy source that drives our sun, one can even speculate that
a miniature “star in a jar” has been created.
A broad overview of this
intriguing phenomenon will be presented as well a critical review of the
potential for acoustic inertial confinement fusion.
2. Space travel, Special Relativity, Transhumanism, and the Singularity
Abstract: There was a recent TV Program in which Stephen Hawking described
how one day humans would travel to planets on other stars and what they might
find.
I dug out my old Special Relativity Lecture Notes and did some
calculations.
First of all, I think Hawking is wrong; Humans will never
travel to other star systems—physics, and physiology, doesn’t allow
it.
Then, I did some research on what serious futurists believe will be the
technologies of the next one hundred, even one thousand years.
My thesis in
this lecture is that unless humans evolve beyond their present mental
capabilities and physical limitations, humans as we now know them, will never
travel beyond our own solar system, and, according, never find (by ourselves)
other intelligent life forms.
On the other hand, we could evolve into
transhumans that might solve some of the challenges of intra-galactic space
travel.
Finally, there are those who have estimated when computers will
have vastly superior “intellectual” powers to humans—the so-called
“Singularity”—and what this might imply. This lecture is for general
audiences, but may offend personal sensitivities.
讲座人简介：Dr. Lawrence A. Crum is currently Principal
Physicist and Founder/Former Director of the Center for
Industrial and Medical Ultrasound in the Applied Physics
Laboratory, and Research Professor of Bioengineering and
Electrical Engineering at the University of Washington.He has
held previous positions at Harvard University, the
U. S.
Naval Academy, and the University of Mississippi, where he was
F. A. P. Barnard Distinguished Professor of Physics and
Director of the National Center for Physical Acoustics.
He has published
over 200 articles in professional journals, holds an honorary doctorate from
the Universite Libre de Bruxelles, and was recently awarded the HelmholtzRayleigh Silver Medal and the Gold Medal of the Acoustical Society of
America.
He is Past President of the Acoustical Society of America, the
Board of the International Commission for Acoustics, and the International
Society for Therapeutic Ultrasound. His principal areas of interest are
therapeutic ultrasound, physical acoustics, and image-guided therapy.