Sonoluminescence: an Introduction

Sonoluminescence: an Introduction

About the LLNL sonoluminescence experiment


What is sonoluminescence?

Sonoluminescence is the emission of light by bubbles in a liquid
excited by sound. It was first discovered by scientists at the
University of Cologne in 1934, but was not considered very
interesting at the time.[1]

In recent years, a number of researchers have sought to understand
this phenomenon in more detail. A major breakthrough occurred when
Gaitan et al. were able to produce single-bubble sonoluminescence,
in which a single bubble, trapped in a standing acoustic wave, emits
light with each pulsation.[2] Before this development, research was
hampered by the instability and short lifetime of the phenomenon.


Why is sonoluminescence so interesting?

Sonoluminescence has created a stir in the physics community. The
mystery of how a low-energy-density sound wave can concentrate
enough energy in a small enough volume to cause the emission of
light is still unsolved. It requires a concentration of energy by
about a factor of one trillion. To make matters more complicated,
the wavelength of the emitted light is very short - the spectrum
extends well into the ultraviolet. Shorter wavelength light has
higher energy, and the observed spectrum of emitted light seems to
indicate a temperature in the bubble of at least 10,000 degrees
Celsius, and possibly a temperature in excess of one million degrees
Celsius.

Such a high temperature makes the study of sonoluminescence
especially interesting for the possibility that it might be a means
to achieve thermonuclear fusion.[3] If the bubble is hot enough, and
the pressures in it high enough, fusion reactions like those that
occur in the Sun could be produced within these tiny bubbles.


What do we know about sonoluminescence?

The study of sonoluminescence has yielded more puzzles than it has
solid clues. Here is a summary of what we know about
sonoluminescence:

The light flashes from the bubbles are extremely short - less than
12 picoseconds (trillionths of a second) long.[4]

The bubbles are very small when they emit the light - about 1
micrometer (thousandth of a millimeter) in diameter.

Single-bubble sonoluminescence pulses can have very stable periods
and positions. In fact, the frequency of light flashes can be more
stable than the rated frequency stability of the oscillator making
the sound waves driving them.

For unknown reasons, the addition of a small amount of noble gas
(such as helium, argon, or xenon) to the gas in the bubble increases
the intensity of the emitted light dramatically.[5]


References:
H. Frenzel and H. Schultes, Z. Phys. Chem. B27, 421 (1934)

D. F. Gaitan, L. A. Crum, R. A. Roy, and C. C. Church, J. Acoust.
Soc. Am. 91, 3166 (1992)

B. Barber, C. C. Wu, R. Lofstedt, P. Roberts, and S. Putterman,
Phys. Rev. Lett. 72, 1380 (1994)

M. J. Moran, R. E. Haigh, M. E. Lowry, D. R. Sweider, G. R. Abel, J.
T. Carlson, S. D. Lewia, A. A. Atchley, D. F. Gaitan, and X. K.
Maruyama, Nucl. Instr. Meth. B 96, 651 (1995)

R. Hiller, K. Weninger, S. J. Putterman, B. P. Barber, Science 266,
248 (1994)



A few more resources for further information

"Sonoluminescence," L. A. Crum and R. A. Roy, Science 266, 233
(1994)

"Sonoluminescence: Sound into Light," S. J. Putterman, Scientific
American, Feb. 1995, p.46

"Bubble Shape Oscillations and the Onset of Sonoluminescence," M. P.
Brenner, D. Lohse, and T. F. Dupont, Phys. Rev. Lett. 75, 954 (1995)

The LLNL Sonoluminescence Experiment


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"Laurent" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...
emits
was
degrees
means
and
increases
J.
266,
P.
(1995)

A proposed explanation, made earlier this year by physicist Claudia
Eberlein of the University of Cambridge, involves an excursion into
the strange world of quantum mechanics, the rules that govern matter
at the tiniest scales. Quantum mechanics states that empty space is
not empty at all, but is made up of fluctuating fields that pop in
and out of existence. These fleeting fields can be considered
“virtual particles,” short lived particles that are ordinarily not
detected. But adding a tremendous amount of energy can drag these
virtual particles into the observable world. Drawing upon ideas
proposed by the late physicist Julian Schwinger, Eberlein believes
that a bubble---or more precisely the boundary layer between the
bubble and the surrounding water--- moving through a space of atomic
dimension in trillionths of a second can provide the extreme
conditions necessary to make the virtual light into the real light
which is observed as sonoluminescence. However, some physicists
consider this theory highly speculative.

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"Laurent" <[Only registered users see links. ]> wrote in message news:<[Only registered users see links. ]>...

It is good to see this introduction, as to me this is a good model for
other things as well.

With M Theory, one reaches a undertanding where the bubble becomes a
interesting figure for looking at the dynamical movement, not only in
regards to fusion, but of signally abstract maths for for this
movement.

For me this is very difficult, being almost illiterate of the maths,
but fully recognizing what this math must say, and how it shall say
it.

The vision we have of this movement to me speaks also to what is
happening with the BEC, as well as describing for us, cosmological
realizations. This is the isometric relationship, such fusions might
take place, in a cyclical universe, where blackholes become new suns.

Einstein's blackholes and his collaboration with Bose, provide a
interesting ground, for how we might use this sonoluminence process.

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Bubble Fusion
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