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03/29/2006
Troubling Bubbles
Life is tenuous. Having completed a wonderful cruise on the
Celebrity ship Summit only a few months ago, I can relate to the
terrible story from Chile last week. Ten people from a retirement
community here in New Jersey were among those who died on a
mountain road when their van driver swerved to avoid an
oncoming truck. They had hired the van, independent of the
Celebrity ship on which they were passengers. As one of their
retirement community friends pointed out in an interview, such a
tragedy could just as well have happened on the New Jersey
Turnpike. I can also relate to that remark, having nearly been
killed myself some years ago on the turnpike when a passing
tractor trailer cut me off, forcing me onto the shoulder. Only 15
seconds earlier there was no shoulder because of construction!
In addition, there was last week’s fire on the cruise ship Star
Princess that caused one death and extensive damage to many of
the ship’s cabins. My wife and I were considering signing up for
a cruise from New York to Nova Scotia in the fall and the ship
was the Star Princess! I should note that in one news account the
Star Princess crew was given high marks by the passengers for
the way in which the fire incident was handled.
In addition to troubles on the high seas, there’s trouble in another
kind of waters, bubbly ones. OK, maybe not water but acetone.
I’ve devoted at least two earlier columns to the work of Rusi
Taleyarkhan and coworkers on so-called “bubble fusion”. It is
well known that, under certain conditions, when bubbles in a
liquid collapse the energy released can lead to very intense local
heating. In the phenomenon known as sonoluminescence,
flashes of light accompany the collapse of bubbles created using
ultrasonic techniques. There has been speculation that the
temperatures in collapsing bubbles might even be high enough to
induce nuclear fusion of hydrogen atoms.
Nuclear fusion is the Holy Grail that would solve the world’s
energy problems and huge sums of money have been spent in
attempts to generate the millions of degree temperatures
necessary to initiate fusion. However, with all the discredited
claims of “cold fusion” in a beaker some years ago, it’s to be
expected that any similar claims would be greeted with
skepticism. Taleyarkhan’s group published a paper in Science in
March 2002 in which they claimed to have seen evidence of
nuclear fusion associated with collapsing bubbles. Instead of
water, they used the solvent acetone, which contains 6 hydrogen
atoms in its chemical formula.
In order to improve their chances of getting fusion, the
researchers replaced some or all of the hydrogen atoms with
deuterium. Deuterium, a heavier isotope of hydrogen, fuses at a
lower temperature than normal hydrogen. This “heavy” acetone
was subjected to powerful ultrasound and pulses of neutrons that
caused bubbles to swell and collapse, emitting the expected
flashes of light. In addition, the researchers said they had indeed
detected the nuclear products expected if the deuterium had
actually fused. The products were either tritium (another
hydrogen isotope) and a proton or an isotope of helium and a
neutron. They later published additional results in other highly
respected journals.
It’s been four years since the first publication and we’re
beginning to see similarities to the events following the
announcement of cold fusion. According to an article by Robert
Service in the March 17 2006 issue of Science, DARPA (the
U.S. Defense Advanced Research Projects Agency) funded
further efforts by Taleyarkhan and an expert in
sonoluminescence, Kenneth Suslick, at the University of Illinois
to confirm Taleyarkhan’s work. DARPA also funded an
independent effort by Seth Putterman at UCLA. Putterman
could not duplicate the results and, a few weeks ago, DARPA
held a contractor’s meeting in Taleyarkhan’s lab at Purdue,
where Taleyarkhan was to demonstrate bubble fusion.
Apparently, the meeting wasn’t very productive insofar as
convincing the attendees that there was nuclear fusion.
According to the Science article, Taleyarkhan’s apparatus wasn’t
working well and, while Taleyarkhan claimed there was fusion,
the others were skeptical. Furthermore, one of Putterman’s
graduate students, Brian Naranjo, had made calculations that
showed the energy levels of the neutrons reported by
Taleyarkhan in the earlier work appeared to be consistent with
neutrons emitted by californium-252. Californium-252 is an
isotope of the element californium that is commonly used in
nuclear labs. Sure enough, it seems that there is californium-252
in Taleyarkhan’s lab but he says it’s contained in a shielded
vault.
At this time, Taleyarkhan is standing by his data, while Purdue is
launching a review of the work and hopes to complete the initial
phase of its investigation by June 1. Let’s hope that bubble
fusion doesn’t go the way of cold fusion. It seems that cold
fusion was a case of two very competent electrochemists
carrying out experiments that required equal competence in the
field of nuclear physics. Sadly, this was not the case and, under
attack, positions hardened and much money and effort was spent
worldwide trying unsuccessfully to reproduce their work.
Last week’s column and this one have been a bit on the gloomy
side and I’d like to end on a lighter note. In the past, I’ve
enjoyed writing about examples of animal intelligence that
compares with our own human smarts. In particular, I’m
enthralled with the fact that some birds show the term “bird-
brained” to be a complete misnomer. A prime example is Alex,
the famed African grey parrot that has a vocabulary of over a
hundred words and knows how to use them. Crows are also
pretty smart and have been observed making tools using twigs to
get at grubs. I believe that I’ve mentioned Betty, a crow that
fashioned a hook from a scrap of wire to get at a goodie tucked
down in a narrow tube.
In a very short item on crows in the April National Geographic,
Margaret Zackowitz mentions Betty and also cites the sighting in
Japan of crows placing nuts they want cracked under the tires of
cars stopped at red lights! She also mentions the work of a
Cornell ornithologist, Kevin McGowan, who has been following
a group of crows near Ithaca, New York for 16 years. Crows live
in groups and tend to mate for life. The West Nile virus hit the
flock hard several years ago and McGowan saw crows that were
not affected standing guard over their dying compatriots. He
even saw a bird that lost her mate take her brood of young
children and move back with her parents! Crows apparently
have compassion and strong family ties, just like us humans.
Finally, in case you’ve been completely out of touch with the
media this past week, a couple of promising developments. The
newly arrived Mars orbiter we mentioned a couple of weeks ago
sent back its first picture of Mars’ surface and it was a beauty –
crystal clear with no smudges. It bodes well for the mission to
map Mars in detail and, hopefully, to search for water under that
surface. The other story got more press. When on Marco Island
last month, I passed the Marriott Hotel on my early morning
beach walks. Typically, as I passed I could smell bacon being
fried and the odor would stir a longing for this off-limits food for
us cholesterol-challenged individuals on Zocor or other statins.
Now, of course, there’s the story of the genetically modified pigs
and the promise of bacon laden with lovely omega fatty acids. I
should live so long!
Allen F. Bortrum
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