Tiny Bubbles Revisited
In last week’s column I described the trauma I experienced when
I picked up what I thought was a dead starfish, found it to be
alive and then witnessed its demise. I closed my column stating
that I would never pick up a starfish again. I lied. Yesterday I
found a young starfish of the same type only the size of a quarter.
I picked it up. This time, however, I threw it as far as I could
back into the Gulf. I’m assuming that it still survives and that
I’ve atoned for my earlier actions. This morning, I passed a
young lady proudly carrying a large starfish of the same species.
So the cycle goes.
Continuing in this downbeat mode, I found a follow-up item on
carbon dioxide buildup in the atmosphere and global warming,
the subjects of two recent columns. In last Sunday’s (March 21)
Naples Daily News, there was an article by Charles Hanley titled
“Carbon dioxide buildup said to be accelerating in Earth’s
atmosphere”. For a half a century, the National Oceanic and
Atmospheric Administration’s climate monitoring laboratory,
which operates the Mauna Loa Observatory in Hawaii, has been
monitoring the carbon dioxide levels there. The levels peak each
year during the winter months.
According to the article, on last Friday (March 20) the CO2 level
was about 379 parts per million (ppm) compared to 376 ppm last
year. This increase of 3 ppm may not sound like much but it’s
three times the 1ppm annual increases when measurements
began half a century ago. It’s also about twice the average
annual increase recorded over the past decade. This acceleration
in the rate of adding carbon dioxide to our atmosphere could be
an indication of positive feedback, in which a process feeds upon
itself so to speak. The more carbon dioxide, the more global
warming; the more warming, the more CO2 vented into the
atmosphere, etc., etc.
I must say that yesterday I felt no evidence of warming here on
Marco Island. The temperature at 6 AM, when I started my
walk, was only 52 degrees Fahrenheit and it was “breezy”. I’m
sure the wind chill factor was making it feel like it was 40. Here
in Southwest Florida, the weather forecasters don’t seem to know
the term “windy”. It’s always “breezy”. Incidentally, I realized
that, during that cold walk yesterday, I saw not a single bird of
any kind on the beach. Obviously, they had more sense than I
had, especially as I made my way back to our condo shivering in
the face of a driving “breeze”!
In the global warming scenario we discussed recently, one of the
consequences is predicted to be an increase in storminess and
windier conditions. Old-timers here all agree that this past
winter here in Florida has indeed been much “breezier” than in
past years. If we could drastically reduce the carbon dioxide we
produce, perhaps we could slow down or halt the warming. To
do this we need a major new alternative energy source to replace
the oil and gas we burn. Two years ago, in my column of March
21, 2002, I discussed a paper in the March 8, 2002 issue of
Science that offered a glimmer of hope in this regard.
In that paper, Rusi Taleyarkhan at Oak Ridge National Lab and
co-workers at Rensselaer Polytechnic Institute reported the
attainment of “desktop” nuclear fusion in a liquid. The claim
was that under certain conditions involving ultrasonic vibrations,
cavitation, in which tiny bubbles form and collapse, can be made
to generate extremely high, very localized temperatures.
Furthermore, the temperatures were high enough to initiate
nuclear fusion of hydrogen, just as occurs in our Sun. I had
written previously about studies in which cavitation was
postulated to generate high local temperatures and about actual
measurements of high temperatures in these collapsing bubbles.
To many, this “sonofusion” sounded a lot like “cold fusion”,
discredited by the overwhelming majority of the scientific
community. Sonofusion was greeted with great skepticism, even
by some of Taleyarkhan’s colleagues at Oak Ridge. In the
intervening two years, I saw no definitive work pro or con on the
subject. Now, almost precisely two years since the publication
of the Science paper, new work from Oak Ridge and Rensselaer
has surfaced. Taleyarkhan and his coworkers have repeated the
experiments using better equipment and claim confirmation of
their earlier work.
According to an article in the March 3 New York Times (called
to my attention by Brian Trumbore), at least one severe critic of
the earlier work has been convinced that there may be something
to this sonofusion. Lawrence Crum of the University of
Washington is quoted as saying the new work is “much better”
and that “It’s getting to the point where you can’t ignore it.”
Taleyarkhan is now a professor of nuclear engineering at Purdue
University and, on the Purdue Web site, he reveals details of the
recent work, performed while he was at Oak Ridge. The
common organic solvent, acetone, was the liquid used in the
experiments. The acetone was not ordinary acetone, but acetone
in which the hydrogen was replaced by deuterium, so-called
heavy hydrogen. Deuterium has both a proton and a neutron in
its nucleus, while ordinary hydrogen has only a proton.
The “deuterated” acetone was subjected to pulses of neutrons
lasting 5 thousandths of a second, also the length of time
between pulses. The neutrons generated cavities in the liquid.
At the same time, the liquid was subjected to high power
ultrasonic vibrations that caused the cavities to form tiny
bubbles. These bubbles then expanded to about 100 thousand
times their initial volumes. The expanded bubbles were visible
to the naked eye. The expansion of a bubble to such an extent
stores up very large amounts of energy. Taleyarkhan likens the
effect to stretching a slingshot from our Earth to the Sun.
This large amount of energy is released when the bubble
collapses, heating up the local area around the bubble. The
researchers estimate that the local temperatures reach 10 million
degrees Centigrade. They also think the local pressures are in
the range of a thousand times the pressure of our atmosphere
here on Earth. These extreme conditions are what they believe
initiates the nuclear fusion of the deuterium. Now, fusion
reactions generate certain products. This was one of the failures
of the cold fusion experiments. Initial claims that fusion
products had been observed proved to be highly questionable. In
reality, “fusion” products were found by other researchers to be
present in the background environment.
The Oak Ridge/Rensselaer researchers claim that they found
tritium, an even heavier form of hydrogen that is formed in the
nuclear fusion of the deuterium. When deuterium fuses, tritium,
gamma rays and neutrons of certain energies are formed.
Taleyarkhan states that all three of these fusion products have
been observed in agreement with theoretical model predictions.
In the work two years ago, they could only follow the reactions
for only short periods of time during the experiment. With the
new, more sophisticated detection equipment, they can follow
the process continuously. According to Taleyarkhan, the
statistics now are such that, whereas the earlier results had a one
in a hundred chance of not being nuclear fusion, the statistics
from the new studies point to a one in a trillion chance it’s not
nuclear fusion. That’s pretty good odds, if true!
When the bubbles collapse, there are flashes of light, the well-
known phenomenon known as sonoluminescence. Taleyarkhan
says that they have detected neutrons coming off at precisely the
time of the light flashes, further evidence for nuclear fusion. In
addition, they have run the same experiments with ordinary
acetone containing no added deuterium and found no effect. If I
remember correctly, it takes a significantly higher temperature to
fuse ordinary hydrogen than to fuse deuterium. I worry about the
fact that neutrons are used to seed the bubbles but the light
flashes and accompanying peaking neutron emissions occur
between the neutron pulses.
I certainly am not qualified to judge the merit of the new work
but, on the face of it, it seems quite promising. So far, the
experiments have been carried out using glass canisters stated to
be about the size of two coffee mugs, one on top of the other;
sounds like between a pint and a quart of liquid. The real test of
whether or not sonofusion will be a possible practical source of
energy is to exceed the break-even point. That is, you have to
obtain more energy out of the experiment than the energy you
put into the experiment. This break-even point has not been
achieved. Taleyarkhan says that they will try to scale up the
experiment and work to find a way to get rid of the expensive
equipment needed to supply the pulses of neutrons.
If a sonofusion company ever comes into existence I envision the
entrepreneurs using the song “Tiny Bubbles” in their
commercials. I love Hawaiian music and the young Don Ho’s
version I heard on our first visit to Hawaii back in the 1960s.
Allen F. Bortrum