Puzzle of the Pendulum by Lee Dye
-------------------------------------------------
A mystery that has stumped scientists for half a century may have moved o=
ne
step closer to being solved during August=92s total eclipse.
It will be months, maybe years, before all the data are analyzed and
scientists can decide whether Maurice Allais was right when he concluded
that an eclipse alters the path of a pendulum. If true, the news would up=
end
our understanding of gravity.
Allais, who won the Nobel Prize in economics in 1988 and has been a
respected researcher in physics, claimed to have detected a slight shift =
in
the motion of a Foucault pendulum during a total solar eclipse in 1954.
A Foucault pendulum is a weight that swings at the end of a wire as
gravity pulls it back and forth in a long arc. The swing of the pendulum
remains nearly constant as the Earth rotates below it, creating the optic=
al
illusion of a change in the direction of the swing. Many museums have
displays in which the pendulum knocks over small figures as Earth rotates
below the swinging weight.
Maurice Allais earned a Nobel Prize =97 and raised eyebrows from physicis=
ts.
But if Allais was right, a solar eclipse shifts the direction of the
pendulum=92s swing and nobody knows why.
=93If, in fact, pendulums go crazy during eclipses it suggests we do=
n=92t
really have an understanding of gravity and the intersection of different
bodies,=94 says physicist Ron Koczor of NASA=92s Marshall Space Flight Ce=
nter in
Huntsville, Ala. =93There=92s nothing we can conceive of within standard =
theory
that would make a pendulum change its swing during an eclipse.=94
Other scientists who have tried to replicate Allais=92 work the ensu=
ing
decades have had mixed results.
The Aug. 11 eclipse gave scientists an ideal opportunity to test All=
ais
=92 conclusions because the eclipse passed directly over scores of Foucau=
lt
pendulums in Europe.
NASA physicist David Noever, an expert on gravity, and Koczor organi=
zed
a global study during the eclipse, and most of the data finally have
trickled in. There=92s a lot, at least 100 gigabytes, and will require pl=
enty
of analysis. But there are some tantalizing leads.
The data consist largely of videotapes of five pendulums both inside
and outside the path of the total eclipse.
In the Path
Here=92s the intriguing part. Nobody outside the path reported seeing any=
thing
unusual when viewing the tapes. But researchers at two sites in Europe =97=
in
the direct path of the eclipse =97 say that when they looked at their tap=
es,
they saw a change in the pendulum=92s direction.
=93We haven=92t looked at their videos in detail yet, and we=92re no=
t going
to reach any conclusions just by eyeballing them,=94 says Koczor, who=92s=
trying
to organize the mountains of data.
A supersensitive gravitometer at the Huntsville lab that can detect =
the
incredibly subtle change in gravity caused by a truck passing nearby
detected nothing, Koczor says. Neither did the lab=92s pendulum. So if th=
e
Europeans are right, the effect takes place only in the path of the eclip=
se.
That=92s a real mystery.
Koczor is still waiting for another bit of fascinating data. Some
scientists used a different pendulum, called a torsion pendulum, which
consists of a weight suspended at the end of a twisted wire that causes t=
he
weight to swing in a circle. Some researchers in Europe reported seeing s=
ome
=93strange changes=94 in one torsion pendulum, Koczor says.
=93But we haven=92t got their data yet,=94 he adds.
It=92s all tantalizing, but the preliminary results are very tentati=
ve.
Let=92s Go to the Videotape
The only way to find out, Koczor says, is to take the six-plus hours of
videotapes that have been shipped to his office, digitize them then analy=
ze
them one frame at a time. And since the cameras record 30 frames every
second, that=92s a lot of analyzing.
The sites used two cameras, one at ground level, recording the
direction of the pendulum as it moved back and forth toward the camera, a=
nd
another overhead. Tapes were shot before, during and after the eclipse.
The data will allow scientists to determine any changes in the perio=
d
of the pendulum (the time it takes for one complete swing) and any change=
s
in the direction it swings. Because the Earth rotates below the pendulum,
the swing normally changes about 10 degrees per hour of a 360-degree circ=
le.
According to Allais, the pendulum he observed changed the angle of i=
ts
rotation by 13.5 degrees during the eclipse.
=93That=92s basically the effect we=92re looking for,=94 Koczor says=
.. =93If the
pendulum moves 10 degrees an hour when there=92s no eclipse, and then all=
of a
sudden it starts moving 20 degrees per hour during the eclipse, and then
goes back to 10 degrees per hour,=94 then something very strange takes pl=
ace
during an eclipse.
Scientific Skepticism
Many scientists have trouble taking Allais=92 claims seriously because, q=
uite
frankly, none of it makes much sense. There=92s a near total eclipse once=
a
month when Earth, the moon and the sun are nearly aligned at the time of =
a
new moon, so a similar effect should be present then.
=93If something is happening to gravity once a month, wouldn=92t we =
have
noticed by now?=94 Noever asks.
That suggests that, in the end, scientists will come up with some
explanation for the results, such as equipment flaws or changes in
temperature or some local problem.
If they can=92t, and the so-called Allais effect is real, they=92ll =
try to
explain why. That may prove far more difficult than running a bunch of
experiments during a solar eclipse.
=93It=92s easy if we see nothing,=94 Koczor says. But if there=92s s=
omething
there, =93it=92s a different ball game.=94
Lee Dye=92s column appears Wednesdays on ABCNEWS.com. A former science wr=
iter
for the Los Angeles Times, he now lives in Juneau, Alaska.
Mixed Results
1954 =97 Frenchman Maurice Allais reported seeing a change in the sw=
ing
of a pendulum during a 1954 eclipse. He reported the effect again in 1959.
Scientists in Scotland and Italy saw no changes.
1970 =97 Scientists at Harvard University reported that a torsion
pendulum sped up during an eclipse then slowed down. That =93cannot be
predicted on the basis of classical gravitational theory,=94 they reporte=
d.
1981 =97 Scientists reported seeing the Allais effect during an ecli=
pse
in Romania.
1990 =97 Using equipment similar to that used by the Harvard researc=
hers
in 1970, scientists tried to repeat the experiment in Finland but saw
nothing. A year later, during an eclipse in Mexico City, they reported
seeing two =93distinct shifts=94 in the pendulum.