While most people take in the awe-inspiring spectacle of a solar eclipse by looking at the sky, a small group of scientists spend their time watching a pendulum, seeking an anomaly that could turn physics upside down.
In 1954 French polymath Maurice Allais performed an experiment in which he release a Foucault pendulum every 14 minutes for an entire month. (A Foucault pendulum is one that, at its hinge point, is free to move in any direction. French physicist Léon Foucault used the device in 1851 to demonstrate the rotation of the Earth: because it can move in any direction, as the Earth rotates the pendulum’s motion slowly shifts relative to the Earth beneath it. )
Maurice Allais’ 30 day experiment happened to coincide with the 1954 solar eclipse, and he was shocked to find that during the eclipse, the pendulum’s angular motion suddenly changed. There was no physical law which would suggest this effect, so Allais was baffled. Allais repeated the experiment in during another solar eclipse in 1959 to check his result, but again recorded an anomalous movement. This change in the motion of the pendulum during an eclipse came to be known as the Allais effect, or Allais anomaly. Suggestions for the cause have ranged from dark matter through to gravitational anomalies.
As with most other scientific anomalies, orthodox science has largely dismissed the Allais effect as likely being due to poor experimental set-up. Results by other experimenters have been inconclusive, with some finding positive results, others finding nothing, adding to the mainstream view that the Allais effect is bogus:
Variations of the experiment have been done with a torsion pendulum (basically a horizontal bar suspended on a wire), and some verified the result and others didn’t. In 1991 a precise torsion experiment was done, and found no effect. Because of this the common view is that the effect isn’t real, but there are still experiments that claim to confirm the Allais effect. Since the effect requires a total eclipse, you can’t do the experiment very often, and you need to have a setup portable enough to do on site. So getting good, consistent results is difficult at best.
The debate over the Allais effect still lingers. Some argue that it isn’t a real effect, some argue that it’s a real effect, but is due to external factors such atmospheric changes of temperature, pressure and humidity which can occur during a total eclipse. Others argue that it’s a real effect, and is due to “new physics.” This latter view has become popular among supporters of alternative gravity models. Allais himself claimed that the effect was the result of new physics, though never proposed a clear mechanism. As a result, the experiment has become “tainted” by fringe science to the point that mainstream scientists don’t really do the experiment any more. The 1991 result is pretty clear, and Allais’ results are likely due to experimental error.
Ironically, while many supporters believed Allais would eventually win a Nobel Prize in Physics for his discovery of this anomaly – with implications that could rewrite the laws of science – he actually went on to win the 1998 Nobel Prize in Economics for completely unrelated work.
Sadly, in recent years internet discussion of the Allais effect seems to have been hijacked somewhat by Flat-Earth proponents (yes, they still exist), who see the anomaly as a possibly way of disputing that pesky Foucault pendulum experiment that showed the Earth was a rotating globe. But hopefully there’s some good science done during future eclipses, and we see honest discussion of any anomalous results that might be recorded.