The paraconical pendulum is a type of

pendulum A pendulum is a device made of a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate i ...

invented in the 1950s by

Maurice Allais Maurice Félix Charles Allais (31 May 19119 October 2010) was a French physicist and economist, the 1988 winner of the Nobel Memorial Prize in Economic Sciences "for his pioneering contributions to the theory of markets and efficient utilization ...

, a French researcher. During the 1950s, Maurice Allais conducted six marathon series of long-term observations, during each of which his team manually operated and manually monitored his pendulum non-stop over about a month. The objective was to investigate possible changes over time of the characteristics of the motion, hypothesized to yield information about asymmetries of inertial space (sometimes described as "aether flow").

Characterization and experiments

The defining feature of the "paraconical" or "ball-borne" pendulum is that the pendulum's

fulcrum A fulcrum (: fulcra or fulcrums) is the support about which a lever pivots. Fulcrum may also refer to: Companies and organizations * Fulcrum (Anglican think tank), a Church of England think tank * Fulcrum Press, a British publisher of poetry * Fu ...

is the changing point of contact between a spherical metal ball and a flat surface on which the ball rests. The pendulum therefore loses energy to

rolling friction Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy nee ...

but not

sliding friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

, and is able to swing freely in both dimensions (forward-backward and side-to-side), similar to an ordinary conical pendulum. The main difference between a paraconical pendulum and an ordinary conical pendulum is the size of the ball involved: shrinking the ball down to a point produces an ordinary conical pendulum. Typically a paraconical pendulum is built as a solid body with a stiff rod, rather than with a flexible wire or cord. If an accurately spherical ball and an accurately planar flat are used, a paraconical pendulum is a highly sensitive instrument. As with the conical

Foucault pendulum The Foucault pendulum or Foucault's pendulum is a simple device named after French physicist Léon Foucault, conceived as an experiment to demonstrate the Earth's rotation. If a long and heavy pendulum suspended from the high roof above a circu ...

, a paraconical pendulum will be affected by the rotation of the Earth; but the changing fulcrum point makes the behavior of this

dynamical system In mathematics, a dynamical system is a system in which a Function (mathematics), function describes the time dependence of a Point (geometry), point in an ambient space, such as in a parametric curve. Examples include the mathematical models ...

rather more complex. As first noted by Allais, and now confirmed by modern researchers, its motion exhibits a 24.8-hour cyclic pattern.

External links

Göde Wissenschafts Stiftung Website: Description of recent experiments with a modern automated paraconical pendulum.

Video of another modern automatic paraconical pendulum.

* {{cite web , title=Photos of the Allais Paraconical Pendulum , date=2005 , url=http://www.allais.info/alltrans/allaispix.htm , url-status=dead , archive-url=https://archive.today/20130217231304/http://www.allais.info/alltrans/allaispix.htm , archive-date=2013-02-17 , website=allais.info Pendulums

Characterization and experiments

See also

External links