Periodic Changes in the Force of Gravity

It is known that, owing to the attraction of the Earth by the Sun and the Moon, the force of gravity at the Earth’s surface undergoes periodic changes. These changes are extremely small—their magnitude does not exceed tenths of a milligram per kilogram.

Recently, however, Courvoisier has developed a theory according to which there should exist other periodic oscillations of the force of gravity, approximately ten times greater than the oscillations caused by the attraction of the Earth by the Sun and the Moon.

The cause of these oscillations is the motion of the Earth in world spa-

space. As a result of motion in the ether, the earth should undergo a Lorentz contraction. This contraction is expressed in daily oscillations of the earth’s surface by several meters, which in turn is capable of producing considerable oscillations in the force of gravity. Curvoisier based his theory on extensive material obtained through prolonged observations.

In view of the extraordinary importance, for the fundamental principles of physics, of the question whether Curvoisier’s effect exists or not, Prof. Tomaschek undertook a careful experimental investigation of oscillations in the force of gravity. Such experiments were also of great interest for geophysics, since they made it possible to investigate the tides of the earth’s crust with an unsurpassed degree of accuracy.

The principal investigations were carried out with the aid of a bifilar gravimeter. In this instrument, changes in the weight of a body suspended in a special manner from a spiral cause the latter to twist. To attain a high degree of precision in the measurements, it is first of all necessary to eliminate temperature fluctuations. Tomaschek’s experiments were performed in a well-isolated shaft situated 20 m below the surface of the earth. Daily temperature fluctuations in such a shaft did not exceed thousandths of a degree. Nevertheless, in the interests of the greatest precision, the spiral, whose length reached 1 m, was made of a special Krupp alloy whose elastic properties are almost independent of temperature.

It is still more important to eliminate changes in air pressure, since the changes in the weight of the body that occur as a result many times exceed the periodic oscillations of the force of gravity under investigation. In the given apparatus the entire equipment was placed in a space completely isolated from external pressure, and photographic recording of the twisting of the spiral was carried out from another room. In this way it was possible to attain such a high sensitivity that changes in the force of gravity as small as \(1 \cdot 10^{-9}\) of its value could be recorded.

Such sensitivity not only ensured very distinct recording of oscillations in the force of gravity due to the influence of the sun and the moon, but also, as a careful analysis of the curves obtained showed, made it possible to distinguish fine details of these oscillations corresponding to the different positions of the sun and moon in the sky.

Since the changes in the force of gravity expected as a result of Curvoisier’s effect should have been approximately 30 times greater than the changes caused by the influence of the sun and moon, they would have given, on the recording curve, enormous oscillations with an amplitude exceeding 10 cm.

However, despite continuous recording of the force of gravity over a period of several months, no such deviations were found. It follows from this that, just as Lorentz contraction cannot be detected by electrodynamic investigations, it cannot be demonstrated gravimetrically either.

Consequently, in these experiments we have an important experimental confirmation of the theory of relativity.

(Prof. Dr. R. Tomaschek, Forschungen und Fortschritte, 8, 1, 1933.)

V. Svechnikov