Ivan Osipovich Yarkovsky and his Gravity meter. In 1887, Yarkovsky put forward the “Kinetic Hypothesis of Universal Gravitation”. In his theory, he gives gravitation a purely mechanistic interpretation, assuming that the gravitational acceleration of bodies is associated with the pressure on them of chaotically moving particles of Ether.
Yarkovsky represented Aether (a hypothetical medium that carries light vibrations) as a completely material gas made of microscopic solid particles. He considered the atoms of chemical elements to be much larger aggregates of these Etheric particles.
Each physical body, according to Yarkovsky, constantly absorbs the particles of Ether, which inside it are combined into chemical elements, thereby increasing the mass of the body – thus the stars and planets grow.
And the effect of gravity is reduced to a simple screening: the presence of a nearby massive body absorbing the flow of etheric particles causes the asymmetry of the acting “Etheric pressure”, which manifests itself as an attraction to this body.
From this, the formula for the Law of Universal Gravitation was derived, which differed from Newton’s formula in the variable value of the dimension coefficient (in modern textbooks it is called the gravitational constant). Yarkovsky was aware that his hypothesis would cause a lot of objections.
Therefore, being a solid man, he first published his work in French, the most widespread in science of those years, under the title “Hypothese cinetique de la gravitation universelle, en connexion avec la formation des elements chimiques” (St. Petersburg, 1888).
He sent three hundred copies to famous scientists from different countries. The title page of the second (posthumous) edition of Yarkovsky’s book “Universal gravitation” of countries and from many addressees received answers. Having studied the reviews, Ivan Osipovich finishes the development of his idea and a year later publishes a more extensive and complete work “Universal gravitation as a consequence of the formation of weighty matter inside the celestial bodies.
The kinetic hypothesis ”(Moscow, 1889). Yarkovsky also tried to give a purely “kinetic” explanation to all other physical phenomena. So, for example, he created a model of the Universe with its complex physicochemical phenomena, relying only on the idea of the existence of a material ether and explaining intermolecular forces by the interaction of ether atoms with physical aggregates of the body.
Using the same kinetic hypothesis, I. Yarkovsky proposed his own interpretation of the periodicity of chemical elements and their properties. In addition, the researcher discussed the original hypotheses of the evolution of stars, terrestrial magnetism, and volcanic activity. One of the main consequences of Yarkovsky’s kinetic hypothesis of gravity was the effect of partial screening of gravity: the mutual attraction of two bodies should have weakened if a third body was located between them. Trying to verify this empirically, Ivan Yarkovsky created a sensitive gravity meter: the Gravity meter (gravitoscope)
For several years, every day, 5-6 times a day, he carried out measurements with it, trying to discover the effect associated with the daily and annual motion of the Earth, which plays the role of a screen for the observer on its surface. At the same time, he tried to take into account the influence of other reasons as much as possible: along with the readings of the Gravity meter, he recorded the temperature and air pressure.
Noticing regular variations in gravity, Yarkovsky decided that the shielding effect had been detected, but he was still in no hurry to draw conclusions. Yarkovsky tried to check the validity of his theory even during the total solar eclipse on August 7, 1887, when the Moon played the role of the gravitational screen. It was probably this last experiment that convinced Yarkovsky of the need to publish his theory of gravity.
His hypothesis refers to those mechanistic models of gravitation that were generated in the 19th century by the successes of the kinetic theory of gases. At a certain stage in the development of science, such models were very popular. But in the end this direction was recognized as a dead end, and professional physicists no longer turned to it. Thus, Yarkovsky’s original mechanistic theory did not find confirmation, but nevertheless one astronomical effect predicted by him became a useful tool of modern science. We are talking about the so-called “Yarkovsky effect”.
An inquisitive researcher came to this idea in search of an answer to the question: “Why is the movement of the planets not hindered by the resistance of the ether?” Indeed, the very existence of the luminiferous ether Yarkovsky did not question at all and considered it to be a thin, but quite tangible medium, consisting of microscopic particles and inhibiting the movement of all bodies immersed in it.
However, astronomy has irrefutably proved that such a slowdown in the movement of celestial bodies is not noticed.
Ivan explained the essence of the effect in this way. In his opinion, the planet absorbs ether, which in its depths partially turns into chemical elements, and partially leaves the planet. The higher the temperature of the planet’s surface in a given place, the more intensely the ether particles rush outward, creating the effect of recoil.
If the planet has no diurnal rotation, then the midday part of its sphere is the warmest; and in this case, the recoil effect acts along the line of attraction to the Sun, slightly weakening it. (In today’s terminology, we would call this “sunlight pressure”.)
In a rotating planet, the diurnal movement transfers the heated section of the Yarkovsky Gravity meter surface to the evening side of the ball, therefore, the recoil effect will be strongest there and will push the planet along its orbit.
This means that the specified effect will counteract the resistance of the ether. “So, – concludes Yarkovsky, – the engine of the planets is the sun’s rays.” Much has changed over the past century in our understanding of the nature of light. Today we no longer need aether to describe the propagation of light and the transfer of momentum by it.
This property of electromagnetic oscillations follows from Maxwell’s wave equations. Quantum theory made light pressure quite “palpable” at the level of common sense. It would seem that all this deprives Yarkovsky of reasoning.
However, the celestial-mechanical effect noticed by him still takes place and plays an important role in the life of the planetary system. We are talking about the effect of sunlight on the movement of small cosmic bodies, for example, asteroids.
The asteroid’s surface, illuminated by sunlight, heats up and, in an attempt to cool, emits infrared rays into space. The heat flow acts like a jet engine: it pushes the asteroid slightly in the direction opposite to the direction of radiation. Since all asteroids, like planets, revolve around an axis, day and night also change on their surface.
When the rotation of the body carries away the surface of the asteroid heated during the day into the night shadow, the accumulated heat is radiated “to the side”, acting as an accelerating or braking jet engine. If the rotation deflects the heated surface of the asteroid forward along the course, then the Yarkovsky effect slows down the movement of the body, and it, descending along the orbit, approaches the Sun.
If the warm surface turns backward due to rotation, then the ray pulse urges the movement of the body and raises its orbit, moving the body away from the Sun. In recent years, interest in the motion of asteroids crossing the Earth’s orbit has increased significantly. It turned out that for an accurate prediction of the possibility of a collision, the “Yarkovsky effect” must be taken into account.
In 2003, the effect predicted by Yarkovsky back in 1900 was experimentally confirmed by a group of American scientists led by Stephen Chesley and Stephen Ostro from the NASA Jet Propulsion Laboratory using the Arecibo radio telescope located in Puerto Rico.
It was the “Yarkovsky effect” that made it possible to explain the mysterious feature of the Apollo asteroid, discovered back in 1862. Yarkovsky effect At present, the “Yarkovsky effect” is better known as the Yarkovsky-O’Keefe-Radzievskii-Paddack effect: YORP-effect (short for the English Yarkovsky-O’Keefe-Radzievskii-Paddack effect). Only in our time has it become obvious how many issues that are relevant today were raised by I.O. Yarkovsky in his scientific works.
Many of them were well ahead of their time. Many bold assumptions are contained in the works of Yarkovsky, and this, in addition to the above-mentioned, the book “A New Look at the Causes of Meteorological Phenomena” (M., 1891), “Passion for Mathematical Theories in Modern Science” (Moscow, 1893), “The Structure of Matter and molecular forces “(M., 1894),” The density of the light ether and the resistance to motion “(Bryansk, 1901), numerous articles in periodicals.