What a strange question, the reader will be surprised. Everyone knows that the Universe is expanding, and the Earth does not change its size. However, scientists did not always think so. At different periods, hypotheses were put forward that tried to explain the features in the geology and geography of our planet by changes in its size.
Baked apple
For the first time, the French geographer Jean-Baptiste Elie de Beaumont spoke about this in 1829. He proposed a theory according to which the relief of the earth's crust, with all mountain ranges and hills, was formed as a result of the decrease of the Earth due to its cooling. This hypothesis is called the theory of contraction (compression).
The scientist developed it in his work "Notes on mountain systems", which he published in 1852. The contraction hypothesis was based on the idea of the origin of the solar system from a rotating nebula. The barely formed Earth was a molten ball, and the Earth's crust formed as it cooled. At first it was smooth, but as the planet's temperature further decreased, its volume and, accordingly, surface area decreased. In this case, irregularities appeared. For clarity, Jean-Baptiste Elie de Beaumont drew an analogy with a baked apple, the skin of which, due to the drying of the pulp, becomes wrinkled.
In his opinion, the mechanical stress of the earth's crust in the places of such "wrinkles" gradually increased, and at the moment of reaching the ultimate strength, the rock broke. Then, due to lateral pressure above the surface, a mountain ridge bulged out. Its central part, most weakened by crushing, was filled with magma.
The contract theory has been heavily criticized from the outset. It was already obvious to many scientists in those years that no amount of compression could form the existing mountain systems. However, the internal consistency of de Beaumont's theory and the absence of an alternative allowed it to remain the main geodynamic concept for a long time.
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Extension theory. Who agrees"?
Meanwhile, in the scientific environment, an opposite concept has matured, suggesting that the Earth does not shrink over time, but expands. Its supporters were prompted by the outlines of the coastlines of Africa and South America - as if the continents were previously one whole, and then unknown forces tore them apart.
One of the clearest formulations of the hypothesis about the expansion of the Earth was put forward by the Italian geologist Robert Montovani in 1889. He suggested that land once covered almost the entire surface of our planet, which was half the size of today's Earth. Due to thermal expansion and volcanic activity, the supercontinent split into several parts, and they became the modern continents. The expansion of the planet continued, the continents "scattered" farther and farther from each other. The resulting dips in the earth's crust were filled with water - this is how the oceans known to us appeared.
Among the Russian followers of the theory of expansion can be called the engineer and naturalist Ivan Osipovich Yarkovsky. At the same time as Montovani, Yarkovskii came up with the idea of transmutation of new chemical elements inside celestial bodies, which leads to their increase.
Even Charles Darwin supported the idea of expansion at one time. During the second expedition on the ship "Beagle" he tried to use it to explain the rise of land in South America, which led to the formation of the Andes and stepped plateaus in Patagonia. True, Darwin quickly abandoned this hypothesis.
In 1956, the Australian geologist Samuel Warren Carey expressed support for the theory of the expansion of the Earth. He suggested the existence of some mechanism for increasing the mass of all existing celestial bodies and emphasized that this scientific problem can be finally solved only in the cosmological perspective.
Another hypothesis was proposed by the Irish physicist John Jolie together with the British geologist Arthur Holmes. They found a compromise between expansion and contraction, calling it the theory of heat cycles. The essence of the concept is simple: when the heat from radioactive decay of isotopes in the Earth's interior exceeds external cooling, the planet removes the excess temperature due to expansion. The resulting cracks in the earth's crust are filled with magma. After the release of excess heat, magma freezes, and the Earth contracts.
Hypothesis of an initially hydride earth
But back to science. Of the existing theories of expansion, the hypothesis of an initially hydride Earth deserves the greatest attention. Its author is a Soviet and Russian scientist, Doctor of Geological and Mineralogical Sciences Vladimir Nikolaevich Larin. The concept of the structure of the planet proposed by him, radically different from the officially accepted theory of plate tectonics, aroused great interest among Russian geologists.
According to his theory, the planet's inner geospheres were originally hydride, that is, composed of hydrogen compounds. This composition still has the earth's core. The release of hydrogen began when a layer of the mantle, called the asthenosphere, descended to the center of the Earth and caused it to warm up. Subsequent features of the planet's development are due precisely to the release of hydrogen from its interior. Including expansion - a side effect of this process.
Of course, the new idea, as is always the case, had many opponents. However, the great advantage of Larin's hypothesis is that it provides a logical explanation for many natural phenomena, which so far have only a conditional theoretical justification.
For example, it would become clear where there is so much water on the planet: hydrogen combines with oxygen in the mantle and then comes out to the surface. Volcanic activity would be easily explained, the origin of coal and oil, methane in mines and much more would be scientifically substantiated.
Dinosaurs could not stand
All of the above theories assume the expansion of the planet due to internal processes. But any physical body has one more opportunity to increase - to "overgrow" with matter from the outside. A similar assumption was voiced in the version of the mass death of dinosaurs put forward by biologists from Vladivostok.
- There is a long-standing paleontological paradox that many biological organisms that have left indisputable evidence of their existence in the stone annals of the Earth, today could not live on it just physically, - said in an interview with TASS, the chief researcher of the Institute of Marine Biology of the Far Eastern Branch of the Russian Academy of Sciences Anatoly - Drozdov, one of the authors of the hypothesis.
With the help of modern mathematical calculations, it has been proved that land dinosaurs, whose weight is measured in tens of tons, and even more so flying pterosaurs, would not have survived with the force of gravity existing on Earth. It was suggested that 150 million years ago this value was 2.079 times less than the modern one. Thanks to this, the fossil animals "grew" to enormous sizes.
The authors of the hypothesis believe that the force of gravity has increased due to the many small cosmic particles that have fallen to the Earth's surface, and this has led to a change in the planetary mass. The reason could be a dense cloud of interstellar dust through which the solar system passed about 150-200 million years ago. The process of falling out of space "precipitation" went gradually, but at some point it accelerated, the size and mass of the Earth quickly increased, and the force of gravity increased accordingly. The dinosaurs could not stand such a gravitational leap …
There are many discoveries ahead
There have always been as many arguments against the expansion of the Earth as there have been for.
By the way, the theory of plate tectonics, which has been dominant in science since the 60s - 70s of the last century, also did not immediately gain its positions. Its author, the German meteorologist Alfred Wegener, also drew attention to the coincidence of the coasts of South America and Africa. In 1912, he submitted a report on continental drift to the meeting of the German Geological Society. As evidence, Wegener cited not only the similarity of the shores, but also the geological rocks located there, which exactly coincided when combined. In addition, he noticed that the same animals and plants are found on both sides of the Atlantic Ocean, which they could not cross. However, then the scientific community did not accept his theory.
As for the idea of changing the size of the planet in one direction or another, then calculations based on modern technologies seem to have finally buried it. Using high-precision geodetic technologies and paleomagnetic data, experts have proved that the planet's radius has not changed over the past 400-600 million years and remains unchanged at the present time. And measuring the movements of tectonic plates using various geological, geodesic and geophysical methods just proves the validity of the theory of plate tectonics.
But who knows if these data will be revised in 10-20 years? Science is beautiful precisely because it is in constant development, and each new day brings new facts awaiting correct interpretation. And our home planet, with all its exploration, still holds many secrets …
Magazine: Secrets of the 20th century №28. Author: Svetlana Yolkina