Group of geophysicists using modern space measuring instruments and new computational techniques could "bury" the popular theory of the expanding past the Earth, said NASA's Jet Propulsion Laboratory.
In the laboratory Xiaoping (Xiaoping Wu) and his colleagues in a paper published in the journal Geophysical Research Letters, wrote that they recorded the Earth's radius variations do not exceed 0.1 millimeters — the thickness of a human hair — per year. This value is not statistically significant."Our study provided independent confirmation of the fact that the Earth is not expanding, at least within the measurement uncertainty," — says Wu Xiaoping.From the first half of the 19th century, geologists have advanced the hypothesis of expansion or contraction of the Earth, to explain the origin of mountains and oceans. In particular, the appearance of folded mountains tried to explain the compression of the earth in the process of cooling of the initial cooling. Proponents of expanding the land came from the fact that the discrepancy between the continents and the oceans due to the appearance of stretch the crust as the volume of mineral resources.In the 1960s, has been formulated and has become the dominant theory of plate tectonics, according to which the earth's crust consists of several plates, which are blocks of ice floating in the water in a viscous upper mantle. Along the boundaries where the plates meet, "podnyrivaya" to each other, concentrated pockets of earthquakes, volcanoes, areas of active mountain building. However, many of geophysics for various reasons and now is subject to extension or "constriction" of the Earth.To evaluate tectonic processes on Earth, to measure gravity and calculate the coordinates, it is necessary to know exactly how the shape of the planet and change it at all. For these measurements was established International Earth reference frame (ITRF — International Terrestrial Reference Frame), which is used for navigation on Earth, and for the tracking of satellites in space. In addition, it is used to measure the position of the Earth's poles, changes in the shape of the Earth and sea level fluctuations.To accurately calculate the radius of the Earth and determine how it varies, use tools such as satellite laser measurements (in which the nearest millimeter measured distance between the satellites and reflectors on Earth), long baseline radio interferometry, data navigation system GPS, and a number of other methods.Group Y Xiaoping used new methods for revaluation of the International System of reference, in particular, they take into account the movement of the earth's crust, as well as accurate data on the Earth's gravity, obtained by satellite GRACE.