As one of the fundamental quantities in physics, the gravitational constant was first mentioned in the 18th century.At the same time the first attempts to measure its value, but due to the imperfection of the instrument and the lack of knowledge in this area, managed to do so only in the middle of the 19th century.Later, the result is repeatedly adjusted (the last time it was done in 2013).However, it should be noted that the principal difference between the first (G = 6,67428 (67) 10-11 m³ · s-2 · kg-1 or H · m² · 2 kg) and the last (G = 6,67384 (80) 10-11 m³ · s-2 · kg-1 or H · m² · kg-2) to the values do not exist.
Applying this ratio for practical calculations, it should be understood that the constant is that of the global ecumenical concepts (if not to make reservations on the physics of elementary particles and other little-known science).This means that the gravitational constant of the Earth, the Moon or Mars will not be different from each other.
This value is the basic constant in classical mechanics.Therefore, the gravitational constant is involved in a variety of calculations.In particular, without having information about more or less the exact value of this parameter, the researchers were unable to calculate such an important factor in the space industry as the acceleration of gravity (which for each planet or other celestial body is his).
Yet Newton's law of universal gravitation voiced in general terms, the gravitational constant has been known only in theory.That is, he was able to formulate one of the most important physical postulates, lacking information on the amount by which he, in fact, is based.
Unlike other fundamental constants, about what is the gravitational constant, physics can only say with some degree of accuracy.Its value is periodically re-receive, each time it is different from the previous one.Most scientists believe that this fact is not associated with changes in it, and more banal reasons.Firstly, it is the methods of measurement (for the calculation of this constant carried out various experiments), and secondly, precision instruments, which gradually increases, the data are refined and a new result is obtained.
Given the fact that the gravitational constant is a value measured at 10 -11 degrees (that classical mechanics ultra low value), in constant refinement coefficient is not surprising.The more that is subject to correction symbol starting with 14 decimal places.
However, there is a wave in the modern physics, a theory that pushed Fred Hoyle and John. Narlikar back in the 70s of the last century.According to their hypothesis, the gravitational constant decreases with time, which affects many other indices that are considered constants.So, the American astronomer Van Flandern was marked by the phenomenon of a slight acceleration of the moon and other celestial bodies.Guided by this theory, it should be assumed that any global errors in earlier calculations was not, and the difference in the results is due to changes in the value of the constants.This same theory suggests impermanence of some other variables, such as the speed of light in vacuum.