Being one of the fundamental quantities in physics, the gravitational constant was first mentioned in the 18th century. At that time, the first attempts were made to measure its value, however, due to imperfection of devices and insufficient knowledge in this area, this was possible only in the middle of the 19th century. Later, the result was repeatedly corrected (the last time it was done in 2013). However, it should be noted that there is a fundamental difference between the former (G = 6.67428 (67) · 10 −11 m³ · s −2 · kg −1 or N · m² · kg −2 ) and the latter (G = 6.67384 ( 80) · 10 −11 m³ · s −2 · kg −1 or N · m² · kg −2 ) does not exist.
Applying this coefficient for practical calculations, it should be understood that the constant is such in global universal concepts (if we do not make reservations on elementary particle physics and other little-studied sciences). And this means that the gravitational constant of the Earth, the Moon or Mars will not differ from each other.
This value is a basic constant in classical mechanics. Therefore, the gravitational constant is involved in a wide variety of calculations. In particular, without knowledge of the more or less exact value of this parameter, scientists could not calculate such an important coefficient in the space industry as gravitational acceleration (which will be different for each planet or other cosmic body).
However, Newton, who voiced the law of universal gravitation in general, the gravitational constant was known only in theory. That is, he was able to formulate one of the most important physical postulates, not possessing information about the value on which he, in fact, is based.
Unlike other fundamental constants, about what the gravitational constant is equal to, physics can only say with a certain degree of accuracy. Its value is periodically obtained anew, and each time it differs from the previous one. Most scientists believe that this fact is associated not with its changes, but with more banal reasons. Firstly, these are measurement methods (various experiments are performed to calculate this constant), and secondly, the accuracy of the instruments, which is gradually increasing, the data are refined, and a new result is obtained.
Given the fact that the gravitational constant is a value measured 10 to -11 degrees (which is extremely small for classical mechanics), there is nothing surprising in the constant refinement of the coefficient. Moreover, the character is subjected to correction starting from 14 after the decimal point.
However, there is a different theory in modern wave physics, which was put forward by Fred Hoyle and J. Narlikar back in the 70s of the last century. According to their assumptions, the gravitational constant decreases with time, which affects many other indicators that are considered constants. So, the American astronomer van Flandern noted the phenomenon of slight acceleration of the moon and other celestial bodies. Guided by this theory, it should be assumed that there were no global errors in the early calculations, and the difference in the results is explained by changes in the constant value itself. The same theory speaks of the inconstancy of some other quantities, such as the speed of light in a vacuum.