The force of gravity may seem strong when a bowling ball hits your foot, but it is actually the weakest of the fundamental interactions. Compare it to electromagnetism: the pull of all of the Earth's gravity won't stop you from sticking a fridge magnet. This weakness makes it incredibly difficult to measure gravity.
A group of scientists from China reports that they were able to perform the most accurate measurement of the force of gravity - the Newtonian or universal gravitational constant G. G describes the gravitational attraction between two objects by their masses and the distance between them. Numerically, it is equal to the modulus of the gravitational force acting on a point body of unit mass from the side of another similar body located at a unit distance from it. The new dimension will be important both for the most accurate atomic clocks and for the study of the Universe, Earth and other sciences that are somehow tied to gravity.
The values measured by the team "have minimal uncertainties at the moment," according to a paper published in Nature.
The most accurate measurement of the gravitational constant
Given the small value of G, it is incredibly difficult to determine its exact value, and the value agreed by the International Committee on Data for Science and Technology (CODATA) is much less accurate than the values of other numerical values that scientists use. Scientists today use the value 0.0000000000667408. But calculating G in this range would be akin to painting with a bold brush, while constants in other experiments are "drawn" with thinner brushes.
In the new study, scientists performed two independent calculations of G using a pair of pendulums in a vacuum, one for each test. Each pendulum swings between a pair of massive objects, the positions of which can be adjusted.
Pendulums measure the force of gravity in two ways. First, they measure the difference between how quickly the pendulum swings in a "near" or parallel position versus a "far" or horizontal position. They also measure how the swing of the pendulum changes depending on the attraction of the test masses.
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Obviously, such experiments require ultrasensitive detectors and carefully controlled installations to accurately determine G. In addition, the laboratory is located in a special room in the cave, which allows you to take into account the possible consequences of temperature changes.
Scientists managed to make two measurements for methods that take into account wobble time and angular acceleration, respectively, and they amounted to 6.674184 and 6.674484 hundred billionths (10 (-11 power). The measurements were accurate, but for unknown reasons they still diverged Perhaps it is the string used for the pendulum.
Ilya Khel