Any mass warps the fabric of space-time around itself. The more the mass, the more the warping. The force that an object feels when travelling along this warped path is called gravity. It tends to move the object towards the mass.

The strength of this force depends on the gravitational constant. Denoted by a ‘G’, it is a fundamental physical constant. It was first accurately determined by Henry Cavendish in 1797. G is an essential component of both Isaac Newton’s law of universal gravitation and Albert Einstein’s theory of general relativity.

In Newton’s theory, the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. G is the proportionality constant.

In Einstein’s theory of general relativity, G appears in the equations that describe the curvature (or the ‘warping’) of spacetime in the presence of mass and energy. This theory provides a more accurate description of gravitation, particularly in extreme conditions, such as near massive celestial objects.

The precise value of G is crucial to understand celestial mechanics and to determine the mass of celestial bodies. Yet its value has been determined only with an uncertainty of about 22 parts per million. Its precise determination remains a topic of ongoing research in the field of experimental physics.