# Gravitational Constant Explained

Gravitational Constant (G) is a fundamental force of nature. Its force of attraction on bodies is proportional to their respective masses and inversely proportional to the square of the distance between them. Its effective radius is known as Hubble mass. The gravitational constant is one when measured in the correct units.

## G is the universal gravitational constant

G is the universal gravitational constant, a fundamental quantity that plays a part in calculating the effects of gravitation. It is part of Sir Isaac Newton’s law of universal gravitation, as well as Albert Einstein’s general theory of relativity. It is the key to predicting the gravitational effects of objects.

However, the value of G is not exactly universal. It depends on the density of matter at astrophysical scales. As such, there are a number of uncertainties associated with this value. The uncertainty associated with G, however, remains relatively small.

## It is a proportionality constant

Gravitational Constant (G) is a physical constant that governs gravity. When two bodies are in a gravitational field, they attract each other and move towards each other. This force is constant everywhere, even within the same universe. Newton first discovered this force around 1680. His discovery led to the formulation of Newton’s law of gravitation.

The Gravitational Constant is the product of two objects’ masses divided by the square of their distance. It is a classic example of the inverse square law and was first measured using a torsional balance. More information on the Gravitational Constant is available at Scientific American and Physics Central.

## It is a fundamental force of nature

Gravity is the force that holds massive objects together. It is also the weakest fundamental force, especially at atomic and molecular scales. This fact has long been debated, but a recent study shows that gravity is the same everywhere in the universe. This fact makes alternative theories of gravity a wild goose chase.

Unlike other fundamental forces, gravity and the force of touch are not fundamental. They are actually the result of complex interactions between quantum theory and electromagnetism. Therefore, they are not included on the list.

## It changes with time

The Gravitational Constant, G, is an important constant in gravity physics. It determines the amount of weight a celestial body has in relation to its gravity and its orbital motion. The official value of G is 6.673889 N*m/kg. However, there are a large number of measurements which show a variation of about 10-4 percent. The variation is believed to be due to measurement inaccuracy. Moreover, gravity is difficult to measure compared to other fundamental forces.

The age of the universe may be one factor that changes the value of the gravitational constant. This may change the critical mass that a star needs to explode and affect the maximum brightness of a supernova. For example, scientists recently discovered that the gravitational constant was about 5% greater eleven billion years ago compared to six billion years ago. However, it gradually decreased over the years, and increased slightly as recent data show.

## It is a key quantity in Newton’s law of universal gravitation

The Gravitational Constant is a physical constant denoted by the letter G and involved in the calculation of gravitational effects. This constant is a central quantity in Newton’s law of universal gravitations, as well as Einstein’s theory of general relativity. It quantifies the relationship between the distance and product of masses between two bodies.

The strength of gravitational attraction between two objects depends on their mass and distance from one another. Newton’s law of universal gravitation puts this attraction into mathematical terms. The gravitational force between two objects is equal to their combined masses. The stronger the force between two objects, the stronger it is. This is why the larger the mass of one object, the stronger the force between them.

## It is measured by measuring acceleration

The gravitational constant, G, is the measure of the acceleration of a body relative to the gravitational field. It is measured in meters per second squared (m/s2) and is equal to 9.81 m/s2 for objects near the Earth’s surface. The acceleration is the same for all bodies and objects, but it increases by about nine meters per second each time an object is free-falling.

A simple method of determining the gravitational force is called a torsion balance. In this experiment, two large cylinders produce a gravitationally induced torque on a small mass. This torque is then balanced by an electrometer producing an electrostatic torque. This torque is adjusted using a servo-control system. A simple, but effective, method of calculating the gravitational force is now available for use by researchers.