The law of gravitation first started as a theory of universal gravitation. The theory was first postulated by Sir Isaac Newton (1642-1727) an English mathematician and physicist. He tried to explain the behaviour of falling objects. Before this theory, mysterious interpretations had been given as the reason why objects do fall downwards when suspended in space.
The theory was the first scientific explanation of the behaviour of falling Newton noted that the earth possesses some force which attracts objects towards it. This force was recognised as gravitational force. Gravitation is the attraction between masses. This is what pulls objects around towards the surface of the earth. Hence, all objects within the earth’s gravitational field fall towards the earth. Why don’t you experiment now? Throw up any object you can lay your hands on and see what happens.
Since the earth has a centre of gravity, all objects in the universe are attracted towards this centre. It was also noted that as objects move away from the earth, the gravitational force decreases, and their weight also decreases. You would agree that this theory of gravitation has turned the fictitious idea surrounding falling objects to science. It did this by explaining theoretically and empirically why objects behave the way they do.
Albert Einstein’s theory of relativity, which was formulated in 1905, explained the Newtonian theory properly by asserting that gravitation is a property of space. The presence of any physical substance within space causes it to curve in such a manner that a field of gravitational force is created . With this clarification by Einstein and others, the theory was elevated to the rank of a law.
Therefore, Newton’s law of universal gravitation states that ‘any two bodies attract each other with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them’.
What this whole statement means is that if the mass (amount of matter) of one of the two attracting bodies is doubled, the gravitational attraction will also be doubled, but if their distance apart is doubled the force will be only one-fourth (1/4) as great .
Newton realized that gravitational attraction applies not only to bodies on the earth but is also responsible for holding the moon in its orbit round the sun. And it is also responsible for the movement of the earth and its fellow planets in their orbits round the sun.
