# Gravitational Force and Field

Gravity is one of the most easily observable force in the universe. Throw a stone upward and it comes down due to gravity. But understanding the actual cause of gravity is not that easy. In fact it's still unknown.

Let's see what people think about gravity- from newton to Einstein to present day theories and discoveries on gravity.

**Newton's discovery: **

It doesn't mean that before newton no one knew about gravity. But rather newton was among the first (as we know) to research on gravity and make laws on it. Before that everyone knew that anything that goes up will come down.

Newton formulated that the gravitational force is directly proportional to the product of the masses, between which gravity acts. Also it is inversely proportional to the square of the distance between them. Gravity is a conservative force. Newton's formula is given below.

Where m_{1 }and m_{2} are the mass of the objects between which gravitational force is experienced, and r is the distance between the objects

**Object under free fall from a height H:
**

An object falling from a height H to the ground freely experience a force as shown

**Einstein's Theory of Relativity:
**

Sir Albert Einstein in his theory of relativity introduced a new term called space-time and stated that space and time are interrelated and are interlinked into the fabric of space. He said that gravity is not because of pull but it is because of th deformation of space by the mass, which result in a curved path of bodies moving near it. It is visualized below

It is just a 2 dimensional projection of the actual 3-d curvature, which is quite hard to visualize.

The Einstein field equation which describes gravity in terms of general relativity is as follows:

**Present day theories and discoveries:
**

After many years of research it was found that general relativity is inconsistent in terms of quantum mechanics. Hence a new variety of theories emerged which includes quantum gravity and many other. However Still gravity is not completely understood and it remains a mystery.

Keep visiting my blog and find more on gravity at http://phisyks.github.io/classical-physics