Mother nature is full of surprises and physical world is no exception. Forces for example are all of same nature. In the sense, they does the same thing. Of all the various forces, gravitational force, electrical force, electro-magnetice force and nuclear force are of some interest. Gravitational force is the one discovered earliest. In 18, 19-th centuary, people were able find the connection between electric force and magnetice force.

**Gravitational Force**

Late 19th centuary and early 20-th centuary developments could relate mass to the energy and other various break-throughs. It is gravity with refused to giveup. I am going to discuss about “gravitational force” here, which is supposed to be most puzzling force ever. We all know by whom, how and when gravitational force was discovered. I am not going to get into that. I was taught and thought that gravitational force the strongest force. Because of which I, you, the chair, desk and the computer I am keying in this sticks to the earth. This very thought is challenged now.

**And I read a book**

All this changed after I read this book written by Michio Kaku. Kaku describes gravitational force as one of the maddingly weak force.

The various forces of nature - gravitational, electrtical and weak forces.

So far, gravitational force is only force which has evaded every scientist from the grand unification. A theory which could explain every force acting on the universe is known as unified theory. Such theory, single equation is supposed to explain electric force, magnetic force, nuclear force and last but not least gravitational force.

**Unified Theory**

Such a theory is to be called as the “grand unified theory”. Theoretical physicists who are working on this have put enormous effort in unifying the strange force, ie, gravitational force.

Why is it that gravitational force is strange? To put it in simple terms, say, earth needs the entire weight of it to keep the pieces of paper on the desk. But where as, if I could rub a comb to a hair and show it to the paper, due to the electrons the comb gained, could attract the paper and levitates it. Overwhelming the gravitational force. But still you could see that rockets and aeroplanes waste so much energy to escape the G force.

The force F is measured using this formula given by Issac Newton and depends on mass of the objects and the distance `r’ between them. In this case,mass of earth and that of paper.

**Supersymmetry and String Theory**

Going forward several theories are proposed to unite gravity with other forces. Supersymmetry is one such theory. This theory proposes that every particle has a super particle or alternative particle. It has it’s own pros and cons. Then comes string theory. String theory involved considerable amount of mathematics in it. So much so that, mathematicians have demanded that string theory should be treated as branch of mathematics in its own right. There is another theory, combining string theory and super symmetry – super strings.

It would be really great to see an unified theory which could explain all forces in one equation. Hoping that it will be accomplished in our life time.