Ever since that apple fell on Isaac Newtons head and he outlined his theories about gravitation in his great work Principia,nobody has really given serious thought to what causes gravity.

For years researchers have been vainly searching for a particle that might mediate this force-the near-mythical 'graviton'-but nobody has yet discovered it.

Maybe it`s because it doesn`t actually exist!

So,is gravity simply something that 'is'-A unique force in its own right which cannot be explained in terms of other forces?

Or can it be explained in terms of other,stronger forces?

I think gravity just 'is'.(Now,you don`t really think you`re supposed to pick this one do you?)

I think that perhaps it can be explained in other terms.