Why every particle attract another particle in universe? and why there is a existance of gravity?
U=-Gm1m2/r
Every object of this universe wants minimum energy and maximum stablity. The particle attract each other so that
they have minimum separation and hence maximum -ve potential energy. As -ve energy shows deficiency of energy hence the object will have maximum deficiency of energy and the object will attain Maximum stabliiy.
Every particle exerts an accelerating force on another particle according to F =Gm(1)m(2)/r^2. This force applies without any screening, or any interruption, and the force on a particle at any given point is the vector sum of the forces from every other particle in the Universe, or at least that is what the equation says.
Why does it do it? That requires an answer to the question, what is gravity? The short answer is we do not know. Our equations tell us what it does, but not why it does it. There is still room for inspiration