Keely
Babcock writes in 1880:- "This discoverer has entered a new world, and although an unexplored region of untold wealth lies beyond, he is treading firmly its border, which daily widens as with ever-increasing interest he pursues his explorations. He has passed the dreary realm where scientists are groping. His researches are made in the open field of elemental force, where gravity, inertia, cohesion, momentum, are disturbed in their haunts and diverted to use; where, from unity of origin, emanates infinite energy in diversified forms." [Vibratory Physics - True Science, Keely and Science - Part 1 and Ether the True Protoplasm]
Momentum is a property of any moving object. For a slow moving object it is given by the mass times the velocity of the object. For an object moving at close to the speed of light this definition gets modified. The total momentum is a conserved quantity in any process. Physicists use the letter p to represent momentum, presumably because m was already used for mass, n for number, and o is too much like zero. (source unknown)
Nikola Tesla
"The view I have advanced is NOT BASED ON A THEORY but on facts demonstrable by experiment. It is not a matter of definition as some would have it. A MASS REVOLVING ON ITS AXIS MUST BE POSSESSED OF MOMENTUM. If it has none, there is no axial rotation, all appearances to the contrary notwithstanding." [Nikola Tesla]
See Also
Heisenberg uncertainty principle
Inertia
Momentum De-Isotropifier