In 1687, Isaac Newton quantified this phenomenon in his Law of Gravity, which states that every object in the Universe attracts every other object. This force between any two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them. This means that gravity is additive, and acts over great distances. Gravity is the weakest of the known fundamental forces, but its quality of being additive makes it the most important force in the Universe. Marc Millis, Lewis Research Center Gravity feels powerful here on the surface of the Earth, for example, because what we feel is the result of the gravitational attraction of the entire mass of the planet.
Gravity is also unique in that it seems to have no opposing force.
All other forces do. The earth and other large bodies, for example, are electrically neutral, with the negative and positive charges involved being equal thus canceling each other out. On the other hand, scientists have long thought that there is no such thing as negative mass, so that there would be no force available to counteract gravity. Now some researchers have questioned the validity of the assumption that there is no such thing as negative mass. If these researchers are correct, and can succeed in demonstrating the existence of negative mass, it could open the way to a new field of science antigravity.