Antigravity is a hypothetical force of repulsion. It is described in some science-fiction stories but has not been observed by scientists. In theory, antigravity would resemble gravity except that it would cause objects to repel, rather than attract, one another. For example, gravity on Earth pulls objects toward the planet’s center. But antigravity, if it existed, would push objects away from Earth’s center.
Some people have speculated that, because electric forces can be attractive or repulsive, gravitational force also may be either attractive or repulsive. However, electric force can be attractive or repulsive because it is proportional to electric charge, which is either positive or negative. For this reason, like charges repel and unlike charges attract. Gravitational force, on the other hand, is proportional to mass (the amount of matter that makes up an object). Mass is always positive and has no known negative counterpart. Therefore, it seems that gravitational force must always be attractive.
Some people have speculated that antimatter, which has some properties opposite to those of ordinary matter, might experience antigravity instead of gravity. But experiments have shown that gravity affects antimatter just as it does ordinary matter.
