Gravity is not a "force" apparently. It is a bending of spacetime such that an object travelling in a straight line appears to "bend" towards the center of the gravity well. This is often demonstrated by placing a heavy object on a cloth sheet, and observing the well created in the sheet and how objects travelling in a straight line across the sheet bend towards the center. However, gravity is the force that pulls the heavy object down distorting the sheet, and gravity is also the force that pulls the travelling object towards the center. So gravity is being used to demonstrate gravity...
So "anti gravity" doesn't make a lot of sense when gravity is not really a force. It is not like a magnet where same poles repel each other. An anti gravity device would be a device that "anti bends" spacetime - but how would that look exactly? A device that runs time in reverse perhaps?
But what about the electric force? Why do we treat gravity as a non-force but we treat the electric field as a force? What is "force" exactly, and can we somehow consider the electric field as a bending of something - perhaps spacetime too?
A "force" is required to accelerate an object, where acceleration means to change the direction an object is travelling in. But we already know that velocity is a relative term, and it is not possible to tell the difference between an object at rest and an object travelling at a constant velocity without some external reference point. That is to say velocity is not a property of an object - an object does not have a "velocity" parameter that is increased or decreased when a force is applied. Gravity deals with this by simply not changing the velocity of an object. The object is moving at a constant velocity relative to the gravitational object, and continues to do so when under the influence of gravity. The objects velocity does not change (because the object has no velocity parameter to change) but it's motion is "modified" by the fact that it moves within distorted spacetime.
Yet, when two objects collide they clearly have their velocity modified. The collision of two objects is essentially an operation involving the interaction of two electric fields. The atoms making up one object come into close proximity to the atoms making up another object, and they "bounce" off each other due to the interaction of their electric fields. This collision is understood as a "force" that causes the objects to accelerate - change direction.
So are we not also looking at a distored spacetime? When two objects bounce off each other there is a local distortion of spacetime that modifies the direction they travel in. That would imply that an electric field is a distortion of spacetime, just like gravity.