Of the forces of nature, gravity is probably the least understood. Gravity is everywhere but the mechanism through which it propagates is not known.
Gravity is an effect of mass, it appears. The gravity field can be calculated with good accuracy given the amount and density distribution of a body of matter. Gravity does not seem to be affected by the materials involved and does not seem to be shielded by anything.
Even what fundamentally constitutes mass and why this mass has inertia is not understood. Inertia and gravity are linked because the effects of gravity are not distinguishable from the effects of an accelerating frame. Empirically, an object's mass determines the force with which gravity pulls it and likewise determines the force with which the same object pushes against an accelerating platform.
General relativity predicts the existence of gravity waves but none such have been detected. These waves would have a particle manifestation called the graviton, a bit like light waves have the photon. The graviton would be the quantum of bending of spacetime by gravity.
General relativity does not see gravity exactly as a force like EM for example. Instead, gravity is curvature of spacetime, geometric in nature. We may understand this by thinking that objects on which no external force works travel in straight lines in 'flat' space. When the space is curved, objects continue to follow lines but these are not straight. For example, for an object orbiting a planet, the straight line is now an ellipse. A line followed by an object is called a geodesic. The closer the object comes to the source of the gravity, the more the space is curved, i.e. the more the geodesic deviates from the straight line. This comes basically to the same as seeing gravity as a force acting on all parts of a body, proportionally to the inverse of the square of the distance. Seeing gravity as geometry rather than force has however advantages in more complex cases.
The speed of propagation of gravity is a matter of debate. This is not readily measurable because gravity cannot be modified in an experimental setting, not at least with any technology that would generally be known. If an object moves, does the vector of the force of gravity point to the present position of the object or at a position the object occupied in the past? Observations are not conclusive.
Of the four forces, gravity is by far the weakest. It has been proposed that gravity act along hidden dimensions, using part of its force towards objects not perceived in the 3+1 dimensions of spacetime.
Various technologies for manipulating gravity have been proposed. None of them are officially recognized to work and theoretical understanding of gravity is not to be found in the public domain. Unifying gravity with the three other forces (EM, strong and weak nuclear forces) is considered to be the holy grail of physics. Approaches towards this include string theory, quantum gravity and other multidimensional theories such as Kaluza-Klein theories. There is reason to believe that key work is suppressed from the public domain and that the science establishment is chasing its tail while the 'real' theoretical and applied work takes place in secret.
The Cassiopaea material comments on gravity in many places. Gravity is, according to this source, the binder of all physical and all ethereal. There is nothing that is not derived from gravity. Even thoughts have gravity. Gravity does not go anywhere, it is eternal and omnipresent but it can be gathered and dispersed in the form of so-called unstable gravity waves. The principles of STO and STS are, as all else, also reflected in terms of gravity, as dispersion and gathering of gravity waves, respectively. Gravity pervades all densities. It can be manipulated by consciousness, sound or other means but details are not given. Manipulation of gravity was used in ancient history for building and even for people levitating. We have no theoretical framework for placing this information at present. Items such as the UFO phenomenon suggest that gravity is most likely technologically manipulable, also the evidence of some ancient buildings would suggest that something of the sort is possible.