Some scientists are trying to do what many other scientists consider impossible. That is, to construct a machine that will produce repulsive or attractive gravity. Here is a link that will provide more information about the research: http://www.scansite.org/scan.php?pid=157" When an object like an electron or a planet spins and rotates, it produces a secondary gravitational field (gravitomagnetism) which the strength of the field depends on its rotational speed and its mass. To control this force, scientists apply a time-varying magnetic field to a superconductor that contains ions in crystal-lattice form. This magnetic field gives the ions trapped in the superconductor energy and causes it to spin, which consequently produces that gravito-magnetic force. If all the ions are perfectly aligned and spin at the same angle and frequency, a coherent gravitational field will be created around the superconductor. According to General Relativity, gravitation can be repulsive as well as attractive. If the pressure in the stress-energy-momentum tensor is negative, than repulsive gravitation will result. So I GUESS that in order to create a repulsive gravitational field, the ions inside the superconductor will have to spin in a way that produces negative pressure. Does any of this make any sense? I guess my question is whether the link I posted or all the science I have described for that matter make any sense. Is it possible one day that people can produce artificial repulsive and attractive gravity?