Anti-gravity also known as non-gravitational field is an idea of creating a place or object completely free from the force of gravity. It does not refer to balancing the force of gravity with some other force acting the opposite way, such as electromagnetism, propulsion or aerodynamic lift. Anti-gravity is a well known concept used in science fiction, particularly in the context of air and space travel. Examples are the gravity blocking metal “Cavorite” mentioned in the H. G. Wells acclaimed novel “The First Men in the Moon” which acted as a gravity shield; after the metal was cooled, objects contained within it, were no longer subject to the gravity force.
As context, Newton’s law of universal gravitation determine that gravity act as an external force transmitted by unknown means versus the recent 20th century model based on general relativity, where establishes that gravity is not a force itself, instead is the result of fluctuations on the geometry of spacetime. According to the general relativity, the anti-gravity is impossible except under contrived circumstances but in the other hand quantum physicists have postulated the existence of gravitons, massless elementary particles that transmit gravitational force, but the possibility of creating or destroying these is unclear.
One person which was determined to discover the possibility of the existence of anti-gravity was Roger Babson, which in 1948 formed the Gravity Research Foundation to conduct investigations on reducing the effects of gravity, in addition he bought Invention Inc., a Washington D.C.-based company in order to have three investigators in the U.S. Patent Office 24/7 to scan for incoming patent proposals. “The investigators were constantly on the watch for any machine, alloy, chemical or formula which directly relates to the harnessing of gravity,” Babson wrote in his autobiography coined as Actions and Reactions. Babson quoted that a gravity harness would most likely take the form of a metal alloy which would act as a “partial insulator”, actually pretty close on the way H.G. Wells presented in their book “First men on the moon” the way that Cavorite works more than 40 years before.
At the gravity research foundation they held conferences where prominent people such as Clarence Birdseye known for his frozen-food products or Igor Sikorsky inventor of the helicopter attended but over time the Foundation turned its attention away from trying to control gravity, to simply have further research on it. The Foundation continues today running an essay award which offer prizes of up to $4,000. As of 2017, it is managed by George Rideout, Jr., son of the foundation’s original director and prominent scientists used to be winners such as the astrophysicist George F. Smoot, who later won the 2006 Nobel Prize in physics.
In Newton’s law of universal gravitation, gravity was an external force transmitted by unknown means. In the 20th century, Newton’s model was replaced by general relativity where gravity is not a force but the result of the geometry of spacetime. Under general relativity, anti-gravity is impossible except under contrived circumstances. Since the shape of space is altered or deformed by massive objects causing gravity, therefore there is not a true force and the equations cannot normally produce a “negative geometry”, in summary the equations used for general relativity do not rule out the existence of a theoretical negative mass.
Both general relativity and Newtonian gravity could be challenged adding the existence of negative mass that would produce a repulsive gravitational field based on the same rules stated in both, but the opposite way. Sir Hermann Bondi proposed in 1957 that negative gravitational mass, combined with negative inertial mass, would comply with the strong equivalence principle of general relativity theory and the Newtonian laws of conservation of linear momentum and energy.
Bondi stated that negative mass will fall toward and not away from “normal” matter, since although the gravitational force is repulsive, the negative mass responds by accelerating in the opposite direction of the supposed force. Normal mass, on the other hand, will fall away from the negative matter. He pointed out that two identical masses, one positive and one negative placed near each other will self-accelerate in the direction of the line between them with the negative mass chasing after the positive mass. Notice that because the negative mass acquires negative kinetic energy, the total energy of the accelerating masses remains at zero.
The Standard Model of particle physics, which describes all known forms of matter, does not include negative mass. Although cosmological dark matter may consist of particles outside the Standard Model whose nature is unknown, their mass behave with surrounding objects as normal matter anyway, which implies their mass is positive. On the other hand proposed cosmological dark energy is more complicated, since according to general relativity the effects of both its energy density and its negative pressure contribute to its gravitational effect.
Under general relativity any form of energy couples with spacetime to create the geometries that cause gravity. A longstanding question was whether or not these same equations applied to antimatter. The issue was considered solved in 1960 with the development of CPT symmetry, which demonstrated that antimatter follows the same laws of physics as “normal” matter, and therefore has positive energy content, therefore causes gravity act as normal matter.
During the 20th century, the physics community was involved in attempts to produce a unified field theory, a single physical theory that explains the four fundamental forces: gravity, electromagnetism, the strong and weak nuclear forces. Scientists have made progress in unifying the three quantum forces, but gravity has remained as unsolvable in every attempt. Anyway, this has not stopped any number of such attempts from being made, however.
Generally these attempts tried to “quantize gravity” by positing a particle, the graviton, that carried gravity in the same way that photons (light) carry electromagnetism. Simple attempts along this direction all failed, however, leading to more complex examples that attempted to account for these problems. Two of these, supersymmetry and the relativity related supergravity, both required the existence of an extremely weak “fifth force” carried by a graviphoton, which coupled together several “loose ends” in quantum field theory, in an organized manner. As a side effect, both theories also all but required that antimatter be affected by this fifth force in a way similar to anti-gravity, dictating repulsion away from mass. Several experiments were carried out in the 1990s to measure this effect, but none yielded positive results.
There are solutions of the field equations of general relativity which describe “warp drives” (such as the Alcubierre metric) and stable, traversable wormholes. This by itself is not significant, since any spacetime geometry is a solution of the field equations for some configuration of the stress–energy tensor field (see exact solutions in general relativity). General relativity does not constrain the geometry of spacetime unless outside constraints are placed on the stress–energy tensor. Warp-drive and traversable-wormhole geometries are well-behaved in most areas, but require regions of exotic matter; thus they are excluded as solutions if the stress–energy tensor is limited to known forms of matter. Dark matter and dark energy are not understood enough at this present time to make general statements regarding their applicability to a warp-drive.
Gyroscopes produce a force when twisted that operates “out of plane” and can appear to lift themselves against gravity. Although this force is well understood to be illusory, even under Newtonian models, it has nevertheless generated numerous claims of anti-gravity devices and any number of patented devices. None of these devices have ever been demonstrated to work under controlled conditions, and have often become the subject of conspiracy theories as a result. A famous example is that of Professor Eric Laithwaite of Imperial College, London, in the 1974 address to the Royal Institution.
Another “rotating device” example is shown in a series of patents granted to Henry Wallace between 1968 and 1974. His devices consist of rapidly spinning disks of brass, a material made up largely of elements with a total half-integer nuclear spin. He claimed that by rapidly rotating a disk of such material, the nuclear spin became aligned, and as a result created a “gravitomagnetic” field in a fashion similar to the magnetic field created by the Barnett effect. No independent testing or public demonstration of these devices is known.
In 1989, it was reported that a weight decreases along the axis of a right spinning gyroscope. A test of this claim a year later yielded null results.
In 1921, Thomas Townsend Brown found that a high-voltage Coolidge tube seemed to change mass depending on its orientation on a balance scale. Through the 1920s Brown developed this into devices that combined high voltages with materials with high dielectric constants, large capacitors in specific; he called such device as the “gravitator”. Brown made the claim to observers and in the media that his experiments were showing anti-gravity effects. Brown would continue his work and produced a series of high-voltage devices in the following years in attempts to sell his ideas to aircraft companies and the military. He coined the names Biefeld–Brown effect and electrogravitics in conjunction with his devices. Brown tested his asymmetrical capacitor devices in a vacuum, supposedly showing it was not a more down to earth electrohydrodynamic effect generated by high voltage ion flow in air.
Electrogravitics is a popular topic in ufology where relates to the known term as “reverse -engineering” which is the reproduction of extraterrestrial technology following the detailed examination of its construction or composition. Other terms are anti-gravity, or free energy, most of them tied with government conspiracy theorists published in books and publications with claims that the technology became highly classified in the early 1960s and that it is used to power earth manufactured UFOs. There is also research and videos on the internet purported to show lifter-style capacitor devices working in a vacuum, therefore not receiving propulsion from ion drift or ion wind being generated in air.
Follow-up studies on Brown’s work and other claims have been conducted by R. L. Talley in a 1990 US Air Force study, NASA scientist Jonathan Campbell in a 2003 experiment, and Martin Tajmar in a 2004 paper. They have found that no thrust could be observed in a vacuum and that Brown’s and other ion lifter devices produce thrust along their axis regardless of the direction of gravity consistent with electrohydrodynamic effects.
In 1992, the Russian researcher Eugene Podkletnov claimed to have discovered, whilst experimenting with superconductors, that a fast rotating superconductor reduces the gravitational effect. Many studies have attempted to reproduce Podkletnov’s experiment, always to negative results.
Ning Li and Douglas Torr, of the University of Alabama in Huntsville proposed how a time dependent magnetic field could cause the spins of the lattice ions in a superconductor to generate detectable gravitomagnetic and gravitoelectric fields in a series of papers published between 1991 and 1993. In 1999, Li and her team appeared in Popular Mechanics, claiming to have constructed a working prototype to generate what she described as “AC Gravity.” No further evidence of this prototype has been offered.
Douglas Torr and Timir Datta were involved in the development of a “gravity generator” at the University of South Carolina. According to a leaked document from the Office of Technology Transfer at the University of South Carolina and confirmed to Wired reporter Charles Platt in 1998, the device would create a “force beam” in any desired direction and that the university planned to patent and license this device. No further information about this university research project or the “Gravity Generator” device was ever made public.
In conclusion, anti-gravity still seems to be an impossible endeavor, but maybe with the upcoming research and future discoveries on how the universe work something different could happen.