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Artistic depiction of a fictional anti-gravity vehicle

Anti-gravity (also known as non-gravitational field) is the phenomenon of creating a place or object that is free from the force of gravity. It does not refer to either the lack of weight under gravity experienced in free fall or orbit, or to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift. Anti-gravity is a recurring concept in science fiction. Examples are the gravity blocking substance "Cavorite" in H. G. Wells's The First Men in the Moon and the Spindizzy machines in James Blish's Cities in Flight.

"Anti-gravity" is often used to refer to devices that look as if they reverse gravity even though they operate through other means, such as lifters, which fly in the air by moving air with electromagnetic fields.^[1]^[2]

Historical attempts at understanding gravity

The possibility of creating anti-gravity depends upon a complete understanding and description of gravity and its interactions with other physical theories, such as general relativity and quantum mechanics; however, no quantum theory of gravity has yet been found.

During the summer of 1666, Isaac Newton observed an apple falling from the tree in his garden, thus realizing the principle of universal gravitation.^[3] Albert Einstein in 1915 considered the physical interaction between matter and space, where gravity occurs as a consequence of matter causing a geometric deformation of spacetime which is otherwise flat.^[4]^[5]^[6] Einstein, both independently and with Walther Mayer, attempted to unify his theory of gravity with electromagnetism using the work of Theodor Kaluza^[7] and James Clerk Maxwell to link gravity and quantum field theory.^[8]

Theoretical quantum physicists have postulated the existence of a quantum gravity particle, the graviton. Various theoretical explanations of quantum gravity have been created, including superstring theory, loop quantum gravity, E8 theory and asymptotic safety theory amongst many others.

Probable Solutions

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.^[9]^[10]^[11]

Gravity shields

In 1948 businessman Roger Babson (founder of Babson College) formed the Gravity Research Foundation to study ways to reduce the effects of gravity.^[12] Their efforts were initially somewhat "crankish", but they held occasional conferences that drew such people as Clarence Birdseye, known for his frozen-food products, and helicopter pioneer Igor Sikorsky.^{[citation needed]} Over time the Foundation turned its attention away from trying to control gravity, to simply better understanding it. The Foundation nearly disappeared after Babson's death in 1967. However, it continues to run an essay award, offering prizes of up to $4,000. As of 2017, it is still administered out of Wellesley, Massachusetts, by George Rideout Jr., son of the foundation's original director.^[13] Winners include California astrophysicist George F. Smoot (1993), who later won the 2006 Nobel Prize in physics, and Gerard 't Hooft (2015) who previously won the 1999 Nobel Prize in physics.^[14]

General relativity research in the 1950s

General relativity was introduced in the 1910s, but development of the theory was greatly slowed by a lack of suitable mathematical tools.^{[clarification needed]} It appeared that anti-gravity was outlawed under general relativity.

It is claimed the US Air Force also ran a study effort throughout the 1950s and into the 1960s.^[15] Former Lieutenant Colonel Ansel Talbert wrote two series of newspaper articles claiming that most of the major aviation firms had started gravity control propulsion research in the 1950s. However, there is no outside confirmation of these stories, and since they take place in the midst of the policy by press release era, it is not clear how much weight these stories should be given.

It is known that there were serious efforts underway at the Glenn L. Martin Company, who formed the Research Institute for Advanced Study.^[16]^[17] Major newspapers announced the contract that had been made between theoretical physicist Burkhard Heim and the Glenn L. Martin Company. Another effort in the private sector to master understanding of gravitation was the creation of the Institute for Field Physics, University of North Carolina at Chapel Hill in 1956, by Gravity Research Foundation trustee Agnew H. Bahnson.

Military support for anti-gravity projects was terminated by the Mansfield Amendment of 1973, which restricted Department of Defense spending to only the areas of scientific research with explicit military applications. The Mansfield Amendment was passed specifically to end long-running projects that had no results.

Under general relativity, gravity is the result of following spatial geometry (change in the normal shape of space) caused by local mass-energy. This theory holds that it is the altered shape of space, deformed by massive objects, that causes gravity, which is actually a property of deformed space rather than being a true force. Although the equations cannot normally produce a "negative geometry", it is possible to do so by using "negative mass". The same equations do not, of themselves, rule out the existence of negative mass.

Both general relativity and Newtonian gravity appear to predict that negative mass would produce a repulsive gravitational field. In particular, 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's proof yielded singularity-free solutions for the relativity equations.^[18] In July 1988, Robert L. Forward presented a paper at the AIAA/ASME/SAE/ASEE 24th Joint Propulsion Conference that proposed a Bondi negative gravitational mass propulsion system.^[19]

Bondi pointed out that a negative mass will fall toward (and not away from) "normal" matter, since although the gravitational force is repulsive, the negative mass (according to Newton's law, F=ma) responds by accelerating in the opposite of the direction of the force. Normal mass, on the other hand, will fall away from the negative matter. He noted that two identical masses, one positive and one negative, placed near each other will therefore self-accelerate in the direction of the line between them, with the negative mass chasing after the positive mass.^[18] Notice that because the negative mass acquires negative kinetic energy, the total energy of the accelerating masses remains at zero. Forward pointed out that the self-acceleration effect is due to the negative inertial mass, and could be seen induced without the gravitational forces between the particles.^[19]

The Standard Model of particle physics, which describes all currently 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 is ostensibly known – since they were postulated from their gravitational effects on surrounding objects, which implies their mass is positive. The proposed cosmological dark energy, on the other hand, is more complicated, since according to general relativity the effects of both its energy density and its negative pressure contribute to its gravitational effect.

Unique force

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 and also causes (and reacts to) gravity like normal matter (see gravitational interaction of antimatter).

For much of the last quarter of 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, and the strong and weak nuclear forces. Scientists have made progress in unifying the three quantum forces, but gravity has remained "the problem" in every attempt. 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.^[20]

In 2013 CERN looked for an antigravity effect in an experiment designed to study the energy levels within antihydrogen. The antigravity measurement was just an "interesting sideshow" and was inconclusive.^[21]

Breakthrough Propulsion Physics Program

During the close of the twentieth century NASA provided funding for the Breakthrough Propulsion Physics Program (BPP) from 1996 through 2002. This program studied a number of "far out" designs for space propulsion that were not receiving funding through normal university or commercial channels. Anti-gravity-like concepts were investigated under the name "diametric drive". The work of the BPP program continues in the independent, non-NASA affiliated Tau Zero Foundation.^[22]

Empirical claims and commercial efforts

There have been a number of attempts to build anti-gravity devices, and a small number of reports of anti-gravity-like effects in the scientific literature. None of the examples that follow are accepted as reproducible examples of anti-gravity.

Gyroscopic devices

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 has ever been demonstrated to work under controlled conditions, and they have often become the subject of conspiracy theories as a result.

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.^[23]^[24]^[25] 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.^[26] A test of this claim a year later yielded null results.^[27] A recommendation was made to conduct further tests at a 1999 AIP conference.^[28]

Thomas Townsend Brown's gravitator

In 1921, while still in high school, 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 (essentially large capacitors); he called such a device a "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, anti-gravity, free energy, with government conspiracy theorists and related websites, in books and publications with claims that the technology became highly classified in the early 1960s and that it is used to power UFOs and the B-2 bomber.^[29] 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.^[29]^[30]

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,^[29] and Martin Tajmar in a 2004 paper.^[31] 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.

Gravitoelectric coupling

In 1992, the Russian researcher Eugene Podkletnov claimed to have discovered, whilst experimenting with superconductors, that a fast rotating superconductor reduces the gravitational effect.^[32] Many studies have attempted to reproduce Podkletnov's experiment, always to negative results.^[33]^[34]^[35]^[36]

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.^[37]^[38]^[39] In 1999, a Miss Li 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.^[40]^[41]

Douglas Torr and Timir Datta were involved in the development of a "gravity generator" at the University of South Carolina.^[42] 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 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.^[43]

Göde Award

The Institute for Gravity Research of the Göde Scientific Foundation has tried to reproduce many of the different experiments which claim any "anti-gravity" effects. All attempts by this group to observe an anti-gravity effect by reproducing past experiments have been unsuccessful thus far. The foundation has offered a reward of one million euros for a reproducible anti-gravity experiment.^[44]

In fiction

The existence of anti-gravity is a common theme in fantasy and science fiction.

Apergy

Apergy is a fictitious form of anti-gravitational energy first described by Percy Greg in his 1880 sword and planet novel Across the Zodiac.^[45]

John Jacob Astor IV used it in his 1894 science fiction novel A Journey in Other Worlds.^[46] Jack London describes it as "the hypothetical existence of a force, the converse of gravitation, which Astor has named 'apergy,'" in his short story entitled "A Thousand Deaths," first published in The Black Cat in 1899.^[47]

Apergy can also be found in an 1896 article, "Some Truths About Keely,"^[48] where Clara Jessup Bloomfield-Moore used it to describe the latent force John Keely harnessed, by employing frequency to release the latent force found within all atomic matter.^[49]

In an ostensibly non-fictitious article published in 1897 in The San Francisco Call titled "The Secret of Aerial Flight Revealed,"^[50] science correspondent Frank M. Close, D.Sc., visits an unnamed Hindu man masquerading as a viticulturist somewhere on the Pacific coast who claims to have invented a flying boat that uses an "apergent"—a rare metal called "radlum"—to produce controlled apergic force, allowing the vessel to ascend and descend. The inventor describes apergy as "a force obtained by blending positive and negative electricity with ultheic, the third element or state of electric energy" and calls apergy a "second phase of gravity," hinting at a third phase as well.

S. P. Meek's short story "Cold Light," which appeared in March 1930 in Astounding Stories of Super-Science,^[51] mentions apergy as the opposite force of gravity.

In Chris Roberson's short story "Annus Mirabilis" from the 2006 second volume of Tales of the Shadowmen, Doctor Omega and Albert Einstein investigate apergy. Apergy is also mentioned in the Warren Ellis comic Aetheric Mechanics, as being generated by Cavorite technology from The First Men in the Moon.

Other terms

H. G. Wells's 1901 novel The First Men in the Moon has space travel based on the gravity-blocking properties of "Cavorite."

Philip Francis Nowlan's 1928 story Armageddon 2419 A.D. describes "inertron," a substance that falls up. The story was the basis for the Buck Rogers comic strip and adaptations.

References

^ Thompson, Clive (August 2003). "The Antigravity Underground". Wired. Archived from the original on 18 August 2010. Retrieved 23 July 2010.
^ "On the Verge of Antigravity". About.com. Archived from the original on 23 February 2017. Retrieved 23 July 2010.
^ Department of Physics A Brief History of Isaac Newton's Apple Tree, University of York, Retrieved 2019-07-20
^ Papachristou, Costas J. (2016). "Electromagnetic waves, gravitational waves and the prophets who predicted them". arXiv:1603.00871 [physics.pop-ph].
^ Albert Einstein Grundgedanken der allgemeinen Relativitätstheorie und Anwendung dieser Theorie in der Astronomie (Preussische Akademie der Wissenschaften, Sitzungsberichte, 1915 (teil 1), 31), Zur allgemeinen Relativitätstheorie (Preussische Akademie der Wissenschaften, Sitzungsberichte, 1915 (teil 2), 778–786, 799–80) Retrieved 2019-06-16
^ Charles W. Misner, Kip S. Thorne, John Archibald Wheeler Gravitation, p. 1231, Princeton University Press, 24 October 2017 ISBN 0691177791, ISBN 9780691177793, Retrieved 2019-06-16
^ Kaluza, Theodor (1921). "Zum Unitätsproblem in der Physik". Sitzungsber. Preuss. Akad. Wiss. Berlin. (Math. Phys.): 966–972. Bibcode:1921SPAW.......966K. https://archive.org/details/sitzungsberichte1921preussi
^ Einstein, Albert (1879-1955). Autograph manuscript, comprising calculations and arguments from the Einheitliche theorie von Gravitation un Elektrizitt Christie's Retrieved 2019-06-16
^ Peskin, M and Schroeder, D.; An Introduction to Quantum Field Theory (Westview Press, 1995) ISBN 0-201-50397-2
^ Wald, Robert M. (1984). General Relativity. Chicago: University of Chicago Press. ISBN 978-0-226-87033-5.
^ Polchinski, Joseph (1998). String Theory, Cambridge University Press. A modern textbook
^ Mooallem, J. (October 2007). "A curious attraction". Harper's Magazine. Vol. 315, no. 1889. pp. 84–91.
^ List of winners Archived 28 December 2012 at the Wayback Machine
^ "The Nobel Prize in Physics 1999".
^ Goldberg, J. M. (1992). US air force support of general relativity: 1956–1972. In, J. Eisenstaedt & A. J. Kox (Ed.), Studies in the History of General Relativity, Volume 3 Boston, Massachusetts: Center for Einstein Studies. ISBN 0-8176-3479-7
^ Mallan, L. (1958). Space satellites (How to book 364). Greenwich, CT: Fawcett Publications, pp. 9–10, 137, 139. LCCN 58-001060
^ Clarke, A. C. (1957). "The conquest of gravity". Holiday. 22 (6): 62.
^ ^a ^b Bondi, H. (1957). "Negative mass in general relativity". Reviews of Modern Physics. 29 (3): 423–428. Bibcode:1957RvMP...29..423B. doi:10.1103/revmodphys.29.423.
^ ^a ^b Forward, R. L. (1990). "Negative matter propulsion". Journal of Propulsion and Power. 6 (1): 28–37. doi:10.2514/3.23219.; see also commentary Landis, G.A. (1991). "Comments on Negative Mass Propulsion". Journal of Propulsion and Power. 7 (2): 304. doi:10.2514/3.23327.
^ Supergravity and the Unification of the Laws of Physics, by Daniel Z. Freedman and Peter van Nieuwenhuizen, Scientific American, February 1978
^ Jason Palmer, Antigravity gets first test at Cern's Alpha experiment, bbc.co.uk, 30 April 2013
^ Tau Zero Foundation
^ U.S. patent 3,626,606
^ U.S. patent 3,626,605
^ U.S. patent 3,823,570
^ Hayasaka, H. & Takeuchi, S. (1989). "Anomalous weight reduction on a gyroscope's right rotations around the vertical axis on the Earth". Physical Review Letters. 63 (25): 2701–2704. Bibcode:1989PhRvL..63.2701H. doi:10.1103/PhysRevLett.63.2701. PMID 10040968.
^ Nitschke, J. M. & Wilmath, P. A. (1990). "Null result for the weight change of a spinning gyroscope". Physical Review Letters. 64 (18): 2115–2116. Bibcode:1990PhRvL..64.2115N. doi:10.1103/PhysRevLett.64.2115. PMID 10041587.
^ Iwanaga, N. (1999). "Reviews of some field propulsion methods from the general relativistic standpoint". AIP Conference Proceedings. Vol. 458. pp. 1015–1059. doi:10.1063/1.57497.
^ ^a ^b ^c Thompson, Clive (August 2003). "The Antigravity Underground". Wired Magazine.
^ Thomas Valone, Electrogravitics II: Validating Reports on a New Propulsion Methodology, Integrity Research Institute, page 52-58
^ Tajmar, M. (2004). "Biefeld-Brown Effect: Misinterpretation of Corona Wind Phenomena". AIAA Journal. 42 (2): 315–318. Bibcode:2004AIAAJ..42..315T. doi:10.2514/1.9095.
^ Podkletnov, E; Nieminen, R (10 December 1992). "A possibility of gravitational force shielding by bulk YBa₂Cu₃O_7−x superconductor". Physica C. 203 (3–4): 441–444. Bibcode:1992PhyC..203..441P. doi:10.1016/0921-4534(92)90055-H.
^ N. Li; D. Noever; T. Robertson; R. Koczor; et al. (August 1997). "Static Test for a Gravitational Force Coupled to Type II YBCO Superconductors". Physica C. 281 (2–3): 260–267. Bibcode:1997PhyC..281..260L. doi:10.1016/S0921-4534(97)01462-7.
^ Woods, C.; Helme, J.; Cooke, S.; Caldwell, C. (2001). "Gravity modification by high-temperature superconductors". 37th Joint Propulsion Conference and Exhibit. doi:10.2514/6.2001-3363.
^ Hathaway, G.; Cleveland, B.; Bao, Y. (2003). "Gravity modification experiment using a rotating superconducting disk and radio frequency fields". Physica C: Superconductivity. 385 (4): 488–500. Bibcode:2003PhyC..385..488H. doi:10.1016/S0921-4534(02)02284-0.
^ Tajmar, M.; De Matos, C.J. (2003). "Gravitomagnetic field of a rotating superconductor and of a rotating superfluid". Physica C: Superconductivity. 385 (4): 551–554. arXiv:gr-qc/0203033. Bibcode:2003PhyC..385..551T. doi:10.1016/S0921-4534(02)02305-5.
^ Li, Ning; Torr, DG (1 September 1992). "Gravitational effects on the magnetic attenuation of superconductors". Physical Review. B46 (9): 5489–5495. Bibcode:1992PhRvB..46.5489L. doi:10.1103/PhysRevB.46.5489. PMID 10004334.
^ Li, Ning; Torr, DG (15 January 1991). "Effects of a gravitomagnetic field on pure superconductors". Physical Review. D43 (2): 457–459. Bibcode:1991PhRvD..43..457L. doi:10.1103/PhysRevD.43.457. PMID 10013404.
^ Li, Ning; Torr, DG (August 1993). "Gravitoelectric-electric coupling via superconductivity". Foundations of Physics Letters. 6 (4): 371–383. Bibcode:1993FoPhL...6..371T. doi:10.1007/BF00665654. S2CID 122075917.
^ Wilson, Jim (1 October 2000). "Taming Gravity". Popular Mechanics. Archived from the original on 5 November 2012. Retrieved 5 January 2014.
^ Cain, Jeanette. "Gravity Conquered?". light-science.com. Archived from the original on 6 July 2013. Retrieved 5 January 2014.
^ "Patent and Copyright Committee List of Disclosures Reviewed Between July 1996 and June 1997 - USC ID". Archived from the original on 2 May 2014. Retrieved 2 May 2014.
^ Platt, Charles (1 March 1998). "Breaking the Law of Gravity". Wired. Retrieved 26 August 2021.
^ "The Göde award - One Million Euro to overcome gravity". Institute of Gravity Research. Archived from the original on 28 April 2015. Retrieved 2 January 2014.
^ Peter Nicholls (1979). The Encyclopedia of Science Fiction: An Illustrated A to Z. Unknown Publisher. ISBN 978-0-246-11020-6.
^ Astor, John Jacob (1894). A journey in other worlds. A romance of the future. D. Appleton and Company. Retrieved 11 March 2020.
^ Haining, Peter, ed. (1976). The Fantastic Pulps. New York: Vintage Books. p. 26. ISBN 0-394-72109-8.
^ J. M. Stoddart (1895). The New Science Review: A Miscellany of Modern Thought and Discovery. Transatlantic Publishing Company. pp. 321–.
^ Theo Paijmans (2004). Free Energy Pioneer: John Worrell Keely. Adventures Unlimited Press. pp. 221–. ISBN 978-1-931882-33-0.
^ http://chroniclingamerica.loc.gov/lccn/sn85066387/1897-01-17/ed-1/seq-20/ The San Francisco Call, January 17, 1897, p.18.
^ "The Project Gutenberg eBook of Astounding Stories of Super-Science, March 1930".

Bibliography

Criteria:

"Newtons discovery of the apple law"
"Newtons principle of gravitation" > "Newtons principle of gravitation apple falls" (google > google books)

External links

Responding to Mechanical Antigravity, a NASA paper debunking a wide variety of gyroscopic (and related) devices
Göde Scientific Foundation Archived 31 May 2010 at the Wayback Machine
KURED Research

[1] Thompson, Clive (August 2003). "The Antigravity Underground". Wired. Archived from the original on 18 August 2010. Retrieved 23 July 2010.

[2] "On the Verge of Antigravity". About.com. Archived from the original on 23 February 2017. Retrieved 23 July 2010.

[york-3] Department of Physics A Brief History of Isaac Newton's Apple Tree, University of York, Retrieved 2019-07-20

[4] Papachristou, Costas J. (2016). "Electromagnetic waves, gravitational waves and the prophets who predicted them". arXiv:1603.00871 [physics.pop-ph].

[5] Albert Einstein Grundgedanken der allgemeinen Relativitätstheorie und Anwendung dieser Theorie in der Astronomie (Preussische Akademie der Wissenschaften, Sitzungsberichte, 1915 (teil 1), 31), Zur allgemeinen Relativitätstheorie (Preussische Akademie der Wissenschaften, Sitzungsberichte, 1915 (teil 2), 778–786, 799–80) Retrieved 2019-06-16

[6] Charles W. Misner, Kip S. Thorne, John Archibald Wheeler Gravitation, p. 1231, Princeton University Press, 24 October 2017 ISBN 0691177791, ISBN 9780691177793, Retrieved 2019-06-16

[7] Kaluza, Theodor (1921). "Zum Unitätsproblem in der Physik". Sitzungsber. Preuss. Akad. Wiss. Berlin. (Math. Phys.): 966–972. Bibcode:1921SPAW.......966K. https://archive.org/details/sitzungsberichte1921preussi

[8] Einstein, Albert (1879-1955). Autograph manuscript, comprising calculations and arguments from the Einheitliche theorie von Gravitation un Elektrizitt Christie's Retrieved 2019-06-16

[9] Peskin, M and Schroeder, D.; An Introduction to Quantum Field Theory (Westview Press, 1995) ISBN 0-201-50397-2

[10] Wald, Robert M. (1984). General Relativity. Chicago: University of Chicago Press. ISBN 978-0-226-87033-5.

[11] Polchinski, Joseph (1998). String Theory, Cambridge University Press. A modern textbook

[12] Mooallem, J. (October 2007). "A curious attraction". Harper's Magazine. Vol. 315, no. 1889. pp. 84–91.

[13] List of winners Archived 28 December 2012 at the Wayback Machine

[14] "The Nobel Prize in Physics 1999".

[15] Goldberg, J. M. (1992). US air force support of general relativity: 1956–1972. In, J. Eisenstaedt & A. J. Kox (Ed.), Studies in the History of General Relativity, Volume 3 Boston, Massachusetts: Center for Einstein Studies. ISBN 0-8176-3479-7

[16] Mallan, L. (1958). Space satellites (How to book 364). Greenwich, CT: Fawcett Publications, pp. 9–10, 137, 139. LCCN 58-001060

[17] Clarke, A. C. (1957). "The conquest of gravity". Holiday. 22 (6): 62.

[Bondi-18] Bondi, H. (1957). "Negative mass in general relativity". Reviews of Modern Physics. 29 (3): 423–428. Bibcode:1957RvMP...29..423B. doi:10.1103/revmodphys.29.423.

[Forward-19] Forward, R. L. (1990). "Negative matter propulsion". Journal of Propulsion and Power. 6 (1): 28–37. doi:10.2514/3.23219.; see also commentary Landis, G.A. (1991). "Comments on Negative Mass Propulsion". Journal of Propulsion and Power. 7 (2): 304. doi:10.2514/3.23327.

[SciAm79-20] Supergravity and the Unification of the Laws of Physics, by Daniel Z. Freedman and Peter van Nieuwenhuizen, Scientific American, February 1978

[21] Jason Palmer, Antigravity gets first test at Cern's Alpha experiment, bbc.co.uk, 30 April 2013

[22] Tau Zero Foundation

[23] U.S. patent 3,626,606

[24] U.S. patent 3,626,605

[25] U.S. patent 3,823,570

[26] Hayasaka, H. & Takeuchi, S. (1989). "Anomalous weight reduction on a gyroscope's right rotations around the vertical axis on the Earth". Physical Review Letters. 63 (25): 2701–2704. Bibcode:1989PhRvL..63.2701H. doi:10.1103/PhysRevLett.63.2701. PMID 10040968.

[27] Nitschke, J. M. & Wilmath, P. A. (1990). "Null result for the weight change of a spinning gyroscope". Physical Review Letters. 64 (18): 2115–2116. Bibcode:1990PhRvL..64.2115N. doi:10.1103/PhysRevLett.64.2115. PMID 10041587.

[28] Iwanaga, N. (1999). "Reviews of some field propulsion methods from the general relativistic standpoint". AIP Conference Proceedings. Vol. 458. pp. 1015–1059. doi:10.1063/1.57497.

[Wired-29] Thompson, Clive (August 2003). "The Antigravity Underground". Wired Magazine.

[30] Thomas Valone, Electrogravitics II: Validating Reports on a New Propulsion Methodology, Integrity Research Institute, page 52-58

[31] Tajmar, M. (2004). "Biefeld-Brown Effect: Misinterpretation of Corona Wind Phenomena". AIAA Journal. 42 (2): 315–318. Bibcode:2004AIAAJ..42..315T. doi:10.2514/1.9095.

[32] Podkletnov, E; Nieminen, R (10 December 1992). "A possibility of gravitational force shielding by bulk YBa₂Cu₃O_7−x superconductor". Physica C. 203 (3–4): 441–444. Bibcode:1992PhyC..203..441P. doi:10.1016/0921-4534(92)90055-H.

[33] N. Li; D. Noever; T. Robertson; R. Koczor; et al. (August 1997). "Static Test for a Gravitational Force Coupled to Type II YBCO Superconductors". Physica C. 281 (2–3): 260–267. Bibcode:1997PhyC..281..260L. doi:10.1016/S0921-4534(97)01462-7.

[34] Woods, C.; Helme, J.; Cooke, S.; Caldwell, C. (2001). "Gravity modification by high-temperature superconductors". 37th Joint Propulsion Conference and Exhibit. doi:10.2514/6.2001-3363.

[35] Hathaway, G.; Cleveland, B.; Bao, Y. (2003). "Gravity modification experiment using a rotating superconducting disk and radio frequency fields". Physica C: Superconductivity. 385 (4): 488–500. Bibcode:2003PhyC..385..488H. doi:10.1016/S0921-4534(02)02284-0.

[36] Tajmar, M.; De Matos, C.J. (2003). "Gravitomagnetic field of a rotating superconductor and of a rotating superfluid". Physica C: Superconductivity. 385 (4): 551–554. arXiv:gr-qc/0203033. Bibcode:2003PhyC..385..551T. doi:10.1016/S0921-4534(02)02305-5.

[37] Li, Ning; Torr, DG (1 September 1992). "Gravitational effects on the magnetic attenuation of superconductors". Physical Review. B46 (9): 5489–5495. Bibcode:1992PhRvB..46.5489L. doi:10.1103/PhysRevB.46.5489. PMID 10004334.

[38] Li, Ning; Torr, DG (15 January 1991). "Effects of a gravitomagnetic field on pure superconductors". Physical Review. D43 (2): 457–459. Bibcode:1991PhRvD..43..457L. doi:10.1103/PhysRevD.43.457. PMID 10013404.

[39] Li, Ning; Torr, DG (August 1993). "Gravitoelectric-electric coupling via superconductivity". Foundations of Physics Letters. 6 (4): 371–383. Bibcode:1993FoPhL...6..371T. doi:10.1007/BF00665654. S2CID 122075917.

[40] Wilson, Jim (1 October 2000). "Taming Gravity". Popular Mechanics. Archived from the original on 5 November 2012. Retrieved 5 January 2014.

[41] Cain, Jeanette. "Gravity Conquered?". light-science.com. Archived from the original on 6 July 2013. Retrieved 5 January 2014.

[42] "Patent and Copyright Committee List of Disclosures Reviewed Between July 1996 and June 1997 - USC ID". Archived from the original on 2 May 2014. Retrieved 2 May 2014.

[Platt1998-43] Platt, Charles (1 March 1998). "Breaking the Law of Gravity". Wired. Retrieved 26 August 2021.

[44] "The Göde award - One Million Euro to overcome gravity". Institute of Gravity Research. Archived from the original on 28 April 2015. Retrieved 2 January 2014.

[Nicholls1979-45] Peter Nicholls (1979). The Encyclopedia of Science Fiction: An Illustrated A to Z. Unknown Publisher. ISBN 978-0-246-11020-6.

[46] Astor, John Jacob (1894). A journey in other worlds. A romance of the future. D. Appleton and Company. Retrieved 11 March 2020.

[47] Haining, Peter, ed. (1976). The Fantastic Pulps. New York: Vintage Books. p. 26. ISBN 0-394-72109-8.

[Stoddart1895-48] J. M. Stoddart (1895). The New Science Review: A Miscellany of Modern Thought and Discovery. Transatlantic Publishing Company. pp. 321–.

[Paijmans2004-49] Theo Paijmans (2004). Free Energy Pioneer: John Worrell Keely. Adventures Unlimited Press. pp. 221–. ISBN 978-1-931882-33-0.

[50] ttp://chroniclingamerica.loc.gov/lccn/sn85066387/1897-01-17/ed-1/seq-20/ The San Francisco Call, January 17, 1897, p.18.

[51] "The Project Gutenberg eBook of Astounding Stories of Super-Science, March 1930".

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+{{Short description|Idea of creating a place or object that is free from the force of gravity}}
-{{Use dmy dates|date=May 2012}}
+{{Use dmy dates|date=May 2015}}
-'''Anti-gravity''' also known as non-gravitational field is an idea of creating a place or object that is free from the force of [[gravity]]. It does not refer to the lack of weight under gravity experienced in [[free fall]] or [[orbit]], or to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift. Anti-gravity is a recurring concept in science fiction, particularly in the context of [[spacecraft propulsion]].  Examples are the gravity blocking substance "Cavorite" in [[H. G. Wells]]' ''[[The First Men in the Moon]]'' and the [[Spindizzy]] machines in [[James Blish|James Blish's]] ''[[Cities in Flight]]''.
+[[File:BOXXX-3W.jpg|thumb|Artistic depiction of a fictional anti-gravity vehicle]]
+'''Anti-gravity''' (also known as '''non-gravitational field''') is the phenomenon of creating a place or object that is free from the force of [[gravity]]. It does not refer to either the lack of weight under gravity experienced in [[free fall]] or [[orbit]], or to balancing the force of gravity with some other force, such as [[electromagnetism]] or [[aerodynamic lift]]. Anti-gravity is a recurring concept in science fiction.  Examples are the gravity blocking substance "Cavorite" in [[H. G. Wells]]'s ''[[The First Men in the Moon]]'' and the [[Spindizzy (Cities in Flight)|Spindizzy]] machines in [[James Blish|James Blish's]] ''[[Cities in Flight]]''.
-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.<ref>Peskin, M and Schroeder, D.; ''An Introduction to Quantum Field Theory'' (Westview Press, 1995) {{ISBN|0-201-50397-2}}</ref><ref>{{cite book | author = Wald, Robert M.| author-link = Robert M. Wald| title = ''[[General Relativity (book)|General Relativity]]'' | location = Chicago | publisher = University of Chicago Press | date = 1984 | isbn = 0-226-87033-2 }}</ref><ref>[[Joseph Polchinski|Polchinski, Joseph]] (1998). ''String Theory'', Cambridge University Press. A modern textbook</ref> [[Quantum physicist]]s have postulated the existence of [[gravitons]], [[Mass in special relativity|massless]] [[elementary particles]] that transmit gravitational force, but the possibility of creating or destroying these is unclear.
-"Anti-gravity" is often used colloquially to refer to devices that look as if they reverse gravity even though they operate through other means, such as [[Ionocraft|lifters]], which fly in the air by moving air with [[electromagnetic field]]s.<ref>{{cite news|url=https://www.wired.com/wired/archive/11.08/pwr_antigravity.html|accessdate=23 July 2010|first=Clive|last=Thompson|work=[[Wired Magazine|Wired]]|date=August 2003|title=The Antigravity Underground| archiveurl= https://web.archive.org/web/20100818230902/http://www.wired.com/wired/archive/11.08/pwr_antigravity.html| archivedate= 18 August 2010 <!--DASHBot-->| deadurl= no}}</ref><ref>{{cite web|url=http://paranormal.about.com/library/weekly/aa081902a.htm|title=On the Verge of Antigravity|publisher=[[About.com]]|accessdate=23 July 2010}}</ref>
+"Anti-gravity" is often used to refer to devices that look as if they reverse gravity even though they operate through other means, such as [[Ionocraft|lifters]], which fly in the air by moving air with [[electromagnetic field]]s.<ref>{{cite news|url=https://www.wired.com/wired/archive/11.08/pwr_antigravity.html|access-date=23 July 2010|first=Clive|last=Thompson|work=[[Wired Magazine|Wired]]|date=August 2003|title=The Antigravity Underground| archive-url= https://web.archive.org/web/20100818230902/http://www.wired.com/wired/archive/11.08/pwr_antigravity.html| archive-date= 18 August 2010 | url-status= live}}</ref><ref>{{cite web|url=http://paranormal.about.com/library/weekly/aa081902a.htm|title=On the Verge of Antigravity|publisher=[[About.com]]|access-date=23 July 2010|archive-date=23 February 2017|archive-url=https://web.archive.org/web/20170223030341/http://paranormal.about.com/library/weekly/aa081902a.htm|url-status=dead}}</ref>
+==Historical attempts at understanding gravity==
-==Hypothetical solutions==
+{{Main|History of gravitational theory}}
+The possibility of creating anti-gravity depends upon a complete understanding and description of gravity and its interactions with other physical theories, such as [[general relativity]] and [[quantum mechanics]]; however, no quantum theory of gravity has yet been found.
+During the summer of 1666, [[Isaac Newton]] observed an apple falling from the tree in his garden, thus realizing the [[Newton's law of universal gravitation|principle of universal gravitation]].<ref name="york">Department of Physics [https://www.york.ac.uk/physics/about/newtonsappletree/ A Brief History of Isaac Newton's Apple Tree], [[University of York]], Retrieved 2019-07-20</ref> [[Albert Einstein]] in 1915 considered the physical interaction between matter and space, where gravity occurs as a consequence of matter causing a geometric deformation of spacetime which is otherwise flat.<ref>{{cite arXiv | eprint=1603.00871 | last1=Papachristou | first1=Costas J. | title=Electromagnetic waves, gravitational waves and the prophets who predicted them | date=2016 | class=physics.pop-ph }}</ref><ref>[[Albert Einstein]] Grundgedanken der allgemeinen Relativitätstheorie und Anwendung dieser Theorie in der Astronomie (Preussische Akademie der Wissenschaften, Sitzungsberichte, 1915 (teil 1), 31),   Zur allgemeinen Relativitätstheorie (Preussische Akademie der Wissenschaften, Sitzungsberichte, 1915 (teil 2), 778–786, 799–80) Retrieved 2019-06-16</ref><ref>[[Charles W. Misner]], [[Kip S. Thorne]], [[John Archibald Wheeler]] ''Gravitation'', [https://books.google.com/books?id=SyQzDwAAQBAJ&pg=PA1231 p. 1231], Princeton University Press, 24 October 2017 {{ISBN|0691177791}}, {{ISBN|9780691177793}}, Retrieved 2019-06-16</ref> Einstein, both independently and with [[Walther Mayer]], attempted to unify his [[general theory of relativity|theory of gravity]] with [[electromagnetism]] using the work of [[Theodor Kaluza]]<ref>{{cite journal |last=Kaluza |first=Theodor |date=1921 |title=Zum Unitätsproblem in der Physik |journal=Sitzungsber. Preuss. Akad. Wiss. Berlin. (Math. Phys.) |pages=966–972 |bibcode=1921SPAW.......966K }}  https://archive.org/details/sitzungsberichte1921preussi</ref> and [[James Clerk Maxwell]] to link gravity and [[quantum field theory]].<ref>[https://Christianize/lotfinder/Lot/einstein-albert-1879-1955-autograph-manuscript-comprising-calculations-1471725-details.aspx Einstein, Albert (1879-1955). Autograph manuscript, comprising calculations and arguments from the Einheitliche theorie von Gravitation un Elektrizitt] [[Christie's]] Retrieved 2019-06-16</ref>
+Theoretical quantum physicists have postulated the existence of a quantum gravity particle, the [[graviton]]. Various theoretical explanations of [[quantum gravity]] have been created, including [[History of string theory|superstring theory]], [[loop quantum gravity]], [[An Exceptionally Simple Theory of Everything|E8 theory]] and [[Asymptotic safety in quantum gravity|asymptotic safety theory]] amongst many others.
+==Probable Solutions==
+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.<ref>Peskin, M and Schroeder, D.; ''An Introduction to Quantum Field Theory'' (Westview Press, 1995) {{ISBN|0-201-50397-2}}</ref><ref>{{cite book | author = Wald, Robert M.| author-link = Robert M. Wald| title = ''General Relativity'' | location = Chicago | publisher = University of Chicago Press | date = 1984 | isbn = 978-0-226-87033-5 | title-link = General Relativity (book)}}</ref><ref>[[Joseph Polchinski|Polchinski, Joseph]] (1998). ''String Theory'', Cambridge University Press. A modern textbook</ref>
 ===Gravity shields===
 [[File:New boston babson monument.JPG|thumb|right|A monument at [[Babson College]] dedicated to [[Roger Babson]] for research into anti-gravity and partial gravity insulators]]
-{{main|Gravitational shielding}}
+{{Main|Gravitational shielding}}
-In 1948 successful businessman [[Roger Babson]] (founder of [[Babson College]]) formed the [[Gravity Research Foundation]] to study ways to reduce the effects of gravity.<ref>{{cite journal | last1 = Mooallem | first1 = J. | date = October 2007 | title = A curious attraction | journal = Harper's Magazine | volume = 315 | issue = 1889 | pages = 84–91 }}</ref> Their efforts were initially somewhat "[[crank (person)|crank]]ish", but they held occasional conferences that drew such people as [[Clarence Birdseye]] known for his frozen-food products and [[Igor Sikorsky]], inventor of the helicopter. Over time the Foundation turned its attention away from trying to control gravity, to simply better understanding it. The Foundation nearly disappeared after Babson's death in 1967. However, it continues to run an essay award, offering prizes of up to $4,000. As of 2017, it is still administered out of [[Wellesley, Massachusetts]], by George Rideout, Jr., son of the foundation's original director.<ref>[http://www.gravityresearchfoundation.org/winners_name.html#s List of winners]</ref> Winners include California astrophysicist [[George F. Smoot]], who later won the 2006 [[Nobel Prize in physics]].
+In 1948 businessman [[Roger Babson]] (founder of [[Babson College]]) formed the [[Gravity Research Foundation]] to study ways to reduce the effects of gravity.<ref>{{cite magazine | last1 = Mooallem | first1 = J. | date = October 2007 | title = A curious attraction | magazine = Harper's Magazine | volume = 315 | issue = 1889 | pages = 84–91 }}</ref> Their efforts were initially somewhat "[[crank (person)|crank]]ish", but they held occasional conferences that drew such people as [[Clarence Birdseye]], known for his frozen-food products, and helicopter pioneer [[Igor Sikorsky]].{{Citation needed|date=January 2022}} Over time the Foundation turned its attention away from trying to control gravity, to simply better understanding it. The Foundation nearly disappeared after Babson's death in 1967. However, it continues to run an essay award, offering prizes of up to $4,000. As of 2017, it is still administered out of [[Wellesley, Massachusetts]], by George Rideout Jr., son of the foundation's original director.<ref>[http://www.gravityresearchfoundation.org/winners_name.html#s List of winners] {{webarchive|url=https://web.archive.org/web/20121228174605/http://www.gravityresearchfoundation.org/winners_name.html |date=28 December 2012 }}</ref> Winners include California astrophysicist [[George F. Smoot]] (1993), who later won the 2006 [[Nobel Prize in physics]], and [[Gerard 't Hooft]] (2015) who previously won the 1999 Nobel Prize in physics.<ref>{{Cite web|url=https://www.nobelprize.org/prizes/physics/1999/summary/|title = The Nobel Prize in Physics 1999}}</ref>
 ===General relativity research in the 1950s===
 {{Main|United States gravity control propulsion research}}
-General relativity was introduced in the 1910s, but development of the theory was greatly slowed by a lack of suitable mathematical tools. Although it appeared that anti-gravity was outlawed under general relativity.
+General relativity was introduced in the 1910s, but development of the theory was greatly slowed by a lack of suitable mathematical tools.{{clarify|reason=The mathematics of general relativity was little known at the time, but it is dubious that new tools would have to be developed to further explore the theory, once it had been formulated. A more important factor is likely that the empirical evidence for GR over Newtonian gravity for several decades consisted of only three astronomical phenomena — why worry about fine details, when you can just barely measure any effect at all?|date=July 2018}} It appeared that anti-gravity was outlawed under general relativity.
-It is claimed the [[US Air Force]] also ran a study effort throughout the 1950s and into the 1960s.<ref>Goldberg, J. M. (1992). US air force support of general relativity: 1956–1972. In, J. Eisenstaedt & A. J. Kox (Ed.), ''Studies in the History of General Relativity, Volume 3'' Boston, Massachusetts: Center for Einstein Studies. {{ISBN|0-8176-3479-7}}</ref> Former Lieutenant Colonel [[Ansel Talbert]] wrote two series of newspaper articles claiming that most of the major aviation firms had started gravity control propulsion research in the 1950s. However, there is little outside confirmation of these stories, and since they take place in the midst of the [[policy by press release]] era, it is not clear how much weight these stories should be given.
+It is claimed the [[US Air Force]] also ran a study effort throughout the 1950s and into the 1960s.<ref>Goldberg, J. M. (1992). US air force support of general relativity: 1956–1972. In, J. Eisenstaedt & A. J. Kox (Ed.), ''Studies in the History of General Relativity, Volume 3'' Boston, Massachusetts: Center for Einstein Studies. {{ISBN|0-8176-3479-7}}</ref> Former Lieutenant Colonel [[Ansel Talbert]] wrote two series of newspaper articles claiming that most of the major aviation firms had started gravity control propulsion research in the 1950s. However, there is no outside confirmation of these stories, and since they take place in the midst of the [[policy by press release]] era, it is not clear how much weight these stories should be given.
-It is known that there were serious efforts underway at the [[Glenn L. Martin Company]], who formed the Research Institute for Advance Study.<ref>Mallan, L. (1958). ''Space satellites'' (How to book 364). Greenwich, CT: Fawcett Publications, pp. 9–10, 137, 139. LCCN 58-001060</ref><ref>{{cite journal | last1 = Clarke | first1 = A. C. | date = 1957 | title = The conquest of gravity | journal = Holiday | volume = 22 | issue = 6| page = 62 }}</ref> Major newspapers announced the contract that had been made between theoretical physicist [[Burkhard Heim]] and the Glenn L. Martin Company. Another effort in the private sector to master understanding of gravitation was the creation of the Institute for Field Physics, [[University of North Carolina at Chapel Hill]] in 1956, by Gravity Research Foundation trustee, [[Agnew H. Bahnson]].
+It is known that there were serious efforts underway at the [[Glenn L. Martin Company]], who formed the Research Institute for Advanced Study.<ref>Mallan, L. (1958). ''Space satellites'' (How to book 364). Greenwich, CT: Fawcett Publications, pp. 9–10, 137, 139. LCCN 58-001060</ref><ref>{{cite journal | last1 = Clarke | first1 = A. C. | date = 1957 | title = The conquest of gravity | journal = Holiday | volume = 22 | issue = 6| page = 62 }}</ref> Major newspapers announced the contract that had been made between theoretical physicist [[Burkhard Heim]] and the Glenn L. Martin Company. Another effort in the private sector to master understanding of gravitation was the creation of the Institute for Field Physics, [[University of North Carolina at Chapel Hill]] in 1956, by Gravity Research Foundation trustee [[Agnew H. Bahnson]].
-Military support for anti-gravity projects was terminated by the [[Mansfield Amendment]] of 1973, which restricted [[United States Department of Defense|Department of Defense]] spending to only the areas of scientific research with explicit military applications. The Mansfield Amendment was passed specifically to end long-running projects that had little to show for their efforts.
+Military support for anti-gravity projects was terminated by the [[Mansfield Amendment]] of 1973, which restricted [[United States Department of Defense|Department of Defense]] spending to only the areas of scientific research with explicit military applications. The Mansfield Amendment was passed specifically to end long-running projects that had no results.
 Under general relativity, gravity is the result of following spatial geometry (change in the normal shape of space) caused by local mass-energy. This theory holds that it is the altered shape of space, deformed by massive objects, that causes gravity, which is actually a property of deformed space rather than being a true force. Although the equations cannot normally produce a "negative geometry", it is possible to do so by using "[[negative mass]]". The same equations do not, of themselves, rule out the existence of negative mass.
-Both general relativity and Newtonian gravity appear to predict that negative mass would produce a repulsive gravitational field. In particular, 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's proof yielded singularity free solutions for the relativity equations.<ref name="Bondi">{{cite journal | last1 = Bondi | first1 = H. | date = 1957 | title = Negative mass in general relativity | journal = Reviews of Modern Physics | volume = 29 | issue = 3| pages = 423–428 | doi=10.1103/revmodphys.29.423|bibcode = 1957RvMP...29..423B }}</ref> In July 1988, [[Robert L. Forward]] presented a paper at the AIAA/ASME/SAE/ASEE 24th Joint Propulsion Conference that proposed a Bondi negative gravitational mass propulsion system.<ref name= "Forward">{{cite journal | last1 = Forward | first1 = R. L. | year = 1990 | title =  Negative matter propulsion | url = | journal = Journal of Propulsion and Power | volume = 6 | issue = 1| pages = 28–37 | doi=10.2514/3.23219}}; see also commentary {{cite journal | last1 = Landis | first1 = G.A. | year = 1991 | title = Comments on Negative Mass Propulsion | url = | journal = Journal of Propulsion and Power | volume = 7 | issue = 2| page = 304 | doi=10.2514/3.23327}}</ref>
+Both general relativity and Newtonian gravity appear to predict that negative mass would produce a repulsive gravitational field. In particular, 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's proof yielded singularity-free solutions for the relativity equations.<ref name="Bondi">{{cite journal | last1 = Bondi | first1 = H. | date = 1957 | title = Negative mass in general relativity | journal = Reviews of Modern Physics | volume = 29 | issue = 3| pages = 423–428 | doi=10.1103/revmodphys.29.423|bibcode = 1957RvMP...29..423B }}</ref> In July 1988, [[Robert L. Forward]] presented a paper at the AIAA/ASME/SAE/ASEE 24th Joint Propulsion Conference that proposed a Bondi negative gravitational mass propulsion system.<ref name= "Forward">{{cite journal | last1 = Forward | first1 = R. L. | year = 1990 | title =  Negative matter propulsion | journal = Journal of Propulsion and Power | volume = 6 | issue = 1| pages = 28–37 | doi=10.2514/3.23219}}; see also commentary {{cite journal | last1 = Landis | first1 = G.A. | year = 1991 | title = Comments on Negative Mass Propulsion | journal = Journal of Propulsion and Power | volume = 7 | issue = 2| page = 304 | doi=10.2514/3.23327}}</ref>
 Bondi pointed out that a negative mass will fall toward (and not away from) "normal" matter, since although the gravitational force is repulsive, the negative mass (according to Newton's law, F=ma) responds by accelerating in the opposite of the direction of the force. Normal mass, on the other hand, will fall away from the negative matter. He noted that two identical masses, one positive and one negative, placed near each other will therefore self-accelerate in the direction of the line between them, with the negative mass chasing after the positive mass.<ref name="Bondi" /> Notice that because the negative mass acquires negative [[kinetic energy]], the total energy of the accelerating masses remains at zero. Forward pointed out that the self-acceleration effect is due to the negative inertial mass, and could be seen induced without the gravitational forces between the particles.<ref name="Forward" />
-The [[Standard Model]] of particle physics, which describes all presently 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 is ostensibly known – since they were postulated from their gravitational effects on surrounding objects, which implies their mass is positive. The proposed cosmological [[dark energy]], on the other hand, is more complicated, since according to general relativity the effects of both its energy density and its negative pressure contribute to its gravitational effect.
+The [[Standard Model]] of particle physics, which describes all currently 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 is ostensibly known – since they were postulated from their gravitational effects on surrounding objects, which implies their mass is positive. The proposed cosmological [[dark energy]], on the other hand, is more complicated, since according to general relativity the effects of both its energy density and its negative pressure contribute to its gravitational effect.
-===Fifth force===
+===Unique force===
 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 and also causes (and reacts to) gravity like normal matter (see [[gravitational interaction of antimatter]]).
 For much of the last quarter of 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, and the strong and weak nuclear forces. Scientists have made progress in [[grand unification theory|unifying the three quantum forces]], but gravity has remained "the problem" in every attempt. 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 [[photon]]s (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.<ref name=SciAm79>''Supergravity and the Unification of the Laws of Physics,'' by Daniel Z. Freedman and Peter van Nieuwenhuizen, Scientific American, February 1978</ref>
+Generally these attempts tried to "quantize gravity" by positing a particle, the [[graviton]], that carried gravity in the same way that [[photon]]s (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.<ref name=SciAm79>''Supergravity and the Unification of the Laws of Physics,'' by [[Daniel Z. Freedman]] and Peter van Nieuwenhuizen, Scientific American, February 1978</ref>
-In 2013 [[CERN]] looked for an antigravity effect in an experiment designed to study the energy levels within antihydrogen. The antigravity measurement was just an "interesting sideshow" and was inconclusive.<ref>[http://www.bbc.co.uk/news/science-environment-22355187 Jason Palmer, Antigravity gets first test at Cern's Alpha experiment, bbc.co.uk, 30 April 2013 ]</ref>
+In 2013 [[CERN]] looked for an antigravity effect in an experiment designed to study the energy levels within antihydrogen. The antigravity measurement was just an "interesting sideshow" and was inconclusive.<ref>[https://www.bbc.co.uk/news/science-environment-22355187 Jason Palmer, Antigravity gets first test at Cern's Alpha experiment, bbc.co.uk, 30 April 2013 ]</ref>
-===General-relativistic "warp drives"===
-{{unreferenced section|date=November 2015}}
-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.
 ===Breakthrough Propulsion Physics Program===
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 ===Gyroscopic devices===
-[[File:H W Wallace force field figure 4.png|thumb|350px|A "kinemassic field" generator from {{US patent|3626605}}: Method and apparatus for generating a secondary gravitational force field]]
+[[File:H W Wallace force field figure 4.png|thumb|upright=1.5|A "kinemassic field" generator from {{US patent|3626605}}: Method and apparatus for generating a secondary gravitational force field]]
-[[Gyroscope]]s 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.<ref>{{cite web|url=http://www.rexresearch.com/laithwat/laithw1.htm#art1|title=Eric LAITHWAITE Gyroscope Levitation|work=Rex research|publisher=rexresearch.com|accessdate=23 October 2010}}</ref>
+[[Gyroscope]]s 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 has ever been demonstrated to work under controlled conditions, and they have often become the subject of [[conspiracy theories]] as a result.
 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]].<ref>{{US patent|3626606}}</ref><ref>{{US patent|3626605}}</ref><ref>{{US patent|3823570}}</ref> 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.<ref>{{cite journal|author=Hayasaka, H.|author2=Takeuchi, S.|last-author-amp=yes |date=1989|url=http://link.aps.org/doi/10.1103/PhysRevLett.63.2701|work=[[Physics Review Letters]]|title=Anomalous weight reduction on a gyroscope’s right rotations around the vertical axis on the Earth|volume=63|issue=25|pages=2701–2704|doi=10.1103/PhysRevLett.63.2701|bibcode=1989PhRvL..63.2701H}}</ref> A test of this claim a year later yielded null results.<ref>{{cite journal|author=Nitschke, J. M.|author2=Wilmath, P. A.|last-author-amp=yes|url=http://link.aps.org/doi/10.1103/PhysRevLett.64.2115|title=Null result for the weight change of a spinning gyroscope|date=1990|work=[[Physics Review Letters]]|volume=64| issue=18|pages=2115–2116|doi=10.1103/PhysRevLett.64.2115|accessdate=5 January 2014|bibcode = 1989PhRvL..63.2701H }}</ref> A recommendation was made to conduct further tests at a 1999 AIP conference.<ref>{{cite journal|author=Iwanaga, N.|date=1999|title=Reviews of some field propulsion methods from the general relativistic standpoint|work=AIP Conference Proceedings|volume=458|pages=1015–1059|doi=10.1063/1.57497}}.</ref>
+In 1989, it was reported that a weight decreases along the axis of a right spinning gyroscope.<ref>{{cite journal|author=Hayasaka, H.|author2=Takeuchi, S.|name-list-style=amp|date=1989|journal=[[Physical Review Letters]]|title=Anomalous weight reduction on a gyroscope's right rotations around the vertical axis on the Earth|volume=63|issue=25|pages=2701–2704|doi=10.1103/PhysRevLett.63.2701|pmid=10040968|bibcode=1989PhRvL..63.2701H}}</ref> A test of this claim a year later yielded null results.<ref>{{cite journal|author=Nitschke, J. M.|author2=Wilmath, P. A.|name-list-style=amp|title=Null result for the weight change of a spinning gyroscope|date=1990|journal=[[Physical Review Letters]]|volume=64| issue=18|pages=2115–2116|doi=10.1103/PhysRevLett.64.2115|pmid=10041587|bibcode = 1990PhRvL..64.2115N |url=https://zenodo.org/record/1233872}}</ref> A recommendation was made to conduct further tests at a 1999 AIP conference.<ref>{{cite conference |last=Iwanaga |first=N. |book-title=AIP Conference Proceedings |date=1999 |volume=458 |pages=1015–1059 |doi=10.1063/1.57497 |title=Reviews of some field propulsion methods from the general relativistic standpoint}}</ref>
 ===Thomas Townsend Brown's gravitator===
 {{Further|Biefeld-Brown effect|Electrogravitics|United States gravity control propulsion research#Brown's gravitator}}
-In 1921, while still in high school, [[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 (essentially large [[capacitors]]); he called such a device a "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.
+In 1921, while still in [[high school]], [[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 (essentially large [[capacitors]]); he called such a device a "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]], anti-gravity, [[Free energy suppression|free energy]], with government conspiracy theorists and related websites, in books and publications with claims that the technology became highly classified in the early 1960s and that it is used to power UFOs and the B-2 bomber.<ref name="Wired">{{Cite news
+Electrogravitics is a popular topic in [[ufology]], anti-gravity, [[free energy suppression conspiracy theory|free energy]], with government conspiracy theorists and related websites, in books and publications with claims that the technology became highly classified in the early 1960s and that it is used to power UFOs and the [[Northrop Grumman B-2 Spirit|B-2 bomber]].<ref name="Wired">{{Cite news
 	| magazine = Wired Magazine
 	| date = August 2003
@@ Line 71: / Line 77: @@
 	| first = Clive
 	| url = https://www.wired.com/wired/archive/11.08/pwr_antigravity.html
+	}}</ref> 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.<ref name="Wired"/><ref>Thomas Valone, Electrogravitics II: Validating Reports on a New Propulsion Methodology,  Integrity Research Institute, page 52-58</ref>
-	| postscript = <!-- Bot inserted parameter. Either remove it; or change its value to "." for the cite to end in a ".", as necessary. -->
-}}</ref> 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.<ref name="Wired"/><ref>Thomas Valone, Electrogravitics II: Validating Reports on a New Propulsion Methodology,  Integrity Research Institute, page 52-58</ref>
-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,<ref>{{Cite news
+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,<ref name="Wired"/>  and [[Martin Tajmar]] in a 2004 paper.<ref>{{Cite journal | last1 = Tajmar | first1 = M. | title = Biefeld-Brown Effect: Misinterpretation of Corona Wind Phenomena | journal = AIAA Journal | volume = 42 | issue = 2 | pages = 315–318 | date = 2004 | doi = 10.2514/1.9095|bibcode = 2004AIAAJ..42..315T }}</ref> They have found that no thrust could be observed in a vacuum and that Brown's and other [[Ionocraft|ion lifter]] devices produce thrust along their axis regardless of the direction of gravity consistent with electrohydrodynamic effects.
-	| magazine = Wired Magazine
-	| date = August 2003
-	| title = The Antigravity Underground
-	| last = Thompson
-	| first = Clive
-	| url = https://www.wired.com/wired/archive/11.08/pwr_antigravity.html
-	| postscript = <!-- Bot inserted parameter. Either remove it; or change its value to "." for the cite to end in a ".", as necessary. -->
-}}</ref>  and [[Martin Tajmar]] in a 2004 paper.<ref>{{Cite journal | last1 = Tajmar | first1 = M. | title = Biefeld-Brown Effect: Misinterpretation of Corona Wind Phenomena | journal = AIAA Journal | volume = 42 | issue = 2 | pages = 315–318 | date = 2004 | doi = 10.2514/1.9095|bibcode = 2004AIAAJ..42..315T }}</ref> They have found that no thrust could be observed in a vacuum and that Brown's and other [[Ionocraft|ion lifter]] devices produce thrust along their axis regardless of the direction of gravity consistent with electrohydrodynamic effects.
 ===Gravitoelectric coupling===
-In 1992, the Russian researcher [[Eugene Podkletnov]] claimed to have discovered, whilst experimenting with [[superconductor]]s, that a fast rotating superconductor reduces the gravitational effect.<ref>{{cite journal|last1=Podkletnov|first1=E|last2=Nieminen|first2=R |url=http://www.sciencedirect.com/science/article/pii/092145349290055H |title=A possibility of gravitational force shielding by bulk YBa2Cu3O7−x superconductor|journal=[[Physica C]] |volume=203|issue=3–4|date=10 December 1992|pages=441–444|accessdate=29 April 2014|bibcode = 1992PhyC..203..441P |doi = 10.1016/0921-4534(92)90055-H }}</ref> Many studies have attempted to reproduce Podkletnov's experiment, always to negative results.<ref>{{cite journal| display-authors=4| author=N. Li| author2=D. Noever| author3=T. Robertson| author4=R. Koczor| author5=W. Brantley| last-author-amp=yes |title=Static Test for a Gravitational Force Coupled to Type II YBCO Superconductors|journal=[[Physica C]]|url=http://www.sciencedirect.com/science/article/pii/S0921453497014627|volume=281|issue=2–3|date=August 1997|pages=260–267|bibcode = 1997PhyC..281..260L |doi = 10.1016/S0921-4534(97)01462-7 }}</ref><ref>Woods, C., Cooke, S., Helme, J., and Caldwell, C., "Gravity Modification by High Temperature Superconductors," Joint Propulsion Conference, AIAA 2001–3363, (2001).</ref><ref>Hathaway, G., Cleveland, B., and Bao, Y., "Gravity Modification Experiment using a Rotating Superconducting Disc and Radio Frequency Fields," Physica C, 385, 488–500, (2003).</ref><ref>Tajmar, M., and de Matos, C.J., "Gravitomagnetic Field of a Rotating Superconductor and of a Rotating Superfluid," Physica C, 385(4), 551–554, (2003).</ref>
+In 1992, the Russian researcher [[Eugene Podkletnov]] claimed to have discovered, whilst experimenting with [[superconductor]]s, that a fast rotating superconductor reduces the gravitational effect.<ref>{{cite journal|last1=Podkletnov|first1=E|last2=Nieminen|first2=R |title=A possibility of gravitational force shielding by bulk YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−x</sub> superconductor|journal=[[Physica C]] |volume=203|issue=3–4|date=10 December 1992|pages=441–444|bibcode = 1992PhyC..203..441P |doi = 10.1016/0921-4534(92)90055-H }}</ref> Many studies have attempted to reproduce Podkletnov's experiment, always to negative results.<ref>{{cite journal| display-authors=4| author=N. Li| author2=D. Noever| author3=T. Robertson| author4=R. Koczor| author5=W. Brantley| name-list-style=amp|title=Static Test for a Gravitational Force Coupled to Type II YBCO Superconductors|journal=[[Physica C]]|volume=281|issue=2–3|date=August 1997|pages=260–267|bibcode = 1997PhyC..281..260L |doi = 10.1016/S0921-4534(97)01462-7 }}</ref><ref>{{cite book | doi=10.2514/6.2001-3363 | chapter=Gravity modification by high-temperature superconductors | title=37th Joint Propulsion Conference and Exhibit | date=2001 | last1=Woods | first1=C. | last2=Helme | first2=J. | last3=Cooke | first3=S. | last4=Caldwell | first4=C. }}</ref><ref>{{cite journal | doi=10.1016/S0921-4534(02)02284-0 | title=Gravity modification experiment using a rotating superconducting disk and radio frequency fields | date=2003 | last1=Hathaway | first1=G. | last2=Cleveland | first2=B. | last3=Bao | first3=Y. | journal=Physica C: Superconductivity | volume=385 | issue=4 | pages=488–500 | bibcode=2003PhyC..385..488H }}</ref><ref>{{cite journal | doi=10.1016/S0921-4534(02)02305-5 | title=Gravitomagnetic field of a rotating superconductor and of a rotating superfluid | date=2003 | last1=Tajmar | first1=M. | last2=De Matos | first2=C.J. | journal=Physica C: Superconductivity | volume=385 | issue=4 | pages=551–554 | arxiv=gr-qc/0203033 | bibcode=2003PhyC..385..551T }}</ref>
-[[Ning Li (physicist)|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.<ref>{{cite journal|journal=Physical Review|date=1 September 1992|url=http://journals.aps.org/prb/abstract/10.1103/PhysRevB.46.5489|doi=10.1103/PhysRevB.46.5489|title=Gravitational effects on the magnetic attenuation of superconductors|last1=Li|first1=Ning|last2=Torr|first2=DG|volume=B46|pages=5489–5495|accessdate=6 March 2014|bibcode = 1992PhRvB..46.5489L }}</ref><ref>{{cite journal|journal=Physical Review|date=15 January 1991|url=http://journals.aps.org/prd/abstract/10.1103/PhysRevD.43.457|title=Effects of a gravitomagnetic field on pure superconductors|last1=Li|first1=Ning|last2=Torr|first2=DG|volume=D43|pages=457–459|accessdate=6 March 2014|doi=10.1103/PhysRevD.43.457|bibcode = 1991PhRvD..43..457L }}</ref><ref>{{cite journal|last1=Li|first1=Ning|last2=Torr|first2=DG|journal=Foundations of Physics Letters|url=https://link.springer.com/article/10.1007%2FBF00665654|title=Gravitoelectric-electric coupling via superconductivity|volume=6|issue=4|pages=371–383|date=August 1993|accessdate=6 March 2014|bibcode = 1993FoPhL...6..371T |doi = 10.1007/BF00665654 }}</ref> 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.<ref>{{cite journal |url=http://www.highbeam.com/doc/1G1-65730414.html|title=Taming Gravity|publisher=HighBeam Reseatch|work=Popular Mechanics|date=1 October 2000|first=Jim|last=Wilson|accessdate=5 January 2014}}</ref><ref>{{cite web|url=http://www.light-science.com/gen2.html |title=Gravity Conquered? |last=Cain |first=Jeanette |publisher=light-science.com |accessdate=5 January 2014 |deadurl=yes |archiveurl=https://web.archive.org/web/20130706031149/http://www.light-science.com/gen2.html |archivedate=6 July 2013 }}</ref>
+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.<ref>{{cite journal|journal=Physical Review|date=1 September 1992|doi=10.1103/PhysRevB.46.5489|pmid=10004334|title=Gravitational effects on the magnetic attenuation of superconductors|last1=Li|first1=Ning|last2=Torr|first2=DG|volume=B46|issue=9|pages=5489–5495|bibcode = 1992PhRvB..46.5489L }}</ref><ref>{{cite journal|journal=Physical Review|date=15 January 1991|title=Effects of a gravitomagnetic field on pure superconductors|last1=Li|first1=Ning|last2=Torr|first2=DG|volume=D43|issue=2|pages=457–459|doi=10.1103/PhysRevD.43.457|pmid=10013404|bibcode = 1991PhRvD..43..457L }}</ref><ref>{{cite journal|last1=Li|first1=Ning|last2=Torr|first2=DG|journal=Foundations of Physics Letters|title=Gravitoelectric-electric coupling via superconductivity|volume=6|issue=4|pages=371–383|date=August 1993|bibcode = 1993FoPhL...6..371T |doi = 10.1007/BF00665654 |s2cid=122075917}}</ref> In 1999, a Miss Li 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.<ref>{{cite journal |url=http://www.highbeam.com/doc/1G1-65730414.html|archive-url=https://web.archive.org/web/20121105040310/http://www.highbeam.com/doc/1G1-65730414.html|url-status=dead|archive-date=5 November 2012|title=Taming Gravity|journal=Popular Mechanics|date=1 October 2000|first=Jim|last=Wilson|access-date=5 January 2014}}</ref><ref>{{cite web|url=http://www.light-science.com/gen2.html |title=Gravity Conquered? |last=Cain |first=Jeanette |publisher=light-science.com |access-date=5 January 2014 |url-status=dead |archive-url=https://web.archive.org/web/20130706031149/http://www.light-science.com/gen2.html |archive-date=6 July 2013 }}</ref>
-Douglas Torr and [[Timir Datta]] were involved in the development of a "gravity generator" at the [[University of South Carolina]].<ref>{{cite web|title=Patent and Copyright Committee List of Disclosures Reviewed Between July 1996 and June 1997 - USC ID|number=96140|url=http://www.sc.edu/faculty/senate/97/annual/patentlist.html|accessdate=30 April 2014}}</ref> According to a leaked document from the Office of Technology Transfer at the University of South Carolina and confirmed to [[Wired (magazine)|''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.<ref name=Platt1998>{{cite news|last=Platt|first=Charles|title=Breaking the Law of Gravity|url=https://www.wired.com/wired/archive/6.03/antigravity_pr.html|newspaper=Wired|date=3 June 1998|accessdate=1 May 2014}}</ref>
+Douglas Torr and [[Timir Datta]] were involved in the development of a "gravity generator" at the [[University of South Carolina]].<ref>{{cite web|title=Patent and Copyright Committee List of Disclosures Reviewed Between July 1996 and June 1997 - USC ID|number=96140|url=http://www.sc.edu/faculty/senate/97/annual/patentlist.html|access-date=2 May 2014|archive-url=https://web.archive.org/web/20140502013440/http://www.sc.edu/faculty/senate/97/annual/patentlist.html|archive-date=2 May 2014}}</ref> According to a leaked document from the Office of Technology Transfer at the University of South Carolina and confirmed to [[Wired (magazine)|''Wired'']] reporter Charles Platt in 1998, the device would create a "force beam" in any desired direction and 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.<ref name="Platt1998">{{cite news|last=Platt|first=Charles|date=March 1, 1998|title=Breaking the Law of Gravity|newspaper=Wired|url=https://www.wired.com/wired/archive/6.03/antigravity_pr.html|access-date=August 26, 2021}}</ref>
 ==Göde Award==
-The Institute for Gravity Research of the Göde Scientific Foundation has tried to reproduce many of the different experiments which claim any "anti-gravity" effects. All attempts by this group to observe an anti-gravity effect by reproducing past experiments have been unsuccessful thus far. The foundation has offered a reward of one million euros for a reproducible anti-gravity experiment.<ref>{{cite web|url=http://www.goede-stiftung.org/uk/institute-for-gravity-research/goede-award.html|title=The Göde award - One Million Euro to overcome gravity|publisher=Institute of Gravity Research|accessdate=2 January 2014}}</ref>
+The Institute for Gravity Research of the Göde Scientific Foundation has tried to reproduce many of the different experiments which claim any "anti-gravity" effects. All attempts by this group to observe an anti-gravity effect by reproducing past experiments have been unsuccessful thus far. The foundation has offered a reward of one million euros for a reproducible anti-gravity experiment.<ref>{{cite web|url=http://www.goede-stiftung.org/uk/institute-for-gravity-research/goede-award.html|title=The Göde award - One Million Euro to overcome gravity|publisher=Institute of Gravity Research|access-date=2 January 2014|archive-url=https://web.archive.org/web/20150428051435/http://www.goede-stiftung.org/uk/institute-for-gravity-research/goede-award.html|archive-date=28 April 2015|url-status=dead}}</ref>
+==In fiction==
+The existence of anti-gravity is a common theme in [[fantasy]] and [[science fiction]].
+===Apergy===
+'''Apergy''' is a fictitious form of anti-gravitational energy first described by [[Percy Greg]] in his 1880 [[sword and planet]] novel ''[[Across the Zodiac]]''.<ref name="Nicholls1979">{{cite book|author=Peter Nicholls|url=https://books.google.com/books?id=NzAqAQAAIAAJ|title=The Encyclopedia of Science Fiction: An Illustrated A to Z|publisher=Unknown Publisher|year=1979|isbn=978-0-246-11020-6}}</ref>
+[[John Jacob Astor IV]] used it in his 1894 science fiction novel ''[[A Journey in Other Worlds]]''.<ref>{{cite book |last1=Astor |first1=John Jacob |title=A journey in other worlds. A romance of the future |date=1894 |publisher=D. Appleton and Company |url=https://archive.org/details/ajourneyinother02astogoog/page/n44/mode/2up/search/apergy |access-date=11 March 2020}}</ref> [[Jack London]] describes it as "the hypothetical existence of a force, the converse of gravitation, which Astor has named 'apergy,'" in his short story entitled "A Thousand Deaths," first published in ''[[The Black Cat (US magazine)|The Black Cat]]'' in 1899.<ref>{{Cite book |title=The Fantastic Pulps |publisher=Vintage Books |year=1976 |isbn=0-394-72109-8 |editor-last=Haining |editor-first=Peter |location=New York |pages=26}}</ref>
+Apergy can also be found in an 1896 article, "Some Truths About Keely,"<ref name="Stoddart1895">{{cite book |author=J. M. Stoddart |url=https://books.google.com/books?id=t7POAAAAMAAJ&pg=PA321 |title=The New Science Review: A Miscellany of Modern Thought and Discovery |publisher=Transatlantic Publishing Company |year=1895 |pages=321–}}</ref> where [[Clara Jessup Moore|Clara Jessup Bloomfield-Moore]] used it to describe the [[:wikt:latent|latent]] force [[John Ernst Worrell Keely|John Keely]] harnessed, by employing frequency to release the latent force found within all atomic [[matter]].<ref name="Paijmans2004">{{cite book|author=Theo Paijmans|url=https://books.google.com/books?id=O3wZ4mbPb-AC&pg=PA221|title=Free Energy Pioneer: John Worrell Keely|publisher=Adventures Unlimited Press|year=2004|isbn=978-1-931882-33-0|pages=221–}}</ref>
+In an ostensibly non-fictitious article published in 1897 in ''[[The San Francisco Call]]'' titled "The Secret of Aerial Flight Revealed,"<ref>http://chroniclingamerica.loc.gov/lccn/sn85066387/1897-01-17/ed-1/seq-20/ ''The San Francisco Call'', January 17, 1897, p.18.</ref> science correspondent [[Frank M. Close]], D.Sc., visits an unnamed Hindu man masquerading as a [[Viticulture|viticulturist]] somewhere on the [[West Coast of the United States|Pacific coast]] who claims to have invented a flying boat that uses an "apergent"—a rare metal called "radlum"—to produce controlled apergic force, allowing the vessel to ascend and descend. The inventor describes apergy as "a force obtained by blending positive and negative electricity with ultheic, the third element or state of electric energy" and calls apergy a "second phase of gravity," hinting at a third phase as well.
+[[S. P. Meek]]'s short story "Cold Light," which appeared in March 1930 in ''Astounding Stories of Super-Science'',<ref>{{Cite web | url=https://www.gutenberg.org/files/29607/29607-h/29607-h.htm | title=The Project Gutenberg eBook of Astounding Stories of Super-Science, March 1930}}</ref> mentions apergy as the opposite force of gravity.
+In [[Chris Roberson (author)|Chris Roberson]]'s short story "Annus Mirabilis" from the 2006 second volume of ''[[Tales of the Shadowmen]]'', [[Doctor Omega]] and Albert Einstein investigate apergy. Apergy is also mentioned in the [[Warren Ellis]] comic ''[[Aetheric Mechanics]]'', as being generated by [[The First Men in the Moon#Plot summary|Cavorite]] technology from ''[[The First Men in the Moon]]''.
+==Other terms==
+[[H. G. Wells]]'s 1901 novel ''The First Men in the Moon'' has space travel based on the gravity-blocking properties of "[[Cavorite]]."
+[[Philip Francis Nowlan]]'s 1928 story ''[[Armageddon 2419 A.D.]]'' describes "inertron," a substance that falls up. The story was the basis for the [[Buck Rogers]] [[comic strip]] and adaptations.
 ==See also==
 {{Div col|colwidth=18em}}
-* [[Gravitational shielding]]
+* [[Area 51]]
 * [[Aerodynamic levitation]]
-* [[Apergy]]
 * [[Artificial gravity]]
 * [[Burkhard Heim]]
@@ Line 106: / Line 123: @@
 * [[Exotic matter]]
 * [[Gravitational interaction of antimatter]]
+* [[Gravitational shielding]]
 * [[Gravitational wave]]
+* [[Ion-propelled aircraft]]
 * [[Heim theory]]
 * [[Magnetic levitation]]
+* [[Nazi UFOs]]
 * [[Optical levitation]]
 * [[Reactionless drive]]
@@ Line 115: / Line 135: @@
 ==References==
-{{Reflist|20em}}
+{{Reflist|30em}}
+==Bibliography==
+Criteria:
+*[https://www.google.com/search?q=Newtons+discovery+of+the+apple+law&rlz=1C1GGRV_enGB858GB858&oq=Newtons+discovery+of+the+apple+law&aqs=chrome..69i57.8545j0j1&sourceid=chrome&ie=UTF-8 "Newtons discovery of the apple law"]
+*[https://www.google.com/search?q=Newtons+principle+of+gravitation&rlz=1C1GGRV_enGB858GB858&oq=Newtons+principle+of+gravitation&aqs=chrome..69i57.10463j0j1&sourceid=chrome&ie=UTF-8 "Newtons principle of gravitation"] > [https://www.google.com/search?rlz=1C1GGRV_enGB858GB858&ei=JWszXa2WFcyU8gK_3pQ4&q=Newtons+principle+of+gravitation+apple+falls&oq=Newtons+principle+of+gravitation+apple+falls&gs_l=psy-ab.3...3593.5878..6069...0.0..0.119.897.11j1......0....1..gws-wiz.......0i22i30j33i22i29i30j33i160j33i21.yJ8BrLKZQMk&ved=0ahUKEwjtvKqtncTjAhVMilwKHT8vBQcQ4dUDCAo&uact=5 "Newtons principle of gravitation apple falls"] (google > google books)
-=== Further reading ===
+== Further reading ==
-* Cady, W. M. (15 September 1952). "Thomas Townsend Brown: Electro-Gravity Device" (File 24-185). Pasadena, CA: Office of Naval Research. Public access to the report was authorized on 1 October 1952.
+* Cady, W. M. (15 September 1952). "Thomas Townsend Brown: Electro-Gravity Device" (File 24–185). Pasadena, CA: Office of Naval Research. Public access to the report was authorized on 1 October 1952.
 ==External links==
 {{Sister project links|Anti-gravity}}
 * [https://ntrs.nasa.gov/search.jsp?R=20070004897 Responding to Mechanical Antigravity], a NASA paper debunking a wide variety of gyroscopic (and related) devices
-*[http://www.gravitation.org/institute_of_gravity_research/institute_of_gravity_research.html Göde Scientific Foundation]
+*[http://www.gravitation.org/institute_of_gravity_research/institute_of_gravity_research.html Göde Scientific Foundation] {{Webarchive|url=https://web.archive.org/web/20100531053008/http://www.gravitation.org/institute_of_gravity_research/institute_of_gravity_research.html |date=31 May 2010 }}
+*[https://sites.google.com/view/kured/research KURED Research]
+{{Science fiction}}
-{{Emerging technologies}}
 {{Spacecraft propulsion}}
+{{Authority control}}
 {{DEFAULTSORT:Anti-Gravity}}