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I want to know if there is any anti-gravity material. I am thinking of making flying vehicles which are made up of anti-gravity material so that they will not experience any gravity on them and can easily take off and be more fuel efficient. Is there any such thing? Or any workaround?

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    $\begingroup$ @downvoters and other commentators: I voted up made it from -2 to -1 since I have no answer for this simple question. Please be gentle with questioners. I would also appreciate if you, knowledgeable person, provide us a simple but reasonable logical answer to the question. You may explain more talking about anti-material too. Everybody can google so if you have something to share please do it otherwise just pass it. $\endgroup$
    – Developer
    Nov 2, 2011 at 11:06
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    $\begingroup$ I am also tempted to downvote because physics.stackexchange requires at least a tiny bit of own research effort to be successful. The person asking the question did not even use wikipedia to look up the term. The article on anti-gravity is well written there and explains why a simple anti-gravity material does not exist and possible directions for future work. I am also in favor of gentle treatment of questioners but a simple google or wikipedia search is not too much to ask for. $\endgroup$
    – Alexander
    Nov 2, 2011 at 12:02
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    $\begingroup$ See meta: meta.physics.stackexchange.com/q/952 $\endgroup$
    – David Z
    Nov 2, 2011 at 21:35
  • $\begingroup$ isn't helium anti-gravity material? it does make balloons define gravity, just because it's gas don't mean it's not material? $\endgroup$
    – Val
    Jan 4, 2013 at 14:00
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    $\begingroup$ Hm.. this makes me remember a video of Feynman where some audience member asked him if there was any way to make an anti-gravity machine, to which he replied: your butt's one such machine. $\endgroup$
    – nervxxx
    Apr 8, 2013 at 0:59

5 Answers 5

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When you say "anti-gravity material", the closest thing I can think of is the hypothetical concept of negative mass:

In theoretical physics, negative mass is a hypothetical concept of matter whose mass is of opposite sign to the mass of the normal matter. Such matter would violate one or more energy conditions and show some strange properties such as being repelled rather than attracted by gravity. It is used in certain speculative theories, such as on the construction of wormholes. The closest known real representative of such exotic matter is a region of pseudo-negative pressure density produced by the Casimir effect.

But it gets more complicated because there are actually three different kinds of mass: gravitational mass, passive grativational mass, and inertial mass:

Thus objects with negative passive gravitational mass, but with positive inertial mass, would be expected to be repelled by positive active masses, and attracted to negative active masses. However, any difference between inertial and gravitational mass would violate the equivalence principle of general relativity. For an object where both the inertial and gravitational masses were negative and equal, we could cancel out mi and mp from the equation, and conclude that its acceleration a in the gravitational field from a body with positive active gravitational mass (say, the planet Earth) would be no different from the acceleration of an object with positive passive gravitational and inertial mass (so a small negative mass object would fall towards the Earth at the same rate as any other object).

In any case, there does not exist any such thing, to the extent of human knowledge.

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    $\begingroup$ Which is precisely why this is a good question! Why is gravity attractive?? Granted this is more philosophical than physics, it is still on the minds of us theorists. $\endgroup$ Nov 28, 2011 at 20:28
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    $\begingroup$ @ChrisGerig: I have often heard it stated that the attractiveness of gravity is a feature of all spin 2 gauge theories. $\endgroup$ Dec 6, 2012 at 14:54
  • $\begingroup$ @JerrySchirmer Why is this so? $\endgroup$
    – resgh
    Dec 6, 2012 at 16:09
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    $\begingroup$ @namehere: I've never seen it adequately proven. But I have heard that statement many times. $\endgroup$ Dec 6, 2012 at 17:18
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    $\begingroup$ @JerrySchirmer The proof is in Zee's QFT book in one of the early chapters. It's due to a simple pattern: spin-0 exchange -> universal attraction, spin-1 exhange -> attraction&repulsion, spin-2 exchange -> universal attraction, spin-3 exchange -> attraction&repulsion etc. Then there is a theorem that rules out interacting spin > 2 particles so all that's left is spin-0 (Higgs/pions), spin-1 (gauge bosons) and a single spin-2 (graviton). $\endgroup$
    – Michael
    Apr 8, 2013 at 2:26
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A from a theoretical physics point of view not completely off the mark approach to anti-gravity effects comes from certain versions of supergravity described in wikipedia, which is a unified supersymmetric point-particle quantum field theory.

Some particular versions of this theory not only contain the "usual" atractive graviton, a spin-2 particle, but in addition a so-called graviphoton is predicted (1). This graviphoton is a spin-1 vector field, interacts with mattar at the normal gravitational strength, and behaves generally like a massive photon. The fun thing about it is that it can give rise to attractive and repulsive forces. The repulsive forces feature can in principle give rise to anti-gravity effects, however the real-world / everyday usefulness of this has not yet been tested ... ;-)

For more see this blog article on Uduality (2).

References:

(1) A model for a light graviphoton, R. Barbiery and S. Cecotti, Zeitschrift für Physik C Particles and Fields, 33(2), 1986, 255-261

(2) Antigravity from Supergravity, Physics blog post on: U.Duality thoughts on the new mathematics and physics, posted 24. November 2012

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  • $\begingroup$ I dont know why people have to downvote (again without saying what is technically or physically wrong!) my answer here; supergravity is an accepted mainstream high energy physics theory. Must be non physics reasons then ... -> Not cool, this takes away the fun of posting anything here on this site :-/ $\endgroup$
    – Dilaton
    Apr 7, 2013 at 19:02
  • $\begingroup$ +1 but The link seems to be broken. Could you fix it? $\endgroup$ Jun 22, 2013 at 14:59
  • $\begingroup$ @dimension10 I can fix it in about 24 hours, I am currently traveling and typing on my iphone ... $\endgroup$
    – Dilaton
    Jun 22, 2013 at 22:04
  • $\begingroup$ @dimension10 hm, from my laptop when I use firefox for example, the links seem to work. I can however add some information to retreave the posts by googling in case it does not work for some reason. $\endgroup$
    – Dilaton
    Jun 24, 2013 at 13:00
  • $\begingroup$ I tried again and now it works. For some reason, there is some serious problem with my internet these days. It singles out certain sites (e.g. the entire of Physics S.E., or arXiV, or certain blogs some times) for a period of time and simply gives random error messages. Maybe I should wait for a longer time before commenting... $\endgroup$ Jun 24, 2013 at 14:00
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Forget anti-gravity material. As far as we know, there is none--gravity is always an attractive force. But there is a workaround: Use something with the appropriate properties, i.e. something that does have repelling force. Electromagnetism! All you need to do is separate enough charge, say a few grams of electrons, place half of them at the airport and attach the other half to your flying machine. Off they go with a mighty force that can lift Mount-Everest sized objects to the moon. Simple as that. (Calculation of the force between two 1g clouds of electrons left as an exercise--it's immense!).

Of course, the hard part is getting at a gram of electrons (without any positive charge nearby).

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    $\begingroup$ And hey! We have mag-lev trains already! $\endgroup$ Dec 6, 2012 at 14:56
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In the spirit of conspiracies and dubious theories, take a look at the so called Biefeld Brown effect.Some have claimed that Penney's 1965 paper as a possible source of rationalizing their beliefs. I don't know enough to offer an opinion either way. However, Mythbusters et al have obtained negative results in all their experiments.Take it for what its worth.

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Anti-gravity is impossible, as it would let you build a perpetual motion system, as follows.

Assume we have a system in which we can capture the kinetic energy of a falling mass. For example, a ball that falls onto a scooped wheel to drive it. Take the ball and move a sheet of anti-grav material under it. As the ball now no longer feels the earth's gravity, we can push it up above the wheel without using any energy. Now remove the anti-grav sheet. The ball will fall onto the wheel and thus generate energy.

This violates the law of conservation of energy, i.e. the first law of thermodynamics. Hence it is impossible, and hence anti-gavity cannot exist.

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    $\begingroup$ It doesn't have to violate conservation of energy if moving the sheet needs appropriate amounts of energy. You simply assume it doesn't. $\endgroup$
    – Jens
    Apr 8, 2013 at 7:50
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    $\begingroup$ This is wrong for three reasons. First, you need energy to move the object because it still has inertial mass. Second, the sheet will move. Third, the sheet (planar) will not homogenously shield the gravitational field of the earth (sphere). $\endgroup$
    – WIMP
    Apr 8, 2013 at 8:18
  • $\begingroup$ This is a very interesting way to think whether something is possible or not, but this particular example does not produce a perpetual motion system: after the ball fell down and you raised it back up using the anti-gravity dish, you would have to apply force to move the anti-gravity dish back down, so that it could raise the ball again. So in theory you are not gaining anything here over simply moving the ball back up with a machine, without any anti-gravity plating involved whatsoever (besides minor possible improvement of efficiency, but definitely not anything like perpetual motion). $\endgroup$
    – John Weisz
    Oct 29, 2019 at 8:42
  • $\begingroup$ (Continued) What you describe would require a technology that can actively change mass in the same object, and also not require more energy in the process than what you would gain back from the mechanism. $\endgroup$
    – John Weisz
    Oct 29, 2019 at 8:45
  • $\begingroup$ The anti gravity sheet only has to move sideways. This does not require a force in a gravitational field. Raise the ball; move the sheet left to let the ball fall; now move the sheet right so you can raise the ball again without gravity. $\endgroup$
    – hdhondt
    Oct 29, 2019 at 8:48

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