See the paper http://arxiv.org/abs/1103.4937 by M. Villata. I find this paper extremely interesting and the arguments rather compelling. It is based upon two ideas. First, the gravitational mass is not the gravitational charge; rather the gravitational charge is the Energy momentum 4-vector. Second, there is a kind of correspondence principle, so that CPT which holds exactly in Minkowski space, holds approximately in weak gravitational fields. The conclusion, that antimatter will fall up, follows.

I would appreciate comments by others who are more knowledgeable, however.

Added the next day: See http://lss.fnal.gov/archive/test-fn/0000/fermilab-fn-0822-cd-t.pdf for a general review of the previously existing experimental evidence from Etvos and other experiments such as accelerometers, Kaons, astrophysical neutrino's from SN1987A.

See the paper http://arxiv.org/abs/1103.4937 by M. Villata for an argument for antimatter falling up. However, see D.J. Cross at http://arxiv.org/abs/1108.5117 for powerful rebuttal arguments, asserting that Villata misapplied the CPT theorem, resulting in an incorrect sign for the matter-antimatter gravitational interaction.

See http://lss.fnal.gov/archive/test-fn/0000/fermilab-fn-0822-cd-t.pdf for a general review of the previously existing experimental evidence from Etvos and other experiments such as accelerometers, Kaons, astrophysical neutrino's from SN1987A.

See the paper http://arxiv.org/abs/1103.4937 by M. Villata. I find this paper extremely interesting and the arguments rather compelling. It is based upon two ideas. First, the gravitational mass is not the gravitational charge; rather the gravitational charge is the Energy momentum 4-vector. Second, there is a kind of correspondence principle, so that CPT which holds exactly in Minkowski space, holds approximately in weak gravitational fields. The conclusion, that antimatter will fall up, follows.

I would appreciate comments by others who are more knowledgeable, however.

See the paper http://arxiv.org/abs/1103.4937 by M. Villata. I find this paper extremely interesting and the arguments rather compelling. It is based upon two ideas. First, the gravitational mass is not the gravitational charge; rather the gravitational charge is the Energy momentum 4-vector. Second, there is a kind of correspondence principle, so that CPT which holds exactly in Minkowski space, holds approximately in weak gravitational fields. The conclusion, that antimatter will fall up, follows.

I would appreciate comments by others who are more knowledgeable, however.

Added the next day: See http://lss.fnal.gov/archive/test-fn/0000/fermilab-fn-0822-cd-t.pdf for a general review of the previously existing experimental evidence from Etvos and other experiments such as accelerometers, Kaons, astrophysical neutrino's from SN1987A.