Gravitational Coupling of Negative Matter
Il Nuovo Cimento B
The relevance of the sign of mass in general relativity is examined by analysing a simple model universe in which Dirac matter distributes uniformly. Mass reversal, converting a source of positive matter into one of negative matter, gives rise to a concomitant change in sign of the gravitational coupling. The principle of equivalence is invoked in order to generalize the result to all negative-matter sources. The admissibility of a Dirac source in general relativity implies that the sign of mass is irrelevant in gravitational interactions.
A. Inomata and D. Peak, "Gravitational Coupling of Negative Matter," Nuovo Cimento 63B, 132 (1969) (with A. Inomata).