PRESENTATION OUTLINE
In modern physics, negative mass (anti matter) is a hypothetical concept of matter whose mass is of opposite sign to the mass of normal matter, e.g. −2 kg.
Such matter would violate one or more energy conditions and show some strange properties, stemming from the ambiguity as to whether attraction should refer to force or the oppositely oriented acceleration for negative mass.
It is used in certain speculative theories, such as on the construction of wormholes.
