Answer to Question #282406 in Mechanics | Relativity for Athirah

Question

Why the mass is negative? Can you explain? Thank you in advance.

Answer 1

Solution:

Negative mass is a type of exotic matter whose mass is of opposite sign to the mass of normal matter, e.g. −1 kg. Such matter would violate one or more energy conditions and show some strange properties such as the oppositely oriented acceleration for negative mass. It is used in certain speculative hypothetical technologies, such as time travel to the past, construction of traversable artificial wormholes, which may also allow for time travel.

Negative mass is any region of space in which for some observers the mass density is measured to be negative. This could occur due to a region of space in which the stress component of the Einstein stress-energy tensor is larger in magnitude than the mass density. All of these are violations of one or another variant of the positive energy condition of Einstein's general theory of relativity; however, the positive energy condition is not a required condition for the mathematical consistency of the theory.