is there minus mass?

Answer 1

Yes. For everything, there is a negative, opposite thing. This can be linked with Sir Isaac Newton's third law of motion: "Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi". ("All forces occur in pairs, and these two forces are equal in magnitude and opposite in direction".)
We cannot observe it, but it is existant, and in a negative universe.

Answer 2

Photons have zero mass, and travel at the speed of light. All matter with positive mass travels at under the speed of light. Maybe, if matter with negative mass existed it would travel at a speed greater than the speed of light. I think that this would make it undetectable.

Gravity is the tendency of objects with mass to accelerate toward each other. "Presumably", objects with negative mass would accelerate towards each other and away from objects with positive mass. That means us. So it would not only be detectable, it would be difficult to find.

IF it existed, IF we could find it, IF we could capture it, it would have amazing results. We could travel without expending energy. We could have inexhaustible power.

"Exotic matter is a hypothetical concept of particle physics. It covers any material which violates one or more classical conditions or is not made of known baryonic particles. Such materials would possess qualities like negative mass or 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 exotic matter is a region of pseudo-negative pressure density produced by the Casimir effect."(WIKIPAEDIA)

It is generally accepted that antimatter has positive mass, and that matter and antimatter are attracted to each other, leading to annihilation. This is not absolutely certain. "If antimatter is found to have negative gravitational mass, and thus 'fall up', it would be a step toward explaining two major cosmological paradoxes. The first is the apparent local lack of antimatter: by theory antimatter and matter would repel each other gravitationally, forming separate matter and antimatter galaxies. These galaxies would also tend to repel one another, thereby preventing possible collisions and annihilations. This same galactic repulsion is also endorsed as a potential explanation to the observation of an accelerating universe."WIKIPEDIA

THIS MEANS THAT the answer to your question is that we don't know, we may never know, but it could be really interesting if minus mass existed.

Answer 3

it would appear that there is such a thing as negative mass.

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Negative mass is not antimatter. When matter and antimatter contact each other, they release energy, and hence mass. For example, an electron contacting a positron causes emission of gamma rays, which have positive energy and, therefore, positive relativistic mass. (Gamma rays, like other photons, do not have rest mass, but, since they have energy, they do have relativistic mass.)

Negative mass is not a shield against gravity. A region of space having negative mass acts as a source of the gravitational field vector which, at any point, is added to all the other other gravitational fields at that point.

A chunk of material having negative mass in a laboratory on Earth would have negative weight. However, if we released it, it would not fall toward the ceiling. Since its mass is negative, it would accelerate in the direction opposite to the direction of the force on it. Since the force on it is upward, it accelerates downward. All masses, whether positive or negative, tend to accelerate toward a positive mass such as Earth. All masses, whether positive or negative, tend to accelerate away from a negative mass.

Answer 4

Mass is a scalar quantity; it has magnitude but no direction. It gives rise to weight, when affected by a force like gravity, and produces a gravitational field itself. Weight is a vector, it has magnitude and acts in a particular direction (which we conveniently define as 'down'). If an object had negative mass, it would exhibit negative weight - i.e. it would fly upwards away from the Earth, and would give rise to an anti antigravitational field, which is not known to exist anywhere in nature, so the answer is no.

Answer 5

No one knows for sure, but physicists are now aware that there is a kind of "dark energy" that permeates the universe that acts as a kind of negative mass, opposing the attractive force of gravity (caused by normal matter) and causing the accleration of the expansion of the universe.

Answer 6

Outerspace would be the closet to negative mass since space has 0 mass. But no, there is no such thing as negative mass.

Answer 7

Mass is a positive definite quantity.

EDIT:
Contrary to a couple posts above, outerspace does not
have zero mass and dark energy is most certainly not
negative mass.

Answer 8

A consideration was given to mass in a B hole. Hawkings has approached this and since adjusted some hypothisis.
MIT have released papers on this, and I would direct you to them.

Answer 9

Rest mass of a photon is zero but no substance can have a -ve mass

Answer 10

Possibly. Dark matter, if it exists, may have negative mass.