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    Does the matter of negative mass exist?

    Wondering if mass can be negative? looking for this information online? On this Ask Expert page find responses from experts.

    Matter mass is always positive in nature. Is there any possibility of matter having negative mass? If not, can we create matter of negative mass in reality. According to physics if mass became negative it will get displacement in direction opposite to applied force.
  • #142418
    Negative Mass is an opposite sighn. If negative mass exist then it would voilate the laws of Universe: Energy, momentum and therefore, negative mass cannot exist. The reference content is available in Wikipedia.

    Infact, negative and positive mass produces counterintuitive behaviours. The negative mass cannot exit because it breaks one of the essential assuption behind the brilliant brain Einstien's theory of general relativity in 1914.

    We remember Albert Einstien for more than his disheveled hair, big eyes, and witty charm. He is genius and physicist who changed the way we see the world. His famous formula of E=mc2 revolutionized scientif thought and brought us into the nuclear age through his special theory of Relativity. He reasoned that since everything in the universe in motion. He also believed that the speed of light is the only constant by which we can measure space, time or physical mass.

    If Negative mass exist, it would turn out that for negative mass there would be no event horizon and this will lead to naked singularity because when distance from the singularity is large, Physicists simply ignore it.

    Negative mass appears to voilate the energy.

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  • #142439
    Let's put this outside the context of therautical physics. In real physics we know, just like energy, the matter just changes it's forms. Negative matter means absence of matter. You can't have negative matter. However the lack of matter in certain regions of space such as black holes goes to show that the law does not hold. For same reason many such concepts don't hold true in space. And this makes you wonder if it is possible to have negative mass to measure it's existence. I think black holes being interesting phenomenon it makes us question the definition of the time, negative mass, absence of energy etc. I'd say there is no conclusive research on this. Not atleast the most peer reviewed research. That;s one reason I think many of us have disagreement towards concepts of negative mass.

  • #142517
    TThis response is marked as DELETED by the admin.

    Negative mass is the hypothetical idea that matter can exist with mass of the opposite sign to the ordinary stuff. ... Their approach means that negative mass can exist in our universe provided there is a reasonable mechanism for producing it, perhaps in pairs of positive and negative mass particles in the early universe.

    We have never seen such a thing experimentally, but theoretically it could be possible. Some people think that antimatter could be gravitational repelled by normal matter, i.e. that it could have negative gravitational mass (its inertial mass is positive, we know that). ... Not let's turn to inertial mass
    There are two kinds of mass: inertial and gravitational. Inertial mass is the one that appears in Newton's second Law F? =ma? F?=ma?. Gravitational mass is the one that appears in the law of gravity - it plays the role of "gravitational charge". General Relativity Theory assumes, that the two are fundamentally equal, but this assumption, like any other, requires experimental testing. Right now we see experimentally no violation of this equality.

    So generally your question is really two questions: can gravitational mass be negative and can inertial mass be negative. If negative gravitational mass were possible, it would mean, that repulsive gravitational interactions between masses are possible. We have never seen such a thing experimentally, but theoretically it could be possible. Some people think that antimatter could be gravitational repelled by normal matter, i.e. that it could have negative gravitational mass (its inertial mass is positive, we know that). This is in principle testable experimentally, and I think there are plans for such an experiment.

    Note that the "dark energy", that supposedly drives the accelerated expansion of the Universe does not have negative mass. In General Relativity the sourceof gravitational field is so-called stress-energy tensor, that consists not only of mass and energy, but also pressure and shear. "Dark energy" has positive energy density, but a peculiar equation of state, that makes in accelerate the expansion of the universe.

    Not let's turn to inertial mass. Having negative inertial mass would lead to all sorts of paradoxes: particles accelerating opposite to the applied force, and negative kinetic energy - meaning that the faster a negative mass particle moves, the lower its kinetic energy. Theoretically you could draw infinite energy from a single negative mass particle. Therefore I don't know about any theories that would consider free particles with negative inertial mass.

    There is one a bit special case where "negative inertial mass" appears: movement of charge carriers in a periodic potential (think crystal). As it turns out when you solve the equations of motion of an electron in such a periodic potential, they appear similar to the equations of motion of a free electron, but with a different mass. This so-called effective mass can be higher or lower than free electron mass, and under certain conditions in can even become negative. However this effective mass is not physical - it is just a number you put into the equations to make them look simpler.
    Very strictly speaking, the mass of any stable mode in a relativistic theory is nonnegative, by definition. In case of particles, this is so because the mass mm is given by m2=E2-p2m2=E2-p2 (where EE is the energy of the particle and pp is the spatial momentum, which together form the relativistic momentum Lorentz vector) and we merely pick the positive root (the case where m2m2 is negative is that of a tachyon which represents instabilities in the theory and will not be considered here). For a field ?? this is so because the mass mm is given by the coefficient -m2-m2 of the quadratic term -m2|?|2-m2|?|2 in the Lagrangian (assuming that the gradient term is |d?|2|d?|2 without any negative sign of its own) and we again pick the positive value.

  • #142736
    The concept o negative mass is against the rules of Universe. For any matter to exist it should have mass and this is Universal truth. We humans have hardly explored the Universe, so maybe hypothetically we can assume that there can be the existance of negative mass in the Universe just like the concept of Black holes where we have only made assumptions but have no proof of its behavior. But as per the present known theories of physics we can definately conclude that negative mass cannot exist. Even the basic atomic theories can explain this. Every matter will have atoms and atoms will have electrons, protons, nucleus, etc. An atom cannot exist without a nucleus and as nucleus has mass the atom will have mass. Therefore the concept of negative mass is impossible as per present human knowledge and theories.

  • #142848
    Actually, the idea of negative mass does not exist. It holds only the negative sign and on the basis of the physics theory, it does not possess. Think the mass or positive mass exists because a thing exists in this universe. The negative mass is against the rule of this universe.

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