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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.

  • #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.

  • #147018
    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. Instead of 2 kg, a lump of negative mass would be -2 kg.
    Nobody knows whether negative mass can exist but there have nevertheless been plenty of analyses to determine its properties. In particular, physicists have investigated whether negative mass would violate various laws of the universe, such as the conservation of energy or momentum and therefore cannot exist. These analyses suggest that although the interaction of positive and negative mass produces counterintuitive behaviour, it does not violate these conservation laws.
    Cosmologists have also examined the effect that negative mass would have on the structure of space-time and their conclusions have been more serious. They generally conclude that negative matter cannot exist because it breaks one of the essential assumptions behind Einstein's theory of general relativity.
    Today, Saoussen Mbarek and Manu Paranjape at the Université de Montréal in Canada say they've found a solution to Einstein's theory of general relativity that allows negative mass without breaking any essential assumptions. 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.
    Their conclusion has far-reaching consequences. They point out that if positive and negative matter particles exist in the universe, they would form a plasma that would have important implications for the future of astronomy.
    First some background. When Einstein published his general theory of relativity in 1916, it immediately piqued the interest of the German physicist, Karl Schwarzschild. He studied the mathematics and soon discovered the first exact solution of the equations other than the trivial one of flat space.
    The Schwarzschild solution describes the nature of space-time around a point-like mass. This is the well-known black hole solution, which is hidden behind a surface called the event horizon. At least, for positive mass.
    These objects are probably the best studied in theoretical cosmology. So it's no surprise that cosmologists have long asked what happens when the mass is negative.
    It turns out that for negative mass, there is no event horizon and this leads to a naked singularity. Although this sounds odd, it needn't be a problem given that physicists have considerable experience similar kinds of mathematical singularities.
    Physicists already deal with exactly this kind of singularity when considering a point charge in electrodynamics, which is also a singularity.
    Here's how they cope. When the distance from the singularity is large, physicists simply ignore it. And they also have a mechanism for dealing with it when the distance is small. "At close distance, we expect that the singular nature of the charge will be smoothed out by a concentrated but non-singular charge density," say Mbarek and Paranjape.
    So it's not hard to imagine that a similar approach ought to solve the problem of a naked singularity generated by a negative mass. Indeed, a couple of years ago, theoretical physicists showed that it was straightforward to smooth out such a singularity in this way.
    But there was an important downside: this was only possible by violating one of the essential assumptions behind Einstein's theory of general relativity. Consequently, physicists concluded that negative mass must be impossible.
    What is this this essential assumption? It comes about because the field equations in general relativity place no limits on the states of matter and non-gravitational fields that can exist in the universe. But physicists are well aware that these can only take certain forms.
    So the additional assumption they impose on general relativity is that only reasonable states of matter and non-gravitational fields are admissible. This is known as an energy condition.
    The problem with negative mass is that it appears to violate this energy condition. Indeed, that's how theoretical physicists have been able to show how negative mass could be used to create exotic objects like wormholes.
    The crucial breakthrough by Mbarek and Paranjape is to show that negative mass can produce a reasonable Schwarzschild solution without violating the energy condition. Their approach is to think of negative mass not as a solid object, but as a perfect fluid, an otherwise common approach in relativity.And when they solve the equations for a perfect fluid, it turns out that the energy condition is satisfied everywhere, just as in all other solutions of general relativity that support reasonable universes.
    That's an interesting result with significant implications. The first and most obvious of these is that negative mass can exist in the universe just as we see it. All that's missing is a mechanism for the production of pairs of particles with positive and negative mass in the early universe. That's surely not beyond the capability of the modern cosmologist.
    But here's an interesting thought. If positive and negative mass particles do, or did, exist, they would create a kind of plasma that would absorb gravitational waves. "Such a plasma would in principle cause an effective screening of gravitational waves, being essentially opaque for frequencies below the plasma frequency," conclude Mbarek and Paranjape.
    Nobody has ever seen a gravitational wave but not through lack of trying. Physicists have built a number of advanced gravitational wave detectors that have been seemingly on the verge of discovering these exotic waves for the last few years.
    For various reasons, these machines have always turned out to be slightly less sensitive than required to actually detect gravitational waves. But having significantly increased the sensitivity of their machines over the years, physicists are running out of excuses. These machines must soon detect gravitational waves or leave physicists with the both exciting and embarrassing task of having to explain what went wrong.
    The existence of a plasma of positive and negative mass particles is one such explanation. And the evidence that could back it up would be the discovery of the threshold frequency above which the waves do propagate, just as Mbarek and Paranjape predict.
    So an interesting question is where does this threshold lie and is it within the sensitivity range of the devices currently in operation.Scientists have created a fluid that exhibits the bizarre property of "negative mass" in an experiment that appears to defy the everyday laws of motion.

    Push an object and Newton's laws (and common experience) dictate that it will accelerate in the direction in which it was shoved.

    "That's what most things that we're used to do," said Michael Forbes, a physicist at Washington State University and co-author of the paper, which shows that normal intuitions do not always apply to physics experiments. "With negative mass, if you push something, it accelerates toward you."

    Negative mass has previously cropped up in speculative theories, including those suggesting the existence of wormholes, a form of cosmological shortcut between two points in the universe. Just as electric charge can be either positive or negative, matter could, hypothetically, have either positive or negative mass.

    For an object with negative mass, Newton's second law of motion, in which a force is equal to the mass of an object multiplied by its acceleration (F=ma) would be experienced in reverse.

    Theoretically, this sounds straightforward, but picturing how this behaviour would work in the real world is bewildering, even for experts.

    "It's very counterintuitive and weird," said Jon Butterworth, a physicist at University College London, who was not involved in the latest work.

    For instance, you might expect a ball with negative mass to be repelled from the Earth's surface, but theory predicts that it would behave just like ordinary matter and fall downwards.

    No fundamental particles with negative mass have ever been discovered, meaning that there have never been any experimental insights into how they might behave – if, indeed, they exist. The latest study provides a new platform to study this hypothetical form of matter, by showing that under certain precise conditions, normal particles can be made to behave as though they had negative mass.

    "It provides another environment to study a fundamental phenomenon that is very peculiar."

    The experiment, described in the journal Physical Review Letters, created the conditions for negative mass by cooling rubidium atoms to just above absolute zero, creating something called a Bose-Einstein condensate.

    In this cooled state, particles move extremely slowly and, following the principles of quantum mechanics, behave like waves. This state of matter is already known to exhibit strange properties such as superfluidity, in which a liquid can creep up the sides of jars and over the top.

    The cooling was achieved by using lasers to slow the particles until they were confined in a laser trap, less than 100 microns across. Breaking the trap causes the rubidium atoms to rush out, expanding in a spherical formation.

    However, when researchers applied a second set of lasers that kicked the atoms back and forth within the trap, they started to behave as though they had negative mass on exiting the trap.

    "Once you push, it accelerates backwards and it looks like the rubidium hits an invisible wall."

    Martin McCall, a professor of theoretical optics at Imperial College London, described the paper as a neat demonstration of a system exhibiting "effective negative mass" – something that has only rarely been created before in laboratory conditions.

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  • #147879
    Science starts with hypothesis, then proceeds to have proofs and justification for the hypothesis to become law or formula or scientific theory. Negative mas is one such hypothesis. If it has to be proved it should be in such a way that its co-existence should be established without it violating al the fundamental laws of science as existing now.
    The research and study goes on.
    In the case of sub atomic particles, first the knowledge was of electrons ,protons and neurons. But then we had negatively charged particles with mass called positron, then we had the hypothesis and justification of neutrinos, There are still more sub atomic particles in theory.

    There was/is a hypothesis of an anti-universe with exactly the opposite properties of Universe. Negative mass can exist in a situation where the physical laws are slightly different. For example as weight is a factor of mass and gravity, in zero gravity what will be the mass of a material? Zero will not be the absolute zero we think. It may become infinite.

    However this type of discussions will yield more results and suitable in more specialised science forums, rather than a general forum.

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