Q: What’s the difference between anti-matter and negative-matter?

Physicist: Anti-matter is exactly the same as matter, but different.  If you, and everything else on the planet, were suddenly turned into anti-matter, you’d never know the difference.  While the “anti-” of anti-matter may seem to give it an air of mystery, it still acts just like ordinary matter in essentially every respect.  Specifically, anti-matter carries positive energy and mass, just like regular matter, while negative matter carries negative energy and mass.

Famously, when you bring matter and anti-matter together they annihilate.  All of their combined mass is converted into buckets of energy in an amount dictated by Einstein’s little-known equation, E=mc2.  For comparison, the largest nuclear device ever detonated, the USSR’s “Tsar Bomba”, is the yield you’d expect from about 1 kg of anti-matter (so about 2 kg of energy total, because it needs some mass to annihilate with).  A single atom of anti-matter (say, anti-carbon) annihilating in your ear would be just barely audible as a pop.  It’s the energetic equivalent of a ant stomping a foot (in anger!).

Negative matter, more commonly called “exotic matter”, has negative energy.  If you were to bring it into contact with ordinary matter you would see, not an awesome explosion, but an underwhelming and abrupt nothing.  When exotic matter in brought together with ordinary matter, the positive energy of the matter and the negative energy of the exotic matter cancel out entirely, leaving nothing at all behind.

Exotic matter is a freaking blank check for sci-fi writers.  Warp drives, worm holes, perpetual motion, and even time machines are possible if you allow for negative matter and energy.  In fact, Hawking proved that if you want to build a time machine smaller than the universe, negative energy/mass is a requirement.  Spacetime, as described by general relativity, is pretty limited by the fact that energy and matter seem to be strictly positive.  About the weirdest things you’ll see are black holes, which are pretty cool, but… time machines.  With a liberal peppering of exotic matter (often far more than the universe’s total stockpile of regular matter) you can really open up the flood gates of the weird.

However the big difference, arguably the biggest difference, between anti-matter and negative matter is that negative matter doesn’t exist.

There are some subtle physical laws that imply that the creation of negative energy, in the form of exotic matter or not, has limitations called “quantum interest“.  Anytime a bit of negative energy is generated (and the methods involved create, like, none), a larger, overwhelming pulse of positive energy must be created almost immediately.  In fact, we’ve never directly observed negative energy and it’s very, very likely that we’ll never be able to do more than infer that negative energy exists.

But anti-matter definitely exists, and can be created and stored (a few particles at a time) here on Earth.  Many particle accelerators today generate and use anti-protons all the time.  When you smash stuff together, or otherwise get a mess of energy in one place, new particles are generated; half matter and half anti-matter.  It’s basically annihilation in reverse.  Once you create a spray of new particles, you sort the matter and anti-matter apart, keep the anti-particles ionized, and store them (briefly) in a “magnetic bottle“.  If they ever becomes electrically neutral the magnetic bottle stops working, and they fall and annihilate with the ordinary matter at the bottom of the container.  Anti-particles are totally the hot potatoes of particle physics.

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24 Responses to Q: What’s the difference between anti-matter and negative-matter?

  1. steve says:

    What’s your take on a proposition by Christian Beck at the University of London and Michael Mackey at McGill University, which seems to indicate that following a phase transition, some zero-point photons below a frequency of about 1.7 THz, making them gravitationally active, whereas above that they are not? Supposedly this resolves the 120 order of magnitude problem which excludes zero point as a candidate for dark energy.

  2. The Physicist The Physicist says:

    Never heard about that idea.

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  4. Alexander Cooke says:

    Negative matter annihilating with matte breaks conservation of energy, the only way for them to have o momentum before annihilation is to being going in the exact same direction at the same speed.

  5. pingpong says:

    antimatter exists but negative matter does not

  6. Xerenarcy says:

    physics is full of funny coincidences… time only goes forward. mass-energy is always positive. gravity always attracts. speed always slows time, doesn’t reverse it. i think we are at a point where there are far too many equivalences implying a preferred energy ‘direction’ for them to be unrelated.

  7. Rob Heusdens says:

    Matter with the property of having negative mass has sure been hypothized and researched as an abstract concept. For example Bondi studied it.
    In fact one can think of two different kinds of negative mass. 1. Using the standard assumption that gravitational mass = inertial mass, or 2. Using the non-standard assumption that gravitational mass = -1 * inertial mass. [or: intertial mass = absolute value of gravitational mass]

    For assumption 1., the properties of negative mass are:
    – negative mass attrackts negative mass, but then (F=ma, inertial mass = gravitational mass) accelerates opposite to the force! Effectively then negative mass self repels.
    – positive mass is repelled from negative mass.
    – negative mass accelerates towards positive mass.

    For assumption 2., the properties of negative mass are:
    – negative mass attracts negative mass (and here: also accelerates in the same direction)
    – positive mass is repelled from negative mass (as in assumption 1.)
    – negative mass is repelled from positive mass.

    [Please note that assumption 2. is in fact unnecessary, because all that it does is interchange the concept of positive and negative, and therefore it would be just the same as negative mass matter in assumption 1.]

    Using assumption 1. and hypothezing that there is indeed negative mass matter (that is, we do not exclude it´s existence, although it has never been found directly) and see how it would behave if it exists in the universe like positive mass matter (from the big bang), for example created in equal amounts as positive mass matter.

    Positive mass matter would as in the big bang model form galaxies and stars. Negative mass matter however self repells and spread out. But since it accelerates still towards this positive matter clumps, it will surround the galaxies, and have influence on the rotation speed of the galaxy. Since it also self-repels, it would therefore not exist inside the galaxy but only around it.

    Another property is the electromagnetic properties of negative mass matter. Here the negative mass matter inverts attraction and repulsion as compared to positive mass matter. Positively charged negative mass matter will attrackt positively charged negative mass matter, that is like charges attrackt, unlike charges repell. For electromagnetic interactions between positive mass matter and negative mass matter, we can also find the interactions for the combinations of the two types of mass and two types of charge (which here for brevity I have left out, but which can easily be resolved).

    Now this is of course purely theoretical, and noone seen ever negative mass matter. Standard physics currently excludes the negative mass concept, and considers it unphysical. But then nobody ever saw dark matter either, in fact we still don’t know what it is, we can only say what it is NOT. It might be that negative mass is the only remaining candidate and can be shown to fit the data quite well.

    Although that is something seperate, previously also the concept of repulsive gravity and negative energy were thought of unphysical/impossible, but inflation just comes with this concept well thought out. This does not imply negative mass should be considered to be physical too solely on that basis, but then maybe it is not too far fetched to consider it physical, and see if that would somehow help explain somethings we currently do not know. Unless it can turn out to have explenatory power and consistentent with the other established framework of physics (or maybe large part do need to be rewritten), there is no use of assuming that it negative mass matter can exist.

    A very speculative thought, which ought to be further explored is if negative mass matter can fit the data we have about dark matter, and also fits the experimental data we have about the evolution of the universe. But we know the impact of this would be enormous, since it would involve many parts of physics, which partly need to be rewritten on the basis of physical existence of negative mass matter (if a case can be made it makes sense as candidate for dark matter and/or dark energy). It would be major paradigm change in physics, and maybe even opens the way to unifying gravity with the other forces.

  8. antonio carlos motta says:

    The violation of cp that permit explanação particles the asymmetry between matter and antimatter, só the dark matter.

  9. Antônio Carlos motta says:

    If the symmetry Pt was strongest brokenthe lorentz’s invariance Wil né violated and would appear vectorial field that would indicate an absolute inertial frame ,and the t.violation would lead to arrozw of time.anything beyond cpt would Imply a new physics beyond str because the speed of light will be infinity.i think that antimatéria Neves had existed same in the early universo.then the are antiparticles?

  10. Antônio Carlos motta says:

    Wrong above,is violation of cpt and not Pt

  11. Rob Heusdens has a very interesting analysis of negative energy based on negative matter. There is however another possibility for negative energy. If the negative energy resides in a different (string theory) brane than our physical universe, having different dimensions, the speed of light will be imaginary and the square of the speed of light will be negative and the matter might be positive and the energy equation is satisfied. Matemetician Luigi Fantappie found in 1941 that the qualities of negative energy matches the qualities of “life” (e. g. reducing entropy with time). “Life” can be called consciousness. The quest for consciousness and the quest for negative energy could be the same thing. String theory could hold an answer and establish a new paradigm. See Wikipedia for Luigi Fantappie or Physics Essays Vol 28, no 1: Negative energy explained by an imaginary speed of light or amatterofmind.net

  12. Nathan says:

    First you must have a gama photon with 1.022Mev. Next the photon must hit something, some underlying structure, it has to be so because a photon is not the same thing as an electron and a positron. There must be a nucleus or a free electron to facilitate the pair production also. But, why we think there is a “creation” and/or annihilation? Only because we do not see?
    E=mc2 is about mass, I wonder, what happens to the charges?
    Maxwell predicted the existence of dipoles in vacuum. The vacuum is considered a dielectric also.
    Maxwell postulated the existence of a displacement current, that is fundamental to the propagation of electromagnetic waves.
    Now we can talk about Quantum Foam , but we do not accept Ether?

  13. antonio carlos motta says:

    In the universe does not exist antimatter same in the early universe.mothing sais that existed equal amounts of matter and antimatter, then antimatter is not negative energy The antiparticles are subproducts of the matter and of the spacetime, then the differences of particles and antiparticles appear due the breakdown of symmetry of CP. Exist not motives for the universe bê symmetric .

  14. Colin says:

    If you want questions about energy answered. > See a hippy.. these folks know more than you thought.

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  16. Antonio Carlos Mota says:

    Antimatter makes not exist the nature same in the early universe.the antiparticles are phenomenon out of common produced by the asymmetry of matter,space and time,but that gives symmetry for space time continuum in 4dimensional manifolds with mirror symmetry breaking as CP and deeply PT the generate the antiparticles in the spacetime continuos

  17. Ben says:

    it doesnt violate conservation laws, because if ngative matter has negative mass, it HAS that mass, nothing is lowly destroying its mass, and when it interacts with positive matter it adds together to make 0, ex: Negative carbon 12 added to positive carbon 12, you can think of negative carbon 12 with mass of -2 or something, and positive would have the opposite, 2 so if they combine they make 0, the masses arent going any where, its like a hole 2 feet deep and you fill it up with dirt 2 feet, you still have positve and negative mass, but they kind of balance each other out so you have 0 mass.

  18. No one has ever found negative mass/matter. Mathematics (the quadratic energy equation) says there is negative energy. Adding positive and negative energy does not make zero energy, but you get a fluctuating balance between construction and destruction (according to Luigi Fantappiè) such as we see in a place with living organisms. Life make construction, matter makes destruction.

  19. Rosy rodrigues says:

    The antiparticles are not negative energy,but are derives by the STR of einstein that implies in the relativity of space and time.the antiparticles hás shortest lifetime,then is are asymmetrics,Given by the violation of CP,and the antiparticles are symmetries generated by the spacetime.the transformations of right handed into left handed and vice-versa are not totally invariant,but observe that the time dilatation and the contraction of spacetime are vinculated by the particles run forward in time and the antiparticles backward in time.also the antiparticles run forward in time,will as the particles run backward in time demostrating that the spacetime is symmetrics and for that reason,violation of CP could measure the time dilatation that occur with speeds near the speed of light

  20. Rosy rodrigues says:

    I believe that the displacement correntes Given by the equations of maxwell for the propagation of the electromagnetic Waves. the foam spacetime are Given by the quantum entanglement ,From where emerge the spacetime,will as to maintain the symmetry of the equations of dirac appear the particles and antiparticles for the discrete spacetime that is originated by the violation of cp

  21. Robert Morrow says:

    Negative matter annihilating with normal matter doesn’t break conservation. The conservation laws apply to the total energy of a system. A system involving such an interaction would begin with zero total energy and end with zero total energy.

  22. Andrew Grundy says:

    The graph of spherical area as a function of volume, A=cube root of 36pi*Volume squared has values of volume that are positive and negative. If volume is an emergent property of the contained matter, would negative volume be an emergent property of antimatter?

  23. Andrew Grundy says:

    Area=4pi((-i*r)^(2)) = -4pi(r^(2)), Volume=(4pi/3)((-i*r)^(3)) =i(4pi/3)(r^(3)). Maybe volume emerges from a bunch of atoms, each having identically charged outer orbitals, likewise with a bunch of anti-atoms, both bunches have classical positive volume, but what about their orbitals can these have imaginary radii?

  24. Andrew Grundy says:

    Found out that Volume is a scalar, a value greater than or equal to zero, negative value indicates that the sphere has rotated by pi radian, or half a turn, i , is a quarter of a turn, -i, is three quarters.

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