What is Negative mass: Definition and 51 Discussions

In theoretical physics, 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, Krasnikov tubes, the Alcubierre drive, and potentially other types of faster-than-light warp drives. Currently, the closest known real representative of such exotic matter is a region of negative pressure density produced by the Casimir effect.

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  1. T

    B Particle with negative mass inside a black hole horizon

    [Moderator's note: Spin off from previous thread due to topic change.] Just as an aside and not related to the OP, would a real particle with negative mass inside the event horizon follow the runaway motion? Would it be ejected?
  2. C

    I Detect Negative Mass Matter: Experiments in Solar System

    How could we detect negative mass matter? The only proposal I've ever heard of is that we could detect there's a cutoff frequency in the gravitational waves we receive, due to attenuation of those lower frequency waves by negative matter. Are there more experiments that could be conducted...
  3. A

    I Negative Mass & White Holes: Does It Create?

    does somebody with a negative mass create a white hole instead of a black hole because of its anti gravity property.
  4. KarlM

    A Dark matter and energy explained by negative mass

    Any thoughts on this paper? https://arxiv.org/abs/1712.07962
  5. bbbl67

    I Is Negative Mass Possible? Exploring the Latest Research and Controversy

    Was reading this article: https://phys.org/news/2018-01-device-negative-massand-lasers.html#jCp The article claims that these guys have created negative mass? If that's true, isn't that ground breaking? It's one of those extraordinary claims that needs extraordinary proof, doesn't it? Or is...
  6. F

    I Negative Mass and Hawking Radiation

    Matter with negative mass, herein called “negative matter”, is different from antimatter. P.A.M. Dirac, on theoretical grounds, proposed the existence of antimatter, and its existence was later confirmed by experiment. Antimatter is the opposite of ordinary matter in some ways, but just as...
  7. Allen_Wolf

    B Exploring the Possibility of Negative Mass: Implications and Limitations

    If we imagine two particles A and B. A has positive mass and B has negative mass and initial velocity 0. This happens in a non interfering environment . If both theses has opposite and equal value of mass, shouldn't they be repelling each other? F=G. (M.-m)/r^2. Value of F should be negative.
  8. G

    A Can Weyl Tensor Look Like Negative Mass?

    The smoothed Weyl tensor can look like space that contains a non-zero Einstein tensor. To verify this, consider that gravitational waves carry mass away from (say) a rotating binary, so the apparent mass at infinity of a large sphere containing a radiating binary will be greater than the mass...
  9. T

    A Is Negative Mass Related to Antimatter in Physics?

    In physics we cannot easily imagine “negative” energy for a particle (not a field) in order to have “negative” mass, although the first concept of Dirac for antiparticles was that they were “holes” that were opposite to particle existence and there was a minus in front of mc2.Regardless of...
  10. RyderP

    Warping an Average Guy Across Town: Exploring Negative Mass

    How much negative mass would it take to warp, say, an average guy across town?
  11. S

    Is it possible that an electron can have a negative mass?

    I have this brain worm and it's been bugging me for ages. I don't know enough about anything to be able to answer this but when I heard a theory that an electron can be in 2 places at once but then appears to be in a specific location when observed I started wondering how this could be possible...
  12. C

    Can Negative Mass at near Speed of Light go Back in Time?

    Sorry if the title was a little vague, character limits. The question at hand is this; If you were to accelerate an object to near speed of light, time around it would speed up, thus forward time travel. We all know this and I am no expert in this area but am incredibly curious. (Assuming we can...
  13. martin25p2

    I Relationship between negative mass, energy and antimatter

    What is the relationship between negative energy, negative mass and antiparticles? I have read some articles but I am still confused. Does negative mass exist? Does negative energy exist with the exception of the Kasimir effect which I understand. Are antiparticles really only the negatice...
  14. V

    B Negative potential energy and negative mass

    My question is: If gravitational potential energy is normally negative, and E=m•c^2, doesen't that means that negative mass could exist? (I don't know much about general relativity so please explain as simple as posible)
  15. Hawksteinman

    I How would negative mass interact with gravity?

    Let's assume that negative mass is possible. How would it react with gravity? Since F=ma, the acceleration would be in the opposite direction to the force applied. Keep this in mind :wink: Now, the gravitational force, F=GMm/r2. Usually this force acts towards the centre of the Earth since 'G'...
  16. N

    B Negative Mass: Does it Impact Spacetime & Gravity?

    Does negative mass have the same affect on spacetime as "positive?" mass with respect to gravity? Just read a BBC article that says peeps are playing with negative mass fluid...guy says "With negative mass, if you push something, it accelerates toward you," uh what? Also with the "law" that...
  17. Greg Bernhardt

    Physicists create 'negative mass'?

    Now this sounds interesting! Is this really "negative mass" or is that marketing spin? Thoughts? Paper: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.155301
  18. K

    A Is Negative Mass Real and How Does It Affect Energy in Space?

    Hello Everyone, While deriving potential energy stored in space due to two stationary opposite charges we end up with negative value of energy which upon dividing by c square provides us with negative value of mass. What is the significance of this mass other than reducing the total mass of...
  19. J

    Exploring Negative Mass: What Would Happen?

    I'm in Physics 1 and this is an extra credit I need 1. Homework Statement From time to time, it is amusing to consider extending physics to unusual circumstances or values of parameters. Consider an object with a negative mass. How would it behave? How would we be able to detect it if it...
  20. Garlic

    Negative Mass Particles: Will They Reach Infinite Speed?

    Hello, I heard that theoretical particles that have negative mass (techyons) are predicted to tend to speed up to infinite, if their energies are low enough. I don't understand why infinite speed instead of 2c (double the speed of light) are predicted? Note: I don't know whose/which theory it...
  21. R

    Infinite Acceleration, Conservation of Energy, and Negative Mass

    I've read that the Alcubierre Drive depends on the existence of negative mass, but I've seen that physicists say it could violate the conservation of energy. Their reasoning is that basically a negative mass and positive mass would interact in a perpetual motion sort of way that eternally...
  22. V

    Negative Mass: Exploring the Question of Momentum After a Collision

    I'm aware that this Topic is generally considered hypothetical, but at least I'm not talking about something that someone can say, "hey, that's your personal theory". A decent number of respected physicists have published papers on one aspect of the subject, or another. There is a...
  23. O

    Consequences of a negative mass universe

    If a universe existed where all the mass was negative but everything else was the same as our universe in terms laws of physics what would happen? To be more specific it appears that all the mass would repel each other, would negative mass atoms form, would these particles absorb or emit light...
  24. O

    Could neutrino have negative mass?

    Can anyone think of an empirical reason the neutrino could not possibly have a negative mass; that is any of its states?
  25. N

    QFT w/ Negative Mass: Spin 0 vs Spin 1/2

    In the Klein-Gordon equation (spin 0), the mass dependence is (only) through m^2, whereas in the Dirac equation (spin 1/2) it's through m. Does this mean that for spin 0 particles, we can just as well describe them as having negative mass without changing any of the physics (whereas for the...
  26. P

    Proof that a negative mass causes superluminal speeds?

    I've heard this theory, based on the assumption that if negative mass objects exist, they would travel faster than light. I planned on mentioning this in a physics paper I have to write for my class, but I just realized that I have no idea what formula shows this correlation. Can somebody help...
  27. W

    Negative Mass: Exploring the Possibilities

    I was thinking, can an object have negative mass? If an object with positive mass needs infinite energy to go at the speed of light, would an object with negative mass need infinitely negative energy (if negative mass were possible, this would be possible too right?) If an object had negative...
  28. E

    Does antimatter (negative matter) have negative mass ?

    Does antimatter (negative matter) have "negative mass"? If not, why is this so suspected? And could anything theoretically have negative mass?
  29. S

    Can Negative Mass Really Defy Gravity?

    Michio Kaku mentions in his TV series "Physics of the Impossible" about negative mass being able to repel gravity. I haven't heard much about this before. How would the negative mass affects the geodesic in spacetime manifold? Perhaps by causing negative curvature of spacetime? Would this...
  30. T

    Β+ decay: voiding conservation of mass or creating something with negative mass

    From Wikipedia: "Positron emission or beta plus decay (β+ decay) is a type of beta decay in which a proton is converted, via the weak force, to a neutron, releasing a positron (the antimatter counterpart of an electron) and a neutrino. Isotopes which undergo this decay and thereby emit...
  31. B

    Exploring the Hypothetical Possibilities of Negative Mass

    Let's say that negative mass existed, what might it look like? Could it look like an ordinary rock stuck in the ground? If so, what would happen if you tried to move it around? If it moves in the opposite direction it is push then wouldn't it be impossible to move it in any direction? Would it...
  32. L

    Is the Schwarzschild spacetime with negative mass geodesically complete?

    Hi, If you look at the Schwarzschild geodesics for negative mass, I believe that radial null rays can hit the naked singularity in finite value of affine parameter? but if L <>0 then the null rays get repelled away from r=0 no matter what their energy? does this mean the spacetime is null...
  33. J

    Imagine there is a piece of paper negative mass

    Imagine there is a piece of paper negative mass simply pushes up while mass pushes down doesn't that mean that a black hole would be created by mass and negative be same a rip in the paper or in other words space ps I am not very advanced in physics so don't flame me and try to keep your...
  34. heusdens

    Here is some weird idea: Dark matter/energy explained by negative mass matter

    I have before theoretized about the idea if matter with a negative mass could theoretically exist, and what it's properties would be, acc. to the standard theories (GR). In fact you could argue for two kinds of models for this hypothetical negative mass matter, namely: model-1: anti-symetric...
  35. S

    Does antimatter have a negative mass

    If this question has an answer I didn't find it on the rest of the forums.
  36. J

    Antimatter, Negative Mass, & Gravity: Unveiling the Mysteries

    In many websites I read that antimatter has antigravity properties. Does negative mass exist. Does antimatter react differently with gravity.
  37. C

    Negative Mass: Fact or Fiction?

    someone told me about this and it doesn't make sense to me how it could even be possible. Because if you had something with negative mass it technically wouldn't even be matter now would it? so what i am trying to ask is this just a ridiculous phenomena such as perpetual motion is.
  38. S

    What Would Happen if Mass Was Negative?

    This isn't really a homework question... but it is homework... and I have a question... so I thought I might as well post it here. This is part of my grade 12 Physics curriculum. For our project, we're supposed to ask ourselves "What if <this happened>?" I chose to do mine on negative...
  39. H

    Wormholes, parallel universes, negative mass

    Hi. I have a few questions. Is it theoretically possible to build a wormhole to a parallel or baby universe? Could a sufficiently advanced civilization do this? Could negative mass play a role in it? Could something else?
  40. J

    Could Negative Mass Exist and Affect Black Holes?

    Looking at gravitational and electrical interation relations, I had an idea: F = kQq/r^2 F = GMm/r^2 Couldn't it exist negative mass? First formula says that electrical charges reject each other if they have same sign, and they pull if they've different sign. We know that masses with same...
  41. S

    Negative Mass and its Implications

    I was thinking the other day about how mass creates valleys in fabric of space-time and how objects follow that path. Then I came to think, isn't it theoretically possible that there could be a negative mass that creates hills in the fabric of space-time? What do you guys think about this...
  42. K

    Do galaxies have a negative mass defect?

    http://en.wikipedia.org/wiki/Binding_energy#Mass_Defect But the opposite is true for galaxies! Quarks too! Their mass appears to be larger than their constituents as well...
  43. F

    Could Gravity Be a Negative Mass Particle?

    i am thinking what if gravity is itself a negative mass particle? like, if you have something in front of a black hole right? how would it gain gravitational potential energy? if anything with positive mass can't cant out of a black hole?
  44. P

    If a particle had negative mass where would it go?

    If an oblect or sub atomic particle had negative mass, would it "fall" up? And if so where would it go? If the universe is infinite the particle would find a place as far away from all other positive mass objests as possible and we would never see it or know it existed at all! It could...
  45. F

    Negative Mass: Explained | Effects on Particles

    Can someone please explain negative mass and what exactly it is? How does it effect subatomic and atomic particles?
  46. M

    Exploring Negative Mass & Its Impact on Gravity

    Hi Please bear with me on this as I’m doing aerospace engineering at college level in the UK, so my knowledge on atomic physics is none to great. What I would like to know is about gravity in a way and yes this has something to do with Quantum physics as well but this is also to do with...
  47. E

    Negative Mass: Possibility of FTL Travel?

    Is there any theories or something of that sort, which allows negative mass? Hence, v > c rather than v < c. This seems like the only logical possibility to FTL travel.
  48. B

    Exploring the Possibilities of Negative Mass

    Anyone tried to imagine a world with negative mass? A mixed world of normal mass and negative mass does not seem so bad in the sense that a negative mass moon would surprisingly still orbit the earth! Might be problems in making atoms though...
  49. M

    Exploring Negative Mass: What Is It & How Does It Differ?

    Ive heard that its believed that a particle with a negative mass, could "in theory" travel faster than light. my question is, what does negative mass mean? how does it differ from a positive mass, or having no mass at all?