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    The difference between matter, antimatter, dark matter, and negative matter
    By Hontas Farmer | November 18th 2010 01:51 PM | 22 comments | Print | E-mail | Track Comments
    Here I will explain the difference between matter, anti matter, dark matter, and negative matter in a concise and understandable way.   I have seen confusion pop up in various online forums and comments on the recent announced trapping of an anti atom by CERN. 

    The first thing to know is that for a physicist there are four fundamental forces of nature which are always at work.  These are the familiar Gravity and  Electromagnetism, as well as the generally unfamiliar strong and weak atomic forces.   The atomic forces work on the length scale of atoms, Electromagnetism and gravity work on the length scale of the universe though in fundamentally different ways.

    The different kinds of matter interact through these forces in different ways. 

    Normal matter like that which we are all made of interacts via all four forces in the ways which we are familiar with.  All of the science and technology we have done to this point is based on normal matter and how it behaves.  But for a few experiments and in certain particle accelerators all we have done has been with normal matter.   Hence it's name. 

    Anti matter is just like normal matter only the sign of certain properties is different.  The classic case would be the electron, which has as it's anti particle the anti-electron also known as the positron.  Electrons are negatively charged, and Positrons are positively charged.  Yet they are identical in every other way.    Then their are particles like neutrons and protons which are made of even smaller particles called quarks.  Quarks interact via the strong atomic force, and electromagnetism.  Anti Quarks have opposite charges to Quarks in those two forces.

    Dark matter on the other hand only interacts by way of gravity and the weak atomic force.  Dark matter does not interact via either the strong atomic force or electromagnetism hence dark matter cannot be seen and is hard to detect.  It only interacts via the weak force which is what keeps neutrons and protons inside the nucleus of atoms together.    Such is why experiments to detect dark matter directly rely on a particle of dark matter bumping into a particle of matter dead bang on the nucleus of an atom of normal matter.  

    Most of the reason we think dark matter exists has to do with the fact that it solves problems in cosmology in a very expedient way without us having to alter General Relativity.  It is widely agreed that dark matter whatever it turns out to be quantifies how much we really don't know about the matter in the universe. 

    Negative matter is a hypothetical type of matter which if it exist will have negative mass and negative energy.  It will in essence have a negative gravitational charge and repel normal matter.  Yet it will interact just like any other matter in every other way. 

    This table summarizes the differences in how each type of matter would interact with the different forces.

     Normal Matter Anti- Dark- Negative- 
    Gravity  As usual As usual* As usualOpposite sign 
    Electromagnetism As usual Opposite sign No charge ?
    Strong Force As usual Opposite sign No charge ?
    Weak Force As usual Opposite sign As usual ?


    *We assume that antimatter behaves as normal matter under gravity.  The truth is we have never seen a large enough mass of it to know for certain it behaves the same.  When it comes to Negative matter we know nothing and it may not even exist outside of certain theories.  Dark matter is on the edge of being a confirmed real entity. 

    Comments

    vongehr
    Why so sure that dark matter interacts weakly (as usual) but has no strong interaction at all?
    Hfarmer
    Dark matter according to what I have read is now thought to not only be electrically neutral...but to be "collisionless".   That it really practically does not interact with itself in any significant way. 

    If a dark particle had a color charge it would not be collision less.   

    This is needed in order to exclude the possibility that the exotic dark matter that we are to spend millions to look for could not be plain old ordinary neutrons.  Supposedly their scattering off themselves and off the Universal medium would screw up cosmology. 
    Science advances as much by mistakes as by plans.
    vongehr
    Still does not explain why you so sure it interacts weakly (= weak force) more than even weaker with the strong force or whatever (except if you believe in a certain model already) - for all I care it might not interact at all weakly either before it decays.
    Hfarmer
    That dark matter interacts by the weak force I believe is part of most standard definitions of what dark matter is.  In fact it's the basis for the dark matter searches such as CDMS.  If it does not interact weakly then their is no way to detect it other than it's gravitational effect...which I for one would rather simply reformulate gravity to make something we cannot detect and prove exist go to the ash heap. 
    Science advances as much by mistakes as by plans.
    MATTER IS NOT COMPOSED OF PARTICLES LIKE MICROSCOPIC SAND, BUT IS INSTEAD COMPOSED OF SPHERICAL QUANTUM WAVE STRUCTURES IN THE SPACE AROUND US AS A SPACE RESONANCE. (MILO WOLFF, a. EINSTEIN, E. SCHRODINGER, E. MACH, ETAL

    Hfarmer
    The definition of wave and particle in field theory has them basically as being the same thing.  
    In QFT a particle is essentially an excited state of the field.  So an electron is something that's created and destroyed by the QED field.  

    Then there is M theory in which everything is an excited state of a N dimensional "brane" which vibrates.  None of which is really needed for this blog and is overkill since I write things like this for laypeople. 
    Science advances as much by mistakes as by plans.
    Check out 'Schrodinger's Universe' by Milo Wolff.

    rholley
    Three questions:

    (1) If there is negative matter, then wouldn’t there also be negative antimatter?

    (2) Looking at the abstract of the paper in question, I gather that the aim of the experiment is to gather enough antihydrogen to look at its spectrum.  It says:
    The charge conjugation/parity/time reversal (CPT) theorem, a crucial
    part of the foundation of the standard model of elementary particles and
    interactions, demands that hydrogen and antihydrogen have the same
    spectrum.

    But I thought that CP or CPT symmetry were already violated in the weak interaction.  Or does the weak interaction not affect the spectrum?

    (3) Only if you have time.   I am having difficulty with my picture of magnetism as a special relativistic consequence of electricity.  Could you please look at these two comments of mine:

         (a) http://www.science20.com/comments/53218/Re_Medieval_Practice_Be_Restored

         (b) http://www.science20.com/comments/53254/Bornerdogge_Here%E2%80%99s_how_I

    This, for me, is proving a real head-banger.  Any help much appreciated.
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    "But I thought that CP or CPT symmetry were already violated in the weak interaction. Or does the weak interaction not affect the spectrum?"

    Robert,
    The weak interaction violates parity. It has a detectable effect on atomic spectra, but this is so small that it is observed only with great difficulty, and has never been observed in hydrogen. CP violation is a much smaller effect still. But actually what they are talking about here is CPT symmetry, which is not violated by anything.

    Hfarmer
    1.) I see no reason that negative anti matter could exist if negative matter does. 
    2.) The spectrum of the particles should be the same as hydrogen because the Schrodinger equation and it's spectrum of solutions should be the same for the particles in question.  The magnintude of the charges hasn't changed, the intrinsic spin of the particles hasn't change.  Only the sign on the electric charge has changed.  That ends up not mattering for the spectrum. 

    3.) The train of electrons becomes Lorentz contracted however all the other laws of physics in the rest frame of the moving particle also adjust themselves.  Suppose that train of electrons is at rest with respect to you.  Your going to see no current and an electric field.  Then the train starts moving... now you see a current and a magnetic field. 

    At the same time an electron in that train only detects a electric field from itself...and a magnetic field from the particle you are sitting on. 

    So what you see is a magnetic field shift into being an electric field or vice versa.  

    The way that relativist look at the problem is using tensor mathematics. The electro magnetic field tensor is just the electromagnetic field tensor no matter what. 




    There it is in the form of it's components.   You have to look at it in that way.  
    Science advances as much by mistakes as by plans.
    rholley
    So what you see is a magnetic field shift into being an electric field or vice versa.
    Hence the displacement current.
    There it is in the form of it's components.   You have to look at it in that way.
    That is the view from the sunlit peak of the mountain.  But I'm still struggling on the misty slopes!

    That is why I could never have been a physics student.  Some folks seem to be able to sail along on pure logic, simply taking on board  “the div of a curl is zero” as a pure fact.  But until I have a grasp of what that really means, I get no drive out of it.
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    Hfarmer
    Well Robert  it took me a long time of being very wrong to get to where I am.  I have had good grades and horrible grades.  Special Relativity was harder for me than General Relativity, go figure? 

    It wasn't easy for any of us.  Though thankyou for making me think of Special Relativity.  It took me a good 15 minutes to come up with that answer.  I really wish I had a more straighforward one.  

    Charges in motion produce magnetic fields...so if you are in motion, and you see a charge going by you will see a magnetic field, and hence a current.  Though in your own reference frame you would not notice anything but some charges moving by and producing a current.  The physics of being at rest while the charges move past you would be exactly the same. 
    Science advances as much by mistakes as by plans.
    rholley
    Special Relativity was harder for me than General Relativity, go figure?
    I don’t  find that at all bizarre.  The maths of GR is much more advanced – when teaching history of maths, on bringing in differential geometry I found that none of the students had any reference points to it – but if you can do that sort of maths it’s a straightforward procedure.  On the contrary, without the help of Minkowski, SR requires all sorts of circus-like mental contortions to understand what’s going on.

    That’s my experience, anyway.
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    rholley
    I’ve found a book which sorts the matter out, and commented on it here:

    http://www.science20.com/comments/53720/I%E2%80%99ve_just_borrowed_Classical
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    You're dumb. No mention of the expanding universe?

    icarus2
    Negative mass(energy) can explain the dark matter and dark energy. 1. Observation evidence for dark matter 1) Galactic rotation curves 2) Galaxy clusters and gravitational lensing 3) WMAP 4) Bullet cluster 5) Structure formation 2. In the Galaxy, No evidence for dark matter 1) At the Earth : non-observation(Xenon100, CDMS II...) 2) At the solar system : non-observation 3) At the center of galaxies : no evidence Greedy Supermassive Black Holes Dislike Dark Matter http://www.universetoday.com/13091 Astronomers Find Black Holes Do Not Absorb Dark Matter http://www.universetoday.com/60422 4) At the galactic plane : no evidence "No evidence for a dark matter disk within 4 kpc from the galactic plane" http://arxiv.org/abs/1011.1289v1.pdf 5) At the galactic halo : no evidence Globular Cluster problem "Evidence Against Dark Matter Halos Surrounding the Globular Clusters MGC1 and NGC 2419" http://arxiv.org/abs/1010.5783 3. Dark matter and dark energy come from one origin(Negative mass) It is simply explained. Dark matter which has negative mass is clustered around galaxy. And centripetal force effect exist in the galaxy from dark matter halo out of the galaxy. Centripetal force effect in the galaxy from dark matter(negative mass) halo out of the galaxy. [Simulation video] http://www.youtube.com/watch?v=ylEi2gpnD08 In the simulation, When negative mass's shells exist at outline, collision time is shorter compared to existing only with positive mass's shells. This implies that there exist additional effects of centripetal force by the dark matter halo at the galaxy's outside in case of the galaxy having the axial symmetry. Motion of the negative mass : http://www.youtube.com/watch?v=jlDl9w8ariI --- Icarus2
    Hfarmer
    Yeah dark matter negative matter etc etc. ... I am a theorist but enough of a realist to want to see it.  My family goes back to the show me state of Missouri.  I still need to be shown a "jar" full of dark matter or a detector that can detect the stuff on demand or even just one good clean detection signal and I'll believe it. 
    Science advances as much by mistakes as by plans.
    icarus2
    I’m sorry. I can’t English well. My native language is not English. So, my expression is insufficient. (-_-);; If you are theorist, I can propose some ways to prove validity of hypothesis of negative mass. 1) Dark matter and dark energy come from one origin According to hypothesis of negative mass, most of dark matters have negative mass and it proves that dark energy is a gravitational potential energy(with positive value) between negative mass and positive mass. Currently, there are Ω_m = - 0.38(±0.22) and Ω_m = - 0.4(±0.1) values what HSS team and SCP team calculated in relation to size of negative mass corresponding with size of dark energy and another one what I calculated in V-2. (HSS(The High-z Supernova Search) team : Brian P. Schmidt, et al. : "Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant" http://arxiv.org/abs/astro-ph/9805201 14P, 26~29lines. If Λ=0, Ω_m = - 0.38(±0.22) : negative mass density SCP(Supernova Cosmology Project) team : S.Perlmutter et al.: "Cosmology from Type Ia Supernovae" http://arxiv.org/abs/astro-ph/9812473 7P If Λ=0, Ω_m = - 0.4(±0.1) : negative mass density From the observance of the HSS team and SCP team in 1998, they gained the mass density of the negative(HSS: Ω_M = -0.38( ± 0.22), SCP: Ω_M = -0.4( ± 0.1)), using field equations which do not have the cosmological constant.(It is inspected Field equation during 70 years.) But, the value was discarded.) What we have to do now, is to induce rotation curve or the quantity of dark matters within the galaxy, referring to the method what I proved in V-4.(Calculating centripetal force in galaxy from Negative Mass(Dark Matter) distributed out of galaxy.) Therefore, when centripetal force effect by density of this negative mass can explain rotation curve within the galaxy after setting density of negative mass outside of the galaxy as Ω=-0.38 or to be five ~ X times bigger than positive mass’s, it would explain dark energy and dark matters at once through negative mass, thus proves that hypothesis is right. ======== In the simulation, Dark matter which has negative mass is clustered around galaxy. And centripetal force effect exist in the galaxy from dark matter halo out of the galaxy. ======== Additional effects of centripetal force exist from the previous simulation. Unfortunately, proving has not been succeeded yet owing to my knowledge shortage. Please try to it. Again, I'm sorry.
    Hfarmer
    Or one can just as validly propose a theory of gravity that makes all those particles of dark matter unneeded.
    Science advances as much by mistakes as by plans.
    icarus2
    Negative mass is stable at the maximum point! Therefore the catastrophe to energy level of minus infinity never happens. Nature prefers stable state, and has the tendency to go to stable state. Additionally, this can be expressed in another way that nature prefers low energy state, and has the tendency to go to low energy state. Such an idea is frequently used as a logic which denies the existence of negative mass. That is, if there is negative mass and negative energy level, negative mass spontaneously emits energy to be stable, and goes to energy state of minus infinity, so finally it is confronted by catastrophe. In case of positive mass, stable state means low energy state, therefore it is not necessary to divide which one nature prefers among two states(stable state and low energy state). By the way, does stable state mean low energy state also in case of negative mass? http://4.bp.blogspot.com/_udXTGLmmdK4/Su-xBLdm3PI/AAAAAAAAAAM/ByaVtThbj_... In the negative mass, F= - ∇U, F= - ma (m>0), a = - F/m As examined in the question of Harmonic oscillation, in case of positive mass, a point of minimum value which energy is the lowest is stable. However, in case of negative mass, stable equilibrium is a point of maximum value, not a point of minimum value. So negative mass is toward a point of maximum value to be stable, not a point of minimum value which energy is low. In the world of positive mass, ground state is a point that energy is low, but in case of negative mass, ground state is a point that energy is the highest. Accordingly, in the world of negative mass, energy level is filled from the highest to the lowest, and stable state means the highest energy state, so the catastrophe to energy level of minus infinity never happens.
    Hontas,
    In the introduction you say that:
    "Dark matter does not interact via the strong atomic force hence dark matter cannot be seen."
    Surely you meant to say: "electromagnetic force" as that's the one that interacts with our vision?

    Hfarmer
    I did leave E and M  out of that statement.   Dark matter cannot be composed of hadrons, or particles which interact via the strong force. Thanks.
    Science advances as much by mistakes as by plans.