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MOND principle

  1. May 4, 2008 #1
    I’ve been studying MOND and some of the ideas behind theories put forward to explain MOND. Based on this I’m now going to describe the simplest, but most critical concept that’s used to begin understand why Newton’s inverse square law breaks down. Dynamics won’t be considered since they are complicated.
    I don‘t mind if you don‘t agree with it, I just hope it’s comprehensible.

    There are some concepts that need to be clarified before the concept can be understood

    Messenger particles.
    It is often theorized that force field interactions are propagated by ‘messenger’ particles, like for the electro-magnetic force, the photon, for gravity, the graviton. I was taught this at college. It is intuitive that such a messenger particle transfer between bodies might result in a repulsive force, because that is exactly what happens for the macro classical case e.g. a ball thrown between 2 people. But what about attractive force? My college teacher was quick to explain the repulsive model, but didn’t say much for the attractive force.
    How are attractive forces intuitively explained?
    Simple. As any good physicist knows, such small entities as messenger particles, theoretical or not, would not be well described simply as particles. Every object in the universe has a wave particle duality, and the wave aspect of a messenger particle helps in describing attractive forces. A messenger particle sent between 2 bodies would have an associated standing wave, which could create an attractive force. E.g. two people with a rope which is then oscillated to create a standing wave will be pulled towards each other. E.g.2. If I recall correctly, van der walls force has been shown to be a result of standing wave attraction.
    Might all attractive forces be a result of standing waves?

    Side note. A standing wave, viewed only at it’s nodes, appears much more particle like. Perhaps it is true to say particles are the nodes of standing waves.


    How many bodies are needed for a messenger particle exchange?
    2 is the obvious answer, and up till the early twentieth century no argument otherwise would have been taken seriously. But, as physics went through the quantum revolution, it became clear a system under observation from outside acted differently to one which was unobserved, and the concept of a quantum jump became central to physics. E.g. the electron - proton interaction inside an atom is much more restricted when under observation, the system has fewer allowed states compared to when it is unobserved.
    More importantly, since observation itself is interaction, a system that is never in some way observed, is not considered to be part of the universe. This is observation in it’s broadest sense of course, not the familiar restricted meaning of electro-magnetic interaction ( e.g. a person looking, touching or smelling etc something ). Any type of interaction can be considered observation.
    So it has some real meaning to say 2 bodies are needed to interact, and a 3rd body is needed to observe the 2 bodies for the system to be part of the universe.

    * Conjecture : To observe a system, a 3rd body must have a standing wave messenger particle interaction with the system.
    If this seems unreasonable then consider that many physical dynamic are known to require this. E.g. Within an empty electric conducting box, all electromagnetic interactions within the box have to be standing waves. Other than this slight justification I won’t go into this here.

    The last bit of physics I need you to have in your mind…
    Wave - energy transfer association
    Every acceleration of mass can be said to have an associated wave. Acceleration of mass implies change of kinetic energy. And energy is associated with waves via the equation E=hf. Subsequently, acceleration can also be said to have an associated frequency and wavelength.
    High energy waves have high frequencies and short wavelength, low energy waves have low frequencies and long wavelengths.
    e.g. Electrons in a particle accelerator often emit high energy electro-magnetic radiation. This is clear example of wave - energy transfer association, but usually the acceleration - wave association is more theoretical. E.g. A car speeds up. Where is the associated wave? In theory it exists, but it is difficult to observe.


    The key principle for MOND a based theory
    Consider a galaxy, and in particular, the gravitational force between the galactic centre of mass and a star in one of the spiral arms. Gravitational attraction between such masses is very weak. The energy transfer in such interactions between an atom in the star and an atom in the galactic centre is typically much less than 1/10 that of the average energy transfers between atoms in the lowest temperature environments ever created on Earth, I.e. Bose Einstein condensate temperatures.
    And so, the theoretical acceleration waves associated with such star - galactic centre interactions are very weak, and so could be expected to have low frequency and long wavelength.
    It is assumed a 3rd body is needed outside the interaction to observe it. Another star in the galaxy seems a good candidate observer, but, and here’s the critical point, assuming * the largest wavelength standing wave between two stars in a galaxy is too short a wave length and thus too high energy to observe accelerations typical of star - galactic centre gravity.
    In fact this is a point migrom made in 1983. The gravity acceleration between star in a spiral arm and the galactic centre is so small that the associated wave would has a wavelength the size of the universe. c^2/R or c/T, where R and T are the length and age of the universe. ( note that R is the non expanding universe R )
    This means it is possible the associated gravity waves between stars and their galactic centres can form standing waves with the galaxies on the edge of the observable universe.

    Now we can answer the question of why there is a cut off, and break down in Newton’s inverse square gravity field for galaxy rotation curves.
    For stars near the galactic centre, the gravity attraction and acceleration is strong, and so the associated wave has relatively short wavelength. Depending on the stars distance from the galactic centre, these waves can form standing waves with nearby to distant galaxies.
    But at greater distances from the galactic centre, the associated wavelength exceeds c/T, and since there are no observable galaxies at distances capable of containing a standing wave at distance of c/T, no standing wave can form.

    This associates the c/T galaxy rotation curve cut off to a principled theory that can be worked into the existing structure of modern physics.

    Summary of theory
    Messenger particles are better described as ‘messenger quantums’ - they can take on particle and wave behaviours.
    Observation and interactions have an associated wave, where the wavelength and frequency are dependant on the energy transfer of the interaction.
    Interactions between 2 bodies require a 3rd body to observe the interaction in order the 2 bodies can be part of the universe.
    To observe and interact, the messenger quantum between 2 bodies must be a standing wave.
    Only inter-galactic distances or greater will suffice for star - galactic centre gravity interactions observations, because the energy transfer between star and galactic centre is so small, the associated wavelength is very long.
    There is a necessarily a cut off for such observations and waves, because beyond the observable universe there are no galaxies to act as observers. This is the cause of the c/T discontinuity of galaxy rotation curves.

    One sentance Summary :
    The galaxy rotation anomaly\cut off is due to the size of the universe setting a lower limit on energy transfer via observer, standing waves principles.

    Hope that was understandable!
    Please give critical feedback if you feel I haven’t explained something well or if there’s a fault in my understanding.
     
    Last edited: May 4, 2008
  2. jcsd
  3. May 4, 2008 #2
    Sounds very interesting. I by no means have the expertise to critique this theory, but from my reading your logic is connected and well formed. I think you'll have to wait a few years for my formal opinion though :wink:
     
  4. May 4, 2008 #3

    cristo

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    Have you got any links you can provide us with on this topic, meemoe_uk?
     
  5. May 4, 2008 #4
    It depends what you want Cristo. I’ve got links to principled MOND theories. But they are not easy reading.
    If you are looking for material to quickly verify what I’ve written then I don’t think there is any available. I’ve been following MOND for several years and I’ve been frustrated at the lack of easy reading on the subject. The only stuff which is easily read is the initial mond theory, the success it had with low surface brightness galaxies and comparisons with dark matter theories.
    I think MOND is suffering from a ‘too much too soon’ problem.
    The situation we’ve got is many theorists independently working for years in isolation, creating several theories which incorporate MOND into some general unified theory. When I read these papers, the concepts and mathematics are foreign to anything I’ve encountered before. It is difficult to draw intuitive meaning from them without a lot of study. This is arising because when the key concept of MOND ( distant observer galaxies are required for Newtonian gravity ) is taken as true, it has massive implications for the rest of physics. Once most of the key concepts I’ve described are realised by the theorist, there is a major temptation to revise large parts of general physics into some completely new equations. It took physicists decades to unravel the many implications and meanings of the equations of Schrodinger and Dirac. By comparison, MOND theorists are now dumping several grand abstract theories and mathematics on a scientific community that has tired of, and is awash with such grand, all incompassing theories, each one stressing some aspect of physics as being the key to unlocking new understanding. The result is, like I say, lots of abstract impenetrable grand theories, and little common agreed on intuitive understanding. Hence the MOND community is slow to unite. Each theorist talks his own language but has little understanding of the others.
    What I’ve written about MOND is what I been able to gather over the years from occasionally hacking away at these abstract theories. I don’t know of any other members of the sci community who’ve made much progress here.
     
    Last edited: May 4, 2008
  6. May 4, 2008 #5

    Chronos

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    MOND is an effective theory - it explains observations but lacks scientific foundations. That does not mean it is wrong, merely suspect. Ptolemy had a similar theory - predictive, but, not well grounded.
     
  7. May 5, 2008 #6

    Wallace

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    Like Ptolemies epicycles, the formalism of MOND may well be a useful tool for further our understanding, even if the conceptual basis turns out to be wrong. In the case of epicycles, the formalism gave astronomers a framework to describe their measurements of the planets motion over the sky. This made doing and recording these motions easier and therefore meant that there was more data, arranged in an understandable way, available for Copernicus to realise what they really meant.

    In the case of MOND, the formalism works remarkable well for a range of mass scales, i.e. galaxies, clusters of galaxies etc. It might not be because MOND is 'right' conceptually, but the fact that the formalism works could tell us something about the nature of dark matter, or whatever else might be found in the future to explain the mass/light discrepancy.
     
  8. May 5, 2008 #7
    Actually, MOND doesn't work well for clusters at all. They too need to invoke extra mass in the form of neutrinos, which may not work either. See this paper for more. Not to mention the bullet cluster, or other clusters where there is an apparent separation of baryonic matter and mass (from weak lensing) eg. Abell 520 and CL0024+16.
     
  9. May 5, 2008 #8

    jal

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    This concept requires an additional concept ... "future cosmic horizon".
    ie. the two people holding the skipping rope.
    jal
     
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