Einstein’s Equivalence Principle is Not True for Non-static Gravity

Discussion in 'Physics & Math' started by cosmodel, Jun 7, 2006.

  1. cosmodel Registered Senior Member

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    Einstein said on the origin of his general theory of relativity:
    “While I sat at my Bonn office, an idea came to my mind: one feels no weight when freely falling. I was shocked at the thought, which gave me deep impression and led to my later theory of gravity.” This is called Einstein’s equivalence principle which says that a freely-falling person does not suffer gravity (weight). However, we can not ignore the condition to which the principle holds. The condition is that earth’s mass is approximately constant and the resulting gravity is accordingly static. If the mass changed significantly with time, would a freely-falling person feel no weight (gravity)?
    We can not make an experiment to test it. There are astronomic bodies, e.g., supernovae, which change masses dramatically within hours or months. We may establish the gravitational theory of varying masses and test it on the phenomena of supernovae. However, simple thought can resolve the above question and indicates that Einstein’s equivalence principle is not true for non-static gravity.

    Earth’s mass introduces spatial in-homogeneity. Einstein’s equivalence principle is true for the gravity due to constant but spatially in-homogeneous mass distributions. I call it static gravity. Now we consider the other extreme case of mass distributions. The mass density of the distribution is the same throughout the space (spatially homogeneous) but varies with time. The resulting gravity no longer has a specific gravitating direction because of the mass homogeneity. Therefore, an initially-motionless person in the field remains to be motionless. The person must feel weight (gravity) exerted from all spatial directions in equal magnitudes. The gravity has the similar properties to the ones of air pressure. Therefore, I call it pressure gravity and Einstein’s equivalence principle is not true for it. The question arises, is there any example of pressure gravity in the real world? Everyone knows the principle of isotropic universe which says that, in the large-scale universe, no position is preferred and people observe the same properties in one direction as in the other. Observations support isotropic universe. Because the large-scale mass distribution in the universe changes with time certainly, the universe presents an example of pressure gravity. I developed a flat-universe model based on the result [1].

    Realistic gravity is non-static, which is the case between the static one and the pressure one. Therefore, Einstein’s equivalence principle is not true for any realistic gravity. Einstein used the principle to introduce the assumption of curved spacetime in his general theory of relativity. Therefore, the assumptions of curved spacetime and all other related assumptions like expanding universe are questionable.

    References:
    1. He, J. The Faulty Assumptions of the Expanding-Universe Model vs. the Simple and Consistent Principles of a Flat-Universe Model. Astrophys. & Space Sci. Submitted (2006).
    http://www.arxiv.org/abs/astro-ph/0605213
     
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  3. Magic Chicken Registered Senior Member

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    You missed the point that the equivalence principle is also only true when tidal forces are neglected.

    However neither this point nor the point you make unseats the equivalence principle nor GR. The reason is that we are already quite used to dealing with factors which hold true over successive vanishingly small intervals - this is why we learn calculus. That the equivalence principle is true over vanishingly small radial intervals dr (per my point above) or vanishingly small time intervals dt (per your point above) doesn't mean it's wrong.
     
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  5. DaleSpam TANSTAAFL Registered Senior Member

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    Welcome to SciForums cosmodel,

    MC has put it well. Also, since any mass distribution can be mapped to an acceleration field then any acceleration field should be mappable to one or more mass distributions. The fact that there may exist no real object with the same mass distribution is irrelevant.

    -Dale
     
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  7. CANGAS Registered Senior Member

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    An exploding star does not lose much mass at all, taking into account that ongoing nuclear reactions convert some small amount of mass into photons and neutrinos which rapidly depart. The mass is redistributed outward in an expanding sphere, most often at a velocity far below the velocity of light, and, on the average equally in all directions. The center of mass remains at the same relative location as if the star had not exploded. It would take some time for the gravitational inverse square rule to start making an astronomically measureable difference in the ex star's gravitational influence on neighboring astronomically observable bodies.

    During his lifetime. it was very obvious that Einstein sought to create an abstraction of all force fields to an acceleration field, and he seemed to me to blur the distinction between a field induced acceleration and a mechanically caused acceleration, to, in my opinion, the detriment of clear understanding of some physical effects.
     
    Last edited: Jun 22, 2006
  8. cosmodel Registered Senior Member

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    62
    Fortunately, my new result was posted as Appendix at
    http://www.arxiv.org/abs/astro-ph/0605213
    Every one can read the Appendix. It is very eazy to understand. The requirement is that you know the famous Galilei leaning tower experiment!!
     

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