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Problems with light speed?

  1. Dec 29, 2006 #1
    In the general theory of relativity the geodesics of spacetime are defined by light rays; the path of a light ray defines the shortest possible path between two points. However, once we remove matter from spacetime there ceases to be a reference frame that seperates physical points, so the Universe would have no spatial extent.* No spatial extent infers no temporal extent; meaning the Universe would literally collapse in on itself instantaneously, becoming a point.

    There is thus a major difference between light, massless electromagnetic radiation, and the 'modes of light' we call particles of matter. Both are the same substance but expressed differently.
    How could we measure the speed of light in a Universe of 'pure light'? Does this mean what we call distance, speed and other dimensional measurements are simply projections of the material observer? Why this distinct boundary between the perspective of light, for which dimensional measurements have no meaning, and the perspective of matter?

    * The intervals of spacetime are defined by the presence of matter so that without matter we literally get no spatial extent

    NOTE: I recognise this post as speculative but would like some feedback. The problem has been bothering me for a long while and I wonder if anyone has encountered some form of solution...?
  2. jcsd
  3. Dec 29, 2006 #2


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    1) Geodesics are not "defined by" light rays. Geodesics are curves which parallel transport their own tangent vectors, and which have constant tangent magnitude everywhere. You seem to be suffering from a confusion between the mathematical model (general relativity) and the physical world. You can't "define" a mathematical concept (like a geodesic) with a physical phenomenon (light). It literally makes no sense at all.

    2) Reference frames don't "separate physical points." Reference frames are coordinate systems, nothing more, nothing less.

    3) There is no reason whatsoever that an absence of matter means an absence of space. I have no idea why you think an absence of matter implies an absence of "spatial extent." This is a non-sequitur, and is nonsense.

    4) Particles of matter are not "modes of light."

    5) Intervals of spacetime have nothing at all to do with the presence of matter. Intervals are the distance between points (events) in spacetime, and are just mathematical concepts. There's no connection between spacetime intervals and matter. None at all.

    I believe you need to spend quite a bit more time studying before trying to come up with theories of your own.

    - Warren
  4. Dec 29, 2006 #3
    If the mathematical models have no correspondence to physical reality then why are they used as a basis to descriptions of the physical world?

    I can assure you this is not 'my own theory' - I wish it was! I'm simply making conclusions, albeit speculative, on the established theory of relativity and quantum field theory.

    Please try to think a bit more on the points mentioned.... or someone else could?

    I'll try to address the scientific criticisms made without math but apologies if they are not detailed.

    1) Dependence of matter on spacetime. This follows on from the work of Eddington (see the mathematical theory of relativity)
    Aside from your 'math/physics' comments, the argument derives from the fact that without curved spacetime there is no spacetime to talk of - its like talking about nothingness as real.
    2) Particles as modes of light. Every bit of matter has a wavelegnth of energy, shown by de broglie and both matter and energy are equivalent. Baryonic particles derived from gamma ray interactions in the past.
  5. Dec 29, 2006 #4


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    I'm not saying the mathematical models have no correspondence to the physical world; I'm saying that you cannot use physical phenomena to define mathematical concepts.

    Your conclusions are nonsense, unfortunately, so they don't really require any further thought. You're claiming that the presence of a vacuum means the universe will collapse -- that's just nonsense. Sorry to burst your bubble.

    1) The existence of spacetime has nothing to do with the presence of matter. I think you must be misunderstanding something.

    2) It's true that particles have wavelike characteristics, as defined by quantum mechanics. It's true that matter and energy are considered, in some senses, interchangeable. It is not true that matter is a form of electromagnetic radiation.

    You seem to have a very ad hoc understanding of physics, and you use words without an apparent understanding of the distinct meaning given to those words by physicists. In other words, your arguments are sloppy, and are nothing more than hand-waving. Your conclusions" are unfortunately meaningless, since they are not based on a thorough understanding of the underlying assertions.

    Please note that speculative material and personal theories are not welcome here, and this thread (like your others) teeters much to close to the border.

    - Warren
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