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Thread: Cosmology

  1. #1051
    Maybe YesNo's Avatar
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    I agree with your two beliefs.

    Symmetry or invariance may be a useful way to see the structure of physical models of the universe. https://en.wikipedia.org/wiki/Symmetry_(physics) I haven't looked at this closely. Relativity is an "invariance" when measuring differences between two events in space-time from any frame of reference. What invariances are there in physical models? Philosophically, what does this tell us about reality?

    I have been re-reading Moffat's "Reinventing Gravity". I would like to understand the theory of gravity well enough to make more sense out of Moffat's modification of it. It appears that Einstein's theory of gravity breaks down when discussing galaxies and larger clusters of galaxies. It no longer makes accurate predictions unless one assumes there is dark matter and dark energy present.

    Then there is also quantum physics. It is easy to confuse the model with reality here, but one has to know the model to philosophically assess the confusion. These all tie together. I don't think it is possible to compress an atom into a black hole which makes me wonder if black holes are possible. If they are not then Einstein's theory of gravity needs to be modified.

    For me, the whole question is philosophical, but I need to understand the mathematics and physical theory to ground that philosophy.

  2. #1052
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    It usually seems to me that the deepest propositions from physics are doomed to failure and usurpation. For instance, What is the nature of matter? is to me likely a doomed question any one answer to which we will never settle on for long. Compared to this, the absolute truth of Quadratic Reciprocity stands out like a granite monument of absolute and unchanging consistency.

    Each temporary answer we accept along the way will take us far and enable many new miracles of technology. But in the end each will show its limitations and contradictions which prepare the way for a new theory to supplant it.

    Each new advancement will have a mathematical framework, sometimes consisting of newly invented or discovered mathematics. When the physical theory it once supported has been supplanted, the skeletal remains of these systems will consist of a funeral scaffolding of mathematics which remains true of itself without the insufficient physical theory it was once thought to support.

    In other words, it is not mathematics which we cannot know with certainty, but the nature of physical reality which eludes and will continue to eldue us. Each best theory of physical reality will become insufficient and contradictory. On the other hand, addition, subtraction, derivatives, integrals and matrices are just as useful, true and efficient as they ever were at containing certain aspects of physical relaity.
    Last edited by desiresjab; 04-20-2017 at 01:19 AM.

  3. #1053
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    That's how I see it also. Mathematics is certain. Technology, when it works, is useful. Physical theory changes.

    I found Frank Wilczek's "A Beautiful Question" in the library. It is about symmetry and physics. I expect it to be a survey of ideas he finds beautiful in science.

  4. #1054
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    I have avoided studies of symmetry because I feel one must know a lot of Group Theory, since that theory is known for ideas on symmetry. But, yes, it is highly provocative, and probably bears a good relationship to the deeper structures we are seeking.

  5. #1055
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    I stopped reading Wilczek's book after reading the introduction. All of a sudden I felt like it might not be what I needed at the moment.

    I am sort of avoiding symmetry for the same reason, but if I think of symmetry as a way to achieve "invariance" in physics theory I start looking at it differently. I do have Carmichael's Introduction to Groups of Finite Order. That will take some time to read and most of it may not be relevant to physics.

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