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Shut the window, or philosophers will get in!

  1. Sep 8, 2003 #1


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    Someone wrote me PM asking about the pedagogical merit and scientific validity of
    three papers by Rainer Zimmermann (Philosophy of Science, some connections to Cambridge and Uni Kassel)

    I cannot judge on my own, but must throw the question open.
    The three papers are
    http://arxiv.org/physics/0107061 [Broken]
    http://arxiv.org/physics/0107081 [Broken]
    http://arxiv.org/physics/0108026 [Broken]

    They can discuss the PHILOSOPHICAL merit of Zimmermann's discussion of LQG over in the Philosophy forum. What I have been asked is not about this. The person writing about this wants to know if it would be a useful non-mathematical introduction to the subject. Anyone who is willing to help, have
    a look and see what you think.

    I have looked at the first paper and can make several observations:

    1. it really is about LQG
    2. it really is non-mathematical (it is all words, no formulas)
    3. the references to technical papers are those of an intelligent
    and knowledgeable person----that is: the bibliography at the end is extensive and competent and invites use.
    4. when he discusses Spinoza and Leibniz I cannot understand much, but when he talks about Baez and Ashtekar I understand some of what he says and it is not all that boring either

    Customary Quantum theory and General Relativity are incompatible at the foundation level and therefore at the level of basic philosophical issues. Therefore to successfully quantize General Relativity one must reconsider basic question like what is space what is time what is the observer what is measurement what about Mach's principle and what do you make of causality.
    The smell of the issues which must be addressed will always attract philosophers. Therefore people who do QGR should keep the window closed or they will be getting in.

    Actually it might help to listen. I have to go. Cant resolve this right now.
    Last edited by a moderator: May 1, 2017
  2. jcsd
  3. Sep 8, 2003 #2
    I will look at them and am posting this short post to determine if the prohibition to my posting has been removed.
  4. Sep 8, 2003 #3


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    I read the first one, and I don't think it would help anyone learn LQG. He throws around the definitions without motivting or really explaining them at all, because he is mostly interested in getting to the metaphysics.

    As to that metaphysics, he shows to his own satisfaction that the LQG physicsits from Penrose on have had a confusion about what was fundamental, and that in attempting to build a combinatorial structure to be prior to spacetime, Penrose ran afoul of the fact the all our language is based on spacetime intuitions, so that nothing "outside of spacetime" can really be imagined. I leave the judgements on those conclusions to those who are intereested in such things.
  5. Sep 8, 2003 #4
    Kicked outr of library in 2 minutes but a fellow grad student at Hopkins who went on to get his doctorate in GR replied to my question of what's outside this expanding bubble. George looked thoughtful(which means the questin wasn't stupid) and replied, "Physics only applies to testable things and we can't communicate "out there" because all comunications is red-shifted out of perception. I disagree with him and wish I could find Murphy now. Please consider my post CONTNUOUS CREATION in Theory Forum.
  6. Sep 9, 2003 #5


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    it was me who pmed you.
    thanks for your answer (although i would have preffered if you had pmed back).
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  7. Sep 9, 2003 #6


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    Re: Re: Shut the window, or philosophers will get in!

    Hello loop, my apologies for acting otherwise than your preference. My problem is that, all joking aside, I cant judge
    the merit.

    I very much appreciated selfAdjoint's reply which was clearcut and frank. Much more precise than I could have been on short notice.

    I believe there is a usefulness to articles like Zimmermann's, but it is not an obvious one. He begins the article by letting us know how angry he was at Abhay Ashtekar for a perceived slight at a conference. there is something curious about the papers. He raises a cultural issue (european versus Indian, Ashtekar is from the Bombay area) in an oblique way.

    What the part of the Zimmerman article I read told me is that there is a gaping hole in the literature----no one has written about quantum general relativity for the layman who rejects equations. There is a communication gap.

    the philosophical questions are very urgent, and can be discussed without explicitly using equations (as Rovelli does in much of his draft book) but exploring philosophical issues does not explain the theory

    I think the best philosophical discussion of quantum gravity would be in a book you would make yourself by printing out all 300 pages of Rovelli and then going thru and throwing away every page that had a formula or equation on it. You would have a thin, and I think fascinating, book----discussing time and Mach's principle and the meaning of spacetime, all sorts of fascinating questions that are philosophical and must be confronted by those who try to bring general relativity and quantum mechanics into a single conceptual framework.

    But this interesting Rovelli book you would make by eradicating formulas from Rovellis "Quantum Gravity" would not teach a novice to understand the theory!

    There is a need for a non-technical introduction but I do not know of any!

    Zimmermann is not it.

    But Zimmermann articles are themselves kind of interesting and
    I wanted to share them. Thanks for alerting me to their existence.
  8. Sep 9, 2003 #7


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    edwardian echo
    nice closure

    before that you said

    he does seem to be speaking for himself there! personally I enjoy
    imagining combinatorial structures outside of spacetime
    and always try to imagine several of them each day before breakfast
    if you do not already do so yourself, allow me to recommend the practice!
  9. Sep 9, 2003 #8


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    But this interesting Rovelli book you would make by eradicating formulas from Rovellis "Quantum Gravity" would not teach a novice to understand the theory!

    There is a need for a non-technical introduction but I do not know of any!
    a simpletons view.
    if someone were to write such a "unbiased", book im sure it would be a best seller, the problem is keeping personal views nonjudgmental.
    if i see phrases such as, "it is 90% certain that BHs exsist",
    or" we dont know what an electon is, "but we know XYZ about it",
    in a book ,i imediatly think an "honest view" buy it.
    once i had read the book i would ask questions about it on PF
    and learn even more.
  10. Sep 9, 2003 #9
    what is 'combinatorial structures' (outside of spacetime)?
  11. Sep 9, 2003 #10


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    I was responding to selfAdjoint's post which contained these phrases. You may be too, wimms, so perhaps I should wait and let selfAdjoint define the terms----which he introduced into the discussion.

    An example of a combinatorial structure is a finite network imagined as consisting of a set of numbers called the nodes {1,2,3,4,5,6,}
    and a set of pairs of nodes e.g. {(1,3), (3,5), ...,(6,2),...}

    The six nodes are not imagined to have locations. They are not arranged in a line or in any particular way.

    The word "node" is not supposed to mean anything spatial.
    the set of nodes could be called the set of tigers, or the set of roses, or the set of ideas, or the set of letters----I only call them nodes to have a name so I can later talk about "pairs of nodes". But "pairs of roses" or "pairs of ideas" would be as good.

    Two nodes a and b are called "linked" if either (a,b) or (b,a) is in the set of pairs.

    So there is a set of nodes and a set of links and that is the combinatorial object or combinatorial structure or what have you.

    In a general sense the most basic objects in math are abstract sets and relations-----certain restrictions (axioms of set theory) are placed on the relations of the abstract objects but these
    have no spatial meaning

    the whole shebang is defined outside of any spacetime context.

    In an undergraduate course on the real numbers it may take several weeks starting from just abstract sets to construct the integers and then the rational numbers and then the continuum.
    Continua like the real line or like three dimensional space are not just running around wild but have to be constructed

    mathematics (20th century style) is not founded on continua but
    on combinatorial structures-----sets, relations, equivalence classes
    of sets, sets of equivalences classes.
    the most basic objects used by mathematicians are abstract---- not imagined to reside in space or time

    Maybe this is good or maybe it is bad. I cannot say. But it would sound really strange to me if someone were to say that abstract combinatorial objects are not thinkable outside a spacetime context.

    Hope this is helpful rather than contributing to confusion.
  12. Sep 10, 2003 #11
    thanks, that was helpful.
    To make sure I get it right, is tesseract example of combinatorial structure? Or set of Lorentz transforms? Fractals, or any chaotic function?
  13. Sep 10, 2003 #12


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    Many questions about the tesseract fall into the category of combinatorial mathematics. The original topology on polyhedra was called combinatorial topology because you calculated with such things as Euler Cahracterstic, # vertices - # edges + # faces.

    The "out of spacetime" figure was introduced in the paper, whose author seemd to think that, for example Marcus' combinatorial thoughts are necessarily spacetime thoughts, at some level.

    Remember that a basic philosophical idea has never got to be true, just persuasive.
  14. Sep 10, 2003 #13


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    There are half a dozen people around PF that would be
    more fun to discuss tesseracts with than me, or fractals and
    chaotic functions too.

    Combinatorial structures should not automatically be hard or strange---they should be the simplest abstract things we've got.
    This is my bias (certainly there are complicated ones too and hard-to-understand theorems as well if one looks for them but it shouldnt have to be hard)

    I bet you CAN think of a tesseract abstractly as a combinatorial structure (but that would only be the abstract "skeleton" of the thing: a list of vertices and edges-----it would get richer as you fleshed the combinatorial thing out with a fuller theory)

    Combinatorics has a "minimalist" flavor, like minimalist art and music. (If I'm wrong someone correct me!)

    Hey, dont lets talk about tesseracts but about a simple
    tetrahedron! A tetrahedron is pictured in space as a pyramid with triangle base.
    A tetrahedron is the "complete graph with four vertices"

    It has 4 nodes or vertices {1,2,3,4}
    and each one is linked to all the others! the edge set or
    link set contains six bi-directional links
    {(1,2), (1,3), (1,4), (2,3), (2,4), (3,4)}

    The idea of a tetrahedron is to have a triangle and go up one dimension and add a point and make all the connections
    (so the tetrahedron is the new "triangle" and it has 4 faces all of which are oldstyle triangles)

    If you enjoy taking risks and are always pushing the envelope you
    can try the same program with the tetrahedron (which lives in 3D space)

    You can go up one more dimension and add a point and make all the connections so you get a "new tetrahedron" with 5 vertices
    and 10 edges and 5 faces all of which are oldstyle tetrahedra.

    There is a name for this tetrahedron-on-steroids but I forget what it is. Anyway it is easy to list the vertices and edges and stuff. It is no big deal as an abstract combinatorial structure.

    There are no best-selling popularly written books about combinatorics.

    It is a required course for undergrad computer science majors (their data structures can be represented using graphs or networks, "trees" and whatnot)
    also for some reason highschool students from Romania and Slovakia and places like that seem to know a lot of graph theory.

    But it is not a jazzy subject by any means. Not like fractals and chaos.
    Last edited: Sep 10, 2003
  15. Sep 10, 2003 #14
    Time is recognized by man as a medium in which to impress a sequence of sounds(and other sequences)bearing information. It is questional that folks who use spatial sequences(writing) to represent sequences(time) of sounds are aware of the inconsistency in using both of these mediums to suggest the mediums aren't necessary for perception of the the physical or non-material part of man.
  16. Sep 12, 2003 #15
    this is a philosopher sticking his nose where it doesn't belong.

    well i think that writing is definitely not neccessary to experience the physical and nonmaterial parts of man, it is a useful tool for articulation and self-clarification and examination.

  17. Sep 12, 2003 #16
    I was referring to a comment about avoiding time and space which means to me something that can't be spoken or even thought about(in English for sure)

    The first article let me understand a bit of what Penrose writes abut. I like the part on the 6th page that explains he considers his "combinatorial exercises" as substance and Gravity(time-space) and Quantum states as "attirbutes"
    this rhymes a bit with G-d and L-rd being attributes of the One(ineffable) The first is the innate power of intellect to reveal and the secone is the unconscious ability to conceal this revelation in a garment of words or perception.
    I assume the nose you menitoned is your own philosophical member. Isn't it fun being a boy and not a puppet?
  18. Sep 12, 2003 #17
    it seems to me that english can be used to stimulate the progess of understanding but the understading must take place within one's soul.

    english such as this:

    when you meet it, you do not see its face.

    when you follow it, you do not see its back.

    when you love it, there is nothing to love.

    the image of nothingness.

    there is no difference between hallucination and non hallucination; all is real/unreal.

    nothing is real except in the mind.

    the mind is not real.

    reality is in the mind.

    there is no way to see reality for what it is. only to "see" it; to KNOW it.

    reality is comprised of a material part and a nonmaterial part. the nonmaterial part are commenly known as CONCEPTS. concepts are real.

    what does the concept of all concepts smell like, look like, taste like, feel like, sixth sense like?

    may your journey be graceful,

    ps: it feels good to be a boy.
  19. Sep 12, 2003 #18


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    here is an example of such a bit of english-----I encountered it in the philosophy forum and transcribe from memory:

    to see a world in a grain of sand,
    and a heaven in a wild flower,
    hold infinity in the palm of your hand,
    and eternity in an hour

    very likely this short rhyme of Wm Blake is familiar to you phoenix and others here

    here is one by Yeats called "In Gratitude to Unknown Instructors"

    What they undertook to do
    They brought to pass:
    All things hang like a drop of dew
    Upon a blade of grass.
  20. Sep 12, 2003 #19
    what blake is saying to my soul is there is no real objective evidence that is 100% reliable that there is such a thing as time or space. just being but not neccessarily self-aware of existing, perhaps like an amoeba. does there exist time for an amoeba? for the only real evidence of time is MEMORY. what if you have no memories of anything? does that mean you don't have an existence or just that you have no evidence of your own existence? descartes said that "i think therefore i am" but what if you learned a meditation in which you silence your mind and stop thinking? do you suddenly not exist? and then exist again once you start thinking again? or, more simply, you're not CONSTANTLY thinking. are you not existing in the moments when you're not thinking?

  21. Sep 12, 2003 #20


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    There was a young man who said "God
    Must find it exceedingly odd
    To see that this tree
    Just ceases to be
    When there's no-one about on the Quad."

    Which was replied to:

    "Dear sir your confusion is odd
    I am always about on the Quad
    So you see that this tree
    Continues to be
    Since observed by yours truly", signed, God
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