The fabric of space-time

Discussion in 'Physics & Math' started by Saint, Feb 12, 2020.

  1. Write4U Valued Senior Member

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    Revisiting your question...

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    Is the question if the universe stores information, IOW, does the universe have memory, other than a direct self-reference to the immediate causality of an "effect"?

    Seems to me that a "measurement" is not measurement of stored information in the fabric of spacetime itself but only of "present" value (potential) information of an object in the universe.

    It occurred to me that looking back in time is not looking at a memory at all. What we observe is the final destination of an observable past "current event". The information of that current event may take millions of years to arrive at the point of observation, but does that make it a "memory", i.e a recall of stored information?

    But then I think about David Bohm's experiment of "enfolding" (storing) and "unfolding" (recalling) "stored" (memorized) information as he demonstrated with the Taylor-Couette "laminar flow" glycerine experiment .


    Does this mean that light propagates in a laminar flow?

    OTOH, in space most all "flow" is turbulent and too complex to be able to store information which can be recalled.
     
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  3. Q-reeus Valued Senior Member

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    Far more knowledgeable answers can be found here:
    https://physics.stackexchange.com/q...a-mathematical-construct-and-not-a-real-thing
    See both the first main answer by Bob Knighton, and second one by G Smith - which is my position.
    Spacetime acts on matter. Matter acts on spacetime. For that reciprocity to be so, both must be physically real entities.
     
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  5. Write4U Valued Senior Member

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    Given that spacetime consists of dynamical fluid media (quantum fields)

    Questions;

    a) Is a point (spacetime coordinate) a physical object or a geometric variable?

    b) If a point is not a physical object, is a straight line (set of points) a physical object?

    c) If a straight line is not a physical object, is an equilateral triangle (set of straight lines) a physical object?

    d) If a triangle is not a physical object, is a fractal set (set of iterated triangles) a physical object?

    e) If a fractal is not a physical object, are fractal patterns physical objects?

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    f) if a dynamic field displays fractal objects (sets of fractals), are fields physical objects ?

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    IMAGE: MATHEMATICIANS FROM UMD HAVE DEVELOPED THE FIRST RIGOROUS PROOF FOR A FUNDAMENTAL LAW OF TURBULENCE. BATCHELOR'S LAW, WHICH HELPS EXPLAIN HOW CHEMICAL CONCENTRATIONS AND TEMPERATURE VARIATIONS DISTRIBUTE THEMSELVES IN A... view more

    CREDIT: NOAA/GEOPHYSICAL FLUID DYNAMICS LABORATORY

    https://www.eurekalert.org/pub_releases/2019-12/uom-rdf121119.php
     
    Last edited: Oct 13, 2020
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  7. paddoboy Valued Senior Member

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    A nice alternative to John Wheeler's (?) quote" “Space-time tells matter how to move: matter tells space-time how to curve”.
     
  8. Write4U Valued Senior Member

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    Is that finally an endorsement of deBroglie-Bohm Pilot Wave Theory ?
     
  9. paddoboy Valued Senior Member

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    It's an endorsement of spacetime telling matter how to move and matter telling spacetime how to curve/warp/bend/twist. And then the obvious reality of both.
     
  10. Write4U Valued Senior Member

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    Yes, the dynamics of spacetime create a giant wave function (fluid field) which guides all matter via a defined "guiding equation".
    https://en.wikipedia.org/wiki/De_Broglie–Bohm_theory#

    It is actually quite elegant as it does away with the contradiction of the particle/wave duality.
     
    Last edited: Oct 14, 2020
  11. paddoboy Valued Senior Member

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    I'm not questioning that quantum aspect of things. I'm simply saying the reality of space and time [spacetime] is quite evident at the macro level and can be summed up by John Wheeler's adage of matter telling space how to curve and space telling matter how to move...an even more elegant phrase, one that I'm having the usual trouble with in convincing the village idiot of.

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  12. paddoboy Valued Senior Member

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    Funny some people like Saint...ask questions, get reputable answers, and then disappear.
    Perhaps it doesn't fit in with his 'God" agenda?
     
  13. QuarkHead Remedial Math Student Valued Senior Member

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    This does not follow. It follows from the non-linearity of the Eisenstein field equations of gravitation, it does not at all prove that both are physical entities.

    Unless you have an ingenuous proof to show us.........
     
  14. Write4U Valued Senior Member

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    This caught my eye;

    Energy
    Main article: Vacuum energy
    I don't know quite what to make of this.

    But if a zero-point energy has an effect on any contiguous conditions, might that explain the BB, which started with a zero-point singularity?

    An implosion which subsequently bounced back into a mega-quantum event and the onset of the 'inflationary epoch"?
     
    Last edited: Oct 14, 2020
  15. paddoboy Valued Senior Member

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    While myself and q-reeus have had a number of disagreements, on many things, I do believe there is more sensibility and logic in saying that spacetime is physically real, rather then the denial and ignorantly declaring it is simply a mathematical construct and not real, as per the rantings of a well known anti mainstream purveyor of fairy tales that I have had the displeasure of crossing swords with.
    I definitely liked the twist on John Wheeler's quote as refreshing.
    And I see something to be physical to mean it can either be touched or felt, at least that is my perception.
    And while I see your point........
    The dictionary says.....
    https://www.merriam-webster.com/dic...(1) : of or,and resistance— Thomas De Quincey
    of or relating to natural science
    b(1): of or relating to physics
    (2): characterized or produced by the forces and operations of physics
    2a: having material existence : perceptible especially through the senses and subject to the laws of natureeverything physical is measurable by weight, motion, and resistance— Thomas De Quincey
    b: of or relating to material things

    ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
    Of course, and the crux of the matter is, that something does not need to be physical to be real. That appears to be your stance also. Spacetime is bent, warped twisted etc in the presence of mass.....light follows geodesics in curved spacetime, caused by mass.
    While my own personal opinion is that it is not physical, it is still real for the reasons given, and certainly real under the auspices of GR.
     
  16. arfa brane call me arf Valued Senior Member

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    So, is measurement real? Is what gets measured also real, or is it physical?

    Do you think anyone in this thread has answered what real or physical means, or how to tell the difference?
     
  17. paddoboy Valued Senior Member

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    Yes:
    It can be real and physical, or just real but not physical for the reasons stated.
    I have given the definition of physical.
    The rest is philosophical banter.
    Space is real: Time is real: Both evolved at the BB.
    Spacetime is real, for the reasons stated.
     
  18. Write4U Valued Senior Member

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    True, time (mathematical duration) becomes real as a result of change, but it is not physical.

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    A right-handed three-dimensional Cartesian coordinate system used to indicate positions in space.

    https://en.wikipedia.org/wiki/Space

    Note: the illustration depicts a static matrix. In reality all portions of the matrix are in constant dynamical change.
     
    Last edited: Oct 15, 2020
  19. arfa brane call me arf Valued Senior Member

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    About classical measurement. My hypothesis (actually it isn't all mine) is that the only measurable in physics is distance, so also area or volume.
    That is, we don't measure time, nor mass, nor charge.

    A spatial measurement always corresponds to some displacement from which we infer the existence ("reality"), of time, mass, or charge.
    So for instance, when you hang a spring and attach a weight, the displacement is what lets you infer an interaction between the mass of the weight and the mass of the planet.
    But the only evidence for this is the directly measureable displacement.

    Moreover, time doesn't seem to be required in quantum mechanics, but maybe that's a different story.
     
  20. QuarkHead Remedial Math Student Valued Senior Member

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    Quite. I would say, in common with most scientists, that anything that can be measured is real.

    It may be accidental that in physics ALL measurements are Real Numbers.

    P.S. I believe that de Quincy wrote in the 16th Century. Am I mistaken?
     
  21. exchemist Valued Senior Member

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    Yes, you are 3 centuries off.

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    He was a c.19th writer, best known for consorting with Coleridge, Wordsworth et al and for being an opium addict. (Coleridge was into drugs too, I think - Kubla Khan etc) . De Quincey wasn't the least bit scientifically inclined, so far as I know.
     
  22. Hipparchia Registered Senior Member

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    I certainly don't recall any scientific content in his Confessions of an English Opium-Eater. It's worth reading if you are into classic literature. It could probably be better appreciated after drinking four pints of lager. (Fewer if you rarely indulge, more if four pints is breakfast.) I've come to think of the Coleridge-Wordsworth association as an odd one, in the category of 'opposites attract'.
     
  23. exchemist Valued Senior Member

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    Nothing would induce me to drink 4 pints of lager. Bitter, certainly, though these days my doctor recommends only 2 pints due to the risk of heart arrhythmia.

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    They were an odd couple, but by all accounts inspired each other. God knows where, if anywhere, de Quincey fitted into the picture.
     

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