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Spacetime

  1. Feb 9, 2004 #1

    wolram

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    i have been looking for a definition of spacetime, not
    something described by pure mathematics, but the real
    world space time that has some tangibility, the one
    that can be bent, twisted ,and have effects on time,
    the fabric of spacetime, relativity, QLG, string, all
    give different answers, so what if anything does
    philosophy say?
     
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  3. Feb 9, 2004 #2

    selfAdjoint

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    Dearly Missed

  4. Feb 10, 2004 #3

    wolram

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    Well, as you can see from this post on the relativity forum, Einstein didn't regard spacetime as something to be rolled, folded or spindled.
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    so how would you explain to someone what "spacetime" is?
    is it correct to say it is a physical entity?
    some are of the opinion that
    the "fabric of spacetime" can be distorted in many ways
    without giving an explanation of what it is that is
    being distorted.
     
  5. Feb 10, 2004 #4
    Imagine a 3 dimensional grid, with a line for every million metres.

    With no mass this grid is perfect, but enter a black hole and the grid appears to get denser around the black hole. The grid does not stretch, simply more lines enter the diagram. The black hole now looks like a white spot as there is an infinite amount of grid lines within.

    This is how to 'imagine' space time.
     
  6. Feb 10, 2004 #5

    wolram

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    Imagine a 3 dimensional grid, with a line for every million metres.

    With no mass this grid is perfect, but enter a black hole and the grid appears to get denser around the black hole. The grid does not stretch, simply more lines enter the diagram. The black hole now looks like a white spot as there is an infinite amount of grid lines within.
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    this is the general concept i understand, the thing i
    do not is the "grid lines", in your analogy these lines
    would be the "fabric", of spacetime another term used
    is geometry, but geometry is a pure mathematical
    conceptualization, these grid lines have no real existence,
    so what is distorting in the presence of gravity?
     
  7. Feb 11, 2004 #6

    Tsu

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    Can it be stapled or mutilated? :wink:

    This is a GOOD thread! When we're done with spacetime, may we approach the philosophical aspects of String/M-Theory and Loop Quantum Gravity? I'm almost bald (from hair pulling - now I know why Einstein's hair looked like it DID!!) in my frustration with those!
     
  8. Feb 11, 2004 #7
    first off, space and time are phenomenons (phenonmenae?) of the physical.

    scientists and/or mathematicians need to have this 'fabric' in order to show how it can be bent, folded and spindled (a visual aid).

    ironically, soon we will accept the fact that we can enter any point in that fabric whenever we want. all we need do is have a better understanding of our consciousness.

    peace,
     
  9. Feb 11, 2004 #8

    wolram

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    as far as i can make out theorists are still arguing
    as to what spacetime is, the maths they use is
    horrendous and can only be fully understood by the
    people that do little else, but nature is not always
    best described in mathematical terms, "try explaining
    a color mathematically", the attempt to discover what
    gravity is, is over one hundred years old now and
    still far from being solved, maybe there is no
    mathematical solution, may be spacetime and gravity
    are so fundamental, "akin to asking who is god",
    that we will never know the answers.
     
  10. Feb 11, 2004 #9
    Hi wolram

    I know this isn't precisely what you were asking for, but I think it will help you think about this. It has to do with a useful term that philosophers of science have come up with called "theory-laden". The idea is that scientific concepts necessarily derive their various meanings from the individual theories in which they arise. Thus spacetime is a theory-laden term whose significance thus depends on the status of a given theory. In fact, philosophers of science generally philosophize about concepts like spacetime from the perspective of specific scientific theories.
     
  11. Feb 11, 2004 #10

    wolram

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    I know this isn't precisely what you were asking for, but I think it will help you think about this. It has to do with a useful term that philosophers of science have come up with called "theory-laden". The idea is that scientific concepts necessarily derive their various meanings from the individual theories in which they arise. Thus spacetime is a theory-laden term whose significance thus depends on the status of a given theory. In fact, philosophers of science generally philosophize about concepts like spacetime from the perspective of specific scientific theories.
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    thankyou for this, it is nice that you can take timeout
    from somewhat heated discussion to philosophize
     
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