What is "time"

Discussion in 'Physics & Math' started by Saint, Nov 9, 2014.

  1. paddoboy Valued Senior Member

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    Here's a paper on time by with references to him....
    http://publish.uwo.ca/~jbell/Time.pdf
    entitled....
    Time and Causation in Gödel’s Universe.
    By John L. Bell


    In which he said.....
    In 1949 the great logician Kurt Gödel constructed the first mathematical
    models of the universe in which travel into the past is, in theory at least,
    possible. Within the framework of Einstein’s general theory of relativity
    Gödel produced cosmological solutions to Einstein’s field equations
    which contain closed time-like curves, that is, curves in spacetime which,
    despite being closed, still represent possible paths of bodies. An object
    moving along such a path would travel back into its own past, to the very
    moment at which it “began” the journey. More generally, Gödel showed
    that, in his “universe”, for any two points P and Q on a body’s track
    through spacetime (its world line), such that P temporally precedes Q,
    there is a timelike curve linking P and Q on which Q temporally precedes
    P. This means that, in principle at least, one could board a “time
    machine” and travel to any point of the past.
    Now in that short paragraph he absolutely shoots down your own thoughts on time travel, and which you highlighted in another provocatively mis-titled thread, as has become so obvious with those with pseudo views on science and the nature of reality.
    "Time Travel is Science Fiction" by Farsight:

    He does go on to say though that....
    "Gödel inferred, in consonance (as he observes) with the views of
    Parmenides, Kant and the modern idealists, that under these
    circumstances there could be no such thing as an objective lapse of time,
    that time or, more generally, change, is an illusion arising from our
    special mode of perception" which does align with your own thoughts.

    Irrespective he concludes......
    "We conclude that, if time travel into the past is possible (and
    feasible), and no restrictions are placed on the purposes to which such
    travel is put, then the universe must branch. Accordingly we have three
    possibilities:
    1. Time travel is impossible.
    2. Time travel is possible, with no “changing of the past”.
    3. Time travel is possible, and the universe ramifies. "

    So while proving time travel is possible, he concludes that time is not real, which I find breathtakingly illogical.
    ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

    That certainly refutes all that farsight has said about Godel and other misinterpretations and dishonesty.

     
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  3. Motor Daddy ☼☼☼☼☼☼☼☼☼☼☼ Valued Senior Member

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    I am asking you, paddoboy. This is a discussion, not a link posting contest.

    Why is it that you come along and make a claim that time exists, but when we ask where it is, you reply with a request from us? Why do we end up with the burden of your claim?
    ..and the 2012-2014-2016 thing too.
     
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  5. paddoboy Valued Senior Member

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    Don't be a big baby MD, just because know one will talk with you.

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    I'll continue posting links when I see fit, just as all others do, and I'll make my comments as I see fit.....
    You just need to live with that fact, wont you?

    Now if you need to defuddle your befuddled brain, read a few of my links, and remember, we see as far as we do, by standing on the shoulders of giants of the present and past....OK?
     
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  7. paddoboy Valued Senior Member

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    http://sciencefocus.com/qa/time-real-or-illusion
    Diverse thinkers, from the ancient Greek philosophers through contemporary quantum cosmology and eternal inflation theory, have called time an illusion. For them, the perception of time passing from present moment to present moment is an artefact of our psychology, so that anything real or true is real or true eternally and timelessly. The belief that reality lies in a timeless realm of truth, rather than in the flow of events our perceptions show us, might be supported by scientific argument but equally it reflects a metaphysical prejudice. Contemporary attempts to extend quantum theory to the cosmological, to encompass the whole Universe and not just a sub-system of it, are often couched in equations which suggest time is emergent from a timeless reality. But these attempts suffer from problems, both technical and conceptual, that are even more challenging than the usual conundrums of quantum theory. Several advances in the study of quantum gravity have shown that our four-dimensional space-time is only recovered in a version of the theory in which time is real and not emergent.Diverse thinkers, from the ancient Greek philosophers through contemporary quantum cosmology and eternal inflation theory, have called time an illusion. For them, the perception of time passing from present moment to present moment is an artefact of our psychology, so that anything real or true is real or true eternally and timelessly. The belief that reality lies in a timeless realm of truth, rather than in the flow of events our perceptions show us, might be supported by scientific argument but equally it reflects a metaphysical prejudice. Contemporary attempts to extend quantum theory to the cosmological, to encompass the whole Universe and not just a sub-system of it, are often couched in equations which suggest time is emergent from a timeless reality. But these attempts suffer from problems, both technical and conceptual, that are even more challenging than the usual conundrums of quantum theory. Several advances in the study of quantum gravity have shown that our four-dimensional space-time is only recovered in a version of the theory in which time is real and not emergent.I would hold that, contrary to the ancient metaphysical tradition, time is not only real, it is likely that it is the only aspect of reality we experience directly that is fundamental and not emergent from anything else.
     
  8. Motor Daddy ☼☼☼☼☼☼☼☼☼☼☼ Valued Senior Member

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    The rules require you to answer questions. Are you willing to answer questions or not?
     
  9. paddoboy Valued Senior Member

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    Your questions??? No certainly not! Not at least until your questions start making sense and you stop trolling.........Okey dokey?
    Over to you.
     
  10. Motor Daddy ☼☼☼☼☼☼☼☼☼☼☼ Valued Senior Member

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    5,105
    The main characteristic of a Troll is that they make statements and refuse to answers questions about those statements. That's you! Okey Dokey?

    You are the one claiming time travel is possible. I asked you a very simple and easy to understand question, if it's 2014 now, and you time traveled for 2 years, did you come from 2012 or 2016?

    If you can't answer that, you have no business claiming you know anything about time or your own capabilities concerning where you came from and what time it was there!

    Waiting for your answers, but not holding my breath. K?

    Over.
     
    Last edited: Dec 12, 2014
  11. QuarkHead Remedial Math Student Valued Senior Member

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    1,502
    Not quite correct

    Observables (Dirac called them dynamic variables) are in 1-1 correspondence with Hermitian operators, so it is customary to use the terms interchangeably. These observables - these operators - are not real in the usual sense of the word. They are simply functions of a special sort that act on a state vector resulting in another state vector.

    But it is a fact, and is easily proved, that the eigenvalues of any Hermitian operator are real numbers. By the 1-1 correspondence above, the set of eigenvalues for a particular operator - the spectrum of the operator - are taken to be the set of all possible measurements for a quantum system in a certain state. It is clearly reassuring that measurements - eigenvalues - are real numbers.

    This not what you asserted above
     
  12. PhysBang Valued Senior Member

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    Importantly, real numbers are not all that is "real".
     
  13. OnlyMe Valued Senior Member

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    3,914
    Paddoboy, the two sentences preceding your earlier bold emphasis (now in bold above) are perhaps more significant. While the whole of Smolin's comment is opinion, that last sentence is far more speculative. In those two earlier sentences he points out that the theory, his opinion is based on still, suffer from unresolved problems and then by referencing quantum gravity, he sets the whole context to one of a theoretical framework. Quantum gravity hasn't moved to the point of experimental testing, it really is theory at its earliest stages.

    Time as a component of the math of quantum gravity, even general relativity is real and indispensable... But then so are all of the rest of the numbers and symbols used in the math describing each. The question here is, whether time is real apart from the theoretical context we use to describe the world.., or is it an artifact of the limitations inherent in how we perceive the world?

    On a separate note it does get tiresome when you quote the whole content of a link, rather than providing the link and an extract... Especially when you put whole posts in bold or large type as if it better makes your point.... And then say little or even nothing in the way of your own comment.
     
  14. OnlyMe Valued Senior Member

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    Real numbers aren't really real. They are abstract concepts which have been given specific symbols, for purposes of communication.

    The real number 1, conveys no information by itself about what in the real world you are referring to.., until it is followed by another abstract sequence of symbols that do have specific counterparts in reality, like 1 dog, 1 cat, 1 apple, 1 orange...

    So we are not getting too far from the topic, time is also aa abstract concept. But we have come to associate it with how we experience the world, which is why we have so much trouble in discussions like this arriving at a consensus definition. How we answer the question, What is time?, is entirely dependent on from where we approach the question.
     
  15. QuarkHead Remedial Math Student Valued Senior Member

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    1,502
    Still garbled

    An observable IS (up to isomorphism) an Hemitian operator, as I explained. I have no idea what you mean by "hermitian invariant".

    And no, Hermitian operators do not "define" observables. As I explained, they are taken to be one and the same
     
  16. QuarkHead Remedial Math Student Valued Senior Member

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    Where?
     
  17. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    you need to actually put some brain function to this contradicting statement.
    along with all other comments you have on these topics.
    you attempt to speak on a level of high degree holder, when in fact, as obvious it is, you do not even have elementary level education of these subjects.
    (shakes head)these want to bes are out of control.
     
  18. OnlyMe Valued Senior Member

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    Krash, English isn't your first language, yes?
     
  19. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    cute

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    , did you just discover this term ?
    you should think before you pretend.
     
  20. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    cute.
    you're obvious, enough said.
     
  21. QuarkHead Remedial Math Student Valued Senior Member

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    Then please explain what is meant by "a negative hermitian".

    What in the name of all that is holy is a "negative hermitian"? And no, even if it makes any sense at all (I claim it doesn't) this by no means implies a 1-1 correspondence between operators and observables.

    You are pretending to understand stuff you quite obviously don't

    Please stop doing that - it helps nobody, least of all yourself
     
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  22. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    what's the difference ?
     
  23. Beer w/Straw Transcendental Ignorance! Valued Senior Member

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    You didn't have to take physics lab class depending on you major.
     

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