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Thread: How many dimensions?

  1. #1 How many dimensions? 
    Forum Bachelors Degree x(x-y)'s Avatar
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    I was just wondering how many dimensions you people agree that the universe has.

    There are many different theories which support a specific number of dimensions: M theory, string theory, loop quantum gravity, twistors, superstring theory, non-commutative geometry etc. So which theory do you believe has the most proof and logical evidence, and thus agree with? Of course, scientists working at particle accelerators across the world are working to find the so called 'theory of everything' which will prove one of these many theories correct, or even all of them wrong...

    Thanks,

    - x(x-y)


    "Nature doesn't care what we call it, she just does it anyway" - R. Feynman
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    I think 3 space-like dimensions, while time is simply a measure of relative motion, though my opinion shouldn't count for much, as I am not really qualified.

    I think the extra dimensions as are being explored by M-theory et al (and even the treatment of time as a fourth dimension a la Minkowski) give reasonable-looking results simply because of a mathematically describable interconnectedness between how things behave, i.e everything affects and is affected by everything else.

    It is an instance where, IMO, the results of mathematics are being used to describe reality in an absolute sense. You can produce extraordinarily elegant exercises in logic with mathematics, but it does not mean that all maths describe some physical reality of course. We are using lacking definitions of certain physical properties to describe other physical properties IMO. The maths might precisely predict the comparative quantitative nature of certain interactions, but using the maths to explain the precise physical nature of the constituents of a system can yield false premises to base an interpretation of secondary, tertiary, etc interactions on. I think you could build more than one mathematical model to describe the same interaction that would cast different lights on the physical nature of the participants in an interaction. This could have the effect that an incorrect assumption somewhere in the chain might hinder further investigations, even if it had been possible to mathematically describe events after the incorrect assumption up to a point.

    Like I said, I don't presume to know more than the people that are actually trained in their respective fields and would readily accept a well reasoned refutation of my opinion. I fully understand that my opinion is of a superficial layman type. It is interesting to think about this stuff though.


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  4. #3  
    Forum Bachelors Degree x(x-y)'s Avatar
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    Yes, I tend to support the theory of 4 dimensions- which is supported by theories such as 'twistors' or '4-D string theory'...

    It makes sense, logically and mathematically, that there are 4 dimensions- 3 of space (x,y and z) and 1 of time (x)...

    However, a lot of theories support a lot more dimensions- a lot of them agree on 11-D. One of the variants of string theory even suggests that there are 26 dimensions!
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    Since we don't need to recognize more than 4 dimensions in order to live our lives we are inevitably biased to believe there are no more than four, and tend to reject as ridiculous theories that require more dimensions. However the survival requirements of hunter-gatherer tribespeople are not necessarily a rational basis for such rejection. Perhaps we should believe the math despite our innate prejudice against it.
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    This which I provide here is unscientific and only speculation and guess work, and a little youtubing M-Theory docs ..etc.

    Imo there are only 3 dimensions, the good old X, Y and Z, times is nothing but a messurement as speed, it doesn't exist as a physical object. That vague proof of time with 2 clocks time dialation doesn't definitivly explain anything, just as "search for longitude" showed that the waves rocking of boats would impact the pendulum clocks.

    The scientist havn't excatly been very scientific with these dimentions, as they have done the blindfolded pin the tail on the donkey game, in order to prevent anomalies in their math, they had to fill in some blank holes for their equation to be complete, and that by inventing some dimesions.
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  7. #6 Re: How many dimensions? 
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    Quote Originally Posted by x(x-y)
    I was just wondering how many dimensions you people agree that the universe has.

    There are many different theories which support a specific number of dimensions: M theory, string theory, loop quantum gravity, twistors, superstring theory, non-commutative geometry etc. So which theory do you believe has the most proof and logical evidence, and thus agree with? Of course, scientists working at particle accelerators across the world are working to find the so called 'theory of everything' which will prove one of these many theories correct, or even all of them wrong...

    Thanks,

    - x(x-y)
    It is quite clear that there are three "large" spacelike dimensions and one timelike dimension. Thst is our everyday experience and is consistent with both relativity and the Standard Model of particle physics.

    However, we know that general relativity and the Standard Model are not adeequate to completely describe nature. So more refined models are needed.

    Some candidates for those more refined models include various string theories and generalizations of string theories. In order to be mathematically consistent theories those theories require more spatial dimensions, and have spacetime as the cross-product of 4-dimensional spacetime with a compact Calabi-Yau manifold. The scale of the Calabi-Yau manifold is sufficiently small that the additional dimensions afforded by it are not noticed by us. These additional dimensions are called "compactified". No one knows if they are viable physical theories.

    So, the bottom line is that everyone agrees that there are three large spatial dimensions. There may be more compactified spatial dimensions, but no one really knows.
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  8. #7  
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    Quote Originally Posted by HexHammer
    Imo there are only 3 dimensions, the good old X, Y and Z, times is nothing but a messurement as speed, it doesn't exist as a physical object. That vague proof of time with 2 clocks time dialation can easily be explained by centrifugal powers, just as "search for longitude" showed that the waves rocking of boats would impact the pendulum clocks.
    ridiculous

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  9. #8  
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    Quote Originally Posted by HexHammer
    ... That vague proof of time with 2 clocks time dialation can easily be explained by centrifugal powers, just as "search for longitude" showed that the waves rocking of boats would impact the pendulum clocks. ...
    You should read up some more information, before you make such accusation. Time dilation is not only a vague concept. It has solid evidence and theoretical foundations. See e.g.:
    http://en.wikipedia.org/wiki/Time_di...l_confirmation
    http://teachers.web.cern.ch/teachers...c/lifecalc.htm
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  10. #9  
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    Quote Originally Posted by Dishmaster
    Quote Originally Posted by HexHammer
    ... That vague proof of time with 2 clocks time dialation can easily be explained by centrifugal powers, just as "search for longitude" showed that the waves rocking of boats would impact the pendulum clocks. ...
    You should read up some more information, before you make such accusation. Time dilation is not only a vague concept. It has solid evidence and theoretical foundations. See e.g.:
    http://en.wikipedia.org/wiki/Time_di...l_confirmation
    http://teachers.web.cern.ch/teachers...c/lifecalc.htm
    GR and SGR ofcause explains the Time Dialation with motion and gravity, but that doesn't really explain anything at all on atomic nor sub atomic lvl, what really changes there.

    But what "solid evidence" are there of what?
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  11. #10  
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    Quote Originally Posted by HexHammer
    GR and SGR ofcause explains the Time Dialation with motion and gravity, but that doesn't really explain anything at all on atomic nor sub atomic lvl, what really changes there.

    But what "solid evidence" are there of what?
    Wrong, or incomprehensible, as usual.

    Quantum field theories, so the Standard Model, which comprises quantum chromodynamics and the electroweak theory, are relativistic theories, compatible with special relativity. Those theories do a very good job of predicting the behavior of elementary particles.
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  12. #11
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    There are three Dimensions and motion with connected theories 8)
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  13. #12  
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    The teams at the Large Hadron Collider (LHC) have been searching for proof. No evidence for particles smaller than quarks or supersymmetry has been found…yet. Finding nothing restricts the discussion and narrows the number of surviving theories, but we will just have to wait for more energetic collisions.

    http://physicsworld.com/cws/article/indepth/44805

    http://indico.cern.ch/conferenceDisp...?confId=113139

    http://cerncourier.com/cws/article/cern/44838
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    Quote Originally Posted by Arch2008
    The teams at the Large Hadron Collider (LHC) have been searching for proof. No evidence for particles smaller than quarks or supersymmetry has been found…yet. Finding nothing restricts the discussion and narrows the number of surviving theories, but we will just have to wait for more energetic collisions.

    http://physicsworld.com/cws/article/indepth/44805

    http://indico.cern.ch/conferenceDisp...?confId=113139

    http://cerncourier.com/cws/article/cern/44838
    True, BUT.......... The LHC is yet to create and detect the top quark!

    which we know exists and has been made and detected at the Tevatron. - Yet the LHC has not found it yet. - strange stuff.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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  15. #14  
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    Not so strange at all. The top quark was discovered 15 years ago.
    A team at the Tevatron manually went over years of old data to find the tracks of a top quark created by weak force decay. We knew that there are top quarks and we knew about the weak force. We now have affirmed that the weak force can create top quarks. With brute force they were able to outdo what the software at the LHC is supposed to do when it is up to speed. Since the LHC is going to stay at 7 TeV perhaps until 2013, the competition should be interesting. However, Fermilab also has no evidence of extra dimensions or quark components, so we will have to wait until the LHC gears up to 14 TeV.

    P.S.: Tadaaah!
    http://www.symmetrymagazine.org/brea...ng-at-the-lhc/
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  16. #15  
    Forum Bachelors Degree 15uliane's Avatar
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    A great book is Warped Passages by Lisa Randall, and esteemed Harvard physicist.

    My guess is that the # of dimensions will only be observed when we find extra dimensional particles. They may be right under our noses.

    Hopefully the LHC will discover something, but I think that the extra dimensions must be past the Weak scale, as the LHC goes pretty close to it, and unless there is some breakthrough test, I doubt w'ell find anything in the conventional manner (I know, I just contradicted myself)
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  17. #16  
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    I suppose it would be useful to distuinguish in these posts whether we're talking about extra dimensions in a predictive theory or observable extra dimensions.

    A theory might employ extra dimensions to predict or explain the behavior of particles or systems, but those dimensions may never be observable. Whether they're real or not isn't important. What's important is whether such a theory predicts behavior that matches observation in our measurable 4-dimensional world.

    As always, introducing arbitrary preconditions and unobservble parameters makes a theory more tenuous and subject to criticism. Still, if the theory makes accurate predictions it can't be dismissed altogether - at least until an equally successful and simpler alternate theory is developed.

    Chris
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