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Tell me about time!

  1. Jan 20, 2010 #1
    Before I go and ask questions that many of you might be able to answer very easily, I'm letting everyone know that I have an extremely limited knowledge of physics. I am, however, about as interested in string theory as a layman could be and am very willing to learn.

    One part of my brain feels like string theory must absolutely be right, but another part feels like it's nothing more than science fiction. I can't imagine how a physicist could have come to the conclusion that time itself is not 1 dimensional. I don't understand how time could be toyed with, and although I've heard of time slowing down when going the speed of light, how can you possibly apply spatial-like dimensions to something as intangible as time? Duration is there, but it's not really there, how can anything happen to it?

    I wish I had the head for the maths used in general relativity, quantum physics and such, so maybe I would be able to look at the formulas used to enforce these theories and have my own little 'ah-ha!' moment.

    I don't know if I'm right, but here's what I gather from string theory, please clear anything up for me --

    5th dimension: time can only move in one direction in the 4th dimension, but in the 5th, time gains another direction and can now branch off (like moving in 2d world) to -- now here's another thing that really bugs me -- create new "possible outcomes"

    6th dimension: 3d properties are given to time, making it possible to move in any direction in time including revisiting passages of time that have already "passed"

    7th dimension -- time itself now has so many possible outcomes due to it moving in any direction, that it basically becomes it's own [something] ...? (???) (I kind of get lost here, but it feels like I almost understand it -- I don't understand what 'single thing' time could possibly become)

    8th dimension -- (completely lost)

    9th dimension -- (completely lost)

    10th dimension -- (completely lost, but this particular dimension sounds interesting!)

    11th dimension -- (can't even find readable information on the "11th dimension"!)

    Thanks to anyone who is able to put up with me!

    - Brett
  2. jcsd
  3. Jan 20, 2010 #2


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    I've never heard it described this way. I'm not sure if it's right or wrong.

    In string theory, there is still only one time dimension; the other 9 are spatial.
  4. Jan 20, 2010 #3


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    different theories will give you different answers..just matters who you believe with scientific proof.
  5. Jan 20, 2010 #4
    Oh no, really? I remember watching an interesting flash video back in 2006 or 2007 that described there being the three dimensions, and the rest all dealt with time and time curvature.

    And yeah, Maroc, I was looking up string theories a bit earlier to refresh my knowledge and I see there are few different types. I think the one I'm dealing with was type I string theory?
  6. Jan 20, 2010 #5
    I think I may have seen the flash video you are talking about. A friend showed it to me once to ask what I think. It is non-sense. It has nothing to do with string theory.

    (EDIT: Okay, I found it again. Goto youtube and search "imagining the tenth dimension", and you get this: )

    While there have indeed been publications wondering what it would mean if there were 2 time-like spacial dimensions, this is not a major endeavor of physics currently and is more a curiosity.

    All the types of string theory, and "M-Theory" which hopefully unites them all, are currently being considered as only have one time dimension and multiple spatial dimensions.
    Last edited by a moderator: Sep 25, 2014
  7. Jan 21, 2010 #6
    Argh, that is exactly the video I watched a while back. I guess that teaches me a lesson about "learning" from the internet.

    Time to do some research about the real string theories and membrane theory then. You know, this is actually a little heartening at least because I can more easily believe that there are several spatial dimensions rather than a multitude of time/probability pathways.

    Thanks for setting me on the right track.
    Last edited by a moderator: Sep 25, 2014
  8. Jan 21, 2010 #7

    Judging by your last comment about not liking a multitude of pathways, you might not like Quantum Mechanics very much. (Though I don't know that there's a way of viewing it in terms of multi-dimensional time. I'm sure someone's look(ed/ing) into it)

    I'm not sure that your descriptions about multi-dimensional time is accurate.

    I'd think the problem with multidimensional time is that it's difficult to say which direction, or set of directions is forward. You essentially need to lay down arrows on your space. In 1 dimension, this is really easy. You just put down 1 arrow and you're done. In higher numbers of dimensions, there are lots of ways of doing this, and it's rarely obvious which way is the correct one for your theory. However, the arrangement of arrows and the arrows themselves are very important to the affects of the extra dimensions. I don't believe that there is currently any classification of what n-dimensional time could look like physically.
  9. Jan 21, 2010 #8


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    The problem is not to think about dimensions, the problem is to think about a low number of dimensions.

    Perhaps the most popular example is to consider the number of regular poligons, or say n-gons. Convex with all the faces, angles, volumes, n-volumes etc equal. We know that there are infinite of them in two dimensions. How many in three? How many in four?

    In some cases the problem does not converge when increasing the numbers of dimensions but it shows some periodicity instead. This kind of problems are more complicated. Perhaps the most popular is "How many different regular ways do you have to pack spheres in a box?" Consider n-dimensional spheres and a n+1 dimensional big big box (and actually, do not consider the box, just put periodicity conditions). This problem is useful to build self-correcting codifications in computer electronics.
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