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String theory=0th dimension?

  1. May 17, 2010 #1
    Is string theory the replacement of the zeroth dimension? Or could it be thought of as such?
     
  2. jcsd
  3. May 17, 2010 #2

    bapowell

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    Your question isn't very clear. Are you asking whether string theory replaces the notion that particles are zero-dimensional points? Yes, string theory conjectures that all particles are 1-dimensional strings, not zero-dimensional points.
     
  4. May 17, 2010 #3
    Yes, that is exactly what i was asking. So since we are treating the string just as we were treating the 0th dimension, in that everything is made up of it, thats why we consider there to be 11 dimensions in that theory correct? it would provide a bend from two tenth dimension possibilities based off chance to combine and form the 11th. However, a string has a dimension as well, and can also be turned and tied together to form a 3-dimensional object. So wouldnt that leave the possibility of 12 or even 13 dimenions? And if the objects in a universe where a 3 dimensional string is the basis of each dimension then wouldnt the second dimension (as we know it) have four dimensions? Thsi leads me to believe that there are an infinate amount of dimensions. You cant just get rid of the other possibilities because it hasnt been seen before. What if there were another dimension based off of what we know of as the fourth dimesion? Just because we cant imagine it doesnt mean it doesnt exist so why do we eliminate the possibility?
     
  5. May 17, 2010 #4

    bapowell

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    There is no direct connection between the 1-dimensionality of the string and the higher dimensional spaces that are required by string theory. I don't really understand the point you are trying to make, sorry. Prior to string theory, physicists considered 0-dimensional particles existing in a (3+1)-dimensional spacetime; now, string theory says the particles are 1-dimensional strings existing in a (9+1)-dimensional spacetime.

    I say there is no direct relation between the dimensionality of the particle and that of the spacetime, but they are related more indirectly. For example, in superstring theory, 10-dimensional spacetime is forced on us by the requirement that unphysical quantum states don't exist. The number of extra dimensions are not chosen at random -- nobody is getting rid of extra dimensions because they haven't been seen before. The number of dimensions of the theory is determined fully by the consistency of the quantum theory and the preservation of important symmetries, like Lorentz invariance.
     
  6. May 17, 2010 #5
    Each dimension created by combining the previous dimension with itself through a line correct? the first dimension is made from a line combining two 0th dimensions, the second dimension is a plane combining two first dimensions (if it is a 4 sided plane) and a cube is made by combining two planes. So if the 0th dimension is now being thought of as a string and a string when fully zoomed in on by a microscope has dimensions, then the first dimension doesnt follow this pattern. It would give the line length and width and therefore not be the first dimension. And if the string was now twisted then the theoretical line connecting it to another string would be in the first dimension. So a line connecting that line to that of another would create a different dimension. If it were based off the 0th dimension idea then it would be a plane.. But in this case it isnt.
     
  7. May 17, 2010 #6

    bapowell

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    The concept of '0-dimensional' is still alive and well in string theory. It's just that the particles are no longer 0-dimensional, but 1-dimensional. The dimensionality of the particles has nothing to do with the dimensionality of the space they find themselves in.
     
  8. May 17, 2010 #7
    Their is still an area though. the area is so small it is almost negligable but it is still there. We can even use an integral to prove it. The probability of touching any point within two bounds on a graph is the area under the curve. Now if u take the same graph and try to find the probability of touching any one point on the graph we normally consider it 0. However, just as i said before the probability of touching that point is very small but still there. Thus, just as before, the area under the curver (or in this case the point) can be used to determine the probability which is obviously very small but still existant. Now if you remove the graph and try to touch any point in space there is an extremely small chance of touching any point and an even smaller chance of touching the same point twice, but, there is still a chance and if there is a chance then there is an area. So that means that since there is a possibility of touching any one point in space (or in string theory touching any one string) then there must be an area. and if that is so then there would be more then 11 dimensions.
     
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