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4th dimension?

  1. Oct 14, 2014 #1
    1. The problem statement, all variables and given/known data
    is there a 4th dimension. if yes can anyone explain it ?


    2. Relevant equations


    3. The attempt at a solution
    4th dimension includes time also am i right ? which is X,Y,Z + time
     
  2. jcsd
  3. Oct 14, 2014 #2

    HallsofIvy

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    Do you understand what a "dimension" is? A "dimension", in a given problem, is just a number you use to specify all the conditions of the problem. If I were doing a geometry problem connected with spheres of different radii with centers at different points in space, to identify a specific such sphere, I would have to give the three coordinates of its center and its radius- four numbers so this is a "four dimensional" problem. If I were doing a problem involving points in the plane, I might set up an xy coordinate system and label each point by its x and y coordinates- two dimensions because two numbers. If I were doing a problem involving points in "R3" I would set up a coordinate system with x, y, and z axes and every point would be labeled by (x, y, z)- three numbers so three dimensions.

    In physics, we are concerned with "events"- things that happen at a particular point in space at a particular time. We require three numbers (coordinates) to identify the point and one number to identify the time. In that sense we are working with four dimensions. Of course, which is the "first", "second", "third", or "fourth" dimension is purely conventional.
     
  4. Oct 14, 2014 #3
    thanks hallsofivy ...
     
  5. Nov 20, 2015 #4
    Also, you could plot a four dimensional point using a constantly changing graph, say, point A's coordinates are 1 by 2 by 3 by 4, which could mean the x is one, the y is 2, and the z is 3 after 4 seconds have passed. Graphing functions like this also works.
     
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