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B A line?

  1. Jan 23, 2017 #1
    If a line in space has no thickness, how can I distinguish the line from its surroundings when I look at the line such that I can't see its length? After all, in three dimensional space, you can look at a line from different angles.
  2. jcsd
  3. Jan 23, 2017 #2


    Staff: Mentor

    A geometric line is a one dimensional mathematical object. It's an abstract idea. It's not a physical object that you might see, touch or run into. The same goes for a point or a plane.

  4. Jan 23, 2017 #3

    Then why do we describe physical objects with coordinates (i.e. points)?
  5. Jan 24, 2017 #4


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    Staff Emeritus
    Science Advisor

    Basically because it is an extremely good way of describing objects and the positions of objects that lets us make useful, accurate predictions.
  6. Jan 24, 2017 #5


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    The fact that you cant distinguish the line when looking at some specific angle (this happens in computer graphics, some objects become invisible when the view camera is at some angles/distances) , doesn't tell us much about how useful lines or points are for describing physical objects. In other words, so what if you cant distinguish the line, it is still useful for the reason @Drakkith says.
  7. Jan 24, 2017 #6


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    Staff: Mentor

    For heaven's sake, don't tell the string theorists. :wink:
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