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3D 'perception' of the world we live in

  1. Sep 14, 2010 #1
    I am not an expert in physics and only have minimal exposure.
    However, I have been struck by something recently that I wanted t bring up with experts in the field.

    I was discussing with a colleague the other day, the ability to imagine 3 dimensions. My colleague stated that most people are unable to do this.

    This brought me to my curious thought. I'll try to explain using a real world example;
    If I am standing in a room, how do I know that the room in which I view real objects is truly 3 dimensional? Of course, based on my presence in the room many times before allows me to know that there are truly 3 dimensions based on my past experience being in the room and touching objects.

    Lets say there was an incredible artist or some form of extremely advanced computer animation that could depict a 3 dimensional view, leading one to believe that they were seeing 3 dimensions when in fact there would only be 2 dimensions presented through this art or advanced imagery.
    I'm sure I sound crazy but my point is this;

    How do we know that we actually live in a 3D world aside from experiencing what we believe to be 3 dimensions based on past experience.

    Whats to say that everything we actually see is in fact only 2 dimensions and we are somehow "tricked" into believing it is 3D.

    Feel free to provide any insight.

    Thanks for reading
  2. jcsd
  3. Sep 14, 2010 #2
    Close you eyes a walk through your house.
    You will quickly self validate that 3-d is a reality(after you run into a wall or trip over something)
  4. Sep 14, 2010 #3
    This is more of a philosophical question rather than a physics one. Physics, as well as other physical sciences, are primarily based on empiricism. We can only know what we experience, etc...

    It's a rather fascinating subject that has been discussed for hundreds of years. If you're interested you might want to pick up some books by Hume, Mach, or Locke. Heck, even Aristotle was a bit of an empiricist.
  5. Sep 14, 2010 #4


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    You are pretty much describing a perspective scene, and someone with only one eye wouldn't necessarily be able to tell the difference between that and reality. A better example would be a holograph, wherein the parallax of the original scene is reproduced via a 2-D object.
  6. Sep 16, 2010 #5


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    Take your hand and move it out from your body and back in. Thats 1 dimension. Now take it and move it from side to side. Thats number 2. Now take it and move it up and down. Thats 3 dimensions. If we didnt live in a 3d universe, we couldnt do that. In a 2d world, you couldnt even "trick" someone into believing the world is 3d. Just like you cannot trick someone into believing they are living in a 4d world. If you take away vision and the tricks it can play, then its very very obvious we live in a 3d world. I saw a video on youtube that explained this really well, but i cant remember the name of it. =(
  7. Sep 16, 2010 #6
    i think what they mean is less literal than that -
    i think they mean the image of everything that is around us ....
    i mean for example if you stay completely still and look at your room it COULD be seen as 2d
    it is only when you move around or something else moves that you can conclude it is 3d
    it's all about frame of reference and perception

    thats what i think anyway :p
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