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Thread: Just a POINT....

  1. #1 Just a POINT.... 
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    Hey! We know that a point has 0 dimensions - no height, no length, no width and also no area. If it has nothing in it, how do we know that it is something?
    I mean, if it has no dimensions and no area, how are we able to identify it(or roughly, see it) ?? What is the THING that it has, which makes it something? (Apart from length, width and height)....


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    Genius Duck Dywyddyr's Avatar
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    Quote Originally Posted by Gaurav(-26.7) View Post
    how are we able to identify it(or roughly, see it) ?? What is the THING that it has, which makes it something?
    Location.
    That's all it has.


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  4. #3  
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by Gaurav(-26.7) View Post
    how are we able to identify it(or roughly, see it) ?? What is the THING that it has, which makes it something?
    Location.
    That's all it has.
    Is "location" relative?
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  5. #4  
    Genius Duck Dywyddyr's Avatar
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    To what?
    We usually (in geometry) define a point (arbitrarily1) and work from there (IOW everything else is "relative" to that point).

    1 So long as it's on the paper!
    Last edited by Dywyddyr; August 18th, 2017 at 09:28 AM.
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    Cooking Something Good MacGyver1968's Avatar
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    Do you have a point to make?
    Fixin' shit that ain't broke.
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  7. #6  
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    Quote Originally Posted by Dywyddyr View Post
    To what?
    We usually (in geometry) define a point (arbitrarily[sup1[/sup]) and work from there (IOW everything else is "relative" to that point).

    1 So long as it's on the paper!
    To a frame of reference? If A is moving wrt B is a point as seen by A different to the same point as seen by B?

    These point particles are not just geometric entities are they? They have a "physical" reality ,don't they ?(am I just shamelessly displaying my ignorance?)
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  8. #7  
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    Quote Originally Posted by MacGyver1968 View Post
    Do you have a point to make?
    Where should I put it?

    https://4.imimg.com/data4/IS/BD/MY-2...in-250x250.jpg
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  9. #8  
    Genius Duck Dywyddyr's Avatar
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    Quote Originally Posted by MacGyver1968 View Post
    Do you have a point to make?
    It's not too late to put you back in the box you know!
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    Quote Originally Posted by geordief View Post
    To a frame of reference? If A is moving wrt B is a point as seen by A different to the same point as seen by B?
    How can you have a "frame of reference" without defining a "start point"?
    If A is moving and defines a point then, surely, that point is defined as (for example) 1 metre from my geometric centre (or 1 metre from the aft-most extremity of my body), in which case that point is already relative to a previously-defined point.
    But both A and B can agree on where the point is (although for B it's a moving point...)

    These point particles are not just geometric entities are they? They have a "physical" reality ,don't they ?(am I just shamelessly displaying my ignorance?)
    They're as physical as "lines". I.e. no. They have no spacial extent, no mass, nothing but location.
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  11. #10  
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by geordief View Post
    To a frame of reference? If A is moving wrt B is a point as seen by A different to the same point as seen by B?
    How can you have a "frame of reference" without defining a "start point"?

    Agreed(I was wondering about the other points in relation to that starting point)

    If A is moving and defines a point then, surely, that point is defined as (for example) 1 metre from my geometric centre (or 1 metre from the aft-most extremity of my body), in which case that point is already relative to a previously-defined point.
    But both A and B can agree on where the point is (although for B it's a moving point...)

    These point particles are not just geometric entities are they? They have a "physical" reality ,don't they ?(am I just shamelessly displaying my ignorance?)
    They're as physical as "lines". I.e. no. They have no spacial extent, no mass, nothing but location.


    It seems strange to have the term "point particle" if they are not physical but I realize I would need to learn about the subject to comment (I do now think I now that "particle" is not what I thought it was when I was at school)
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  12. #11  
    Genius Duck Dywyddyr's Avatar
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    Quote Originally Posted by geordief View Post
    It seems strange to have the term "point particle" if they are not physical but I realize I would need to learn about the subject to comment (I do now think I now that "particle" is not what I thought it was when I was at school)
    Ah.
    "In the Standard Model, elementary particles are represented for predictive utility as point particles."
    "A point particle (ideal particle[1] or point-like particle, often spelled pointlike particle) is an idealization of particles heavily used in physics."
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    I always thought of it like a zero, a beginning point. No real anything, just a place to start from. The point where negative turns to positive......Does that sound right?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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    Quote Originally Posted by zinjanthropos View Post
    I always thought of it like a zero, a beginning point. No real anything, just a place to start from. The point where negative turns to positive......Does that sound right?
    Point particles are concerned with physics. The Cartesian plain is composed of an infinitude of geometric points. In the Cartesian plain there is a single origin point, and it is at the orthogonal axis of the abscissa and ordinate lines and has coordinates (0,0).
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