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Scale IN variance

  1. Oct 18, 2012 #1
    Hello, I consider myself an up-and-comer theoretical physicist (although getting a bit of a late start), and there's something that continues to trouble me about the way physics is taught both professionally and popularly, and I want to survey how others feel about the issue.

    The issue is the portrayal of scale. For example, we always see the moon right next to the earth in almost every depiction. Perhaps even more famously are the depictions of the scales of electron orbitals and the relative sizes of particles. I know the short argument is that it is impractical to portray the actual scale variances in these depictions. Even so, rarely do educators ever even try to sidebar a visualization of these scale differences which I think have seminal importance in understanding these systems.

    For example, I just recently came across this scale appropriate depiction of the earth-moon radius and the subsequent scale appropriate transmission of light.


    Before seeing this, I basically had to guess this. Is it so hard for educators to incorporate these types of desciptions into their presentations? Am I alone here?
    Last edited: Oct 18, 2012
  2. jcsd
  3. Oct 19, 2012 #2


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    In many cases, the scales involved are so different that it is hard to draw everything to scale.

    Just take our solar system as an example: In an image where you see all planetary orbits on a screen, even sun would be smaller than a pixel. And on a scale where the sun fills the screen, earth (1/100) and moon (1/500) are like that: O . (with more distance in between) - but at a distance of ~150 screens from the sun.
  4. Oct 19, 2012 #3
    In perspective, the electrons exist very far from the nucleus. If you were to draw in a text book a nucleus the size of a golf ball, and show correct distance relationship between it and its electrons, your text book would need to be 2.5 kilometers long!...that would make an expensive text book!
    Last edited: Oct 19, 2012
  5. Oct 19, 2012 #4
    Thanks, it would be great to have more descriptions like those in the textbooks I've been reading.
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