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            This is a file from the  Wikimedia Commons. Information from its  description page there is shown below.  Commons is a freely licensed media file repository.  You can help. 
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        Summary 
        
         
          
           | Description | 
           Diffusion animation.gif
             English: This example illustrates the process of gaseous diffusion. The colored blocks represent molecules that are experiencing Brownian motion. Over time the two colors will be approximately evenly distributed between the top and bottom half.  The image is an animated output of a CAGE simulation. The display is a two-dimensional black grid on a white background. A purple line is drawn horizontally spitting the grid in half, leaving the right one-quarter of the separation open. The simulation begins with about 20 light purple squares randomly placed above the delineation and the same number of green squares below. The squares are immediately set in motion and bouncing off any border it makes contact with. Squares are able to pass from top-to-bottom and bottom-to-top through the gap left on the right. Eventually the light-purple and green squares are equally distributed on the top and bottom. The simulation  simply continues indefinitely, resetting itself periodically.  
             
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           | Source | 
            http://classwww.gsfc.nasa.gov/CAGESite/pages/demo3.htm | 
          
          
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             This file is lacking author information. 
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        Licensing 
        
         
          
           | Public domainPublic domainfalsefalse | 
          
         
         
          
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           This file is in the  public domain because it was solely created by  NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". (See  Template:PD-USGov,  NASA copyright policy page or  JPL Image Use Policy.) | 
           
            
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