| Joined: | Wed Apr 11th, 2012 |
| Location: | Melbourne, Australia |
| Posts: | 525 |
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| View single post by richw | ||||||||||
| Posted: Thu Dec 12th, 2013 04:25 |
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richw
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http://www.slate.com/blogs/bad_astronomy/2013/12/07/optical_illusion_shades_of_grey.html
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