We’re working on Light and Color in physics right now, so today I had fun showing the students various Optical Illusions. I started with how our brains can put individual images together to make “movies” in our heads. I have a cool toy that I bought at Disney during our New Years trip. It has 8 LEDs that light up quickly and if you spin the toy, it spells out words in the sky. Well, I actually managed to take a picture of judiang when she was spinning it, so I started the class with that picture. (Now all of my physics students know what Judi and hergrace look like.)

Cool Magic Floating Words!

I then did a demonstration that I saw last night at the Dash & Dine session where you wave a white stick in front of an out-of-focus projector and people see the entire image – sort of like how the toy works and how TVs and monitors work. They were suitably impressed.

Then it was time for the PowerPoint presentation of Optical Illusions. I found a few websites with cool illusions. I used several from Optillusions and many from Akiyoshi’s illusion pages. But I think the one that they loved/hated the most was the Checker Shadow Illusion. Even when I showed them the two blocks were the same color using PaintShop Pro, they still didn’t want to believe. Heck, I didn’t want to believe it either! If you don’t believe it either, copy the image into your favorite drawing program and see for yourself.