Yesterday, it seemed like the (now free and open) internet was going to break thanks to a photo of a dress that to some people looks white and gold while others swear is blue and black. First, what do you see?
Okay, now imagine your friend vehemently disagrees with you. If you say it's white and gold, they'll say blue and black. Or vice versa. Who's eyes are screwed up?
The answer is both of your vision are probably fine. The dress, Atlantic CityLab reports, is an example of an optical illusion first identified in the 19th century and explained in Josef Albers's Interaction of Color.
Basically, color is relative. If you'd like to read the book, you can pick up the free iPad app on iTunes.
(For the record, the owner of the dress in question says it's blue and black. I saw it that way at first, then could only see it as white and gold, and now it is back to blue and black for me. I thought I was going crazy, but at least color science assures me I'm not.)