Colour perception is FASCINATING!
Alright, so first off, I don't *really* care what the actual colour of that dress is (I'd describe it as pale-blue, distressed bronze if pushed), but the whole debate is fascinating to me. Ever since I was little, I have thought and worried a lot about whether people view colours the same way I do, and how can we even tell? I have a pair of shoes I am CONVINCED are green, but I'm frequently told they're blue (worrying, because blue should definitely clash with the outfits I wear the shoes with). What other colours do people disagree with me about? Do I dress like a weirdo because my colour preception is off? And what causes all these differences? Is it the brain? The eyes? How can we tell????
Thankfully, there are cleverer people than me working on this. One great resource for learning about how our eyes interpret colours, and how many colours humans can see vs. other animals (the Mantis Shrimp has CRAZY visual abilities!) is to listen to the RadioLab podcast on Colours. For more human-based discussion, xkcd just published a colour survey that shows that generally, people agree on the broad colour definitions.
So, the truth of the dress itself - not interesting. The fact that me and my officemates see very different colours when we look at it: SUPER INTERESTING!