Cyberspace is being consumed by an acute philosophical debate over a picture of a dress many claim is obviously white and gold but others argue just as trenchantly is black and blue.
The hashtag #TheDress is leading trends on Twitter worldwide, boosted by a stream of tweets from celebrities voicing support for either of the opposing camps.
"From this day on, the world will be divided into two people. Blue & black, or white & gold," US comedian Ellen DeGeneres tweeted.
The picture of the dress was uploaded on image-sharing website Tumblr by a user named "swiked" on Wednesday.
Not since Liz Hurley went out with a load of safety pins on has a dress caused so much controversy. #TheDress pic.twitter.com/Fpt2bf2u4m
— Eleanore Hutch (@elehutch) February 27, 2015Yesterday, Buzzfeed asked for reader opinions, which got people talking.
Buzzfeed's post had been viewed nearly 25 million times on the website as of early this morning.
A poll alongside found 72% of respondents believed the dress to be white and gold.
Musician Taylor Swift was gripped by ontological uncertainty.
"I don't understand this odd dress debate and I feel like it's a trick somehow. I'm confused and scared. PS it's OBVIOUSLY BLUE AND BLACK," she tweeted.
Swift was supported by others, including Justin Bieber.
The white and gold camp was supported by the likes of reality TV star Kim Kardashian West.
"What color is that dress? I see white & gold," West tweeted, adding that her husband, rapper Kanye West, saw black and blue.
According to British physicist Isaac Newton, colour is not inherent to objects.
Humans perceive the colours reflected on the surface of objects through light that hits the retina in the back of the eye.
Reena Garg, an assistant professor at the New York Eye and Ear Infirmary of Mount Sinai in New York, said the varied reactions can be explained by how we understand colour, noting that the poorly exposed photograph was likely taken with a cell phone camera.
"If you see the dress as black and blue, you're probably seeing the photo as over-exposed, meaning there is too much light, so the colors in the dress appear darker to you after the retina has compensated," Ms Garg told AFP.
"If you see the dress as white and gold, you're probably seeing the photo as under-exposed, meaning there is too little light and the colors in the dress appear lighter to you after the retina has compensated."
Of course, there is an answer to it all.
A description on British manufacturer Roman Originals confirms that the dress is, in fact, royal blue with lace.
