The world has suddenly been divided into two groups: the Blue and Blacks and the Gold and Whites. 
 
 The BBs and the GWs are screaming at each other in loungerooms, in offices, in different lighting across the globe. The cause of the great debate? The color of a dress. 
 
 On Thursday, a user going by the name of Swiked posted a photo of a striped dress to Tumblr, which was then picked up by BuzzFeed. "Guys please help me — is this dress white and gold, or blue and black? Me and my friends can’t agree and we are freaking the fuck out." 
 
 The Tumblr post that started everything. Image: Swiked / Tumblr 
 
 With this one insignificant question, the Internet fell apart and we all forgot about llamas. Some people claim the stripes are blue and black, while others can only see gold and white. Various techniques are being deployed in an attempt to change the side you were born on: dimming lights, changing brightness, switching device, throwing computers off balconies. 
 
 And if the world wasn't pushed to the brink already, Taylor Swift goes and passes out. 
 
 The dress is tearing us all apart. A photo posted by Alex Goldschmidt (@alexandergold) on Feb 26, 2015 at 6:47pm PST 
 
 There are random theories popping up about what causes the violent difference of opinion — yet many are just reduced to name calling — such as one posted on the forum Neogaf that blames your cones and your rods in your eyes. 
 
 Blue and Black: Your retina’s cones are more high functioning, and this results in your eyes doing subtractive mixing. White and Gold: Our eyes don’t work well in dim light so our retinas rods see white, and this makes them less light sensitive, causing additive mixing, (that of green and red), to make gold. 
 
 Or there is this Vine, which insulted everyone for even thinking there could be a paranormal explanation. 
 
 Or this patronizing tweet. 
 
 So, as an example of how fun color perception works, A and B are EXACTLY the same color in this image: pic.twitter.com/pU66dkNgZs — Kathryn Long (@StarKat99) February 27, 2015 
 
 Finally, an ophthalmologist came to the rescue. Well, kinda. 
 
 "It is yellow and gold in this lighting," Dr. Robert Freedman of Swampscott, Massachusetts, told Mashable, appearing to destroy the hopes of the BBs everywhere. 
 
 He clarifies: "Scientifically it has to do with the lighting and reflectivity of the material." Before adding: "But who gives a F? Really. Who is wearing it?" 
 
 Freedman then produces a kicker and knocks both parties back to harsh-lit reality using scientific reasoning: "G-d help us if that's a story." 
 
 Don't tell Freedman about the llamas. Or this. ||||| Oops. Something went wrong. Please try again later 
 
 Looks like we are having a problem on the server. ||||| Official @ BuzzFeed statement on the dress post says "it drew more visitors to our site at one time than ever before" pic.twitter.com/xuBbGhYHEu ||||| Oops. Something went wrong. Please try again later 
 
 Looks like we are having a problem on the server. ||||| Not since Monica Lewinsky was a White House intern has one blue dress been the source of so much consternation. 
 
 (And yes, it's blue.) 
 
 The fact that a single image could polarize the entire Internet into two aggressive camps is, let's face it, just another Thursday. But for the past half-day, people across social media have been arguing about whether a picture depicts a perfectly nice bodycon dress as blue with black lace fringe or white with gold lace fringe. And neither side will budge. This fight is about more than just social media—it's about primal biology and the way human eyes and brains have evolved to see color in a sunlit world. 
 
 Light enters the eye through the lens—different wavelengths corresponding to different colors. The light hits the retina in the back of the eye where pigments fire up neural connections to the visual cortex, the part of the brain that processes those signals into an image. Critically, though, that first burst of light is made of whatever wavelengths are illuminating the world, reflecting off whatever you're looking at. Without you having to worry about it, your brain figures out what color light is bouncing off the thing your eyes are looking at, and essentially subtracts that color from the "real" color of the object. "Our visual system is supposed to throw away information about the illuminant and extract information about the actual reflectance," says Jay Neitz, a neuroscientist at the University of Washington. "But I've studied individual differences in color vision for 30 years, and this is one of the biggest individual differences I've ever seen." (Neitz sees white-and-gold.) 
 
 Usually that system works just fine. This image, though, hits some kind of perceptual boundary. That might be because of how people are wired. Human beings evolved to see in daylight, but daylight changes color. That chromatic axis varies from the pinkish red of dawn, up through the blue-white of noontime, and then back down to reddish twilight. "What's happening here is your visual system is looking at this thing, and you're trying to discount the chromatic bias of the daylight axis," says Bevil Conway, a neuroscientist who studies color and vision at Wellesley College. "So people either discount the blue side, in which case they end up seeing white and gold, or discount the gold side, in which case they end up with blue and black." (Conway sees blue and orange, somehow.) 
 
 We asked our ace photo and design team to do a little work with the image in Photoshop, to uncover the actual red-green-blue composition of a few pixels. That, we figured, would answer the question definitively. And it came close. 
 
 In the image as presented on, say, BuzzFeed, Photoshop tells us that the places some people see as blue do indeed track as blue. But...that probably has more to do with the background than the actual color. "Look at your RGB values. R 93, G 76, B 50. If you just looked at those numbers and tried to predict what color that was, what would you say?" Conway asks. 
 
 So...kind of orange-y? 
 
 "Right," says Conway. "But you're doing this very bad trick, which is projecting those patches on a white background. Show that same patch on a neutral black background and I bet it would appear orange." He ran it through Photoshop, too, and now figures that the dress is actually blue and orange. 
 
 The point is, your brain tries to interpolate a kind of color context for the image, and then spits out an answer for the color of the dress. Even Neitz, with his weird white-and-gold thing, admits that the dress is probably blue. "I actually printed the picture out," he says. "Then I cut a little piece out and looked at it, and completely out of context it's about halfway in between, not this dark blue color. My brain attributes the blue to the illuminant. Other people attribute it to the dress." 
 
 Even WIRED's own photo team—driven briefly into existential spasms of despair by how many of them saw a white-and-gold dress—eventually came around to the contextual, color-constancy explanation. "I initially thought it was white and gold," says Neil Harris, our senior photo editor. "When I attempted to white-balance the image based on that idea, though, it didn't make any sense." He saw blue in the highlights, telling him that the white he was seeing was blue, and the gold was black. And when Harris reversed the process, balancing to the darkest pixel in the image, the dress popped blue and black. "It became clear that the appropriate point in the image to balance from is the black point," Harris says. 
 
 So when context varies, so will people's visual perception. "Most people will see the blue on the white background as blue," Conway says. "But on the black background some might see it as white." He even speculated, perhaps jokingly, that the white-gold prejudice favors the idea of seeing the dress under strong daylight. "I bet night owls are more likely to see it as blue-black," Conway says. 
 
 At least we can all agree on one thing: The people who see the dress as white are utterly, completely wrong. ||||| The seed for Wide00014 was: 
 
 - Slash pages from every domain on the web: 
 
 
 
 
 
 -- a ranking of all URLs that have more than one incoming inter-domain link (rank was determined by number of incoming links using Wide00012 inter domain links) 
 
 
 
 -- up to a maximum of 100 most highly ranked URLs per domain 
 
 - Top ranked pages (up to a max of 100) from every linked-to domain using the Wide00012 inter-domain navigational link graph ||||| Sarah Weichel, above, and Caitlin McNeill. Business Insider Two women are behind the viral dress that has everyone confused. Here's what they told us. 
 
 The picture was initially posted on Tumblr by a 21-year-old singer named Caitlin McNeill who lives on the tiny Scottish island of Colonsay. 
 
 In a telephone conversation with Business Insider on Thursday evening, McNeill explained that the dress in the picture was worn to her friends' wedding. Some people see the dress as it appears in the photo as white and gold, while others see it as blue and black. 
 
 The dress was worn by the bride's mother. McNeill and her friends first realized something was different about the dress when the mother sent her daughter the now-famous photo. 
 
 "What happened was two of my close friends were actually getting married and the mother of the bride took a photo of the dress to send to her daughter," McNeill said. "When my friend showed the dress to her fiancé, they disagreed on the color." 
 
 The bride then posted the picture on Facebook, and her friends continued to debate the color of the dress. 
 
 "All of our friends disagreed," McNeill said. 
 
 After seeing the Facebook thread, McNeill decided to share the picture on a fan page she has on Tumblr dedicated to a woman named Sarah Weichel. That was where the dress went viral. 
 
 Weichel is a talent manager who represents several YouTubers including Hannah Hart. 
 
 Weichel told Business Insider her phone began blowing up on Thursday after McNeill's post started going viral. 
 
 "The crazy thing is, I actually have nothing to do with the post," Weichel said. "It's literally just a fan account of me, so my name and my photos are all over the account. I actually don't have anything to do with it ... But I have been getting a ton of phone calls and emails tonight." 
 
 The situation was even weirder for Weichel because also on Thursday her client, Hart, was just announced as the star of a new television series. 
 
 "Between that announcement and the dress thing my phone has been going crazy with congratulations and, 'What the hell is happening?'" Weichel said. 
 
 For Weichel, there is no question about what color the dress is. 
 
 "Black and blue of course!" she said. 
 
 Weichel put Business Insider in touch with McNeill, who said one of the oddest parts of the experience had been watching celebrities share her picture. 
 
 "I thought my followers on Tumblr would maybe have a good reaction, but I never would have considered that Taylor Swift and Mindy Kaling would be tweeting about it," McNeill said. 
 
 Of all the celebrities who became interested in her post, McNeill would like to meet Swift. 
 
 "Oh my god," she said when we asked about Swift. "That would be something." 
 
 McNeill plays guitar and sings in a band named Canach that plays what she described as "traditional Scottish folky music." Her band played at the wedding. She actually saw the dress in person and told us definitively what color it really was. 
 
 "I got to the wedding and the mother was wearing the dress," McNeill said. "Obviously it was blue and black."
– Is it white and gold—or blue and black? A picture of a dress uploaded to Tumblr has created what Gawker calls "an Internet schism that may never be healed," with the opposing sides unable to fathom each other's view of the dress. At BuzzFeed, the white and gold side is leading heavily in a poll—and its story on the dress "drew more visitors to [the] site at one time than ever before" (at one point, more than 300,000 were reading the dress post; it's up to 23 million views). More: Assorted experts have weighed in to discuss the effects of the poor lighting in the photo and the peculiarities of color vision. "It is yellow and gold in this lighting," an ophthalmologist tells Mashable, explaining that "scientifically it has to do with the lighting and reflectivity of the material." A neuroscientist also in the white and gold camp tells Wired, "Our visual system is supposed to throw away information about the illuminant and extract information about the actual reflectance. But I've studied individual differences in color vision for 30 years, and this is one of the biggest individual differences I've ever seen." Scottish musician Caitlin McNeill, 21, started it all by posting the image on Tumblr. She explains the back story to Business Insider: "Two of my close friends were actually getting married and the mother of the bride took a photo of the dress to send to her daughter. When my friend showed the dress to her fiancee, they disagreed on the color." And in an example of how odd the Internet can be, the Tumblr McNeill posted it to is a fan page she has on talent manager Sarah Weichel, who BI says represents a number of YouTubers. Says Weichel, "The crazy thing is, I actually have nothing to do with the post. It's literally just a fan account of me, so my name and my photos are all over the account."