Does the Yellow colour exist?

  Using GPS, these trails represent pizza delivery in Manhattan on a typical Friday night. And is this a frog or a horse? This lemon looks yellow to me, and it probably looks yellow to you as well, but not in the same way. You see, lemon is "Subtractively Yellow." It absorbs all visible wavelengths of light except for yellow light, which it reflects onto retina. But the screen that you are using doesn't produce yellow light at all. In fact, it can only produce red, blue,or green light. The really cool, but kind of disturbing thing about this is that herein the room, I am actually seeing "real" yellow light. But you are seeing "fake" yellow. Absolutelyno yellow is coming off your screen and falling onto your retina. But it still looks yellowbecause it's quite easy to lie to the brain. 

 Our retinas contain three different typesof cone cells that are receptive to color and each one is best suited to detect a certaincolor. One is great for blue, the other is great for green and the third is great forred. Notice that there is no individual cell looking for yellow. So, the way we actuallysee yellow happens like this. The wavelength of yellow light falls between the wavelengthsof red and green. And, so, when an object reflects yellow light onto your retina, boththe green and the red cones are slightly activated, which your brain notices and says "well, that'swhat happens when something's yellow, so it must be yellow." 

All a computer monitor or a mobile phone screenhas to do to make you think you're seeing yellow is send a little bit of red and a littlebit of green light at you. As long as the pixels and the little subpixels on them aresmall enough that you can't distinguish them individually, your brain will just say "well,I'm recieving some red and some green, that's what yellow things do...hmm...it must be yellow."Even though it actually is not... Lemons can also produce electricity. A littlebit of zinc, a little bit of copper, and boom, you're moving electrons around. But not thatmany, I mean, the current voltage are quite low.You could run an LCD, but even a potato could do that... If you wanted to run a flashlight bulb, thatwould take 3,000 lemons. And if you wanted to run a halogen bulb, well, that would take37,000 lemons. But artist Caleb Charland doesn't care.

 He spent 11 hours hammering nails into 300living apples hanging on trees. By connecting them to a household lamp, he was able to makeit glow just dimly enough to capture this image with a 4 hour exposure. Less alive and more frightening are SteveShaheen's sculptures: little dudes with bulb heads desperately trying to plug themselves in. Merve Kahraman's "Revitalizer" never dies.It's a lightbulb surrounded by wax. Now, the wax melts because of the lightbulbs heat,and drips into a special container into all kinds of weird new shapes, but whenever youwant you can just flip it so that the new, cooled wax is at the top.

 But my favorite is the Fukusada wooden lightbulb.It looks like a solid block of wood, but it's actually hollow and chipped to a nearly paper-thinwidth. When you turn it on you can see the light coming from inside. Combos. Artist Tang Yau Hoong blew my mind this week.

We've got clear days and smoke, boats and crocs, whales and hearts, Pie-bike, brainsand boxing gloves, day and night, but don't be scared, you can always paint yourself somelight. Or just swing on some light. Ok, let's frame it this way. Climbing Wall.This fitness club in Japan uses frames and other pretty interior elements to create adecidedly less rugged climbing wall. But let's get simple. Like, minimal. Thanks to Lego, here are their bricks arrangedto represent famous characters. Enjoy. Now for some Art Illusions. Here's a cute couple, but can you see, inthis very same image, the baby they will soon have? Or how about these zebras? There'sa lion hiding amongst them. Can you find it?

 Billboards can be clever, but here's a greatone that makes it look like someone is pushing out a section of the building. But how many of you will remember seeing it?If we assume that you don't remember experiencing major cultural events before you're 5 or 6years old, that means that every year there are fewer and fewer people alive who rememberexperiencing recent historical events. xkcd made this amazing chart to show when,in the future, the majority, more than half of living americans, will not remember beingalive when certain things happened. 

For instance, he calculated using data from the US CensusBureau that 2012, this very year, is the first year in American history since in whichfewer than half of living Americans remember being alive in the 1970's. By 2041, most of us won't remember a timewhen Pluto was actually called a planet. By 2043, most of us alive won't remember livingduring George W. Bush's presidency. And by 2047, more than half of living Americanswill not have been alive to have remembered anything that you did today.