Is it actually true that seeing is believing?

What colour are the dots?

The dots inside these hearts are distinctly blue or green, right?

Distinctly blue and green, right?

Wrong. The dots inside the hearts are all exactly the same colour. Here’s a section of the top left of the same image, where I’ve blanked out the misleading colours (I made a bit of a mess of it to be honest, but hey, I don’t get paid to do this).

Don’t believe me? By all means, prove it to yourself if you need to. (If you’re using the Firefox browser, you can use the built-in eyedropper: Click the main menu in the upper right corner, scroll to More Tools and then to the eyedropper.)

What colour is the star Betelgeuse?

The other day, my brother (no, not him, another one) told me that he’d seen the star Betelgeuse in his binoculars, and that it was yellow. I found this odd, as it’s my understanding that Betelgeuse is a red supergiant; I’ve seen it in the sky on numerous occasions, and it’s always looked red to me. At first, in discussion with my bro, I accepted that I could be mistaken: knowing that it’s called a ‘red supergiant’ may have primed me to see it as red, when, maybe, its colour doesn’t appear that way in reality.

But the very next day, by one of those ‘coincidence‘ things, YouTube presented me with the following video:

Transcription below

… and, naturally, because it’s entitled ‘This Is Not Yellow’, I watched the video (I couldn’t resist: I’d been primed to do so by my conversation with my brother the previous day). And what I learned from it in the first few minutes (as is his wont, Michael Stevens soon changes tracks to other matters) was that the human eye isn’t actually capable of perceiving the colour yellow.

So, I did some digging. And various sources confirmed my original belief that Betelgeuse is a red supergiant star.

What colour is our sun?

This reminded me of a conversation I’d (coincidentally) had recently with Professor Kipping, of ‘Cool Worlds‘ fame, in the comments section of a recent video of his (The Red Sky Paradox) in which he’d claimed that our own sun is ‘yellow’. Although I respect Prof. Kipping immensely, he’s wrong about this: our sun is actually not yellow, it’s white (with a hint of pink). Interestingly, in the comments on that video, Prof. Kipping talks about our sun being yellow ‘because that’s how it appears when we look at it’. I find it odd that he would make this assertion, since we can’t look at our sun directly, at least when it’s overhead: if anyone were foolish enough to do so, they’d quickly go blind. The only time one can look at it safely is at sunrise and sunset; and then, it appears to be red (not yellow, not white) because the intervening atmosphere slows down the incoming light.

Since moonlight is just reflected sunlight, if the Sun were yellow, the Moon would appear to be, too. And anyone who’s been fortunate enough to observe Baily’s Beads during a total solar eclipse will confirm that the ‘diamond ring’ is white (not yellow, and not red).

All of which is a bit of a sidetrack: the main point I wanted to make here is that these are good illustrations of how easily our brains and our beliefs can mislead us, and how important it is to retain an open mind, and to remain sceptical of beliefs — especially our own.

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Transcript of ‘This Is Not Yellow’

Michael Stevens: Using GPS, these trails represent pizza delivery in Manhattan on a typical Friday night, and is this a frog… or a horse? It’s episode 52 of IMG.

This lemon looks yellow to me, and it probably looks yellow to you as well, but not in the same way. You see, here in this room, this lemon is subtractively yellow. It absorbs all visible wavelengths of light except for yellow light, which it reflects onto my retina. But the screen that you are using to watch this video 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 here in the room I am actually seeing real yellow light; but you are seeing fake yellow. Absolutely no yellow is coming off of your screen and falling on your retina, but it still looks yellow because it’s quite easy to lie to the brain.

Our retinas contain three different types of cone cells that are receptive to color, and each one is best suited to detect a certain color: one is great for blue; the other is great for green, and the third is great for red. Notice that there’s no individual cell looking for yellow. So the way we actually see yellow happens like this: The wavelength of yellow light falls between the wavelengths of red and green, and so when an object reflects yellow light onto your retina, both the green and the red cones are slightly activated, which your brain notices and says, well, that’s what happens when something’s yellow, so it must be yellow. All a computer monitor or a mobile phone screen has to do to make you think you’re seeing yellow is send a little bit of red and a little bit of green light at you. As long as the pixels and the little sub-pixels on them are small enough that you can’t distinguish them individually, your brain will just say, well, I’m receiving some red and some green; that’s what yellow things do: it must be yellow, even though it actually is not.

(The rest of Vsauce’s video is totally irrelevant to this post, but it’s been transcribed anyway so here it is — you may find it of interest.)

Lemons can also produce electricity: a little bit of zinc, a little bit of copper and boom, you’re moving electrons around; but not that many. 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, that would take 3,000 lemons. And if you wanted to run a halogen bulb, well, that would take 37,000 lemons. But artist Caleb Charland doesn’t care. He spent 11 hours hammering nails into 300 living apples hanging on trees. By connecting them to a household lamp, he was able to make it glow just dimly enough to capture this image with a four hour exposure.

Less alive and more frightening are Steve Shaheen‘s sculptures; little dudes with bulb heads desperately trying to plug themselves in.

Merve Kahraman‘s ‘revitalizer’ never dies. It’s a light bulb surrounded by wax. Now the wax melts because of the light bulb’s heat and drips into a special container and all kinds of weird new shapes. But whenever you want, you can just flip it so that the new cooled wax is at the top. But my favorite is the Fukasada wooden lightbulb: it looks like a solid block of wood, but it’s actually hollow and chipped to a nearly paper thin width. 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; pi-bike; brains and boxing gloves; day and night — but don’t be scared, you can always paint yourself some light 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 a decidedly less rugged climbing wall.

But let’s get simple, like minimal. Thanks to Lego, here are their bricks arranged to represent famous characters.

Now for some art illusions. Here’s a cute couple, but can you see in this very same image the baby they will soon have? Or how about these zebras? There’s a lion hiding amongst them; can you find it? Billboards can be clever, but here’s a great one 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 five or six years old, that means that every year there are fewer and fewer people alive who remember experiencing 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 being alive when certain things happened. For instance, he calculated using data from the U.S. Census Bureau that 2012, this very year, is the first year in American history since in which fewer than half of living Americans remember being alive in the 1970s. By 2041, most of us won’t remember a time when Pluto was actually called a planet. By 2043, most of us alive won’t remember living during George W Bush’s presidency. And by 2047, more than half of living Americans will not have been alive to have remembered anything that you did today, like when you made that funny face in the yearbook. No, no, no. That funny face. If you’re not following @tweetsauce, you are missing out on daily Vsauce content, most of which never makes it to a video. So go follow us on Twitter and I’m going to leave you with another combo, a tessellation, while you listen to Jake Chudnows‘ [unclear]. He made a music video for the song over on his channel, so check that out.

And, as always, thanks for watching.

Michael Stevens AKA Vsauce; transcript courtesy of Sonix

Header image adapted from
‘closeup photo of person‘
by Marina Vitale on Unsplash