let's discuss 13 things.

To begin, where to spend all that cash you picked up over the holidays?

Now, plenty of website sell cool stuff. United Nuclear sells

Aerogel, radioactive isotopes, jet engine schematic

and even marbles doped with uranium. Maths Gear sells these cool non transitive

dice I actually bought

yesterday, as does Grand Illusions. But they also carry for explosive magic

tricks,

optical illusion masks and a poster of

this image. What makes that

image so special? Well, it's an example

of the land effect. Even though it appears to contain

a bunch of different colors - oranges and yellows and greens,

the entire image is actually made out of nothing

but red. Seriously. I've linked the image down in the descriptions, so you can grab

it and investigated using

your favorite image editor. The yellows are actually

light reds or pinks. And the green is just dull grey

red. What's going on is called

color constancy. Your visual system, your eyes and brain

calculate the average illumination conditions of a scene

and then subtract those conditions, so that colors remain relatively constant.

This is why a blue object looks blue, whether you're viewing it

under the midday Sun or a dark red sunset or fluorescent light or

incandescent light.

It's a very brilliant system, but it can fool

us. Special images, like this one, appear to be illuminated with a lot of red

light,

so your brain actually subtracts the red and makes assumptions.

There are plenty of other examples of the land effect and other ways our visual

system lies to us.

But you know what else is a lie?

Raindrops. Well, at least

that depiction of raindrops. Raindrops are not shaped like

teardrops. Surface tension means that small drops are spherical,

but when they combine the air and get bigger, the pressure of the air below

them as they fall causes the bottom to

flatten, which means that raindrops are shaped less like

teardrops and more like hamburger buns.

But how many raindrops have fallen

on land ever? It's a fun question

and there are plenty of resources discussing how many raindrops fall

during a typical storm,

but throughout all of history? Let's go to mathforum.org for this one.

Doctor Ian calculated,

quite roughly but amusingly, that given the percentage of earth

usually covered in land and the amount of rain that

typically falls on earth and the volume of a raindrop,

the total number of raindrops that have fallen on land,

ever since earth began, is about 16 times

10 to the 28. So, earth

has had a lot of raindrops.

But you know what earth doesn't have a lot of? Nice big, old chunks of Moon rock.

Material from the Moon is incredibly rare.

We can only get pieces of the Moon in two ways. By

visiting it or by finding chunks of the Moon that were blown off

a long time ago and eventually fell to Earth.

Interestingly, you can buy paintings

containing traces of Moon dust made

by an astronaut. I discussed this with my friends over at emotistyle,

video link in the description. But the point is, you will not be owning

a big old Moon rock anytime soon. Interestingly,

a surprising number of the rocks we brought back from the Moon

have been stolen or just plain

lost. For instance, in 2002

interns Thad Roberts and Tiffany Fowler stole

101 grams of lunar material

from the Johnson Space Center. They celebrated by throwing the rocks onto a

bed,

and I guess the best way to explain what happened next would just be to point out

that the book based on this true story

is called "Sex on the Moon." Or, from a different angle,

fun. This was built using the Side View maker.

Type in a word or name and it will construct the word using

dots, which from another angle say something else. For instance, Vsauce

can be vacuum. If you prefer dots that represent people,

Brandon Martin-Anderson's got just what you need. The entire 2010 US Census

on a map with a dot for every single

person. The data is specific down to the size of an individual

block. It's really fun to play around with, as is

the searchable Calvin and Hobbes. I shared this on @tweetsauce a few weeks ago.

Type in a word and you can find every single Calvin and Hobbes comic strip

that used that word. Words or phrases that help you remember something are

called

mnemonics. For instance, if you wanna remember the exact

speed of light in meters per second in a vacuum, just count the number of letters

and each word of this sentence. "We

guarantee certainty, clearly referring to this light mnemonic."

Or if you're like me, your biggest struggle is spelling the word

diarrhoea. Well, don't worry. Just remember

diarrhoea is a really runny heap

of endless amounts. We've all seen illusions like this before.

Four circles with corners cut out of them. We perceive

an actual square resting on top of circles, even though no square

is there. Now interestingly, if you take this shape

and put it on top of text, the letters within the

fake square appear bigger than the rest of the letters.

This is because our brain assumes the letters are closer to us

than the rest of the text. After all, the letters are on top of a square

that's on top of circles on top of text.

Speaking of size, let's take a look at the scale

of our solar system. OMGspace.net

is a website containing images of the Sun and the planets

to scale. Not just in size, but also

distance. If you scroll long enough, you will eventually get to Mercury

and then Venus and then Earth and so on. Or, just click a planet's name

and have the site take you there right away. If that sort of thing makes you

feel

small and insignificant, rush on over and grab yourself

emergency compliment dot com.

The site will keep complimenting you until you feel better,

but if practicing patience is more your thing, check out

chickenonaraft.com. Geo sketch is a really fun way to draw.

You have this strange folding mechanism that

draws. You can individually control the rate of rotation for each

joint to see how it affects the image. But if you'd rather combine rotation

with our solar system,

check out gravity. Click and drag to place

objects of varying size in the space and watch how

they interact. So there you go

that was about 13 things.

I guess. I don't really know. But there's more.

I created a playlist of videos that you should totally see.

I host the playlist and you can start it by clicking the link at the top of this

video's description

or this annotation. I call it a lean back,

because you start the playlist and just lean back and let YouTube

do the work. So, what are you waiting for? Go ahead and click

and I will see you over there.

And as always,

thanks for watching.