Why is the number 13 evil?

In Sunday school last week, our teacher explained to us how numbers can be evil. I don't like going to Sunday school anymore since my friend Steve got kicked out. (If you want to know how it all happened, you'll have to read my post on 'So, when was God invented, then?'). But my parents think it's a good idea to have at least some religious education. Most of the stuff we get told doesn't make any sense to me, but I still go because my dad promised to get me a new bike for Christmas...

I think what our teacher was trying to tell us was that the devil has a number and that we should avoid using it (it's 666 - in case you're interested). He wanted us to know that 13 can be evil too. I didn't believe any of it and so I tried to think of more interesting things (such as building a fort this winter and playing Quidditch with my friends - we use broomsticks as well, but none of us can fly). I also tried to think of my new bike.

But I know that some people like to believe in strange things. My mom for example thinks that our uncle Herbert is special because he was born on Christmas Day. He believes in angels and sees people who aren't there. (He also uses aluminum foil to wrap his furniture in case aliens want to steal his lunch.) I think Uncle Herbert is schizophrenic. But my mom is convinced that he has visions. And when I asked her about the numbers, she couldn't explain any of it. So I decided to do some more research ...

Here's what I found: a normal year in our calender has a little over 12 lunar cycles, so there's an odd month every four years or so. In the old days, some of the monks who were responsible for coming up with new calenders didn't like this because it was too difficult. That's probably why they thought the 13th month was unlucky. (Find out more about lunar cycles and the blue moon on space.com)

13 is also important for Christians because, when Jesus had his last supper, there were 12 apostles at his table (13 people altogether). One of them betrayed him, so I guess he must have thought 13 was evil. 

In the Jewish religion, a boy achieves maturity when he turns 13. He then becomes a full member of the community (although I don't know if this is a good or a bad thing.) I think witches are cool, so I think it's important that there are normally 13 witches in a coven.

I guess people are a little afraid of the number 13 because there are some very complicated things you can do with it in Maths (and Maths is always scary). There are 13 Archimedean solids, for example, and people say that there are 13 ways for the three fastest horses to finish a race (if you're into this kind of stuff, you will be interested to know that this is because 13 is the third ordered Bell number - you can find out more about Bell numbers here). 

I also think people believe 13 is unlucky because it's an odd number that doesn't seem to fit in anywhere. Some people think it's bad to start a new project on a Friday or on the 13th. But I think that's mostly because you would run way into the weekend before you could finish it...

I like funny words, so I think it's pretty cool that fear of the number 13 is called 'Triskaidekaphobia'. But - as it turns out - the number 13 is not an evil number after all, it's just been a bit unlucky. Not because it's evil but because superstitious people don't seem to like it very much. 

I'll have to talk to my Sunday school teacher on Sunday. Steve and I wanted to start building a boat next Friday. If I talk to him about his superstitions this week, I think there's a good chance that we'll have enough time to finish it next Sunday morning. If I do it right, he'll kick me out too and I could tell my dad it wasn't my fault ...

If you want to know a little more about why people don't like the number 13, check out this post on mentalfloss.com. I took the Quidditch picture from Harrypotter.wikia.com. The first 13 came from the Telegraph website and the calendar with Friday 13 came from a blog called blog.pch.com.
  

What's the difference between a Raven and a Crow?

I haven't posted anything for a while. The reason is that my parents had this great idea to refurbish our house. They had been planning to do it for years, so I didn't think it would ever happen. But a few weeks ago they told me that they would need my room for storing bricks and cement and stuff. And that's why I had to go and stay with my grandma for a while.

My grandma's a little crazy, but she's also very nice. I didn't mind living with her for a few weeks. She bakes the most amazing cakes! The only problem is that she doesn't have any broadband at her place...

Anyway. I'm back home now. My parents are almost finished (there's still lots of cement bags and bricks stored on our driveway). So I thought I should post something new...

Last week, my cousin Carl (who is a few years older than me and totally into horror stuff) told me something very strange about crows. He said that they sometimes attack people and hack out their eyes. I thought he was just trying to scare me, so I asked my dad about it. He didn't think they did. But he also couldn't explain the difference between a raven and a crow. So I got online and did a little research.

Here's what I found out: Crows and Ravens are actually all part of the same crow family called corvus. Crows are a bit smaller than ravens (pigeon size), and they are less shiny. Ravens are huge, almost as big as a falcon. But they live farer away from cities and from people, so we usually see them less.

I only ever see crows when they sit outside my window in our neighbour's garden. Sometimes there's a few flying over our house (a few crows flying together is called a 'murder of crows'- which I think is pretty cool!). It's hard to tell what they look like when they're flying. But apparently they have a very different shape of tail (which you cannot see when they are sitting down). Crows' tail feathers are fan-shaped and a raven's tail looks a little more wedge-shaped.

Another way to tell crows and ravens apart is the way they sound. A crow's call sounds a bit like an angry poodle and a raven's call sounds more like a complaining old person. Check out these videos on YouTube for an example:

Video 1: angry poodle crow

Video 2: old person raven

Crows eat almost everything they can find. Berries, little insects and also dead things. In the stories of old, people saw them after battles and such because they fed on the dead bodies and the fallen horses. I think that's why a few of them together are always considered to be a bad sign.

So - as it turns out - crows actually will hack out your eyes if you're a dead soldier lying in a ditch somewhere. They will also eat your horse. But the good thing is that they would not try and eat you while you're still alive, so there's no need to worry.

What most people don't know is that ravens also eat dead things. But they usually do it alone. Maybe that's why they're not as well known for it.

 If you want to find out a little more about crows and why they sleep together in roots, check out this informative website: http://www.birds.cornell.edu/crows/crowfaq.htm.

For some more information on crows and ravens in celtic and native American myths, you could have a look at this blog.

The picture with the crow and the pram was designed by Dark Shepard - I found it on imgfave.com. The image with the flying raven came from people.tribe.net.

Where does Rust come from?

Sorry for the long silence, everyone. The weather was really nice here in Britain and I spent a lot of time outside. My friends Tommy and Steve came over and my dad helped us build an awesome treehouse. We pretended to be Aliens who wanted to take over the world from up in our treehouse. Steve even invented a little lift we could use for transporting food and stuff... It was pretty cool!

We also wanted to go on a bike ride through the woods the other day. But when I got out my bike, it was pretty rusty. My parents don't have a lot of money, so they got the bike off one of my cousins when he got a new one last year. It was a very old bike, and when I got it, it already had a few rusty patches. But because we don't have anywhere to put it, I had to keep it outside over the winter (which was really cold and rainy!). And when I got it out for our bike ride the other day, the rust had gotten everywhere...!

There was rust on the chain, on the crank arm, on the handle bars, under the seat and all over the brakes. And when I tried to get it off with the sponge and the old cloth my mom gave me, one of the crossbar clamps came off in my hands and crumbled into a million pieces.

First, I got really upset because I couldn't go on the bike ride with my friends. But then I thought it might be a good idea to find out a little more about rust. Especially because my dad keeps complaining about all the rust on his old VW. He clearly has no idea how to get rid of it properly. So here it goes...

My dad calls rust the 'tin worm', but rust is a chemical reaction and not an animal. When metal rusts, it turns into a compound called 'Iron Oxide'. Iron oxide (Fe₂O₃₎ looks a bit like brown and leafy dirt (If you're a real chemistry nerd, you might want to have a look at the whole chemical formula on Chemicalformula.org). The whole process is called 'corrosion' and it happens when metal reacts with water and with oxygen (air). (Check out a few cool experiments with different oxygen levels and rusty steel wool on Physicsinsights.com here.)

Rusting is actually pretty cool. It is a full-on electrochemical process. The metal acts as an anode and the water as the electrolyte of the reaction (check out this video on YouTube for an introduction into electrolytes). When the oxygen in the water reacts with the metal, electrons are set in motion - which then flow to the cathode and convert the metal into rust (the metal also expands - which explains the flaky bits). If you're living close to the sea, sea water makes things even worse because it's got a lot of salt in it. (Higher salt levels make for better electrolyte action.)

Because water and air are pretty much everywhere, it turns out that the only way to prevent metal from rusting is to keep it in a vacuum or to coat it with lots of paint or with corrosion inhibitors. You can also 'galvanize' it with a special zinc coating (they do this with cars). But there are some more advanced techniques that can be used for corrosion protection.

On offshore oil platforms, big oil companies use something called Cathodic Protection to keep their steel from rusting. Instead of letting the structure rust, cathodic protection uses a fake bit of metal as a cathode. Once the first layer is fully covered with rust, it can then protect the rest of the metal because it creates a separate electro-chemical cell. This method is also used in storage tanks and home heating systems. But I don't think it will work on my bike or on my dad's VW because I don't think he will want to drive around in a car that's totally covered in rust...

If my parents had more money, I would ask them to buy me a bike with a full aluminum frame. Some people think aluminum can't rust but that's wrong. It does. But when it does, the rust on top looks a lot like the original aluminum because it's grey. It acts as a natural galvanizer and protects the surface from further corrosion.

I think I will have to sand off the rust on my bike and then put some zinc primer (which is a lighter version of cathodic protection) and some paint on it. This is also what my dad should do with his VW. I hope he has one of those masks people use for painting because some of the stuff I found online seems pretty potent. I don't think he should do this alone. He's not very good with technical things and I don't want him to go blind or faint...


The alien picture came from a website called Sodahead.com. The VW picture is from a project I found on TheSamba.com. The oil platform came from a website on rust protection and anti-corrosion paints www.aquasteel.co.uk).