Monthly Archives: June 2014

Metacognition

I first learned the word metacognition when I was about six or seven years old, in a Moscow school. It means thinking about thinking. In this post, I will be making up a few words.

So recently, I started thinking about metacognition, or thinking about thinking about thinking; I’d call it metametacognition. Is it really useful to think about thinking? I decided that it was.

Then came thinking about thinking about thinking about thinking, or metametametacognition.  Should you really think about metacognition? I decided that sometimes you could.

Next I started metametametametacognition. Then I stopped because I realised where this was going to go.

It’s interesting to think about thinking, and sometimes to think about thinking about thinking, but you shouldn’t get too lost in the many repetitive levels of thinking about thinking and so on, because there are much more interesting things to think about than thinking.

Finally I thought, ” Is it possible to have a level lower than cognition, or thinking? Is it possible to have, maybe, atemcognition?”

I think that the only way that atemcognition is possible is if your cognition, or thinking, is about doing something, e.g. kicking a ball, moving a vase. Atemcognition would then be actually doing the activity that you were thinking about. It would be interesting if you were thinking about doing metacognition; then you could have atematematemcognition. Of course, thinking about doing metacognition is just metametacognition! So atematematemcognition would be back to doing something, like accidentally deflating a ball or dropping a vase. Either way, you should still not get too lost in all those layers of thinking. There are more important things to think about, like paying to fix the ball and sweeping up the pieces of the vase.

Thanks for reading!

Magnetism(2)

There are four basic magnet-related categories that every material falls under: diamagnetic, ferromagnetic, antiferromagnetic and paramagnetic.  Materials have these properties mainly due to the charges of the nuclei and their electrons in the material, and their arrangements with respect to each other.

Ferromagnetic materials(ferro- comes from the Latin name for iron) are attracted to magnets, and can also become magnetised, either by a magnet or an electric current. Nickel, Iron, and Cobalt fall into this category. However, at cooler temperatures, gadolinium is also ferromagnetic, and at even colder temperatures, most of the lanthanides are also ferromagnetic.  Despite what you may have heard about neodymium magnets, they are not pure neodymium.  They are actually alloys.  Pure neodymium would not be ferromagnetic at room temperature.  They cannot be ferromagnetic above certain temperatures, for reasons I will explain later.

Paramagnetic materials are like ferromagnetic materials, but they are not attracted to magnets.  It seems to me that the prefix para- indicates that paramagnetism has some of the properties, but not all, of ferromagnetism, which is essentially correct.

Antiferromagnetic materials are materials that are not affected by magnets, unless, of course, you push them with magnets or heat the materials until they become plasmas, in which case the materials cease to be antiferromagnetic and you will still not have achieved the goal of causing antiferromagnetic materials to be affected by magnets, even though the plasmas are affected by magnets.

Finally, diamagnetic materials are repelled by magnets.  Glass and water are good examples.

Now why do these materials behave in these ways? At the most basic level, there are atoms and electrons. Electrons are negatively charged while the protons, at the nucleus, are positively charged. There are also neutrons at the nucleus but they have no charge so they don’t really matter. If I remember correctly, all, or most, atoms are like very tiny magnets.

At a slightly higher level, there are domains of atoms. In transition metals, there are a few electrons that are not as tightly bound to the atom as the others, so they float around in the metal like a sea of electrons. This essentially means that atoms in metals can affect the north pole and south pole of the atom. In domains, most of the atoms are pointing the same way, but atoms from two different domains are less likely to be pointing the same way.

In ferromagnetic and paramagnetic materials, when there is a magnetic field, the atoms in the domains all point the same way and are attracted to the magnet. The difference is that in paramagnetic materials, when the magnetic field is taken away, the domains point in different directions again, whereas in ferromagnetic materials the domains can still point the same way, i.e. the material is still magnetic. Antiferromagnetic materials can still have domains, but they never all point the same way. As for diamagnetic materials, I don’t know. I  could search Wikipedia, but I like to write from what I’ve read prior to writing the blog post.

Then why do some ferromagnetic materials become paramagnetic or antiferromagnetic above a certain temperature? The answer is that the direction atoms are pointing in can also be affected by heat; thus with too much heat, the domains will no longer point in the same direction, even if the materials is ferromagnetic, essentially demagnetising the magnet. Depending on the material, the temperature at which the material must be at in order to do this is called the Curie point.

That’s most of the basic things you need to know about magnetism itself! Other magnetic phenomena, such as why positively charged particles are repelled from electric currents, are quite complicated. In the example I have given, you need to know about relativity, although I forgot if it was general or special. These phenomena are also quite numerous. You can also search two other types of magnetism: ferrimagnetism and superparamagnetism, but I don’t think I will be able to explain those in a satisfactory manner.

Bye!

 

Oops…

I was looking at my old blog posts when I realised that many of them were very rude. For example, when I talked about why the days were called what they were, I asked readers(actually I didn’t specifically ask them) whether they knew, and then I wrote, “That’s what I thought.”

It’s a bit shocking to find out how rude you used to be; I can hardly imagine why I would say such things. I think that it’s always good to look at what you’ve done before and see where you went wrong(and where you didn’t).

PSLE

I haven’t been blogging in a while. In Singapore there’s a big, infamous examination called the Primary School Leaving Examination. The results of this examination a very important factor in determining which secondary school you go to; a lower score means that you will not be able to get into prestigious schools such as Raffles Institution, Anglo-Chinese School Independent, and Hwa Chong Institution, unless you have previously applied for a school through the Direct School Admission and have been given a confirmed offer. As such, students in Singapore study much harder for it than many other examinations(also resulting in PSLE guides, workbooks and textbooks becoming a profitable line of business in Singapore).

I am a bit worried that my T-score, which is based upon my English, Math, and Science scores* will not be high enough to get into the top schools. I do not believe that I do not know the key concepts themselves. The problem is that many questions set in Singapore examinations require you to phrase your answers in a certain way, such how you must state that decomposers break down substances into simple substances, and detritivores break up substances into simpler substances; even now, without the aid of previous worksheets, I am not certain that my previous statement was correct.

As a result, it seems to me that the PSLE is not so much a test of knowledge, but rather a test of carefulness. I am most worried about my English, since I have not been performing up to my expectations in that area. I have been trying some applications that help me to learn English phrases and the correct words and tenses to use. However, I believe that if I can check thoroughly and properly when I have time in the examination, I will be able to achieve a satisfactory score.

*Mother Tongue, one of the other subjects Singaporean students must take, is not included since I have been overseas for a long time, and therefore I am exempted.  This reduces my workload by a lot.