钱不是万恶之源。。。

它，才是万恶之源。

万恶当然不是指所有的恶，而是指 "数量极多，而且品种繁复的恶行"。我方认为世上穷凶极恶的恶行都来自xxx。

家庭暴力，是为了钱。但，再怎么凶，家庭暴力不是恐怖主义；
恐怖主义，是恶。但，再怎么残忍，恐怖主义不是为了钱；
麻原彰晃，既是恐怖主义也是为了钱。但他不是霸权；

可是xxx，比他们都还恶。
它，聚集了霸权、金钱、以及恐怖主义于一身。
它为了钱和权，无所不做。
它是贪、嗔、痴。
它“异化了人与钱之间的关系”。
它是万恶之首的淫。

可是它不是钱。它来自马来西亚。

A gifted child...

Son: Dad, I want to quit school.

Me: What?! But why?

Son: School is so boring. They are teaching calculus, which I already knew since I was 6, and they are still learning Newtonian physics. When are they going to start on quantum mechanics?

Me: Yes, you are a gifted child. But do stay in school, dear. If you find the academic side of the school is boring, try joining student organisations, like the Chinese Language Society or debate team.

Son: Like what you did when you attended high school?

Me: Yes. You can learn about people relationship, people management, organisational skills but most of all it is fun! You could also do some charity work in the local community. By helping the poor and the weak, you get to see things from other people's point of view and it will change your life. You could also play some games, mix with people, go after girls, you know, those things that other high school boys do?! (laugh)

Son: But what's the point?

Me: What's the point of going after girls? (*Gasp*)

Son: No, dad. (=.= "') I know about going after girls. I meant, what's the point of learning people skills, etc ...

Me: Great to hear you are interested in girls already (*wink*). Well, there's a lot more to school than just knowledge, you know. And that's certainly true as well when you step into the society to work, which will happen soon enough. To make the right decision, you must learn how to appreciate the people around you, the culture and history. To realise a plan, you must make people to work with you. You don't expect to get everything done by yourself, do you?

Son: Didnt' Einstein developed theory of relativity all by himself?

Me: No. First of all, without Newton and all the subsequent scientist's groundbreaking work in gravity, there would be no theory of relativity. They were the necessary foundation to Einstein's work. Let's not forget that he had to rely on Eddington to verify his theory. And most important of all, Einstein was not just a physicist, he was also actively involved in politics and was influential in both the World War 1 and 2.

Son: Really? I see.

Me: Your knowledge must have a positive impact to yourself, to the people around you and ultimately to humanity, but you would not be able to do that if you do not first appreciate and respect the people around you. What good is knowledge if it doesn't help yourself and those around you?

Son: Does it always come in that order? Self, people around me, and then humanity? Sounds a bit far-fetched don't you think? Humanity, eh?

Me: Your sphere of influence grows in that order - you first influence yourself, the people around you and then, if you are lucky, humanity. But the importance is in the reverse order. Always place others before yourself. You will never know though, that some day you may be some one great and influential. But even if you are not the leader of the world, you are always important to me, to your family and those around you.

Son: Thanks dad.

Me: You are welcome. Remember, stay in school. Spend the extra time with friends and learn more about people, it's much more complex than quantum mechanics and string theory, trust me on it. There's no hurry in learning quantum physics and string theory. You can always accelerate your academic skills after high school when you start your university education. So what do you think? You feel better about school now?

Son: I guess so. I will check out the notice board tomorrow to see if any student project interests me.

Me: Good. Now, go out and play with your friends.

Son: OK. But I think I would go to my room and finish the book "The strange theory of light and matter" by Feynman. I am already at the last chapter. Love you, dad.

Me: Love you too.

Malaysian Job

It took half a dozen people in "Italian Job" to pull off a 35 million dollar heist;

It took almost a dozen professionals in "Ocean's eleven" to steal millions from casinos;

But all it took was TWO Malaysians to steal 2 multi-million dollar jet engines from a high-security Malaysia Air Force base in the middle of the busy Klang Valley, smuggle it out of the country, and somehow find a buyer for ... jet engines?

Screw Hollywood. The real deal is in Malaysia!

0, 1, 2, smile ...

Q: How many economists does it take to screw in a light bulb?
A: None. If the government would just leave it alone, it would screw itself in.

Q: How many gorillas does it take to screw in a light bulb
A: Only ONE, but it sure takes a shitload of light bulbs!

Q: How many Malaysians does it take to screw in a light bulb?
A: TWO. One to dismantle it, put it on the forklift, move it to the truck, evade all security personnel, drive the truck all the way to the port, move it into the container, lie to the customs officers, and get the engines offshore. The other just sells them.

Oh wait, I was describing jet engines, not light bulbs...

Allah must be laughing now...

Allah (whichever God you might refer to) must be laughing so hard now that His teeth is falling off from the sky in the form of meteor showers tonight.

I am pretty sure Allah can understand more than one language, so He must be bemused by the people who are worried that He could not understand you if you do not address Him in the right language. He must be even more bemused that some of His followers actually got confused when a different name is used to call Him.

I am neither Christian nor Muslim, but I am pretty sure that "what is the correct name to call Me" is the last priority for God's teachings. If it isn't, you should reconsider your religion because it sounds too damn easy to go to heaven.

Certain quarters of Christians and Muslims felt insulted. I think Allah aka Tuhan aka God should be the one that feels most insulted because of all His teachings passed down over the centuries, we were most concerned with what to call Him. I am sure this make a heck of a religion.

My mentor in high school once told me this, "There will always be problems in your life. A beggar and a businessman millionaire have the same number of problems. But the level of problems faced by these two people is what distinguished them. One is of higher stature, the other is not..." I cannot help but to think that this applies to religion too.

(in reference to the recent uproar by some Malaysian Muslims against the usage of 'Allah' by Christians to refer to the Christian God)

2.3 Electric field in materials

Previous sections:
1. Introduction
2. Electrostatic
2.1 Coulomb's Law
2.2 Gauss's Law of electrostatic

2.3 Electric field in materials

So far we have considered the electric field in free space. Obviously, if we now consider the electric field in materials (insulators or conductors), things will be quite different.

In the previous section, we shown that ∇.E=ρ/ε. Let's call this ρ as free charge since it represents the electric charge that is 'free' to move around (note: only free charge contributes to electrical current). Let us now assume that when we apply an electric field to the material, the material will modify the electric field either by strengthening it or weakening it, depending what kind of material it is. Let us represent this effect by introducing an additional charge, called the bound charge, ρ_bound. (These charges are not free and are 'bound' to the material and they cannot freely move about to generate electrical currents.)

One of the ways to imagine bound charge is to consider applying an electric field to a perfect conductor. Assume that the material consists of many electrical dipoles, i.e. opposite charges separated at short distance. (Such dipoles may exist, for example, in molecules with ionic bonding. The electrical field will displace the positive and negative ions slightly to create a dipole.) Now, further assume that these dipoles are not free to move about. They are fixed or bounded to the material. They can only rotate about their axis. What the applied electric field would do to these dipoles is to align them along the electrical field lines with the head of one dipole lining up behind the tail of the other dipole (refer to the diagram below). The result of this 'bound charges' aligning is that the internal electric field cancel each other out (due to the positive and negative charge lying close to each other). This result is important, so remember it: Electrical field inside a perfect conductor is zero. What happens if it is not a perfect conductor? Then, the dipoles cannot align perfectly and the electric fields will attenuate/diminish but it will not be completely cancelled out. You may also ask, what allows us to make such assumption about the electrical dipoles? Nothing, except that experimental results seem to suggest that such assumption is reasonable. As with previous, science is always about suggesting a good assumption to explain the experimental results.

Therefore, in the presence of any material (insulator or conductor), we modify the equation to become ∇.E=(ρ+ρ_bound)/ε to include the bound charges in a material. Having different kinds of charges (bound and free) in the equation is very confusing, this is why in Maxwell's equation all charges always refer to free charges. In order to be consistent with this, we rearrange to 'get rid' of the bound charge in the equation, i.e.

∇.εE - ρ_bound = ρ ;

∇. (εE + P) = ρ ; where ∇.P= - ρ_bound

∇. D = ρ ; where D = εE + P

The polarisation vector P, is the electric dipole moment density. By considering that an electric field causes dipoles to re-arrange in materials, one can calculate that the actual effect an electric field has on a material is to generate a 'surface charge' and a 'volume charge' which is related to P. You can refer to many textbooks on how this is calculated, or you can take my approach, which is just to assume P is a value (like kilograms is for weight) to indicate how much the electric field is affected by the material.

Since the electric dipole is induced by E, we may suspect that P is related to E too, and this is indeed the case. However, the relation may not be a linear one. In most cases we can assume it is linear, i.e. P=kE. But we write P=εχE, where ε=permeability of free space (as usual) and chi, χ=electric susceptibility.

Then D = εE + P = εE + εχE = ε(1+χ)E = ε . ε_r . E ;
where ε_r = (1+χ) is the relative permeability

If ε_r is independent on position, i.e. the same throughout the material, then the material is said to be homogenous. If it is homogeneous, then in general, D = ε . ε_r . E is in matrix form where D and E is a 3 x 1 matrix and (ε . ε_r) is a 3 x 3 matrix. If only the diagonal elements of (ε . ε_r) is non-zero, i.e. the relative permeability is only dependent on the principal (x, y and z) axes, the material is called biaxial, or isotropic:
Dx = ε . ε_r11 . Ex
Dy = ε . ε_r22 . Ey
Dz = ε . ε_r33 . Ez
(where the number indicates the position in the 3 x 3 matrix)

Furthermore, if ε_r11=ε_r22, then the material is said to be uniaxial.

In summary, in the presence of (any) material, the electric field will be different than from the free space and this difference is accounted for by using ε_r, the relative permeability. The equation that relates relative permeability to the electric field, E and displacement field, D is

D = ε . ε_r . E.

But this equation can be confusing sometimes. We can essentially move the relative permeability to other side of the equation and it will now look like this: E = D / (ε . ε_r ). So does the relative permeability serve to modify D or E to account for the presence of a material? If, for example, a dielectric material is placed between two conductor plates (like a capacitor), a constant (electric or displacement?) field will be generated across the dielectric material. What happens at the interface between free space and this dielectric material? Does the displacement field or the electric field change due to the presence of this material? Or both? Although we can use sheer mathematics to find out the answer, it is much more meaningful if we instead rely on our intuition to understand why and which should be the answer. Obviously if both D and E change, and by the same amount, then there is no difference between the two quantity, so this is not allowed. The equation tells us that D and E is related by the permeability, but it does not tell us which is the constant and which is being 'affected' in this case. But if we pay attention to the words I have used so far, I have always said "the materials affect the electric field" and NOT the displacement field. This is a very reasonable statement, since inside a material, especially a conducting one, the charges are BOUNDED, NOT FREE. Displacement field's relation to the charge as indicated by Maxwell's equation ONLY refer to free charges. The free charges, accumulated at the surface of the conductor plates, are constant and therefore D should be constant. The electrical field, on the contrary, is related to the free charge AND the bound charge inside the material. And therefore it is the electric field that will be affected in the presence of a dielectric. (note: there are no free charges INSIDE a conductor but free charges can reside at the SURFACE of a conductor)

In short, the difference between D and E is that "D is the field due to the free charge only" and "E is the field due to both the free and bound charge", the effect of the bound charge is included indirectly through the relative permeability. The quantity D is introduced so that we can make Maxwell's equation look much neater, i.e. always only referring to free charge only. But the usefulness of this displacement field will be more obvious when we disscuss the dynamics of electromagnetism.

Although we have introduced many terms like the polarisation vector, the electric susceptibility, and the relative permeability, it is the relative permeability that is most commonly used to describe the effect of materials on electric field. However, we must always bear in mind that relative permeability is obtained through a series of assumptions. There will be time when we cannot use the relative permeability but instead must use the 'original' equation that contains the polarisation vector or susceptibility, especially for the case of describing in depth behaviour of materials. As a special case, consider a perfect conductor. What is the relative permeability of a perfect conductor? Because D = ε . ε_r . E and E is zero inside a perfect conductor, D will always be zero inside a perfect conductor but this is not true! If we instead use D = εE + P, then when E is zero inside a perfect conductor, D = P. The polarisation vector represents the contribution from the bound charge and thus D is non-zero even in a perfect conductor. Remember, relative permeability is useful because it is a GOOD APPROXIMATION to the 'overall' behaviour of electrostatic systems but it does not work all the time.

New Year Resolution for 2010

My 10 New Year Resolution for 2010:

1. Publish at least 2 scientific journal papers, with at least 1 in high impacting factor journals.

2. Finish the book on introduction on quantum mechanics and the chapter on density functional theory (this should be easy, since I'm already half-way there!).

3. Finish reading '1434'.

4. Read another (non-academic book).

5. Complete project Ascension (my little project on a motivational and skill course for PhD students)

6. Complete my little online book on EM.

7. Exercise, exercise and exercise - regular exercise per week, i.e. at least 3 times a week.

8. Play Mass Effect 2

9. Purchase original Starcraft 2 DVD. (yeah, noticed the difference with no. 8?)

10. Travel to Europe.