3.26 march

CNN depicts the march as a public protest for peace, for freedom, for democracy, and against potential war. Sina tells us that the march is a completely political show, and any sensible people are not in it.

兼听则明，偏信则暗。

mad thought

I often heard that we live in a four dimension world: three dimension of space and one dimension of time. In space dimension, we can travel up and down, forward and backward, left and right. But in time dimension, we have only one direction.

Of course, everyone knows that.

Since space and time are linked, and everybody think about if we can travel to the past, what will happen... I am sometimes in that kind of dreams, but recently I find that I forget one thing.

If we can travel to the past, we change one property of the dimension of time, i.e., from one direction to two directions. So, we have to pay for what we get. What is the price? We have to sacrifice a direction from a space dimension. In other words, if we can travel to the past, we will sacrifice our ability to go right(left), or up(down), or forward(backward).

maths and language are abstracted symbols

--for memory of theoretical physics

The above formula means that internal energy of ideal gas is not a funtion of the volume of the ideal gas, in other words, the internal energy of ideal gas will not change if only the volume of the ideal gas changes. It is a direct application of the first law thermodynamics in ideal gas.

In the above paragraph, I use one sentence, 42 words, to explain briefly what the equation means. But from another point of view, I used 42 words to explain the result of direct application of the first law of thermodynamics to ideal gas. And the same application (or fact) can be described by only one equation.

Of course, the letters U, V and T need definitions before the equation, or any combination of them, has any meaning. But is the 42-word sentence self-contained or self-sufficient? No, what is ideal gas, what is internal energy, what is volume, what is temperature and what is function. Even what is "change"?

In maths, definitions are like building blocks, one upon another, which form the mansion of maths. I try to find out what is at the bottom of this mansion. I look at numbers: 1 to 9 and the 0. They are abstracted symbols of the things in real world. 1 apple, 2 apples...From the real things, we get the idea of 1 and 2 and so on.

Language more or less serves the same function: to describe the real things. But a big difference between maths and language is that too many words in a language do not have clear definition. And it seems that people do not care about whether they have clear definitions or not.

a handful of photons

Guess what will you get more if you make a hollow fist, photon or air molecules? I guess it is photons. But the calculation prove that I was wrong.

Under room temperature, a hollow fist will have about one billion photons while the number of air molecules is 25 billion billion, two billion times than photons.

The meaning of life

My high school classmate, a young life, came to an end not long ago. Death comes to me so near again and deliberately to show me the fragile nature of life. It once again lets me to ponder about the meaning of life.

Everybody knows that "we're all going to die, and it's just a matter of time", but few keep it in mind. Perhaps that's why Russell once wrote that "a certain awareness of the ends of human life" is an indispensable portion of wisdom. When fear and despair take the full control over reason, to die seems to be a good option. So reason alone cannot prevent one to choose that option. "On the one hand, by knowing things somewhat remote in time or space, and, on the other hand, by giving to such things their due weight in our feelings" we might broaden our mind and our feelings, and ergo prevent letting fear and despair take the control.

Most of the world is in peace now, and the country is growing. And there is no tyranny to fight against. It's suitable to take a lighthearted attitude towards life. Forget the burden, forget the stress. "人生就像是在旅行,在乎的不是目的地,而是沿途的风景和看风景的心情." So, one part of meaning of life, it seems to me, is to experience and feel everything--the human, the world and the universe.

Small thoughts

Standing upside-down bring more blood to the head, a good practice during reading breaks.

I help my young cousin with her middle school math every Sunday. She is learning elementary algebra now. All her homework is about how to substitute the variables in formula with other monomial or polynomial. The basic thinking pattern--substitution--is one work we now still practise in college.

子贡问曰:"有一言而可以终身行之者乎?"子曰:"其恕乎! 己所不欲, 勿施于人。"I read similar thoughts in Dale Carnegie's How to Win Friends and Influence People: "If out of reading this book you get just one thing--an increased tendency to think always in terms of other people's point of view, and see things from their angle--if you get that one thing out of this book..." Humans are similar in nature whether we are yellow, white or black.

chemistry joke

When my instructor describe how class for graduate student in Harvard Chemistry department is. He quipped: "After the four courses, the thermodynamics problem is solved (the students get fully prepared of knowledge in a particular research area), and what is left is kinetics problem (how to apply those knowledge in actual research work).

new semester and boring lecture

The new semester began officially on Monday. But for me, it just begins today, because I have no classes on Monday and Tuesday. I feel a little excited of having classes again after a terribly long three-month holiday. But after listening to two lectures, I was bored.

The first lecturer has a little enthusiam but cannot articulate his speech clearly. Further, by constantly mentioning his position as a teacher and our positions as students, who should work hard on his subject as he also nags , he seems to prevent a intellectual intercourse on a mutual equal ground.

The second lecturer has no enthusiasm at all. He delivers his lecture in a monotonous voice, which easily send people to sleep.

Lectures do not always like that. I still remember the well-organized and well-articulate mathematics lecture from Prof. Su, and humourous and enlightening philosophy letures from Prof. Holbo. Those lecturers not only transmit knowledge but also enthusism of their own subjects as well.