# Physical laws are low-energy approximations to reality, 1.3.1

Symmetry breaking is important.

When there is symmetry-breaking, the system goes to a low-energy state.

Each possible low-energy state can be regarded as a new “physical world”.

One “physical world” cannot jump to another, unless through quantum tunnelling. But the probability of quantum tunnelling happening is low.

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Low-energy physics theories, such as harmonic oscillator, are often simple and beautiful.

— Professor Renbao Liu

— Me@2019-04-08 10:46:32 PM

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# Physical laws are low-energy approximations to reality, 1.2

When the temperature $\displaystyle{T}$ is higher than the critical temperature $\displaystyle{T_c}$, point $\displaystyle{O}$ is a local minimum. So when a particle is trapped at $\displaystyle{O}$, it is in static equilibrium.

However, when the temperature is lowered, the system changes to the lowest curve in the figure shown. As we can see, at the new state, the location $\displaystyle{O}$ is no longer a minimum. Instead, it is a maximum.

So the particle is not in static equilibrium. Instead, it is in unstable equilibrium. In other words, even if the particle is displaced just a little bit, no matter how little, it falls to a state with a lower energy.

This process can be called symmetry-breaking.

This mechanical example is an analogy for illustrating the concepts of symmetry-breaking and phase transition.

— Me@2019-03-02 04:25:23 PM

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# 知識論

（導師：李天命）

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Aside（題外話）：

《四大聖哲：蘇格拉底、佛陀、孔子、耶穌》

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［科學有科技，哲學無哲技］

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— Me@2002-01-10

— Me@2019-02-20

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# Age of Computer

Year 1995-1996

for my love of physics, computer, and painting

— Me@2019-02-18 11:18:46 PM

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# Pandemonium

E: Can you just, you know, like, just tell me the answer?

J: Sorry?

E: You know, the answer. To everything.

What’s the point of love if it’s just disappear?

There has to be meaning to existence, otherwise the universe is made of pain and I don’t like the thought of that.

J: The more human I become, the less things make sense.

But that’s part of the fun. Right?

E: What do you mean?

J: If there were an answer I can give you to, how the universe works, it wouldn’t be special. It would be just a machinery fulfilling its cosmic design. It would be just a big, dumb food processor.

But, since nothing seems to make sense, when you find something or someone that does, it’s euphoria.

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In all of this randomness, in this pandemonium, you and Chidi found each other and you had a life together.

Isn’t that remarkable?

E: Pandemonium is from Paradise Lost. Milton called the center of hell “pandemonium”, meaning “place of all demons”.

I guess all I can do is to embrace the Pandemonium.

Find happiness in the unique insanity of being here, now.

— The Good Place

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2019.01.27 Sunday ACHK

# Physical laws are low-energy approximations to reality, 1.1

These notes was taken by me in 2008, during the course PHY5510 Advanced Statistical Mechanics.

— Me@2019-01-31 11:54:13 PM

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# （反對）開夜車 2.1

Ken Chan 時光機 1.4.2.1

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（我暫時不記得，他以下說話的上半句是什麼。）

… 如何不是那樣，我就毋須於，放榜當天的晚上，在家裡哭。唉！還是不說了。

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— Me@2019-01-18 03:47:50 PM

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Publish! 11

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— Me@2011.07.03

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# Ken Chan 時光機 2.2

— Me@2019-01-06 02:18:47 PM

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# Amazing University

The meaning of life is “entering university”.

Turn your real life into an amazing university, for otherwise, your life has no meaning.

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[At this amazing university,]

Which year (of study) are you in?

— Me@2011.07.01

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# Ken Chan 時光機 2.1

— Me@2018-12-27 03:50:13 PM

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# A pretty girl, 2

Women are directly fitted for acting as the nurses and teachers of our early childhood by the fact that they are themselves childish, frivolous and short-sighted; in a word, they are big children all their life long–a kind of intermediate stage between the child and the full-grown man, who is man in the strict sense of the word. See how a girl will fondle a child for days together, dance with it and sing to it; and then think what a man, with the best will in the world, could do if he were put in her place.

— Of Women

— Arthur Schopenhauer

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When the elderly Schopenhauer sat for a sculpture portrait by the Prussian sculptor Elisabet Ney in 1859, he was much impressed by the young woman’s wit and independence, as well as by her skill as a visual artist. After his time with Ney, he told Richard Wagner’s friend Malwida von Meysenbug, “I have not yet spoken my last word about women. I believe that if a woman succeeds in withdrawing from the mass, or rather raising herself above the mass, she grows ceaselessly and more than a man.

— Wikipedia on Arthur Schopenhauer

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Anybody can look at a pretty girl and see a pretty girl. An artist can look at a pretty girl and see the old woman she will become. A better artist can look at an old woman and see the pretty girl that she used to be. But a great artist — a master — and that is what Auguste Rodin was — can look at an old woman, portray her exactly as she is… and force the viewer to see the pretty girl she used to be…. and more than that, he can make anyone with the sensitivity of an armadillo, or even you, see that this lovely young girl is still alive, not old and ugly at all, but simply prisoned inside her ruined body. He can make you feel the quiet, endless tragedy that there was never a girl born who ever grew older than eighteen in her heart…. no matter what the merciless hours have done to her. Look at her, Ben. Growing old doesn’t matter to you and me; we were never meant to be admired — but it does to them. Look at her! (UC)

— Robert A. Heinlein

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2018.10.27 Saturday ACHK

# CSS

— Me@2018-04-05 06:09:36 PM

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# Cat

— Me@2018-02-19 02:33:42 PM

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# The Sixth Sense, 2

It is difficult only for the others.

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It is also true when you are stupid.

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2018.01.26 Friday ACHK

# Teachers, 2

The most important teachers in my life, 2

6. 程兆海 (pure maths)

7. Christopher Nolan (film director)

8. Lubos Motl (physicist)