這段改編自 2010 年 4 月 3 日的對話。
《SICM》（Structure and Interpretation of Classical Mechanics）中的編程語言，除了 Scheme 的本體外，還會用到作者特製的力學程式庫 Scmutils。而這個程式庫（library）卻只有 Linux 的版本，不能安裝在 Windows 之中。那導致我要特意在我的 Windows 中，先裝一個 virtual machine（虛擬機器），從而在那個虛擬機器之上，再安裝一個 Linux 作業系統。
閱讀《SICM》，除了間接令我，發現「時間」的定義外，還令我第一次接觸「virtual machine」這個概念。兩者各自都是，我個人智力發展的一個里程碑。
— Me@2012.12.25
2012.12.25 Tuesday (c) All rights reserved by ACHK
Universe 2.2
Defining the word “universe” as “all the things” does not totally make sense, since the meaning of “all” is relative to a place. Without a context such as “all things in this house“, the word “all” is meaningless. To be meaningful, you have to specify what the word “all” is with respect to.
Instead of “all the things“, we can define “universe” as
universe = all the things observable by an observer, directly or indirectly, in practice or in principle, plus the observer itself
— Me@2012.10.16
— Me@2012.12.24
2012.12.24 Monday (c) All rights reserved by ACHK
All civilisation was just an effort to impress the opposite sex …
— I Dated a Robot
— Futurama
.
.
2012.12.24 Monday ACHK
這段改編自 2010 年 6 月 15 日的對話。
那你們在下次見我時，就要遞交完成了的 1990 年 past paper。
你練習 past paper 時，記住要「計時間、計分數」，然後還要做改正，記低需要背誦的重點，於「魔法筆記」之中。不懂改正的地方，就正正是下次問我的問題。
你留意，那是頗辛苦的，因為每年的試卷，價值起碼六個小時。
（CPK：六個小時？）
不是嗎？每一年的高考的物理科，都有卷一和卷二。而它們各自的時限，都是三個小時。
（CPK：但是，高考的課程，還有大概有三分之一的課題，學校還未開始教。）
你不可理會這類事件。
（CPK：不理會？）
試想想，如果你要等所有課題，也完成授課，你就要等到明年的二月。到時，距離真正的高考，就只有一至兩個月的時間。那時才開始做 past paper（歷屆試題）的話，你就只有那一兩個月。記住，在那麼短的時間中，你還要有其他科目要處理。結果，每一科，你至多只可以做到，大概三年的 past paper。那和你「奪 A」目標的要求，相去甚遠。
正確的心態是，無論如何，你也先開始執行，做 past paper 的大計；不管怎樣，你也「計時間、計分數」，完成所有你已懂的題目。
如果你在缺少三分一課題的情況下，都仍然可以得到（例如）55% 的分數，你的進度就十分理想。
— Me@2012.12.24
2012.12.24 Monday (c) All rights reserved by ACHK
Nonlocality vs entanglement
In the media and popular science, quantum nonlocality is often portrayed as being equivalent to entanglement. While it is true that a bipartite quantum state must be entangled in order for it to produce nonlocal correlations, there exist entangled states which do not produce such correlations. A well-known example of this is the Werner state that is entangled for certain values of p_{sym}, but can always be described using local hidden variables. On the other hand, reasonably simple examples of Bell inequalities have been found for which the quantum state giving the largest violation is never a maximally entangled state, showing that entanglement is, in some sense, not even proportional to nonlocality.
In short, entanglement of a two-party state is necessary but not sufficient for that state to be nonlocal. It is important to recognise that entanglement is more commonly viewed as an algebraic concept, noted for being a precedent to nonlocality as well as quantum teleportation and superdense coding, whereas nonlocality is interpreted according to experimental statistics and is much more involved with the foundations and interpretations of quantum mechanics.
— Wikipedia on Quantum nonlocality
2012.12.23 Sunday ACHK
箭之所以可貴
因為有靶
— Lee
2012.12.23 Sunday ACHK
SICM, 3 | SICP, 2
這段改編自 2010 年 4 月 3 日的對話。
當年，我初看《SICM》（Structure and Interpretation of Classical Mechanics）時，我不太懂做那些練習題目，因為那時，我是只是初學，而尚未能掌握，內裡的編程語言 Scheme programming language。
為了熟習 Scheme，我先行閱讀了《SICM》的姊妹作，《SICP》（Structure and Interpretation of Computer Programs）的頭幾課。
《SICP》跟《SICM》，同樣是超級名著。但是它不易理解。幸好，它官方網站提供了，一些 1986 年的講課錄影。當年（2006），尚未流行使用 YouTube，所以我要花很多時間，下載那些錄影。我還記得，每節課的錄影檔案，有 600MB 那麼大。
雖然那麼費神，但卻換來意外的收穫。《SICP》令我瞭解「時間」的定義。
 |
| This image is taken from 《SICP》 and 《SICP》 itself is licensed under a Creative Commons Attribution-Noncommercial 3.0 Unported License. |
最令我意想不到的是，那竟然是來自一本電腦書，而不是物理書。
— Me@2012.12.23
2012.12.23 Sunday (c) All rights reserved by ACHK
— Draft only. These few lines are not 100% correct. —
In other words, whatever list you have constructed, it contains only part of the universe, not all of the universe. The universe, as infinitesimal and infinity, is not a thing, but a process (of keeping collecting things). The universe is a logical implication, or a logical limit.
— Draft only. These few lines are not 100% correct. —
— Me@2012-12-20
2012.12.23 Sunday (c) All rights reserved by ACHK
To get a feeling of dying, play the video game Dear Esther till the end.
— Me@2012.12.16
When you finish a video game, you go back to the real world;
when your real world is over, you go back to your realer world.
— Me@2012.12.21
There is another theory, that in a car crash, Esther was put in a coma, and the voice is her husband talking to her, in hopes that she can hear him. She wanders along beaches and through caves that are filled with sometimes strange things, things that are bits and fragments of what she is hearing and what her mind is putting together. At the end when Esther jumps, it is possible her heart rate increased, showing up on the hospital monitor, which would explain the voice at the end saying “Come back,” and the darkness at the end would probably be her dying in the coma.
— Wikipedia on Dear Esther
— 21:01, 29 May 2012
2012.12.22 Saturday (c) All rights reserved by ACHK
這段改編自 2010 年 6 月 15 日的對話。
我先給功課你們。你想拿什麼 grade（成績等級）？
（LMC：可以拿什麼 grade？）
如果要拿到 A 級成績，你就要做足，總共 20 年的 past papers（歷屆試題）。
（CPK：吓？你要我們下次見面前，完成 20 年的 past paper？）
當然不是。我要計一計，你們應哪一年的 past paper 開始做。你們將在 2011 年參加高考。倒數 20 年，即是你應該大概由 1990 年的那一份，開始操練。那你們在下次見我時，就要遞交完成了的 1990 年 past paper。
你練習 past paper 時，記住要「計時間、計分數」，然後還要做改正，記低需要背誦的重點，於「魔法筆記」之中。不懂改正的地方，就正正是下次問我的問題。
— Me@2012.12.22
2012.12.22 Saturday (c) All rights reserved by ACHK
EPR paradox, 7
Some people have interpreted this as telling us that “everything is connected to everything else” or that “quantum mechanics entangles us all in one universal whole.”
After all, the reasoning goes, at the big bang everything emerged from one place since, we believe, all places we now think of as different were the same place back in the beginning.
— p.122
— The Fabric of the Cosmos
— Brian Greene
2012.12.22 Saturday ACHK
Easy 3
“Easy” in Chinese is “容易”, literally meaning “able to change“.
— Me@2012-11-29 10:47:38 AM
It is not the strongest of the species that survives, nor the most intelligent, but rather the one most adaptable to change.
— Charles Darwin misquotation
The definition of insanity is doing the same thing over and over and expecting different results.
— Albert Einstein misquotation
If you are willing to change based on the feedback from the reality, many difficult things will become easy.
— Me@2012.12.17
易，窮則變，變則通，通則久。
— 系辭下
— 易經
2012.12.21 Friday (c) All rights reserved by ACHK
這段改編自 2010 年 4 月 3 日的對話。
《SICM》（Structure and Interpretation of Classical Mechanics）總共花了我兩年的時間。我大概由 2006 年，閱讀至 2008 年。除了閱讀課文外，我還把內裡的幾乎所有練習，無論是數學題，還是程式題，都一一擊破。要花那麼長的時間才能完成，主要是因為上班的工務繁忙。每日可以花在自修的時間，通常也不會超過半小時。
雖然時間成本奇高，但是，我仍然覺得是值得的。一來，它是一本名著，質素非常高。二來，它竟然把我人生的兩大興趣，重疊在一起。
— Me@2012.12.21
2012.12.21 Friday (c) All rights reserved by ACHK
Universe 2.1
“All” is “所有” in Chinese. Literally,
all = 所有 = the place has
The definition of word “universe” is “everything” or “all the things“.
universe = all the things
However, this definition is not 100% sharp, because the meaning of “all” is relative to a list or a place. In order to give a meaning to the word “all“, you have to provide a list or a place in the sentence it appears.
When referring to a list, for example, the meaning of the phrase “all of A, B, and C” is the same as “A, B, and C“.
all of A, B, and C = A, B, and C
However, the definition of “universe” does not specify a list, such as
universe = all of A, B, and C
When referring to a place, for example, the meaning of the phrase “all the people in this house” is:
You keep looking for people in this house. Whoever you can find, include him or her onto your list of people. Once you cannot find new people in the house anymore, your list will have “all the people in this house“.
In other words, in order to give the word “all” a meaning, you have to provide a range for searching. However, the definition of “universe” does not specify a place, such as
universe = all the things in X,
unless we define the word “universe” as
universe = all the things in universe
However, this is a circular definition.
— Me@2012.10.16
— Me@2012.12.11
— Me@2012.12.20
2012.12.21 Friday (c) All rights reserved by ACHK
既然沒有將來，何不活在當下？
— Me@2011.08.03
2012.12.19 Wednesday (c) All rights reserved by ACHK
SICM, 1.3
這段改編自 2010 年 4 月 3 日的對話。
即使有時會剛巧得到正確的結果，但是由於胡亂推導，大家也不知道，那個正確結果的真正由來。所以，每一代的學生，都不可能明白那一個部分。
要戒除「暗地裡轉換意思」的陋習，並不困難。如果透過編寫程式，來解決力學問題，你就要先把那個力學問題，翻譯制訂成電腦程式的版本。那樣，在過程中，你自然會百分百釐清了，所有符號的意義，因為，在同一個程式中，同一個符號，電腦只會容許，有唯一的一個意思。電腦不會讓你（，在沒有事先特別聲明的情況下），任意放大、縮小 或 更改，那一個符號的意思。電腦不會錯失，你任何的「概念扭曲」或者「概念滑轉」，所以不會有絲毫的容忍。
由於要你「寫程式學力學」，《SICM》（Structure and Interpretation of Classical Mechanics）會教你一種編程語言 Scheme programming language。這種語言的好處是，你學了一句後，就可以立刻應用那一句，而不像一般的程式語言，應用前，要先行學習一大堆語法。
（安：那本書真的用 programming（電腦編程），來講解 mechanics（力學）？）
無錯。正如一般的教科書，課文以外，《SICM》還有例題和練習題。而例子和練習之中，有超過一半是程式題目。其餘的則是文字題目和數學題目。
但是，《SICM》的正題始終是力學，而不是寫程式。正如，力學需要用數學。但是數學在這本書內，只是工具，不是主菜。
— Me@2012.12.18
2012.12.19 Wednesday (c) All rights reserved by ACHK
The claim that EPR effects violate the principle that information cannot travel faster than the speed of light have been countered by noting that they cannot be used for signaling because neither observer can control, or predetermine, what he observes, and therefore cannot manipulate what the other observer measures.
— Wikipedia on Copenhagen interpretation
2012.12.17 Monday ACHK
種子意念 7
ars 304 days ago | link
Isaac Asimov and Piers Anthony have both written in their books that they never suffer from writers block, and the reason both gave is that they read and reply to letters from their audience. Isaac Asimov especially replied to every single letter he received (I’m not sure about Piers Anthony).
Penn and Teller seem to have the same idea: Interact with every member of your audience who wants to talk to you. And they are one of the most successful magicians.
I think everyone should learn from this. Do you write a blog? Read every single comment you get, and reply to as many as you can. Run a business? Read as much customer service mail as you can. And if you are small read ALL of it.
— 14 years ago: the day Teller gave me the secret to my career in magic
— Hacker News
2012.12.17 Monday ACHK
SICM, 1.2 | 程式員頭腦 14
這段改編自 2010 年 4 月 3 日的對話。
“In almost all textbooks, even the best, this principle is presented so that it is impossible to understand.” (K. Jacobi, Lectures on Dynamics, 1842-1843). I have not chosen to break with tradition.
— V. I. Arnold, Mathematical Methods of Classical Mechanics, footnote, p. 246
— Structure and Interpretation of Classical Mechanics
這本書的主要好處是，它會要求你，透過編寫簡短的電腦程式，來解決力學問題。反過來說，你亦可以透過解決力學問題，來練習 programming（電腦編程）。
這本書的主旨是，在經典力學，人們做公式推導的過程中，有時會把一些數字符號的意思，不自覺地改了一點，導致推導失效。例如，運算步驟的第二行和第五行，都會出現的函數 f 這個符號。但是，第二行的 f ，是代表 f(x,y)。而第五行的 f ，卻是指 f(x(t),y(t))。
即使有時會剛巧得到正確的結果，但是由於胡亂推導，大家也不知道，那個正確結果的真正由來。所以，每一代的學生，都不可能明白那一個部分。
如果透過編寫程式，來解決力學問題，你就可以避免了「暗地裡轉換意思」的陋習，因為在同一個程式中，同一個符號，電腦只會容許，有唯一的一個意思。電腦不會錯失，你任何的「概念扭曲」或者「概念滑轉」，所以不會有絲毫的容忍。
— Me@2012.12.17
2012.12.17 Monday (c) All rights reserved by ACHK
意念可樂 3
A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible. There are no prima donnas in engineering.
— Disturbing the Universe
— Freeman Dyson
handrake 2 days ago | link | parent
I think MS was pretty much the same way until very recent. Maybe companies really start making money when they stop being innovative.
— Amazon Has the Most Generous Shareholders in the World
— Hacker News
The difference between design and research seems to be a question of new versus good. Design doesn’t have to be new, but it has to be good. Research doesn’t have to be good, but it has to be new.
I think these two paths converge at the top: the best design surpasses its predecessors by using new ideas, and the best research solves problems that are not only new, but actually worth solving. So ultimately we’re aiming for the same destination, just approaching it from different directions.
— Paul Graham
2012.12.17 Monday ACHK
Physics Town 
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