Event horizons 3

The black hole entropy is a fundamental property of quantized space. The information may be generally attributed to surfaces – the event horizons. In Jacobson’s derivation of Einstein’s equations via Rindler spaces – much like in the case of the “cosmic horizon” of the anti de Sitter space – these event horizons depend on the observer. But there are also event horizons that are shared by pretty much everyone who lives in the Universe – the event horizons of localized black holes that causally separate their finite internal volume from the rest of the Universe.

— Event horizons and thermodynamics: more than an analogy

— Lubos Motl

2013.04.30 Tuesday ACHK

藉口 4.3

原因 5.3

這段改編自 2010 年 4 月 3 日的對話。

但是,如果沒有「理由不同原因」這個常識,你就往往在不知不覺間,把「原因」當作「理由」。把「原因」誤用成「理由」,就為之「藉口」。

例如,我認識的人之中,有一部分人,會胡亂向身邊的人發脾氣。假設甲向我發脾氣,而我不知我做錯什麼,在可能的情況下,我會這樣回應:

你為什麼發脾氣?

甲:「因為我十分不開心,需要發洩一下。」

「因為」這個詞語,有時是指「原因」,有時是指「理由」。而這裡「因為」所講的,是「原因」,並不成「理由」。你有不開心可以向我傾訴,看看我有沒有辦法,協助你解決問題。你沒有必要攻擊我,向我發脾氣。

又例如,學生乙欠交功課,我會這樣回應:

你為什麼欠交功課?

乙:「因為我忘記了做。」

「忘記」只是「原因」,並不是「理由」。

乙:「為什麼?」

「理由」是一個「決定」。你問一問自己,「忘記做功課」是不是你自己的決定?

乙:「不是。」

那樣,「忘記」就不是「不做功課」的理由。

還有,你真正重視的事情,你自然會記得。試想想,如果你和你的女朋友有約會,你會忘記嗎?

你會忘記做功課,證明你不夠重視學業。如果你真正重視那一份功課,你自然會想辦法,保證自己不會忘記它,例如利用記事簿。如果你要成功,你會找一個方法;如果你要失敗,你會找一個藉口。

— Me@2013.04.29

2013.04.30 Tuesday (c) All rights reserved by ACHK

Event horizons and thermodynamics

In early 1995, Ted Jacobson found an intriguing way to “localize” the relationship between the temperature and entropy on one side, and the acceleration and areas on the other side. In fact, he derived Einstein’s equations from a well-known thermodynamic equation. See also Einstein’s equations as equations of state.

— Event horizons and thermodynamics: more than an analogy

— Lubos Motl

2013.04.29 Monday ACHK

Trust paper

Trust is like a piece of paper. Once it’s crumpled, it can’t be perfect again.

You can flatten the piece of paper and try to make it as straight as you want. But it will never be the same any more.

2013.04.28 Sunday ACHK

藉口 4.2

原因 5.2

這段改編自 2010 年 4 月 3 日的對話。

(安:我選中大的理由是,李教授在中大任教。而我獲得中大取錄是原因是,我選了中大?)

無錯。不過,那仍然只是簡化了的講法。完全版的描述是:

1. 你當年「選中大」的理由是,那時李教授在中大任教。

2. 你「有『選中大』這個決定」的其中兩個原因是,「李教授在中大任教」和「你很想上李教授的課」。

3. 而你「入到中大」(獲得中大取錄)的其中兩個原因是,「你做了『選中大』這個決定」和「你考試成績足夠好」。

那是三個層次的問題。這三句在日常對話中,會過份詳細,所以會簡化為一句:

「我當年選中大的原因是,那時李教授在中大任教。」

為了語言應用上的效率,這種簡化是合理的,所以不單應該接受,而且應該鼓勵。但是,如果沒有「理由不同原因」這個常識,你就往往在不知不覺間,把「原因」當作「理由」。把「原因」誤用成「理由」,就為之「藉口」。

— Me@2013.04.28

2013.04.28 Sunday (c) All rights reserved by ACHK

Elementary particles, 5

There is another consequence of the UV/IR connection: this connection makes the black hole microstates simultaneously composite as well as elementary.

They’re elementary because they can be thought of as some excitations of a collection of strings and branes. Even if you had a different theory, it would have to be able to calculate the black hole entropy from the number of excited states of “something”. This “something” would play the very same role as strings in perturbative string theory. And differently excited strings must be interpreted as different fields in spacetime – in an effective field theory. The same has to hold for “something” whatever it is.

On the other hand, the number of black hole microstates is so large that there must exist many ways to excite the “something”, some internal degrees of freedom.

— Event horizons and thermodynamics: more than an analogy

— Lubos Motl

2013.04.27 Saturday ACHK

Ethical laws

Except physical and ethical laws, make and follow only your own laws.

— Me@2009.03.11

2013.04.26 Friday (c) All rights reserved by ACHK

Posted in OCD

藉口 4.1

原因 5.1

這段改編自 2010 年 4 月 3 日的對話。

(安:我當年選中大的原因是,那時李教授在中大任教。)

平時,我們為了方便,會視「原因」和「理由」為同義詞。但是,如果假設現在不是「平時」,而是在研究「邏輯」和「語言」,「原因」和「理由」的意思,其實是不同的。

較為精確的講法是,你選中大的理由是,李教授在中大任教。而你獲得中大取錄是原因是,你選了中大。

「理由」是一個「決定」。「理由」是權衡輕重時,支持一個「決定」的一些考慮元素。由於是內在的主觀判斷,「理由」有所謂「充不充分」。一個「決定」沒有充分的「理由」,就為之「不合理」。

「原因」不是一個「決定」。「原因」和「結果」,只是客觀描述事件發生的時間先後次序。由於是外在的客觀事實,「原因」沒有所謂「合不合理」。

— Me@2013.04.26

2013.04.26 Friday (c) All rights reserved by ACHK

Hardware designers 3

I worked with Mike for a couple of years on Newton. I had tremendous respect for his breadth of understanding of systems, from transistors and batteries all the way up to user interaction. He was a hardware designer who really understood software, too; in my experience, that’s rare.

— kabdib 2 days ago

— Hacker News

2013.04.24 Wednesday ACHK

一步一生 1.1

這段改編自 2010 年 4 月 3 日的對話。

很少工作,會好像我現在的工作一樣,有那麼大的影響力。

(安:何出此言呢?)

有時,我一句說話可以節省別人幾個月,甚至幾年的時間。例如,有學生說想看某一本書。但是,我年青時看過那本書,知道它不好。所以,我建議他不要看。如果他肯聽我這個意見,他就立刻節省了多個星期的時間。

又例如,另一個學生在大學選科時,想修某一科。但是,我年青時聽過一些可靠的朋友講過,那一科不好,教授非常不負責任。所以,我建議他選過另一個主修。如果他肯聽我這個意見,他就立刻節省了幾年的時間。

(安:不只幾年吧?大學主修的科目不同,整個人生路向也會完全改寫。)

— Me@2013.04.23

2013.04.24 Wednesday (c) All rights reserved by ACHK

Fluctuation theorem

The fluctuation theorem (FT), which originated from statistical mechanics, deals with the relative probability that the entropy of a system which is currently away from thermodynamic equilibrium (i.e., maximum entropy) will increase or decrease over a given amount of time. While the second law of thermodynamics predicts that the entropy of an isolated system should tend to increase until it reaches equilibrium, it became apparent after the discovery of statistical mechanics that the second law is only a statistical one, suggesting that there should always be some nonzero probability that the entropy of an isolated system might spontaneously decrease; the fluctuation theorem precisely quantifies this probability.

Note that the FT does not state that the second law of thermodynamics is wrong or invalid. The second law of thermodynamics is a statement about macroscopic systems. The FT is more general. It can be applied to both microscopic and macroscopic systems. When applied to macroscopic systems, the FT is equivalent to the Second Law of Thermodynamics.

— Wikipedia on Fluctuation theorem

2013.04.23 Tuesday ACHK

Dear Esther, 3

Process, not a state, 10

An event is a change of state.

— Me@2011.01.01

Dying is not just a change of state from one to another.

In order words, dying is not a single event, but a lifelong process.

In a sense, your whole life is already a near-death experience. 

— Me@2010.12.31

— Me@2013.04.22

2013.04.22 Monday (c) All rights reserved by ACHK

超世 5

這段改編自 2010 年 6 月 29 日的對話。

(HCY:原來你已經在這裡,剛才看不到你。你真的好像一個中學生。)

不要這樣說,我已經三十歲了。

如果講心理年齡,我可以說有七十歲。物件有「物理定律」;人有「心理定律」。我覺得我已經破解了大部分定律,再沒有「娛樂」,所以生活沉悶。

(CPK:那麼快就破解了?你是不是已經「出了世」?)

我又不是「出了世」…

(CPK:看透世事?)

其實要我「入世」還是「出世」都可以。但是,「入世」的遊戲中,大部分也很無聊,雖然,如果要玩「入世遊戲」,我都有信心要贏,因為我了解「人情定律」。

— Me@2013.04.21

2013.04.22 Monday (c) All rights reserved by ACHK

The Killer Question

And if the Labs leadership believes a researcher is too attached to an idea in the exploration phase, they’ll make sure that individual isn’t involved in the company’s founding.

Why? Because in Afeyan’s view, entrepreneurs who get attached become afraid to ask the “killer question” that will expose the flaw in their idea. At Labs, where the idea is to get to No as quickly as possible, that’s not OK.

— No Founders Required: How Flagship Starts Companies

— Walter Frick

2013.04.21 Sunday ACHK

惜此際 3.2

這段改編自 2010 年 4 月 3 日的對話。

(安:那時你的工作量,真的是那麼驚人嗎?)

無錯。

其實,真正令我厭惡那份工作的,是當中的大部分工序,沒有意義,對人對己也沒有益處。大部分時間,我也被迫在「忙碌做虛事」;而對人有用的「實事」,反而沒有機會去實現。

那不禁令我慨嘆,我的人生就這樣,給那些不用腦袋思考的人,白白浪費掉。如果我可以用那些時間,做真正有意義的事,我一早就已經,改善了很多人的一生。

有意義的辛苦我不怕。我真正「怕」的,是辛苦來沒有價值。不過,如果是有意義的工作,就自然不會叫你,企圖違反自然定律,例如,要你在一天之內,完成價值兩天的事情。所以,「工作過量」這種辛苦,往往反映了那些工作指令,不經大腦;那些工作內容,沒有意義。

— Me@2013.04.20

2013.04.20 Saturday (c) All rights reserved by ACHK