網絡記憶 1.3

（CSK：但是，你剛才又叫我們不要期望可以自己想出那些數學技巧，而一定要在考試前背誦好。現在，你又叫我們不要背誦？）

1. A

2. B

3. C

4. D

5. AB （原來 B 是由 A 推算出來的。）

6. BC （原來 B 和 C 只不過是同一個意思的不同講法。）

7. AD （原來 D 只是 A 的一個特例。）

8. CD （原來 D 可以用來驗算 C 的運算結果。）

9. etc.

— Me@2011.03.31

M-theory and Loop Quantum Gravity

The odd thing is that there are a lot of mathematical connections between string theory and the loop representation. Gradually, as time went on, I became more and more convinced that maybe the layfolk were right – maybe the loop representation of quantum gravity really WAS string theory in disguise, or vice versa. This made a little embarrassed by how much I had been making fun of string theory.

I decided to write a paper about this, and as I did some research I was intrigued to find more and more connections between the two approaches, to the point where it is clear that while they are presently very distinct, they come from the same root, historically speaking.

So what I’m hinting at, in brief, is that a bunch of category theory may provide the links between modern string theory with its conformal fields and the loop representation of quantum gravity. This is not as outre as it may appear. The categories being discussed here are really just ways of talking about symmetries (see my stuff on categories and symmetries for more on this). As usual in physics, the clearest way to grasp the connection between two seemingly disparate problems is often by recognizing that they have the same symmetries.

September 11, 1993
This Week’s Finds in Mathematical Physics (Week 18)
John Baez

2011.03.31 Thursday ACHK

PayPal

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No, because I think we didn’t know what we were doing. I think the hallmark of a really good entrepreneur is that you’re not really going to build one specific company. The goal — at least the way I think about entrepreneurship — is you realize one day that you can’t really work for anyone else. You have to start your own thing.

— Max Levchin

— Founders at Work

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2011.03.31 Thursday ACHK

多重自我 下世傳奇

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「靈魂」即「意識」，既可以分開，又可以組合。

— Me@2011.03.29

— Me@2022.07.24

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Startup

The best way to come up with startup ideas is to ask yourself the question: what do you wish someone would make for you?

— Paul Graham

2011.03.29 Tuesday ACHK

Great Idea 4

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If so, this is good news indeed. Good ideas always tend to win eventually. The problem is, it can take a very long time. It took decades for relativity to be accepted, and the greater part of a century to establish that central planning didn’t work. So even a small increase in the rate at which good ideas win would be a momentous change — big enough, probably, to justify a name like the “new economy.”

— Paul Graham

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2011.03.29 Tuesday ACHK

學問潛行凶間

This essay is adapted from a dialogue on 2010.11.11.

CCL: One more question, should I

1. sleep more to maintain a high level of efficiency; or

2. sleep less to prolong the working hours?

Which one do you think is better?

Me: I suggest you to do BOTH. Let me explain:

2. sleep less to prolong the working hours

Method: shorten the night sleeping hours

1. sleep more to maintain a high level of efficiency

Sleeping hours

= 5 hours (night) + 8 x 15 minutes (day)

= 7 hours

Understand?

CCL: OK.

— Me@2010.11.11

— Me@2011.03.27

網絡記憶 1.2

（CSK：但是，你剛才又叫我們不要期望可以自己想出那些數學技巧，而一定要在考試前背誦好。現在，你又叫我們不要背誦？）

— Me@2011.03.25

Metric tensor

In the mathematical field of differential geometry, a metric tensor is a type of function defined on a manifold (such as a surface in space) which takes as input a pair of tangent vectors v and w and produces a real number (scalar) g(v,w) in a way that generalizes many of the familiar properties of the dot product of vectors in Euclidean space. In the same way as a dot product, metric tensors are used to define the length of, and angle between, tangent vectors.

— Wikipedia on Metric tensor

In general relativity, the metric tensor (or simply, the metric) is the fundamental object of study. It may loosely be thought of as a generalization of the gravitational field familiar from Newtonian gravitation. The metric captures all the geometric and causal structure of spacetime, being used to define notions such as distance, volume, curvature, angle, future and past.

— Wikipedia on Metric tensor (general relativity)

2011.03.25 Friday ACHK

I don’t know, 2

The more confident people are, the more willing they seem to be to answer a question “I don’t know.” Less confident people feel they have to have an answer or they’ll look bad.

— Paul Graham

2011.03.24 Thursday ACHK

時間無額外

Tomorrow will be like today. Life wastes itself whilst we are preparing to live.

– Ralph Waldo Emerson

There is no extra time.

— Me@2011.03.23

— Me<2011.03.23

I am a Strange Loop, 2.2

（安：等一等 … ）

（安：同意。）

— Me@2011.03.23

Women like when guys are nice to them, but only when they don’t have to be.

— The Nice Guy Paradox [Solved]

— Daniel Miessler

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2011.03.22 Tuesday ACHK

The computer software industry

The most amazing achievement of the computer software industry is its continuing cancellation of the steady and staggering gains made by the computer hardware industry.

— Henry Petroski

2011.03.22 Tuesday ACHK

Blog 4

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In an attempt to avoid that trap, and to clarify my own thinking, I’ve decided to write for a very limited audience: me, and people who might be similar to me.

— Paul Buchheit

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2011.03.22 Tuesday ACHK

網絡記憶 1.1

（CSK：即是微積分和物理有關？）

（CSK：不知。）

（CSK：哪個頓哥？）

— Me@2011.03.22

The Social Network

Speaking to an audience at Stanford University, Zuckerberg stated that the film portrayed his motivations for creating Facebook inaccurately; instead of an effort to “get girls”, he says he created the site because he enjoys “building things”.

— Wikipedia on The Social Network

One of the most interesting things to me was his analysis of what The Social Network got wrong. People in Hollywood couldn’t imagine that someone would build something because they were interested in building things, so they had to create another, perhaps more “movie-compatible,” motivation for him.

— Mark Zuckerberg on What Hollywood Doesn’t Get About Silicon Valley

— Jessica Livingston

2011.03.21 Monday ACHK

— Me@2010.11.10

Point of view

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“Point of view” is that quintessentially human solution to information overload, an intuitive process of reducing things to an essential relevant and manageable minimum.

— Paul Saffo

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2011.03.21 Monday ACHK