The Door 1.1

The following contains spoilers on a fictional work.

In Westworld season 2, last episode, when a person/host X passed through “the door”, he got copied, almost perfectly, into a virtual world. Since the door was adjacent to a cliff, just after passing through it, the original copy (the physical body) fell off the cliff and then died.

Did X still exist after passing through the door?

Existence or non-existence of X is not a property of X itself. So in order for the question “does X exist” to be meaningful, we have to specify “with respect to whom”.

With respect to the observer Y, does X exist?

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There are 3 categories of possible observers (who were observing X passing through the door):

1. the original person (X1)
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X_1 == X

2. the copied person (X2) in the virtual world
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For simplicity, assume that X2 is a perfect copy of X.

3. other people (Y)

— Me@2019-02-09 1:09 PM

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心懷混亂 6

I tell you: one must have chaos within oneself, to give birth to a dancing star.

— Friedrich Nietzsche

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— 尼采

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— 林夕

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2019.02.27 Wednesday ACHK

（反對）開夜車 2.3

Ken Chan 時光機 1.4.2.3

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（問：那有什麼「嚴重的後果」？）

「嚴重後果」中，較為輕微的，我也經歷過，而且可以視為「不可逆轉」的。

（問：「良性飛蚊」？）

「良性飛蚊」的「良性」，並不是說真的有益，而只是指「不會致盲，只會帶來精神困擾」。

(問：如果開始有飛蚊，自己又怎會知道是，「良性」還是「惡性」呢？）

• 第一，你要在未有飛蚊時，防範於未然。

• 第二，萬一仍然出現飛蚊的話，要立刻看眼科醫生，讓他為你檢查，是否視網膜開始脫落。

• 如果不是，就不用擔心。

• 如果是，可以立刻做手術，制止視網膜脫落，保住完整的視力。視網膜開始脫落，而不立刻做手術制止之，有致盲的風險。

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（問：但你剛才說，飛蚊症「會帶來精神困擾」？）

（問：為什麼呢？）

— Me@2019-02-25 04:01:37 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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Path-distinguishing function, 2

$\displaystyle{\gamma(t)}$ = configuration path function

$\displaystyle{\mathcal{F} [\gamma]}$ = a function of time that measures some local property of the path

……….It may depend upon the value of the function $\displaystyle{\gamma}$ at that time

……….and the value of any derivatives of $\displaystyle{\gamma}$ at that time.

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We can decompose $\mathcal{F} [\gamma]$ into two parts:

1. a part that measures some property of a local description

and

2. a part that extracts a local description of the path from the path function.

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— 1.3 The Principle of Stationary Action

— Structure and Interpretation of Classical Mechanics

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1. The function that measures the local property of the system depends on the particular physical system;

2. the method of construction of a local description of a path from a path is the same for any system.

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\displaystyle{ \begin{aligned} \mathcal{F} [\gamma] &= \mathcal{L} \circ \mathcal{T}[\gamma] \\ \mathcal{T} [\gamma] &= (t, \gamma (t), \mathcal{D} \gamma (t), ...) \end{aligned}}

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— 1.3 The Principle of Stationary Action

— Structure and Interpretation of Classical Mechanics

— Me@2019-02-22 11:46:50 PM

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2019.02.24 Sunday ACHK

Quantum decoherence 9

This is a file from the Wikimedia Commons.

In classical scattering of target body by environmental photons, the motion of the target body will not be changed by the scattered photons on the average. In quantum scattering, the interaction between the scattered photons and the superposed target body will cause them to be entangled, thereby delocalizing the phase coherence from the target body to the whole system, rendering the interference pattern unobservable.

The decohered elements of the system no longer exhibit quantum interference between each other, as in a double-slit experiment. Any elements that decohere from each other via environmental interactions are said to be quantum-entangled with the environment. The converse is not true: not all entangled states are decohered from each other.

— Wikipedia on Quantum decoherence

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2019.02.22 Friday ACHK

Mind, 2

Mind is unstable.

Mind is liquid.

You can confirm it into almost anything you want.

— Me@2011.08.23

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PhD, 3.3

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（問：那是什麼意思？）

（問：他們大概毋須，任何博士學位吧？

（問：什麼意思？）

— Me@2019-02-21 03:06:38 PM

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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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Path-distinguishing function

So we will try to arrange that the path-distinguishing function, constructed as an integral of a local property along the path, assumes a stationary value for any realizable path. Such a path-distinguishing function is traditionally called an action for the system. We use the word “action” to be consistent with common usage. Perhaps it would be clearer to continue to call it “path-distinguishing function,” but then it would be more difficult for others to know what we were talking about.

— 1.3 The Principle of Stationary Action

— Structure and Interpretation of Classical Mechanics

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2019.02.17 Sunday ACHK

Logical arrow of time, 7

When we imagine that we know and keep track of all the exact information about the physical system – which, in practice, we can only do for small microscopic physical systems – the microscopic laws are time-reversal-symmetric (or at least CPT-symmetric) and we don’t see any arrow. There is a one-to-one unitary map between the states at times “t1” and “t2” and it doesn’t matter which of them is the past and which of them is the future.

A problem is that with this microscopic description where everything is exact, no thermodynamic concepts such as the entropy “emerge” at all. You might say that the entropy is zero if the pure state is exactly known all the time – at any rate, a definition of the entropy that would make it identically zero would be completely useless, too. By “entropy”, I never mean a quantity that is allowed to be zero for macroscopic systems at room temperature.

But whenever we deal with incomplete information, this one-to-one map inevitably disappears and the simple rules break down. Macroscopic laws of physics are irreversible. If friction brings your car to a halt and you wait for days, you won’t be able to say when the car stopped. The information disappears: it dissipates.

— The arrow of time: understood for 100 years

— Lubos Motl

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If there is a god-view, there is no time arrow.

Time arrow only exists from a macroscopic point of view. Microscopically, there is no time arrow.

If there is a god-view that can observe all the pieces of the exact information, including the microscopic ones, there is no time arrow.

Also, if there is a god-view, there will be paradoxes, such as the black hole information paradox.

Black hole complementarity is a conjectured solution to the black hole information paradox, proposed by Leonard Susskind, Larus Thorlacius, and Gerard ‘t Hooft.

Leonard Susskind proposed a radical resolution to this problem by claiming that the information is both reflected at the event horizon and passes through the event horizon and cannot escape, with the catch being no observer can confirm both stories simultaneously.

— Wikipedia on Black hole complementarity

The spirit of black hole complementarity is that there is no god-view. Instead, physics is always about what an observer can observe.

— Me@2018-06-21 01:09:05 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

（反對）開夜車 2.2

Ken Chan 時光機 1.4.2.2

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The light that burns twice as bright burns half as long, …

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Ken Chan 事後回心一想，才醒起：「Nitrogen 又點會有味咖？」（氮氣又何來會有味道呢？）

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— Me@2019-02-03 07:02:42 AM

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SICM

Structure and Interpretation of Classical Mechanics (SICM) is a classical mechanics textbook written by Gerald Jay Sussman and Jack Wisdom with Meinhard E. Mayer. The first edition was published by MIT Press in 2001, and [the] second edition was released in 2015. The book is used at the Massachusetts Institute of Technology to teach a class in advanced classical mechanics, starting with Lagrange’s equations and proceeding through canonical perturbation theory.

— Wikipedia on Structure and Interpretation of Classical Mechanics

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2019.02.02 Saturday 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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