# 無限旅程 3.2

The main use of doing academic works is to enlarge your personal world.

Just like travel: travel in itself is useless, unless you are going to live there.

— Me@2011.10.11

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… or the travel experience travels with you.

— Me@2019-09-15 10:53:15 PM

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# 財政自由 1.2

（問：那就即是話，要在還年青時，就賺到一生夠用的金錢？

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（問：但是，財政自由，又可以如何實現呢？）

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（問：依靠「售賣時間」而來的收入，就為之「主動收入」？

（問：有自動生成收入的話，就當然十分高興。但是，那些「自動收入」，又從何而來呢？

— Me@2019-09-10 08:33:38 PM

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# 事件實在論，更正

Event Realism | 事件實在論 6.1

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exist = can be found

— Me@2013.09.25

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If the consequences of an event cannot be found anymore, that event no longer exists.

— Me@2019.09.05

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The surprising implications of the original delayed-choice experiment led Wheeler to the conclusion that “no phenomenon is a phenomenon until it is an observed phenomenon”, which is a very radical position. Wheeler famously said that the “past has no existence except as recorded in the present“, and that the Universe does not “exist, out there independent of all acts of observation”.

— Wikipedia on Wheeler’s delayed choice experiment

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「事件」並不完全「實在」。

— Me@2019-09-05 09:08:41 PM

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# A Tale of Two L’s

Lagrange’s equations are traditionally written in the form

$\displaystyle{\frac{\mathrm{d}}{\mathrm{d}t} \left ( \frac {\partial L}{\partial \dot{q}} \right ) = \frac {\partial L}{\partial q}}$

or, if we write a separate equation for each component of $\displaystyle{q}$, as

$\displaystyle{\frac{\mathrm{d}}{\mathrm{d}t} \left ( \frac {\partial L}{\partial \dot{q^i}} \right ) = \frac {\partial L}{\partial q^i}}$

In this way of writing Lagrange’s equations the notation does not distinguish between $\displaystyle{L}$, which is a real-valued function of three variables $\displaystyle{(t, q, \dot q)}$, and $\displaystyle{L \circ \Gamma[q]}$, which is a real-valued function of one real variable $\displaystyle{t}$.

— Structure and Interpretation of Classical Mechanics

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2019.09.04 Wednesday ACHK

# Quantum observer 2

Consistent histories, 6.2 | Relational quantum mechanics, 2 | Eigenstates 2.3.2.2

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Would an observer see itself being in a superposition?

In a sense, tautologically, an observer is not a superposition of itself, because “an observer” can be defined as “a consistent history”.

an observer ~ a consistent history

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Because “state” is expressed in RQM as the correlation between two systems, there can be no meaning to “self-measurement”.

— Wikipedia on Relational quantum mechanics

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Would an observer see itself being in a superposition?

When we say that “before observation, observable B is in a superposition of some eigenstates”, you have to specify

1. it is a superposition of what?

2. it is a superposition with respect to what apparatuses or experimental setups?

— Me@2018-02-05 12:45 AM

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# The Time Machine

This is the place.

So it is.

_But there’s nothing here.

Well, it was different then. My laboratory was all around here. The kitchen was up there where that tree is. Not that Mrs. Watchit ever let me go in there.

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I don’t know what to tell you, sir. He’s been gone this whole week.

_And you’ve no idea where he went?

No, sir.

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_[Alexander] This would be my greenhouse. There was a garden outside.

Gren’tormar’tas?

Yes.

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_Sir?

Maybe he’s finally found some place where he can be happy.

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This was my home.

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His home.

— The Time Machine (2002 film)

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2019.09.01 Sunday ACHK

# Ken Chan 時光機 2.1

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1.1 除了是物理補習天王外，

2.1 他宣稱有在大學教書。是教授、講師，還是其他，我就不知道。我忘記了，他有沒有講過。

2.2 他在大學做研究。據我理解，他當時研究的是有關激光的實驗物理。

2.3 他有時要往大陸作學術演講。

3.1 然後，他亦是某某什麼工程學會的主席。

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— Me@2019-08-30 09:31:52 PM

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