Author Archives: rpflee

Paradox 2

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Meta-time 2

Paradox is due to the mixing of para-level (meta-level) and original level.

— Me@2012-09-29 02:22:14 PM

… including the time-travel paradoxes.

As long as you put time-travel into a story, you mix the meta-time and the original time within that story. Thus time-travel paradoxes appear.

— Me@2012-10-01 10:33:05 AM

The two typical time-travel paradoxes are the grandfather paradox and the ontological paradox.

The grandfather paradox is that time-travel would create an inconsistent story. For example, if you time-travel back to 10 years ago and kill your younger self, you present-self cannot exist. So you could not have time-travelled back to 10 years ago and kill your younger self, you present-self can exist. But your present-self have time-travelled back to 10 years ago and kill your younger self, then you present-self cannot exist.

The ontological paradox is that information can come from nowhere and events can happen with no cause. For example, your future-self goes back in time to give you the solution of a homework problem. After copying it, you go back in time to give your past-self the solution of that homework problem. The question is, where does that homework solution come from?

The meta-time is the author’s time or the readers’ time, which is the real, in a sense that it is the real causal chain. The original-time is the time within that story, which is fake, in a sense that it is not the real causal chain. As long as we distinguish the meta-time (author’s time) and the original-time (story-time) clearly, the two paradoxes can be transcended.

To avoid the grandfather paradox, only the author should be allowed to go back into an earlier story-time. For example, after finishing the 10 chapters of a story, the author goes back to the first chapter to rewrite and polish it. The characters within that story should not be able to go back into an earlier story-time.

To transcend the ontological paradox, we should realize that the “information from nowhere” is actually from the meta-time; the “event with no cause” is actually caused by the author of that story.

— Me@2012-10-03 02:21:45 PM

2012.10.03 Wednesday (c) All rights reserved by ACHK

Memory 4.3

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Copy Me, 5.2

這段改編自 2010 年 4 月 3 日的對話。

「十年前的我」和「現在的我」的記憶不盡相同，而導致不是「同一個人」，有兩重意思。

第一重是，「現在的我」（三十歲）比「十年前的我」（二十歲），多了十年的記憶。那就是我剛才所講的「增加」。

第二重是，即使只比較人生頭二十年的記憶，「三十歲的我」回憶（例如）「十六歲那年」發生了什麼事，已經不及「二十歲的我」回憶「十六歲那年」那麼詳細和準確。那就是我剛才所講的「變形、刪減 和 篡改」。

更震撼的是，如果我真的問你，「十六歲那年」發生了什麼事，你可以答到的，可能不出十件，甚至只有一兩件事。震撼的地方在於，「十六歲那年」共有 365 日，而你竟然只講到不夠十件事情。「十六歲那年」對於一個「三十歲的人」來說，只一堆模糊的印象，記憶的疑團。

根據我的經驗，近乎只有一個情況，會令我真正明確回憶起，中學時代的某一件特定事件。那就是當收拾房間，整理一大堆物件的時候，偶然會見到那個時代的一些「紀念品」，例如 成績表、筆記、書籍、相片 和 電影戲票 等。

— Me@2012.10.03

2012.10.03 Wednesday (c) All rights reserved by ACHK

Individual neurons

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snippyhollow 192 days ago | link

A neuron “could” store a generalized memory (the amount of information it stores is gigantic, w/o pendantically considered the DNA). However, it’s more complex than that (there are many types of memories and many means of retrieval). Basically, memories are sets of synaptic connections, and a neuron has many synapses (average ~7,000 synaptic connections/neuron to multiply by our 10^11 neurons/brain).

As you said, it may be a “key”, but it should be seen more like the memory _is_ a complete list of hashes. Not {“key”: memory} but {“key1”: {“key2”: {“key3”: {…} } }, {…}, {…}, …} and the set of {key1..keyN} is the memory. So if you removed whichever keyI in the middle, you lose the information.

(That’s not really true because there is high redundancy, but there are keys/synapses/nodes less redundant than others. The fact is, they don’t fire on only “one” neuron, they fire at a very precise region but the light still goes through a population of neurons.)

— MIT discovers the location of memories: Individual neurons

— Hacker News

2012.10.02 Tuesday ACHK

Paradox

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Meta-time

para- (“above, beyond; abnormal”)

— Wiktionary

Paradox is PARAdox.        

Paradox is due to the mixing of para-level (meta-level) and original level.

— Me@2012-09-29 02:22:14 PM

… including the time-travel paradoxes.

As long as you put time-travel into a story, you mix the meta-time and the original time within that story. Thus time-travel paradoxes appear.

— Me@2012-10-01 10:33:05 AM

2012.10.01 Monday (c) All rights reserved by ACHK

Looper

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Looper is a 2012 American science fiction action film written and directed by Rian Johnson. The film stars Bruce Willis, Joseph Gordon-Levitt, and Emily Blunt.

— Wikipedia on Looper (film)

If everyone just looks out for themselves, you just get this perpetual loop of everybody pointing fingers, and everybody blaming each other, and everybody killing each other. And it takes an act of selflessness to maybe break that.

— Rian Johnson

— The Insane Things Joseph Gordon-Levitt Did to Become Bruce Willis in Looper

— Charlie Jane Anders   

— io9

2012.10.01 Monday ACHK

Memory 4.2

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Copy Me, 5

這段改編自 2010 年 4 月 3 日的對話。

.

怎樣才為之「同一個人」，或者「同一個自我」呢？

洛克（John Locke）的標準是，有同一個記憶，就為之同一個自我。

但是，即使是同一個人的記憶，又會隨時間 變形、增刪、篡改。如果用洛克的標準，我們平時所講「同一個人」之中的「同一」，只是幻覺。即使是「同一」個人，其實「自我」亦在不斷變化之中。例如，「十年前的我」和「現在的我」，並不是完全相同的「同一個人」。

— Me@2012.10.01

.

.

2012.10.01 Monday (c) All rights reserved by ACHK

Digital physics, 6

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Many people interested in physics keep on believing all kinds of evidently incorrect mystifications related to the notion of a “minimal length” and its logical relationships with the Lorentz invariance. Let’s look at them.

…

— Myths about the minimal length

— Lubos Motl

2012.09.30 Sunday ACHK

Universal Grammar, 2

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Predicate logics may be viewed syntactically as Chomsky grammars. As such, predicate logics (as well as modal logics and mixed modal predicate logics) may be viewed as context-sensitive, or more typically as context-free, grammars. As each one of the four Chomsky-type grammars have equivalent automata, these logics can be viewed as automata just as well.

— Wikipedia on Predicate logic

2012.09.29 Saturday ACHK

Memory 4

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這段改編自 2010 年 4 月 3 日的對話。

正常健康的腦袋，不會記下所有東西，而會把經驗過濾，把握重點記下，把其他遺忘。所以，記憶既不是事實的全部，亦未必是事實的真相。記憶時常會不完整，甚至不準確。

一個簡單的實驗，就可以證實，「記憶」和「事實」，並非百份百相乎。你可以試試再看，一部以前看過的電影。你會發現，電影中的很多細節，和你的記憶不一致，甚至相反。例如，你記得某輛車明明是在畫面的左邊，重看時，卻發現它竟然在右邊。

— Me@2012.09.29

2012.09.29 Saturday (c) All rights reserved by ACHK

西瓜 5

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[physical geometry]

In so far as the statements of geometry speak about reality, they are not certain;

[mathematical geometry]

and in so far as they are certain, they do not speak about reality.

— Albert Einstein

Analytic statements are about the languages.

Synthetic statements are about the world.

Choosing the best language describing the world is itself a synthetic problem. 

— Me@2012-03-24 12:02:44 AM 

“Is logic empirical?” is not a valid question, because it does not specify the meaning of “logic”.

“Is logic empirical?” is due to the confusion of two different concepts. 

If you have no such confusion, the answer to the question is trivial.

As systems of analytical statements, the different theories of logic are not empirical.

But choosing the best among the logic systems to describe the real world is itself empirical.

— Me@2012-09-23 05:10:23 PM

2012.09.28 Friday (c) All rights reserved by ACHK

Completeness theorem, 4

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Why truth table is not used in logic?

— JiminP

… the difference between semantics and syntax. A syntactic proof is a finite formal derivation of a sentence from the axioms of a theory using the logical axioms and the rules of inference of a logic. A proof by a truth table is a semantic proof; in allowing truth tables you are tacitly assuming the completeness theorem of propositional logic. Essentially, a priori, we don’t know that everything we can prove by studying the models of a theory (i.e. truth tables, in the case of propositional logic) can be proven syntactically, or even for that matter vice versa. It’s a non-trivial result in logic, …

— Zhen Lin

— This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

— Mathematics – Stack Exchange

2012.09.27 Thursday ACHK

Digital physics, 5

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Part of our disagreement is a misunderstanding. I am not questioning that the usual notions of geometry break down at the Planck scale (or earlier).

But the reason in string theory is that it does not make sense to talk about shorter distances because the physics at “shorter” distances is not just normal geometry plus something else, but a stringy generalized fuzzy blah blah structure.

Loop quantum gravity, on the other hand, says that geometry is a good variable at all distance scales, and the areas etc. have discrete spectrum, which contradicts Lorentz invariance in any theory with local excitations.

— Lubos Motl

2012.09.26 Wednesday ACHK

Punishment

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以直報怨 2

Punishment is for avoiding further harm, not revenge, unless revenge has such an effect.

If no further harm is possible, no punishment needed.

— Me@2011.11.11

— Inspired by Bertrand Russell

— Me@2012-09-26 11:06:48 AM

2012.09.26 Wednesday (c) All rights reserved by ACHK

考試美術 1.2

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這段改編自 2010 年 6 月 9 日的對話。

正確的方法是，你先把整幅畫（人、樹、屋）的大致輪廓，先畫出來。因為你只是令「人、樹、屋」成形，所花的的時間一定不多。接著，你才為整幅畫，畫第一重的細節。之後，還有時間剩餘的話，你就加上第二重的細節。下一步，再有時間的話，你再增添第三重的細節，如此類推。

這個策略的好處是，無論考官在什麼時刻宣佈停筆，你都可以宣稱，你的畫作經已經完成。你不可能不合格。

— Me@2012.09.26

2012.09.26 Wednesday (c) All rights reserved by ACHK