Visualize

visualize ~ feel all at once

— Me@2016-09-28 08:20:18 PM

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visual ~ same-time representation ~ spatial representation

— Me@2016-06-30 07:38:28 AM

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難得有情人

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— Me@2022-02-08 11:50:35 PM

「你是要找『條件最適合你』的人，如果你剛巧又，最適合她的話。」

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Today I found my soulmate; she didn’t.

「你是要找『與感情最深』之人，如果你剛巧也是，『與她感情最深』之人。」

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「情人」的重點在於情。

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— Me@2022.05.11 07:07:43 PM

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Someone who causes people to do that which they ought to do but which they would not do in his absence.

— John T. Reed

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2022.03.21 Monday ACHK

The 4 bugs of quantum mechanics popular, 1.3

The common quantum mechanics “paradoxes” are induced by 4 main misunderstandings.

1.  A wave function is of a particle. Wrong.

2.1  A system's wave function exists in physical spacetime. Wrong.

physical definition

~ define the microscopic events in terms of observable physical phenomena such as the change of readings of the measuring device

~ define unobservable events in terms of observable events

— Me@2022-01-31 08:33:01 AM

superposition

~ lack of the existence of measuring device to provide the physical definitions for the (difference between) microscopic events

— Me@2022-02-12 10:22:09 AM

a physical variable X is in a superposition state

~ X has no physical definition

~ in the experiment-setup design, no measurement device is allowed to exist to provide a definition of different possible values of X

— Me@2022-02-18 02:04:45 PM

2.2   A superposition state is a physical superposition of a physical state. Wrong.

“Quantum state” is a misnomer. It is not a (physical) state. It is a (mathematical) property. It is a system property (of a physical variable) of an experimental-setup design.

“State” and “property” have identical meanings except that:

State is physical. It exists in physical time. In other words, a system's state changes with time.

 

Property is mathematical. It is timeless. In other words, a system's property does not change. (If you insist on changing a system's property, that system will become, actually, another system.)

For example, “having two wheels” is a bicycle’s property; but the speed is a state, not a property of that bicycle.

superposition state

~ physically-undefined property

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In the phrase “superposition state”, the word “superposition” is also a misnomer.

A superposition state is not of physical waves, nor of physical states. Instead, it is a superposition of physical meanings of some variables in a physical system.

a physical variable X is in a superposition state

~ X is a physically-undefined property (of the physical system)

— Me@2022-02-18 02:04:45 PM

— Me@2022-02-20 06:44:32 AM

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What is more difficult to understand is the non-classical part:

What if, instead of turning on a detector before the time of emitting, we turn it on after the pair is emitted but before either of them has reached its destination?

In the common (but inaccurate) language, the action of activating a detector has collapsed the wave function of the system.

Would the pair of (such as) spin values be correlated?

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(Me@2022-02-16 12:07:25 AM: I think I have the answer now. I plan to publish it soon. But I keep the following as a record of thoughts.)

There are 2 possibilities.

(I do not know which of them is true, because I have not yet found an actual experiment that has tested against them.)

[guess]

1.

They are correlated only in the statistical sense.

2.

Every pair is correlated.

This is stranger than the first case, because if the two detectors are several light-years apart, the whole system exists across those light-years. The strangeness is the fact that even for a system-across-light-years, operations at one end can influence the probability of an event at the other end.

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For the time being, I guess that the second case is the true one.

Even if the first case is the true one, it is still strange because it implies that an action at one part of the system influences the statistical properties of another part, which may be several light-years away.

[guess]

Even in this stranger case, all experimental results are still consistent with special relativity (aka causality), because wave functions are not physical quantities. Instead, they are mathematical quantities for calculating probabilities, which themselves are also mathematical quantities, for predicting experimental results.

— Me@2022-02-11 12:47:14 AM

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Bug fixes:

1.1  It is not the particle’s state that is in a superposition or not, but the system’s state.

2.1  We need to specify which observer that the wave function is with respect to.

A wave function is for an observer to calculate the probabilities of different possible results in an experiment.

2.2  There is no “god’s eye view” in physics.

Every physical event must be described with respect to an observer. Every physical event, even if the event is “to compare observation results”, must be described with respect to an observer. — Me@2017-05-10 07:45:36 AM

2.3  A wave function is mathematical, not physical.

It is a mathematical function for an observer to calculate the probabilities. It is not something existing in physical spacetime. Thus superposition is also not something existing in physical spacetime. So it is meaningless to ask if the system state is in a superposition at a particular time.

Instead, whether a system is in superposition or not (with respect to a particular variable) is an intrinsic property of your experimental setup design, which includes not just objects and devices, but also operations.

“Wave function collapse” is not a physical event that happens during the operation of the experiment. Instead, it “happens” when you replace one experiment design with another.

— Me@2022-02-16 10:45:01 AM

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What is more difficult to understand is the non-classical part:

What if, instead of turning on a detector before the time of emitting, we turn it on after the pair is emitted but before either of them has reached its destination?

Since neither of the detectors at the two end destinations is activated in the beginning, the entangle variables are still physically-undefined (i.e. in a superposition) at that moment the pair is emitted.

However, while the particles are still on the way, at the moment one of two detectors is first activated, the entangled variables get their physical definitions. The system state is no longer in a superposition state. Instead, it becomes a mixed state. In other words, the system has become a classical system (with respect to those entangled variables).

In the common (but inaccurate) language, the action of activating a detector has collapsed the wave function of the system.

Would the pair of (such as) spin values be correlated?

.

(Me@2022-02-16 12:07:25 AM: I think I have the answer now. I plan to publish it soon. But I keep the following as a record of thoughts.)

There are 2 possibilities.

(I do not know which of them is true, because I have not yet found an actual experiment that has tested against them.)

[guess]

1.

They are correlated only in the statistical sense.

Individual pair of values may be not correlated, but a lot of pairs that have the same superposition (at time of emitting) will form that statistical pattern that is indistinguishable from the one that predicted with the assumption that every pair is correlated.

In analogy, in the double-slit experiment, an individual dot on the final screen cannot tell whether the particle was in a superposition. It is only after a lot of dots forming on the final screen, we can check whether there is an interference pattern. When the interference appears (and we assume that the wave function that governs every particle is the same), we say that every particle is in a superposition state. Or put it more accurately, the system is in the same superposition state before each particle has reached the screen.

2.

Every pair is correlated.

[guess]

— Me@2022-02-11 12:47:14 AM

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physical definition

~ define the microscopic events in terms of observable physical phenomena such as the change of readings of the measuring device

~ define unobservable events in terms of observable events

— Me@2022-01-31 08:33:01 AM

In the EPR experiment, if at least one of the detectors at the two end destinations is already turned on at the time of emitting, then (the system that contains) the pair is NOT in a superposition since the beginning.

The entangled variables (that the detector measures) are already physically defined by the detector’s potential behaviors. The system state is already a mixed state, not a superposition.

superposition

~ lack of the existence of measuring device to provide the physical definitions for the (difference between) microscopic events

— Me@2022-01-31 08:33:01 AM

— Me@2022-02-12 10:22:09 AM

With respect to that pair of entangled variables, the experiment setup is just a classical one, which directly follows Aristotle’s 3 laws of logic.

For any proposition $\displaystyle{A}$, either $\displaystyle{A}$ is true or $\displaystyle{\text{NOT}~A}$ is true, but not both.

There is nothing non-classical about the correlation between the (such as) spin values of the pair.

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What is more difficult to understand is the non-classical part:

What if, instead of turning on a detector before the time of emitting, we turn it on after the pair is emitted but before either of them has reached its destination?

— Me@2022-02-11 12:47:14 AM

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It shouldn’t be so surprising that unitarity survives completely while causality doesn’t. After all, the basic postulates of quantum mechanics, including unitarity, the probabilistic interpretation of the amplitudes, and the linearity of the operators representing observables, seem to be universally necessary to describe physics of any system that agrees with the basic insights of the quantum revolution.

On the other hand, geometry has been downgraded into an effective, approximate, emergent aspect of reality. The metric tensor is just one among many fields in our effective field theories including gravity.

— Black hole information puzzle

— Lubos Motl

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identical particles

~ some particles are identical, except having different positions

~ some particle trajectories are indistinguishable

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trajectory indistinguishability

~ particle identity is an approximate concept

~ causality is an approximation

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spacetime is defined by causality

~ so spacetime is also an approximation

— Me@2022-02-11 12:47:14 AM

— Me@2022-02-13 03:38:35 PM

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physical definition

~ define the microscopic events in terms of observable physical phenomena such as the change of readings of the measuring device

~ define unobservable events in terms of observable events

— Me@2022-01-31 08:33:01 AM

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superposition

~ lack of the existence of measuring device to provide the physical definitions for the (difference between) microscopic events

— Me@2022-01-31 08:33:01 AM

— Me@2022-02-12 10:22:09 AM

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In the EPR experiment, how come the two always correlate if there are no definite states before the measurements?

When you actually know the results of your experiment, it does affect your expectations of the faraway results if there are correlations – and correlations are almost always there iff the two subsystems have interacted or been in contact in the past). — Lubos Motl

Microscopically, there is no time, in the sense that all the (past and future) quantum states have one-one correspondences. All results are deterministic. No causality violation required nor allowed. — Me@2016-10-14 07:55:48 PM

This is called quantum determinism, which may or may not be correct. But quantum determinism, even if true, is not necessary for explaining the EPR experiment, if we understand that:

1. Superposition is mathematical, not physical.

2. “Wave function collapse” is mathematical, not physical. It just means that we have to replace the wave function with another if we replace the system with another.

The system before and after the detectors activated should be regarded as two distinct systems. In other words, when you activate the detectors, you have actually replaced a system-without-detectors with a system-with-detectors.

“Wave function collapse” replaces the pure state wave function with a mixed state wave function. In other words, it replaces the pure state of superposition with a mixed state of eigenstates. In other other words, it replaces quantum probability with classical probability.

Before opening the box, the cat is not in a superposition state. Instead, it is in a mixed state.

The uncertainty is classical probability, which is due to lack of detailed knowledge, not quantum probability, which is due to lack of definition (in terms of physical phenomena difference).

— Me@2022-01-29 10:38:19 PM

— Me@2022-02-12 10:28:57 AM

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superposition

~ lack of the existence of measuring device in the definition of the experimental setup to define the difference between microscopic events in terms of the difference between observable physical events

— Me@2022-01-31 08:33:01 AM

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Note that superposition is mathematical, not physical. A wave function is not probabilities, nor a physical wave. Superposition applies only to wave functions, not to probabilities, nor to physical realities.

If superposition had been of probabilities or of physical realities, there would have been no interference patterns in the double-slit experiment.

— Me@2022-02-11 03:32:47 PM

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For example, in the double-slit experiment, if no detector is installed, the system is in a quantum superposition state.

It is not that each individual photon is in a superposition, because an individual particle has no 100% objective identity, due to the indistinguishability of identical particles. Instead, it is that the system of the whole experimental setup is in a superposition.

This applies also to other more complicated experimental setups, such the EPR experiment, the delayed-choice experiment, the delayed-choice quantum eraser, etc.

— Me@2021-01-23 12:57 AM

— Me@2022-02-11 03:29 PM

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physical definition

~ define the microscopic events in terms of observable physical phenomena such as the change of readings of the measuring device

~ define unobservable events in terms of observable events

— Me@2022-01-31 08:33:01 AM

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a definite state

~ an eigenstate

~ a state that has given a physical definition

— Me@2022-02-11 01:19:57 PM

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What we do in the present does not change the past, but changes we can see/say about the past. — Wheeler on Delayed choice quantum eraser, paraphrased, Me@2018-02-04 03:40:27 PM

Physics should deduce what an observer would observe, not what it really is, for that would be impossible. — Me@2018-02-02 12:15:38 AM

It is because, tautologically, any state that cannot be physically defined is logically and physically meaningless.

In other words, any state that has no distinguishing observable effects does not make sense. For example, if in a double-slit experiment, no detector is allowed, then it is no point to label the state either as “go-left” or as “go-right”. Instead, we have to label the state as a superposition state.

Some unobservable (aka microscopic) variables are meaningless. It is not because of any philosophical points of view, but because we have not defined those variables in terms of observables or observable events, aka physical phenomena. In other words, those variables have no physical definitions yet.

— Me@2022-02-11 03:50:59 PM

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Quantum mechanics, and physics in general, gives the rules of storytelling about reality. A story is a post hoc description of a physical event. In other words, quantum mechanics, and physics in general, is about phenomena, not noumena.

phenomenon (plural phenomena)

~ thing appearing to view

~ reality with respect to an observer

noumenon (plural noumena)

~ thing-in-itself

~ reality independent of any observers

— Me@2022-02-11 3:00 PM

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The superposition language

classical language

~ all particles are distinguishable

~ every particle has an objective identity

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quantum language

~ some particles are identical

~ some particles are indistinguishable

~ Not every particle has an objective identity

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[guess]

When you insist on using all-particles-are-distinguishable language on the maybe-indistinguishable particles, you get the superposition language.

[guess]

— Me@2022-02-05 09:26:26 PM

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Superposition always exists, 3

The question

Are there still any superpositions?

is the same as

Are there still any unobservable (aka microscopic) events that have not been defined in terms of observable (aka macroscopic) events yet?

— Me@2022-02-05 12:24:41 AM

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友情演義

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「愛情故事」是故事，不是事實全部真相。

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《三國演義》的英文是 Romance of the Three Kingdoms，即《浪漫三國》。

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「求婚」必為事先同意，或「雖則未必知悉，但必早已預期」，才合乎禮儀。

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「愛情誠可貴，自由價更高」的原因，全在邏輯方面：

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— Me@2022-01-28 01:43:04 PM

— Me@2022-02-07 10:29:03 AM

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Spinoza 3.2

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Intellect is invisible to those have none.

— Arthur Schopenhauer

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A stupid man’s report of what a clever man says is never accurate, because he unconsciously translates what he hears into something that he can understand.

— p.83

— Chapter XI. Socrates

— A History of Western Philosophy (1945)

— Bertrand Russell

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（安：根據羅素的講法，有很多人學習深奧學問時，所謂的「明白」，未必是真正的明白，因為他們會不自覺地，把那些新知識，翻譯成自己明白的版本；即是夾硬用，舊知識的語言，以理解新知識。Paul Graham 說在小時候，曾經用這個方法，去學習數學；即是將數學概念，翻譯成日常生活的概念。）

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（安：我記得是。當然，我可以記錯。但是，有沒有講過，或者誰講過，並不是重點。重要的是，那些講法，有沒有道理。

Everything which exists, exists either in itself or in something else.

That which cannot be conceived through anything else must be conceived through itself.

— Baruch Spinoza

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— Me@2022-02-03 12:09:36 PM

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理智與感情, 2

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~ 客氣

~ 保持距離

— Me@2016-09-03 02:58:13 PM

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To realize is to realize, 1.2.2

So in theory, there is no free will, because the future is already fixed, by the physical laws.

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However, even if we knew the exact physical laws, it would be still logically impossible to get all the data of the present state of the whole universe, because it is logically impossible for any observer to observe itself, with 100% details, directly. For example, no camera can take a picture of itself directly.

So “in practice”, which is actually also “in principle”, there is free will, because logically, no one can predict, with 100% accuracy, your future actions.

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In one logical sense, the future is already fixed, so there is no free will. In another logical sense, the future is fixed, but no observer can know that “fixed future” with 100% accuracy, so there is free will.

As a result, whether you label your actions are due to “free-will” or “not-free-will” has no real consequence. In other words, whether there is free will or not has no meaningful difference.

The difference that makes no difference makes no difference.

So you can actually transcend the free will problem altogether. You can just ignore it and live your life.

Or, you can somehow capitalize on this freedom of labelling your (future) life as either fixed or free, depending which label is more beneficial for you in a particular situation.

For example, when you are highly under pressure, you know that everything is fixed by the physical laws, from god’s point of view. When you are highly above pressure, you know that you are partially responsible for creating your own reality, because the future is not fixed for any one observer, for there is no “god’s point of view”.

You have the flexibility to label it in one way or another.

— Me@2021-05-07 10:27:04 PM

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To realize is to realize, 1.2

For example, when you ask “how to be a polite person”, you become a polite person.

In other words, when you realize that you should be a polite person, that polite person is realized at that moment.

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The ultimate self-fulfilling prophecies:

1. free will or not

2. god or no god

3. afterlife or not

4. future spouse exists or not

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Why self-fulfilling?

1. free will or not

If we knew the exact physical laws and all the data of the present state of the universe, we would be able to predict, with 100% accuracy, the state of the universe at any future moment.

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In theory, the exact physical laws exist, whether we know them or not. Also, in theory, all the details of the present state of the universe exist, whether we know them or not.

So in theory, there is no free will, because the future is already fixed, by the physical laws.

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However, even if we knew the exact physical laws, it would be still logically impossible to get all the data of the present state of the whole universe, because it is logically impossible for any observer to observe itself directly. For example, no camera can take a picture of itself directly.

So “in practice”, which is actually “in theory”, there is free will, because logically, no one can predict, with 100% accuracy, your future actions.

— Me@2021-04-16 04:45:47 PM

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Being conscious

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What is the meaning of “a company exists”?

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A company exists when the people inside it cooperate.

They have a leader, getting the needed information by using the employees as sources.

If a company’s employees no longer cooperate or its leader can no longer get the information needed, that company no longer exists.

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What is the meaning of “being conscious”?

A brain is conscious if its different (hardware or software) parts cooperate by exchanging information.

— Me@2013-08-10 06:48 PM

— Me@2021-04-06 10:44 PM

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Story

A story means data with a context. A storyline is a linear and more understandable context.

— Me@2011.08.27

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Serialize, 2

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~ 安排

~ stably list

~ serialize

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An in-series path gives no choice.

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