What is the nuance between 内に and 間に in these sentences?

Question

This will be a long question.

I referred to the other questions that were already answered,

1. Difference between 前に and うちに

2. When describing time span, are 間 {あいだ} and 内 {うち} interchangeable?

3. What's wrong with using 内に in this sentence?

and made my own summary of 内に and 間に based on these answers:

内に

A 内に B

A: a state (where it is implied that the state will change from state X to state Y - the time frame)

B: an action

Usage:

• Used when it is difficult for the speaker to determine a start and end point of the state.
• B is completed while A is still in effect (Often implies that if B is not completed within the time frame of A then B becomes more difficult or impossible to achieve.)

• 2 types:

  1. A person intentionally takes action before something changes
  2. While something is taking place, something changes without the speakers volition

天気がいいうちに散歩する。

I will go on a stroll while the weather is nice. (If the weather becomes bad, I can't walk/it will be difficult to walk.)

Point 1 is satisfied: I cannot predict when the good weather will start becoming bad weather.

Point 2 is satisfied: I will complete my walk while there is good weather (If good weather (state X) becomes bad weather (state Y) then it will be difficult/impossible to walk.)

Point 3 is satisfied: type 1

間に

A 間に B

A: a state or action (where the state or action occurs within a fixed time frame X and Y)

B: a momentary action

Usage:

• The speaker has the ability to determine a start and end point at the moment of making the statement. (or if there is a "default standpoint" [2.])
• B is performed within the time span that A is performed.

天気がいい間に散歩する。

I will go on a stroll while the weather is good. (merely strolling while the weather is nice.)

Point 1 is satisfied: There is a "default standpoint"

Point 2 is satisfied: Going for a walk during the time span that the weather is good.

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The problem

Now bearing that in mind, most of the examples i see explain type 1 内に sentences

But these examples of type 2 sentences I found don't seem to nicely fit into the interpretations above (or I just don't see it):

1. 知らないうちに、眠ってしまってた。 I fell asleep while I didn't know. ○

   知らない間に、眠ってしまってた。 I fell asleep while I didn't know. ○

I can't see the difference between 内に and 間に here. If I had to guess, the nuance provided by 内に "if I did know, then I wouldn't sleep". That kind of meaning?

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2. 酒をゴクゴクと飲むうちに、また顔が真っ赤になってた。My face became completely red while I gulped down sake. ○

   酒をゴクゴクと飲む間に、また顔が真っ赤になってた。My face became completely red while I gulped down sake. ×

Why is using 間に wrong in this case?

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3. 家へ帰るうちに、傘を忘れて来たのに気づいた。While going home, I noticed that I had come without my umbrella. ○

   家へ帰る間に、傘を忘れて来たのに気づいた。Before getting home, I noticed that I had come without my umbrella. ○

According to another website, when using 内に, this has the nuance of noticing before going home, but 間に means noticing while going home. I don't understand why this is so.

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4. しばらく見ないうちにまた大きくなった！You grown big again while I didn't see you! ○

   しばらく見ない間にまた大きくなった！You grown big again while I didn't see you! ○

I also don't understand the difference here.

Answer 1

あいだ（間）に implies parallel timeline, and switching the contxt between them or describe the synchronous nature of events between the two timelines. While something is happening, something else is also happening, whereas うちに implies single timeline, in which "until" condition exists.

They are interchangeable, when it can be thought of two timelines or one. 天気のいいうちに散歩する (emphasized for nuance: Take a walk WHILE weather is good (for me).) 天気がいい間に散歩する (I go for a walk, while the weather (the universe, the nature, that acts on its own timeline) is fine.

so, in this case that's interchangable. However, in a cooking show - it's definitely not interchangeable. Let's say you boil the water, and while the water is coming to a boil, you cut the carrots. You have two separate timelines going on here, water in the pot and carrots on the cutting board.

◎　お湯が沸く間に、ニンジンを切ります。

✕　お湯が沸くうちに、ニンジンを切ります。

Back to your question:

酒をゴクゴクと飲む間に、また顔が真っ赤になってた。My face became completely red while I gulped down sake. ×

Why is using 間に wrong in this case?

Well, there's one time line going on. That's you. So うちに applies, not 間に. If you involve someone else, making it a two-timeline narrative, you can use 間に。This whole narrative is about you, without introducing another situation or a person.

ボクが酒を飲んでいる間、愛犬のチロは家でずっと待っていたんだ。

My beloved dog Chiro has been waiting for me at home WHILE I was drinking sake.

Two timelines. There's you, and there's the dog. Therefore, うち doesn't apply, あいだ works.

Answer 2

うちに is within the time, a.k.a 'while' with a nuance of within.

酒をゴクゴクと飲むうちに、また顔が真っ赤になってた。My face became completely red while I gulped down sake. ○

Within the time it took me to gulp down the sake, my face became completely red.

酒をゴクゴクと飲む間に、また顔が真っ赤になってた。My face became completely red while I gulped down sake.

間に is a duration used with time. i.e. ２年間 a duration of two years. With this in mind.

The duration of time of gulping down the sake, my face became red.

Sounds strange in English no? It also sounds this way in Japanese.

An easy way to see the difference is to break the sentence in two parts. Is the later part of the sentence occurring within the time of the first part?