Chapter 6
Next morning.
The moment I opened my eyes, I ran into the living room.
Pitter-patter-!
But Mom stopped me by lifting me up under the arms.
“Hwet!”
Wriggle-wriggle-!
“A-yeon? When you get up, you should brush your teeth and wash your face first.”
“Tch.”
I ran straight to the bathroom.
For the record, if you double my height, you get my IQ.
Which means I'm 80 cm tall.
So to use the sky-high sink, stepping up on a child's stool was a must.
After stepping onto the stool, I took out my cute pink toothbrush from atop the sink.
I squeezed on strawberry toothpaste, scrubbed my still-underdeveloped baby teeth with the brush, then splashed some water on my face and did a cat-style wash.
Brush-brush-.
Splash-splash-.
Okay, now that I've brushed my teeth and washed my face, I can go read the journal, right?
I brought the journal over and started reading it while lying face-down on the blanket.
Pah-pah-pah-.
“Ow...”
Flap, flap-.
Seeing me read the journal so happily, A-rin seemed to get interested and waved her arms toward me.
“A-rin, do you want to read this? Only adults can read this. A-rin is still too little, so no.”
You're only seven months old, so don't even think about snatching my book—just drink more of Mom's milk!
Of course, Mom's milk did taste pretty good.
“A-yeon, you're still little too.”
Mom said from the kitchen.
“Nihihi. At 27 months, I'm all grown up!”
“Uu.”
Since A-rin kept showing interest in the book, I had no choice but to play with her by shaking a rattle in my left hand while turning the pages of the journal with my right hand.
An IQ of 160 can even handle this kind of high-level multitasking.
For the record, if you try this with an IQ below 160, your head might explode, so do not imitate me.
I did warn you, didn't I?
Then, while reading a journal on materials engineering, my eyes stopped on a certain part.
'Sputtering...? What does that even mean?'
When I read papers outside my field, unfamiliar terms like this would often pop up.
Usually I just ignored them and inferred the meaning roughly from the surrounding context, so it wasn't a big problem.
But this word was one I couldn't figure out no matter how I looked at it—from the front, from the side, or even upside down.
“Hmmm... I really dunno this one.”
A newspaper everyone reads would be one thing, but the terminology in papers written on the assumption that experts will read them is this unfriendly.
'Well, that's exactly why I'm reading it.'
There's a reason I focused on reading papers from other fields that I couldn't fully understand.
To develop my brain, of course!
Like muscles, the brain is something that develops the more you use it.
A normal baby develops their brain by getting new stimulation through touching, seeing, and hearing all sorts of things while growing up.
But I already had the knowledge from my previous life.
Ordinary things couldn't give my brain fresh stimulation, so it was hard to develop it enough.
That's why I force myself to use my brain by feeding it unfamiliar knowledge.
'Besides, this is the period when the brain grows explosively. It'd be such a waste to miss this golden time!'
Neuroscientifically speaking, by the time you turn three, the density of connections between brain cells—synapses—is said to be at its highest over the course of your entire life.
A synapse density twice that of an adult brain, and energy consumption twice as high as an adult brain's.
Knowledge learned during this period is said to be engraved into the brain and never forgotten for life.
Perfect pitch and multilingual ability are concrete examples.
'Come to think of it, Mozart showed musical talent at age three, and Gauss showed mathematical ability at age three too, didn't he?'
Geniuses are extraordinary even in childhood.
In fact, that's a misleading way to put it.
It was because of the knowledge injected into their brains in childhood that they later displayed genius in that field!
In the end, geniuses are made in childhood.
Anyway.
For that reason.
I want to accumulate as much diverse knowledge as possible during this important period.
Even after hitting the ceiling at an IQ of 160, the one who doesn't settle and keeps improving is me, Yoo A-yeon.
“But no matter how I look at it, I just dunno... A-rin, do you know what sputtering is? If you do, nod nod, and if you don't, shake your head no.”
“Mm-hm-.”
Shake-shake-.
“Really? So A-rin, you don't know either?”
I asked just in case A-rin might be the reincarnation of a genius engineer, but I guess not.
With no choice, I went to Mom, who was cooking in the kitchen, and tugged on her skirt.
“Mom.”
“Hm? What is it?”
“What is sputtering?”
I showed Mom the paper I had been reading.
“Hmm... Is that in materials engineering? Sorry, Mom had never heard of it either.”
Mom took off her rubber gloves for a moment, turned on her phone, and looked it up.
“Apparently it's a physical vapor deposition method where argon plasma is used inside a vacuum chamber to knock target atoms loose and coat a substrate with a thin film. It looks like it's used to apply thin layers of metal when making semiconductors or displays.”
“Aha.”
“Did you understand?”
“Yeah! Mom's the best!”
Now that the thing I didn't know had been solved, it felt like a huge weight had been lifted.
Of course, I didn't even have all my baby teeth yet, let alone aching ones.
I went back to the living room and turned the page.
Pah-pah-.
✒️✒️✒️
A few days later.
I pestered Mom.
“Mom, I can read books!”
Mom looked somewhat puzzled.
“Hm? Picture books? But A-yeon, didn't you stop reading picture books because they aren't fun anymore?”
“Not picture books.”
“What kind of book?”
“This!”
I pulled a book out from the study.
Mom looked somewhat surprised.
What I'd pulled out was none other than a foreign mathematics journal.
“Uh... A-yeon? Why a math journal all of a sudden? There's so much English, so it's super hard... no, not just English, the content is a total headache.”
“I like things that are hard and headache-y! And... I want to hear Mom read it to me!”
The book I'd pulled out was a foreign journal on pure mathematics that Mom had subscribed to back when she was in graduate school.
Now that I'd filled myself with knowledge from other fields too, it was time to activate my brain with mathematics, my own field.
Just in case.
If I stimulated my brain with math, maybe I'd be able to remember the three-month-long proof process for the Riemann Hypothesis that I'd forgotten?
...And there was one more reason.
'It'd be nice if Mom studied with me too.'
Instead of going on to a PhD, Mom chose to raise children, and said she hoped to do more research later if she ever got the chance.
It had been over three years since she'd completely stepped away from academia.
She'd probably started forgetting the more niche details and lost some of her edge by now.
'I have to stimulate Mom's math brain even if it's only like this.'
It would be a huge loss to the world of mathematics if Mom's talent were buried like this.
For when she might return to the math world someday, I had to keep Mom's math brain nice and pliable.
“It's super hard, so even Mom doesn't know all of it.”
“But... I want to read it with you, Mom...”
Mom said with a look that said she couldn't help it.
“All right. Then shall we read it together?”
“Yay-!”
Mom sat on the sofa, and I perched on her lap.
Mom opened the journal.
“Which one should we start with?”
“This one!”
I pointed to a chapter with my finger.
It was a paper about the triangulation of Riemann surfaces.
“Triangulation of Non-Compact Riemann Surfaces...(Triangulation of Non-Compact Riemann Surfaces)”
Mom began reading the sentences slowly in a familiar English pronunciation.
Slowly and clearly, as if she were reading a picture book.
I listened, pressed close against her.
Whenever she came across a word she didn't know, Mom would stop, look it up on her smartphone, and then continue reading.
'She's reading well.'
I followed the content and organized it in my head.
The topological structure of Riemann surfaces.
In particular, an approach to proving the existence of triangulation under non-compact conditions.
The page turned.
Then.
"...and the exhaustion function ψ satisfying certain convexity conditions allows us to construct— (and the exhaustion function ψ satisfying certain convexity conditions allows us to construct—)"
Mom quickly read a sentence and moved on.
'Wait.'
An exhaustion function.
Convexity conditions.
This part was the key to the paper's logical flow.
If you gloss over this part, the logic that follows will hang in midair.
Mom probably didn't understand it well.
Of course.
Even specialists don't take it in at a glance the first time they see it.
I tilted my head, pretending not to know.
“Mom.”
“Hm?”
“That thing just now...”
“...Which thing?”
“The exhaustion function... what is that?”
“...The exhaustion function...”
Mom read the sentence again.
“Hmm...”
Then she took out her phone and searched for it.
“An exhaustion function... it's a function used when dealing with non-compact spaces. The larger the value gets, the farther outward it goes... so you can cut the space from the inside and look at it in pieces.”
“Why do you need that?”
“Um... hold on.”
Mom looked back at the paper.
About three minutes of silence passed.
A groan leaked from Mom's lips.
“So... when working in a non-compact space, you can't handle the whole thing at once, so you use this exhaustion function to break the space into compact pieces and deal with them step by step.”
Mom said it herself and thought for a little longer.
“...Ah. So instead of triangulating everything at once at the end, you build it step by step.”
It was almost a mutter to herself.
I hadn't led her; Mom had connected the dots herself and arrived at the answer.
'As expected.'
Mom's talent hadn't rusted yet.
“Mom, then what's this?”
I pointed to a certain word with my finger.
“strictly plurisubharmonic...”
Mom frowned and kept muttering quietly.
“Ah, what was this again... I saw it in complex analysis...”
Mom kept looking uncertain, then finally couldn't resist and picked up her phone.
Thunk-.
I grabbed the phone and pressed it down firmly.
“Huh, why?”
“It's just... I thought Mom might not need to look at her phone...”
'Trying to get comfortable, are we.'
This was definitely a concept Mom had dealt with when she was a graduate student.
If she tried to remember, she could bring it back.
If Mom succeeded in recalling this concept, the corresponding synapse would get even stronger.
On the other hand, if she looked it up the easy way, she'd know what it meant for now, but forget it soon enough.
That's the kind of dutiful daughter I am.
I even take Mom's brain activity into account.
Hearing me, Mom closed her eyes and thought, as if something had clicked.
Yes, yes.
Keep connecting those brain cells and activating them.
Drag distant memories up from beyond the shores of forgetfulness.
All the time spent thinking will come back as an asset in the end.
...And so, about three minutes passed.
“...It's something like the convexity they talk about in the complex plane... extending a convex function on the real line into the complex direction.”
Then she started muttering to herself again.
“Ah! So because of this condition, the function doesn't bend weirdly and keeps the structure stable...”
'Correct.'
Seeing Mom like that, I smiled in satisfaction.
It felt like I was experiencing again the same feeling I had when I directly tutored Mom in my previous life.
Heh-heh.
I kicked my legs back and forth while smiling.
Once she'd grasped the core logic, Mom started reading the rest smoothly without a hitch.
By the time she finally finished reading the conclusion.
Mom lowered her head.
“A-yeon, how was it?”
“Mm-hm. It was fun!”
“Wasn't it hard?”
“The harder it is, the more fun it is...”
Mom let out a small laugh at that.
“That's exactly what my advisor used to say all the time in grad school.”
“Really?”
“Yeah. I don't know why, but A-yeon, you seem like that professor. You're smart, and you point out the parts I miss.”
“Hmph. But maybe I'm even smarter than that professor~?”
“Hehe, that's right. Our A-yeon is a genius.”
Swoosh-swoosh.
Mom smiled and stroked my head.