Chapter 94
Yoo A-yeon and Han Seol-ae headed to work.
Only Yoo Jin-ho and Yoo Arin remained at home.
Vrrrrrrrr-!
Yoo Jin-ho had quit his job and become a househusband.
He opened the windows for ventilation and diligently ran the vacuum cleaner.
And then.
Pitter-patter-pitter-patter-!
“Dad! What's this?”
Yoo Arin came running over with a thick magazine hugged to her chest and grabbed the trouser leg of Yoo Jin-ho, who was vacuuming.
“Let's see. Which one?”
What she had been reading was a section of a science magazine explaining AI technology.
Arin pointed at a particular word with her tiny finger and asked about it.
“This word here! Gradient descent!”
“Uh… well, you see.”
Yoo Jin-ho thought for a moment about how he should explain it.
“Imagine coming down a mountain with your eyes closed.”
“Okay. I imagined it.”
Arin said this with her eyes squeezed shut.
“Since going uphill is hard, let's say you only walk downhill.”
“Okey-dokey-. Uphill makes me huff and puff! I'm going down!”
“Since my daughter wants to get down quickly, she'll keep walking only along the steepest downhill slope beneath her feet. Then eventually she'll reach the bottom of the valley, right?”
“Yeah. I made it to the valley. There isn't any downhill left!”
With her eyes closed, Arin vividly imagined herself descending to the bottom of the valley.
“Right. What I just explained is how AI finds answers. You close your eyes and keep going down along the steepest slope. Then eventually, you arrive at a valley with no downhill left.”
“Aha… So gradient descent? Because you keep going straight down along the gradient?”
Arin said this as she opened her eyes.
“I get it! Thanks, Dad!”
Arin nodded as if satisfied, then scampered back over and started reading again.
Yoo Jin-ho smiled fondly.
As expected, that's our youngest.
She has such strong intellectual curiosity thanks to her older sister's influence.
But then.
Pitter-patter-pitter-patter-!
Not long after returning to her spot, Yoo Arin came running back again and pointed at a word in the magazine.
“Dad! What's this one? Penicillin!”
Yoo Jin-ho couldn't remember it clearly, but he somehow dredged up his old memories and explained.
“Uh… what was it again…? It's the world's first antibiotic, and I think it came from mold.”
“What's an antibiotic?”
“When our daughters come home after running around at the playground, Mom always tells them to wash their hands, right?”
“Yep!”
“The reason we wash our hands is because of bacteria we can't see. And antibiotics are medicine that gets rid of those bacteria.”
“I see! Then penicillin is good because it gets rid of bad bacteria! Thanks!”
Pitter-patter-pitter-patter-.
And ten minutes later.
“Dad! What's disposable income?”
Another ten minutes later.
“Dad! What's radiation attenuation?”
Another ten minutes later.
“Dad! What's schadenfreude?”
Another ten minutes later.
“Dad! Dad! Daaaad-!”
……
“A-Arin.”
Beads of sweat began to form on Yoo Jin-ho's forehead.
She was simply asking questions far too frequently.
‘Did Arin always ask this many questions?’
Yoo Jin-ho realized that A-yeon and Seol-ae had been handling Arin's barrage of questions all this time.
Now that only the two of them were left at home.
The entire barrage had landed squarely on him.
But what truly flustered Yoo Jin-ho was something else entirely.
For a five-year-old, the level of the words she asked about was far too high.
Engineering, biology, economics, physics, psychology…
How were the fields so wildly varied?
It was enough to make him wonder if she was practicing CSAT non-fiction reading comprehension or something-.
Yoo Jin-ho took a surreptitious look at what Yoo Arin was holding.
“…Huh. Isn't this what A-yeon was reading?”
“Yep-! Big Sis gave it to me!”
What Yoo Arin was reading were magazines and newspapers full of difficult material that Yoo A-yeon had read in the past.
Even now, a corner of the study was piled high with books that Yoo A-yeon had read so relentlessly as she grew that their pages had worn thin.
And now, her little sister was reading them.
“Sweetheart, can you understand this?”
Yoo Jin-ho asked carefully.
Arin answered innocently.
“Yeah, no? It's hard, so I don't understand all of it!”
After saying that, Arin planted both hands on her hips.
“But Big Sis always says this!”
“What did she say?”
“She said if I read lots of difficult stuff and try to guess unknown words as much as possible, I'll use my brain a whole lot and become a super-smart genius like her! I wanna be a super-genius like Big Sis too!”
…
Yoo Jin-ho was speechless.
Even his five-year-old youngest daughter was trying to study such difficult things under the influence of the ultra-genius A-yeon.
He thought that perhaps the greatest of his daughters' talents was their eagerness to study on their own.
That eagerness to study on their own might be their greatest talent of all.
Yoo Jin-ho's large hand gently covered Yoo Arin's tiny crown.
Pat-pat-.
“As expected, that's my daughter. You're totally amazing.”
Muuuu-.
But Arin suddenly puffed out her cheeks.
“Dad! Big Sis answered every single question kindly, one by one, whenever I asked! But you keep trying to waffle your way past things!”
“……Ghk.”
Arin's instincts were frighteningly sharp, and she had caught him trying to hand-wave his way past things.
Her tone sounded almost as if she were comparing him to her super-genius big sister.
Those brutally honest words from a five-year-old drove an arrow straight into Yoo Jin-ho's heart.
Yoo Jin-ho was facing the greatest crisis of his life: a test of his qualifications as a father.
No matter how much his eldest daughter was a genius destined to be recorded in history.
If he was even outdone by his eldest when it came to teaching his youngest, then wouldn't that be a blow to his dignity as a father?
Besides, A-yeon had now become a professor and was busy, while Seol-ae went to work with her to look after her.
From now on, staying by Arin's side was his responsibility.
‘Seol-ae used to read math books to A-yeon often too… Now I should read to Arin as well.’
To be honest.
These difficult newspapers and magazines weren't things Yoo Jin-ho himself usually looked at very closely.
Even though he had majored in statistics and worked in finance.
Biology and physics were outside his field of study, after all.
He had also been too busy with work to have time to read them to her.
But so what?
‘I've quit my job and have plenty of time now. If it can make Arin smarter, this much is nothing.’
For the first time in a long while, Yoo Jin-ho decided to work his brain to the limit, just like his admirable daughters.
“All right.”
Then he rolled up his sleeves.
“Come here, sweetheart.”
Pat-pat-!
He patted his lap.
“Huh? Yay-!”
Yoo Jin-ho grabbed Yoo Arin by the sides and lifted her onto his lap.
Rustle-.
Then he opened the magazine Arin had been holding so they could read it together.
“Dad will read it with you.”
“Gasp, really?”
“Of course. Dad doesn't know all of this either, but let's read it aloud together. Like Mom and A-yeon did.”
“Ooh! Awesome! Dad, you're the best—!”
Overexcited, Arin kicked her legs back and forth while sitting on Yoo Jin-ho's lap.
✒️✒️✒️
“All right, then. Shall we start with this article?”
“Oh, it's quantum mechanics! The thing Big Sis explains sometimes!”
The father and daughter found an article about quantum computers.
Yoo Jin-ho began reading the article aloud.
“A technology has been developed to finely control qubits, the information-processing units of quantum computers, using only voltage instead of a magnetic field. —”
Blah-blah-blah-.
After they finished reading the difficult article, Arin lifted her head and met her father's eyes before asking a question.
“Dad, what does qubit mean?”
“Hmm… Dad doesn't know exactly either. But if you look below…”
Yoo Jin-ho pointed to the paragraph below with his finger.
“It says they store the quantum states of very small particles, like molecules, in units called qubits.”
“Hmm…”
“So I guess a qubit refers to the state of a very small particle? It can be 0 or 1.”
“So it's like you can't tell tiny grains of sand apart from far away, but you have to look really closely~ through a microscope to know whether they're asphalt sand or fine beach sand?”
“Oh, that sounds plausible.”
Yoo Arin pointed at a sentence with her finger.
“Then what does it mean here that it's controlled by voltage? Is it like running electricity through it to switch it on and off? Like a light switch?”
“…That's what Dad thought at first too.”
Yoo Jin-ho furrowed his brow and reread the article.
“Look, it says here that ‘when the voltage was increased, the spin-resonance frequency changed significantly.’”
“Yep.”
“So it doesn't feel like electricity is flowing through it to operate the machine. It seems more like the voltage changes something around it, which changes its state.”
“Hmm, then is it like poking it from far away with a stick, going poke-poke-?”
“That's a pretty good way to put it.”
Yoo Jin-ho grinned.
Seeing that expression, Arin giggled as if she found it amusing too.
✒️✒️✒️
The father-daughter reading session continued after that.
Unlike her older sister's cute, adorable voice.
Though it was the low, resonant voice of an adult man.
Arin leaned against her father's body and listened with her ears pricked up, as if his voice alone reassured her.
Then, whenever something she didn't understand came up.
“Dad, Dad, what does this mean?”
“Hmm… Dad doesn't really understand it either.”
“Dad doesn't know either?”
“Yeah, Dad doesn't really know either. But judging from the context of the article, it probably means something like this. What do you think, sweetheart?”
“Hmm….”
Arin pressed her index finger to her lips and thought hard.
“I think it means this! Because that's how it explains it later!”
“Good guess. That's my girl.”
“Heheheh.”
The father and daughter put their heads together and interpreted the difficult material one piece at a time.
When they didn't know something, they guessed together, discussed it with each other, and worked out a plausible answer.
After they finished reading everything, they used a smartphone together to determine the exact meanings and correct their errors.
This was actually a study method Yoo A-yeon had recommended.
She had said that when something unfamiliar came up, they shouldn't look up the answer right away, but should think it over and reach their own conclusion first, then compare the correct answer with the parts that differed from their own thoughts.
Sure enough, reading difficult books the way her older sister recommended made Yoo Arin feel as if the knowledge was sinking neatly into her head.
✒️✒️✒️
While stroking his youngest daughter as she kicked her legs back and forth on his lap while reading, Yoo Jin-ho suddenly thought of a scene.
It was about a year ago.
During Yoo A-yeon's close-up interview.
The exact scene where Han Seol-ae had Yoo A-yeon sitting on her lap and read an overseas mathematics journal with her.
That scene had caused quite a stir at the time.
People had asked if that family really read things like that to a five-year-old.
And now.
He was sitting with his youngest daughter on his lap and reading a difficult book with her.
“Wow, Dad, this is seriously super hard! My head is throbbing-!”
“Right? Dad finds it hard too. But isn't it fun reading difficult things together?”
“Yeah! I like reading with Dad!”
Arin giggled and leaned her back against Yoo Jin-ho's chest.
At that tiny yet warm weight.
Yoo Jin-ho unconsciously smiled contentedly.