Lesson Three: Light and Electromagnetic Force

After a day of enjoyable lessons, Naruto went home to continue practicing Fire Release.

Sasuke went home to recuperate.

Hui also had to go back for his lesson.

Once again, father and son sat across from each other at the table.

"Hui, I'm sure you've noticed. Based on what I taught you earlier, ninjutsu is essentially a kind of simulated substance created by ninja."

"That applies to both the Five Nature Transformations and Kekkei Genkai."

"But matter is matter. The destructive power of chakra—a kind of matter—in the macroscopic world is simply astounding."

"Hui, think about how we should understand this phenomenon."

Hui lowered his head and thought for a long time, then finally shook it, indicating that he didn't understand.

This kind of question was still too difficult for him.

Chuanhe smiled and once again tore a sheet of paper from Hui's notebook.

Then he slowly tore it in half in front of Hui.

Afterward, he asked, "What did you notice during that process, Hui?"

Hui, who had been brimming with confidence, felt deeply discouraged. He didn't understand anything at all.

He couldn't even tell what Chuanhe was asking.

Seeing the completely bewildered expression on his son's face, Chuanhe continued.

"I once told you that all motion in the world can be described in terms of four fundamental forces."

"So, Hui, in what just happened, was the electromagnetic force holding the two parts of the paper together severed?"

At last, Hui understood.

Then chakra with the wind nature surged in Chuanhe's hand, and he used a hand blade to slice one half of the paper in two.

"Now look again. The paper has been split in half once more. Doesn't that mean the electromagnetic force connecting the two pieces of paper has been cut again?"

Hui hesitated, then nodded.

But what did this have to do with chakra's unusually great destructive power?

"Haha, Hui, it's normal not to understand."

"Keep this phenomenon in mind and listen to what I have to say."

Chuanhe formed Hand Seals.

[Summoning Technique]

A necklace appeared in his hand, with a small metal sphere hanging from it.

"This is my auxiliary weapon. Once today's lesson is over, it'll be yours."

"How well you can use it will depend on your understanding."

Hui sensed a fluctuation in chakra, and gradually, the entire room sank into darkness.

Was this that genjutsu? No, there was a chakra fluctuation.

A three-dimensional star chart appeared in the room before Hui.

What kind of genjutsu could achieve so many effects at once?

Hui was a little puzzled.

He saw the sun in the center shining with blazing light, with eight planets revolving around it.

"Since today's lesson is a little abstract, we'll use questions and answers to help you understand."

"First question: does a force take time to act?"

Hui immediately knew the answer. Chuanhe was clearly telling him that a force did take time to act.

But why?

Hui began thinking. What would happen if forces acted without taking time?

Looking at the solar system before him, his thoughts wandered. For some reason, he began thinking about interstellar communication.

If forces acted without taking time, wouldn't information be transmitted instantly this way?

In short, it would travel faster than light.

The speed of light was the fastest speed in the universe.

That statement wasn't quite right. More precisely, the speed of information transmission couldn't exceed the "speed of light."

The speed of light could change, after all; it traveled at different speeds through different mediums.

Wouldn't that phenomenon conflict with forces acting instantaneously?

That meant forces took time to act.

Hui excitedly explained his reasoning to Chuanhe.

Chuanhe nodded in satisfaction.

"Second question: if a force takes time to act, then what do you think a force is?"

Was this familiar question another way of asking whether force was matter or energy?

No, those were completely different concepts. So why would a force need time to act?

Matter... energy!

That was it. The fact that it took time meant matter was involved.

Time only came into being when the motion of matter was involved.

After a long while, he finally worked out his idea.

Take the "sun" before him, for example. The force wasn't acting on the surrounding planets out of nowhere.

Instead, some unknown particles were colliding with one another between them.

It was simple: energy existed on the basis of matter.

The existence of a force gave the corresponding matter new energy.

That meant unknown matter was involved in the process.

Hui felt as if his old understanding of force had completely collapsed. In truth, there was no such thing as "force."

There was only matter—nothing but matter.

People had simply given this phenomenon the name force.

Take gravity, for example: the sun pulled on the planets.

A kind of particle acting as a medium—the graviton—carried and transmitted energy between the sun and the planets.

The result was the macroscopic phenomenon of gravity.

Hui told Chuanhe about his discovery once again.

Chuanhe nodded in satisfaction again and said,

"These intermediate particles are called gauge bosons. Of course, I prefer a name that's easier to understand. They're also called mediator particles."

Hui was puzzled. He understood what force was now, but what did that have to do with chakra?

"Father, could these mediator particles have something to do with chakra?"

Chuanhe laughed heartily.

"Exactly, exactly. Electromagnetic force is one of the four fundamental forces. Do you know what its mediator particle is?"

Hui looked troubled. If he knew, why would he be taking lessons?

"Take a guess. I've given you such an obvious hint. You should be able to figure it out."

Chuanhe looked at Hui expectantly.

After thinking for a moment, Hui blurted out,

"Light?!"

"So that's it! That's it!"

Hui suddenly understood, and a strange excitement took hold of him.

"Oh? Then tell me about it."

Hui explained his understanding.

Light was the mediator particle of electromagnetic force. If the transmission of light was cut off, that meant the electromagnetic force had been cut off as well.

Chuanhe had said earlier that chakra was matter about the size of light.

Combining that with the fact that light was the mediator particle of electromagnetic force perfectly explained why chakra's destructive power was so astonishing.

Chakra merely interfered with the transmission of light, only doing so more efficiently than people could on a macroscopic scale.

All it had to do was cut off the transmission of light—no, perhaps it only had to interfere with it a little.

On a macroscopic scale, it would be like that sheet of paper, split in two.

This might also explain why red-hot metal became soft.

The fact that visible light appeared meant that the electromagnetic force holding the matter together had weakened.

"Not bad, not bad. That last idea is new to me. That's an interesting connection."

Chuanhe praised him without holding back.

"Father, does that mean the Magnet Release used by those people in Sunagakure is powerful? If they truly mastered it, couldn't they separate all matter into atoms?"

"That would be the true Dust Release!"

Hui excitedly speculated.

Chuanhe paused in surprise.

"Since you've thought of that, Hui, why not consider this: based on what we've seen so far, is Magnet Release really the kind of magnetism we know?"

The excitement on Hui's face faded. It wasn't magnetism?

Recalling the descriptions in the books—the control of Iron Sand, Gold Dust, and sand—Hui furrowed his brow. It really didn't seem to be. This Kekkei Genkai appeared to let its user control only one specific type of matter with chakra.

Hui said dejectedly, "It really doesn't seem to be. Why did the people of Sunagakure choose such a misleading name?"

Chuanhe smiled faintly. "There has never been an all-purpose technique in this world. But Magnet Release is powerful enough; they just don't know how to use it."

"Precisely controlling a single substance is an enormous boon to any kind of machinery."

Chuanhe paused and looked at Hui.

"Earlier, you asked how I solved the problem of flying too slowly and becoming an easy target."

"For starters, my flight speed is already enough to eliminate most of the problems."

"Hui, think about it: which is better, dodging an enemy's attacks or making it impossible for the enemy to find a target?"

Hui was slightly taken aback by the question. Looking at the star system before him, he found the answer.

"Father, do you mean using genjutsu to make the enemy unable to tell where our real bodies are? But genjutsu can be seen through."

Chuanhe pointed to the sun before them.

"Hui, why don't you try touching the sun?"

Hui reached out, puzzled. What could be special about something made by genjutsu?

Before he even touched it, Hui realized something was wrong.

The sun really was warm.

How was that possible?

A master of genjutsu could indeed affect all five senses.

But Hui was certain that his hand had truly been burned.

"This isn't genjutsu?" Hui asked.

Chuanhe smiled mysteriously, then said, "I call it True Illusion: a blend of real and unreal, truth and falsehood, leaving the enemy unable to tell the difference."

"It's the result of combining several different abilities. It's not just a simple genjutsu."

"All I do in this process is provide chakra. This necklace handles everything else."

"Hui, everyone has limits to how much they can control."

"Day after day, year after year, most ninja practice ninjutsu, yet can only master a few C-rank techniques."

"People are only human, and humans make mistakes."

"That's why I invented this. Mechanical tasks shouldn't have to take up our capacity to think."

"What you said was right too: this isn't just genjutsu. It also involves the Five Nature Transformations."

"I used the Soul Sealing Technique to create this 16-Core Ninjutsu Core. With a few simple preset instructions, it can release sixteen ninjutsu simultaneously."

"Be careful when you feed chakra into it. If you're too rough, the core inside will be damaged."

Soul Sealing Technique? A core? Could it be... a soul?

Hui shuddered. Had his father imprisoned sixteen people's souls in there?

Chuanhe saw Hui's unease.

"Don't worry. Since then, I've done my best to honor the vow I made with Yuki."

"These cores are actually blank Shadow Clones that can't return to their original bodies."

"The techniques Second Hokage Tobirama Senju invented are truly absurd. Their potential is immense, too."

"Shadow Clones aren't real people, but they can think independently."

"But these blank Shadow Clones can't think for themselves. They can only repeat tasks mechanically."

There was such a use for them?

Hui stared at the tiny necklace in shock.

"The Shadow Clone Technique can already be used to perform compound ninjutsu. That old Third Hokage developed his signature move based on it."

Chuanhe dispelled the technique through the necklace and handed it to Hui.

"Happy birthday, Hui! This is your birthday present."

Chuanhe ruffled Hui's hair.

Hui blinked. "My birthday isn't for another three months..."

Hui seemed to understand something. He took the necklace and put it on.

He had grown a year older again, even if only on the level of his soul.

The necklace felt heavy. From what his father had said, it was clear that he had put a great deal of effort into making it.

That necklace seemed almost like cheating.

Hui looked at his hands. Did he really still need to learn ninjutsu?

This necklace could already solve all his problems.

The jokes he'd once made had become reality.

With this necklace, he really could become the kind of game character who could kill people just by casually tossing out skills.

Seeing Hui fall silent, Chuanhe patted him on the shoulder.

"This necklace is indeed incredibly powerful, but the strong have never been strong because of their equipment. You still have to make yourself strong."

"Hui, remember that ninjutsu you developed called Scrap Gauntlet?"

"Back then, because your fundamentals weren't strong enough, you used it to push yourself forward."

Chakra surged in Chuanhe's hand, forming a gauntlet identical to the one from back then.

"How can you let such a small thing stop you from moving forward now?"

Chuanhe pointed the gauntlet at Hui's eyes.

Seeing this familiar technique, Hui's confusion faded.

Although today's lesson had ended, Hui suddenly realized there was a small problem.

It seemed Chuanhe had forgotten to tell him whether self-awareness was actually the fifth fundamental force.