The experiments using Mityanite commenced.
"Vibrations usually mean sound, light, or electromagnetic waves. Let's start with the basics and try to generate electromagnetic waves at the highest frequency possible."
Jin wrote the necessary magi-formula into the main magi-crystal and attached the Mityanite to the generating section to act as an amplification device.
"There, that should do it."
Since he couldn't conduct the experiment inside the workshop, he decided to head outside. It was 9:00 PM and pitch black.
"Father, please don't overexert yourself. Whether this succeeds or fails, please promise to rest for the night after this."
Reiko finally pleaded with Jin.
"…I know. But right now, I have to do what only I can. Please understand, Reiko."
"…Yes. I will assist you to the best of my ability."
Jin's determination was firm, and Reiko had no choice but to concede.
"Alright, starting the test. Laojun, monitor the situation."
"Yes, Father."
『Yes, My Lord.』
At Jin's instruction, Reiko triggered the prototype to wake up, and Laojun began observing the test conditions.
"Firing electromagnetic waves."
To reduce risk, the test was conducted by aiming toward the sky with the operating time limited to 0.1 seconds.
"Fire!"
In an instant, a pale blue beam streaked into the void and vanished.
"What was that just now?"
Normal electromagnetic waves should have been invisible to the naked eye. It was Laojun who answered.
『My Lord, it is likely that because the electromagnetic waves were of extremely high energy, the atmosphere was ionized and emitted light.』
"I see."
While this might have had applications as a weapon, it wasn't what he was currently aiming for.
"I guess this method won't work… In that case…"
Jin decided to try his next idea.
"Father, what is that?"
"What I just tried was a transverse wave, but this time it’s a longitudinal wave."
Also known as a compressional wave, sound waves are an example of this.
Vibrating free ether instead of air results in an ether wave, which includes mana waves.
However, ordinary ether waves are transverse waves, not compressional waves.
Jin was wondering if he could make free ether vibrate like a sound wave.
『My Lord, how do you intend to do that specifically?』
Even Laojun didn't seem to have an inkling.
Jin explained his theory to Laojun, partly to verify his own thoughts.
"First, the starting point was the 'Mana Explosion'."
He knew from experience that space vibrated during such an event. He had even used it as a vibration source when he had No. 700672 measure the reaction speed of the Space Isolation Barrier.
"But that is far too uncontrollable."
『That much is clear.』
"So, I thought about why a Mana Explosion causes space to vibrate, even if only slightly. I think it's… harmonics."
『Harmonics? I see.』
Harmonics are frequency components that are integer multiples of a wave with a certain fundamental frequency. In music, they are called overtones.
The original frequency is called the fundamental wave; twice that frequency is the second harmonic, and n times that frequency is the nth harmonic.
Jin was desperately trying to recall topics he had learned in high school physics.
"Fourier something-or-other, my teacher used to say…"
Though it was material typically learned at the university level, Jin's high school teacher had occasionally brought up such topics to pique the students' interest in mathematics.
Among those topics was an explanation that properly overlapping sine waves of different frequencies would result in a square wave.
"If you're interested in this kind of thing, please go to university and study ‘Fourier—’"
He had said… Jin recalled. Incidentally, he couldn't remember the word that followed.
In fact, through a Fourier "series expansion," as you layer harmonics, a sine wave gradually approaches a square wave.
In other words, a square wave contains harmonics.
In reality, devices that handle square waves require measures to suppress the effects of external noise.
But back to the point.
Mobilizing all of this qualitative knowledge, Jin was wondering if he could produce ultra-high frequencies.
"I suspect the reason a Mana Explosion can vibrate space is that the explosion's waveform contains square waves."
『Understood.』
"Father, specifically, how do you intend to create a square wave as a compressional wave?"
Laojun was convinced, but Reiko asked for a concrete example.
"I’m thinking of using force generators."
Force generators radiate a force of the same nature as gravity waves.
"If I flip the polarity in a short amount of time, it should become a compressional wave, right?"
『Certainly so.』
In short, it was the idea of alternating between "pushing" and "pulling."
"I thought that if I could control that in a square-wave fashion, maybe space itself would shake."
"I understand, Father."
『I see. When space shakes, the gravitational field inevitably vibrates as well. You intend to vibrate space by fluctuating gravity, then?』
"You could put it that way."
To control square-wave-like vibrations, a considerably large output was required. For that, Jin used Mityanite.
"There, that's it."
At 10:00 PM, the second prototype was complete.
"Alright, let's test it."
This, too, would be done outside like the previous one. Reiko took the prototype in her hand once more and activated it.
"Wake up!"
This time, it seemed to take just under a second to reach a stable square wave.
"Oh?"
For a moment, in the middle of the dark night, he felt as though he saw… something.
Then, after one second, the operation stopped.
"Laojun, what was that just now?"
『Yes, My Lord. It appeared as though space emitted a faint light.』
When exercising magic, magic circles or magi-formulae sometimes emerged; this seemed similar yet entirely different.
『While the luminous phenomenon is similar, the light during magic is mainly from surplus mana. I believe this luminescence was from free ether.』
"So that's what you think, Laojun?"
『Yes. However, No. 700672 would be superior regarding such measurements.』
"True."
It was frustrating, but that gap wasn't something that could be closed overnight.
"Well, whatever.…The luminescence of free ether—can I take that as a bit of a hopeful sign?"
『I wonder. Luminescence of free ether can be seen in various cases.』
When an ether converter turned large amounts of free ether into mana, surplus free ether or mana would sometimes emit light.
"But I feel like I might be able to do something along this line. I have to do everything I can."
He couldn't yet vibrate space intentionally, but Jin felt that he might have at least grasped a clue.