Jin felt a slight pang of disappointment upon hearing that No. 700672—and even his masters—had failed to create a warp engine. Nevertheless, he decided to voice his thoughts.
"…Would you mind hearing out my theory?"
No. 700672 nodded.
"Of course. I do not possess the same level of creativity as my masters once did. Memory and support are my primary functions."
As a homunculus, No. 700672 seemed to possess a memory far superior to any human’s while lacking in creative spark, much like the automata and golems Jin had created.
"Warp Gates, the transporters I use, and various transfer devices… these essentially connect two points in space, correct?"
"That is correct."
"My hypothesis is that they work by connecting those two points via a spatial tunnel."
No. 700672 reacted instantly to the suggestion.
"Hmm, interesting. What brought you to that conclusion?"
"Well, I believe there are a few ways to move an object between two distant points, A and B."
No. 700672 nodded, encouraging him to continue.
"One: move it at ultra-high speeds. Two: connect points A and B spatially and move through the link. Three: decompose the object at point A and reconstruct it at point B."
"Hoho… regarding that third method, is such a feat actually possible?"
"No, it’s just a concept from the science fiction stories of my world."
"Truly intriguing. Decomposing an object to eliminate its mass, moving it across vast distances in the form of energy, and then reconstructing it at the destination… I see."
"In my world, there was a saying: 'Anything a human can imagine, they can make real.'"
No. 700672 looked deeply impressed.
"Umu, quite so. I wonder if the day would have come when my masters could have achieved such a thing, had they remained."
Jin and No. 700672 conversed on the topic for a while. Eventually, Jin noticed Elsa, who hadn't said a word—or rather, hadn't been able to find an opening to speak—and addressed her.
"Elsa, this must be boring for you to just sit and listen to, isn't it?"
"No, that’s not true. Just listening is educational for me."
"If you're sure."
"Haha, Elsa-dono is certainly being supportive of Jin-dono."
"Eh..."
Elsa's face turned a shade of pink.
Jin and No. 700672 then returned to the main subject.
"I believe a Warp Gate utilizes the second method."
"Hmm, the one you mentioned first—connecting two points with a spatial tunnel."
"Yes."
In this context, the "tunnel" referred to a three-dimensional entrance and exit. One might think of it as the relationship between a black hole and a white hole.
"I realized that the receiving side of a Warp Gate mainly serves as a marker for the tunnel's exit. The transporter was developed so that an object could be sent even without a receiving unit on the other end."
No. 700672 clapped his hands in admiration.
"Splendid. Jin-dono, your intuition is second to none, even when compared to that of my masters."
"And from here, it’s purely speculation."
"Hmm, let us hear it."
No. 700672 leaned forward in anticipation.
"When sending something, the transporter creates a tunnel that bridges the space between the current location and the destination. This tunnel is, so to speak, 'subspace,' and it is separated from our space even in terms of time."
"Oh? Why do you say in terms of time?"
"Well, first of all, despite it being a tunnel—meaning there should be a 'distance' between the entrance and exit—objects are sent to the destination with almost no passage of time."
No. 700672 nodded repeatedly.
"Please, continue," he urged Jin.
"If there is 'distance' but no passage of time during the transit, wouldn't that imply that time within the tunnel does not flow the same way it does here?"
This was a familiar concept in the sci-fi novels, manga, and anime of modern Japan. However, it was a revelation to No. 700672, who looked profoundly struck by the idea.
"Hmm... such a concept... and yet, the logic holds..."
Jin continued his explanation.
"Even if it takes almost no time, my theory starts with the premise that a minuscule amount of time must be passing."
"Umu, and then?"
"After the tunnel is generated, even if the energy supply is cut, the tunnel should still persist for an extremely short duration. If one could dive into that established tunnel, they might be able to move themselves... That is my concept for the warp engine."
"Splendid!"
No. 700672 stood up in a fit of excitement. Neige, Reiko, and Elsa all looked on in surprise.
"Ah, I apologize. Jin-dono's theory is so magnificent that I lost my composure."
No. 700672 sat back down.
"With that logic, it certainly seems plausible."
"Yes. However, there are several hurdles. First, how does one 'dive' into the tunnel they've created?"
"True. One would have to cease the creation of the tunnel to enter it. And that entry would have to occur in the infinitesimal window before the tunnel collapses."
"Precisely."
Jin nodded at No. 700672's assessment.
"Presumably, the time window for that entry is extremely short?"
"Yes, likely around a millionth of a second."
It was a world of microseconds and nanoseconds.
"Is mass... a hindrance?"
Elsa spoke up for the first time. To accelerate, mass needed to be as small as possible. Jin nodded to her.
"That's part of it. Since a stationary object has to dive into the tunnel, it would need to reach maximum speed in zero time... Wait—that’s it!"
In that moment, Jin had a flash of inspiration: gravity control magic. With this magic, it was possible to make mass infinitely small.
It was the same technique he had used during his failed attempt to launch a satellite.
And there was one more possibility. If they were in outer space, they could simply be moving from the start. They could create the tunnel and be traveling at a speed high enough to dive into it before it vanished.
Of course, the latter wouldn't work on the ground.
Having followed that train of thought, Jin returned his focus to the present.
"Hmm, it seems Jin-dono has hit upon something," No. 700672 said with a smile, reading Jin's expression.
"Yes. Please, listen to this."
Jin then laid out the theory he had just conceived.
"Fascinating! That is a concept I could never have imagined!"
No. 700672 praised him unreservedly.
"I truly hope you will proceed with experiments along those lines."
"I will. And one day, I'm sure..."
"...If it's Jin-nii, I know you can do it."
"Yes, if it's Father, he certainly will."
Not only Elsa, but Reiko, who had approached them at some point, voiced her agreement.
"Hahaha, Jin-dono, you are truly well-loved."
Laughing, No. 700672 praised the bond between Jin and his companions.
"Well then, until next time."
"Umu, you are welcome here anytime."
After promising to meet with No. 700672 and Neige again, the group returned to Hourai Island.
"Elsa, thanks for your help today."
It was already midnight... no, it was closer to dawn.
"You too, Jin-nii."
"Father, please rest, even if only for a short time."
"Yeah, you're right."
Following Reiko's advice as she fussed over his well-being, Jin decided to get some sleep, however brief it might be.