“But note that if you keep going in the same direction, you’ll eventually make a trip around the globe and end up where you started. Standing there, you’ll feel that you’ve seen the place before and perhaps feel nostalgic. Now, let’s say someone had seen you off at your starting point. How would your actions have appeared to him? He gazed at your back as it grew smaller and smaller toward the horizon. You kept on walking and dropped off the horizon, disappearing for a while. From the viewer’s perspective, you vanished from the world. He was surprised, but not as much as when you approached from his back while he waited there for the missing person.
“For someone who mistakes a three-dimensional sphere for a two-dimensional plane, the world can proffer a phenomenon as strange as that. The same goes for the universe. Let’s say you wanted to measure how large the universe is and boarded a faster-than-light spaceship and headed for the end of the world. Can you picture what would happen?”
Hashiba had imagined himself taking such a journey. Beyond the end, outside of the universe, there was darkness, emptiness … Or was there even any boundary that separated an inside and an outside?
“The same thing happens,” Isogai instructed.
“The same thing?” Hashiba tried to picture himself returning to the same location after heading out to the end of the universe, but he found it difficult.
“Almost without a doubt, we exist on the surface of a multi-dimensional structure. We don’t know if there are five, or ten, but since we’re on the surface and our movement is limited, our spatial recognition is truncated at three. For someone who is affected by the structure without realizing it, the universe would seem to be expanding. If the observation speed and range increased, the rate of expansion at the margins would also appear to increase. The notion of dark energy is just an attempt to tie up loose ends; no such thing exists.
“If you went on a journey beyond dimensions to the end of the universe, just as that horizon would recede, all that would ever present itself is a world with a more than ten billion light-year radius. If you keep your bearing, then just like the traveler on the sphere you’ll return to the same point. If your constraints are somehow removed by passing through a gap in the multi-dimensional structure or a space-time bubble, your journey back to the starting point could be instantaneous. But in that case, there could be a shift. The addition of a temporal axis to the multi-dimensional structure gives it a limitless complexity that we can’t imagine in concrete terms. Time would probably shift.”
“That’s why we’d end up in the past?”
“Yes, the past. From the tip of time where we stand, the future is uncertain and undecided. The past can be described in words, not so with the future. The past, it is.”
“But traveling back into the past and affecting history would change the present …” Even Hashiba was aware of time-travel paradoxes.
“So what if it did? The sort of paradox where killing your grandfather fifty years ago leads to your extinction today is predicated on there being only one universe. When we go through the wormhole, we’ll probably go to a past world, but for that world, the future is unknown and not tied to a preceding historical path and can be cut out anew.”
What Isogai was saying seemed to draw on his own unique viewpoints and wasn’t persuasive on every point. Still, the idea of cutting out a new future made Hashiba feel like the courage to act was being bestowed upon him.
When Saeko finally managed to get through to Hashiba’s phone, he immediately began to explain that a wormhole could open just before the phase transition reached Earth. For a moment, it was enough to make Saeko completely forget about the noises she’d heard in the living room.
“I know it’s a lot to take in. Did I explain it well enough?” Hashiba asked uncertainly. He had gone into great detail about the mechanism of the phase transition and the wormhole.
“It makes sense. Yes, that would fit,” Saeko was quick to reassure him.
Wormholes weren’t such a new concept. She remembered the time when her father had explained the basics of spatial inflation theory and the possibility of their existence. It was at least logical that wormholes could open before a phase transition. The other universe might also be suitable for human life since physical laws were preserved in the face of manipulations of CPT — charge, parity, and time.
“Saeko? Hello? I think we’re losing the sig—”
The magnetic anomaly seemed to interfere with communication devices, and Hashiba’s voice faded into a background of static. The line went dead.
Saeko noticed an eerie silence and realized that there were no noises coming from the living room. Whether the TV had been turned off or the volume muted, it felt certain that someone was there.
The quiet and what Hashiba had told her deepened her sense of solitude. Even if a wormhole did open before the phase transition reached them, even if she could cross it to embark on a trans-dimensional journey, there would be nothing there for her. Just loneliness. Soon she would lose all of her friends, everyone she had ever cared for. She’d dealt with the devastating disappearance of her father when she was in high school, and the thought of even more loss was too much to bear. Was there even any point in living under such circumstances? Saeko pulled her jacket together, suddenly cold, as though her loneliness was causing the temperature of the room to drop.
Her thoughts returned to the room next door. Was it just her imagination? Was she being too jumpy? Just trying to think was making her head spin. She had already locked the door, but would that stop whoever it was from getting into the bedroom? Saeko looked at the thin door; if someone really tried, it wouldn’t be too hard to break in.
If Isogai was correct, a portal to another world could open somewhere in the house. Saeko felt that the living room would be the most likely place. According to the evidence — the half-empty glasses of tea, discarded banana skins, and such — that was where the family had disappeared. If it had opened upstairs, it was possible that only the children would have disappeared. No, it had happened when all four family members had been gathered together.
If she were to stand a chance of escaping the phase transition, she couldn’t stay cooped up in the bedroom. Though she knew she had to get back to the living room, her body wouldn’t play along. Saeko understood something then: you had to be brave in order to act. It took far more courage to make some move than to await salvation.
Her father had not wanted for her a passive life of drifting with the current. Why else had he taught her how to interpret the world? It was so she could overcome obstacles and face strange worlds. Without the courage to take a step into a new realm, life wasn’t worth living.
Saeko was pacing towards the door.
What remained was a matter of will. Should she go, knowing that her loneliness would only worsen? Was it better to step into the unknown and bet on survival?
Saeko turned the lock and crossed the threshold. The Fujimuras’ living room had no door and simply opened up from the hallway. Saeko sneaked to the edge and peeked in.
The TV set glowed under the fluorescent ceiling lights, and the flickering screen showed the sky in California, horizon faintly crimson as dawn approached. From the vantage point of the camera the chasm in the ground resembled a dark belt strapped to the land below and snaking towards San Francisco.