Parallel spaces?
Qiu Yun recognized each of those words individually. She might have heard the term before, perhaps in some sci-fi movie, but in this specific context, she didn't quite understand.
"What do you mean?"
"It’s... a bit difficult to explain all at once. At first, I didn't understand the cause either; I thought there were simply two different worlds. But later, by a stroke of luck, I attended a lecture by a physics professor named Liang at a university. I learned that beyond our world, there is another."
"Another world?"
"Yes, or perhaps many worlds. Right now, as you are breathing and speaking here in 1988, there is another person—or many other people—breathing and speaking in other worlds. They are like your doubles, or perhaps identical multiples. But you don't know each other, and you don't affect each other. In any single world, there is only one unique you."
"Wait..." Qiu Yun was a bit dazed, unable to digest Qiu Zhenghong’s words immediately. This... this physics was way beyond her syllabus!
"Let me give you an example," Qiu Zhenghong said, as if seeing through her confusion. "It might be a bit morbid, but it will help you understand. For instance—and this is just an example—suppose you have a handgun, the kind with a revolving cylinder like in those old Hong Kong movies. You know the type?"
Qiu Yun nodded blankly.
"Good. Now, suppose you feel you can't go on and decide to end it. But you don't know which chamber the bullet is in. Every time you pull the trigger, it could be an empty click, or it could be the end. Right?"
Qiu Yun understood the logic, so she nodded again.
"Then can we understand it like this: every time you fire, there is a one-in-six chance of success. If every attempt is an independent event, then every time you try, you enter a parallel universe where you are either dead or alive. In this complex web of worlds, there is always a parallel universe where you are still living. Do you understand what I’m saying?"
Qiu Yun thought she understood, yet she still felt lost. Doesn't a person only have one life? You're either dead or alive; how could you be both, existing in different universes?
"You might think of it this way," Qiu Zhenghong continued his patient explanation. "Suppose the person holding the gun is Sun Wukong. Doesn't he have the power to create many clones of himself? If there are six clones and one bullet corresponds to one clone, wouldn't there be five living Sun Wukongs and one dead one?"
Qiu Yun thought for a moment. "Yes."
"If these six Sun Wukongs, whether dead or alive, are all in six identical environments," Qiu Zhenghong pointed to the surrounding tables, chairs, roof, and windows, "and they are unaware of the other five, wouldn't each one believe they are the only one?"
Qiu Yun followed the logic. "Yes."
"Then wouldn't their outcome also be unique to them?"
Qiu Yun nodded again. "Yes." Then she shook her head. "Not exactly."
"Why?"
"Because there are actually five others in different rooms."
"Exactly! That is the point," Qiu Zhenghong’s eyes lit up. "Whether the outcome is unique or not depends on whether you are the observer or Sun Wukong—that is the key to the problem."
"The key to the problem..." Like a flash of lightning, everything became clear to Qiu Yun. "Are you saying... I came from the world of 2018 back to the world of 1987? I am that Sun Wukong? And at the same time, I am the observer who has seen both worlds, and both worlds are currently existing simultaneously?"
"Precisely. That’s the logic."
"Then, following that, does it mean the Sima Qiu Yun in the 2018 world is still alive? And there is also an identical Qiu Xiaoyun alive—probably a woman in her fifties. Meanwhile, in this world, I—Sima Qiu Yun—haven't even been born yet, because I was born in 1994."
"That is correct."
"Then..." Qiu Yun frowned. "If the 2018 version of me came into the 1987 body of Qiu Xiaoyun, is the 1987 Qiu Xiaoyun currently living in my 2018 body? Have she and I... swapped souls?"
"You could put it that way," Qiu Zhenghong said. "But there is a problem here. I wonder if you’ve noticed it."
"A problem...?" Qiu Yun carefully reviewed the reasoning they had just established, then suddenly looked up. "According to the rules just now, a single double can only exist in one world. Right now, in the 2018 world, are there two Qiu Xiaoyuns? Even if one is 'residing' in my body."
"You really are clever," Qiu Zhenghong nodded. "You understand perfectly with just a little hint. Yes, two souls of the same person cannot exist in one world at the same time."
"Then..."
Just as the word left her mouth, Qiu Zhenghong spoke: "The Qiu Xiaoyun of 2018 is already dead."
"Dead?" Qiu Yun’s eyes widened. "How... how did she die?"
"In one world, there can only be the soul of one double. If two appear, the one with less energy will die, whether by natural disaster or human accident."
"This... this..." Qiu Yun was frightened. For a moment, she felt like she was watching a play, wondering if this was all just the delusions of a madman or some superstitious nonsense. She tried to recall their conversation, attempting to find a logical flaw, but she couldn't find one for the life of her. In truth, ever since she had accepted the fact that she had traveled through time, her belief in a purely materialistic scientific view had already been shaken.
"Don't worry," Qiu Zhenghong said, seeing her dazed expression and assuming she was terrified. "Those are the rules of parallel worlds, but Xiaoyun's cause of death wasn't because of the travel. It was because, in your world, she passed away in 1994."
"Passed away?"
"Yes," a trace of sorrow appeared on Qiu Zhenghong’s face. "Brain cancer."
Qiu Yun didn't know what to say. In this situation, she should have comforted him, but her instinctual reaction was: "It's 1988 now. Does that mean in six years, I am going to die too?"
Qiu Zhenghong nodded.
Qiu Yun was stunned. "Can't it be treated?" Then she asked tentatively, "Wait, I won't be staying here for six years, right? You called me here today to help me travel back, didn't you?"
Qiu Zhenghong looked at Qiu Yun for several seconds before speaking. "Do you know why Xiaoyun traveled in the first place?"
This... was another question beyond her knowledge! Qiu Yun thought, *If I knew that, I would have gone back long ago!*
"I was the one who made her travel. You asked me earlier why this courtyard causes people to travel randomly, yet my family could live here peacefully for decades. It’s not because jumping into the well causes the travel, but because of—the water in the well. Once a person drinks the water from that well, they have a chance to travel to another space within a certain timeframe. My comrades who vanished, and the others who appeared here, all did so because they drank that water. After I discovered this secret, I sealed the well in the courtyard. My wife, son, daughter-in-law, and granddaughter never knew there was a well here. Until three years ago, when Xiaoyun started complaining of frequent headaches. A hospital visit revealed a malignant tumor in her brain. She was hospitalized for a while, but then she came home—the doctors said there was no hope. Of course, Xiaoyun herself didn't know this. When she was discharged, I told her she was cured."
Qiu Yun listened, dumbfounded. After a long silence, she touched her own head. "You mean, inside here... there's a tumor?"
"Yes," Qiu Zhenghong said. "At that time, I remembered the well. If I could send Xiaoyun to the future, to a world with advanced medicine, her illness could surely be cured. Just like my leg."
"Your leg..."
"Have you forgotten? I told you, when I returned from Korea in 1952, I only had one leg. Later, by chance, I traveled a hundred years into the future and was fitted with a prosthetic that is no different from a real leg. In that era, robotics and artificial intelligence were highly developed. You could buy a leg in a roadside shop after a trial run, as easily as buying groceries."
"As easily as buying groceries..." Qiu Yun was so overwhelmed by this fantastical story that she could only repeat his words.
"So, I dug up the well again. It had been sealed for decades, but the water was still crystal clear when I opened it. However, the travel is unpredictable. I didn't know where the world would be—China or abroad? A hundred years in the past or a hundred years in the future? It was qualitative, not quantitative. Therefore, I had to experiment on myself first."
"You mean, you've traveled many times?"
"More times than I can count on both hands."
Qiu Yun’s mouth hung open in shock. A word came to her mind: "Wandering...?"
Qiu Zhenghong smiled slightly. "Very clever."
"And did you reach any conclusions?"
"Three. First, the temperature and dosage of the water have a subtle relationship with the time of travel. Cold water takes you to the past; hot water takes you to the future. Second, traveling brings side effects to the body—you can see that by looking at me."
"So you look this young because of the travel?"
"Yes. The side effects can be good or bad. They are unpredictable."
"And the third?"
"The third is that travel involves both the soul and the body together."
"...I know that. Oh! Wait!" Qiu Yun almost jumped up. "Then what happened to me? Only my soul came to 1987! My body is still in 2018! And your granddaughter, Qiu Xiaoyun, too! Why did only our souls swap?!"
***
