Building the Earth Era cost 2.07% of all humanity's GDP every year. After all these years, its total price tag had already reached a staggering 159 trillion Federal Credits!
That was an astronomical sum. Naturally, ordinary people weren't happy about it after all this time.
After all... plenty of people on Earth were still eating dirt!
Li Cheng sighed again. "The Deep Space Foundation still has to set aside at least a trillion in funding to build a laser highway for the Earth Era."
"Over the next 20 years, Jupiter Industrial Base will have to collect a huge amount of nuclear fuel, whose fusion energy will be used to fire long-range lasers..."
Zhang Yuan nodded, turning the matter over in his mind.
The Earth Era used a dual propulsion system: light sails and nuclear fusion.
Light sails relied on the pressure of light. When photons struck a smooth surface, they could change direction like ping-pong balls bouncing off a wall, exerting a corresponding force on the object they hit and propelling the spacecraft forward.
However, the pressure exerted by sunlight was far too weak to quickly propel a gigantic spacecraft weighing tens of millions of tons. Only large artificial light sources on the Moon and at Jupiter Base could generate enough pressure to push it along.
Think about it: even though the nuclear fuel on Jupiter was inexhaustible, it still took manpower to collect.
On top of that, the laser highway had to fire continuously for 20 years. It would take tens of thousands of laser emitters, which would need constant replacement—a colossal expense in its own right.
It was hard to imagine how Professor Qi Yuanshan, the "father of nuclear fusion," had managed to persuade those shrewd businessmen and wily politicians in the first place.
Deep-space colonization, this enormous undertaking, had absolutely no benefits to offer.
It wouldn't bring any returns for hundreds or even thousands of years.
That was strange.
After chatting for a while, Li Cheng also felt that discussing these things with the younger generation was a bit pointless. "Whether there's enough funding is something the bigwigs up top should worry about. You don't need to concern yourselves with it. Just focus on doing your own jobs."
He shook his head, as if he'd thought of something, and stopped eating altogether. Getting up from the dining table, he walked into his study and started pondering something on his own.
Zhang Yuan was curious about the gossip surrounding all this, but seeing Li Cheng like that, he had to let it go.
After dinner, Zhang Yuan muttered under his breath, "Your dad's just like mine—a workaholic. He suddenly gets an idea, gets all excited, and starts writing it down. You absolutely can't interrupt him then, or he'll either get mad or say something completely incomprehensible."
"Exactly!"
Li Zhendong wholeheartedly agreed. "I remember asking my dad when I was little why one plus one equals two. Do you know what he said? He actually started talking to me about the Peano axioms, and I was still in kindergarten! I seriously wondered if he had any common sense!"
"Did he teach your sister like that too?"
"Yeah."
Li Zhendong said with exaggerated emphasis, "Once, my sister asked him why the area of a rectangle is length times width. He immediately started talking about Euclidean space, inner products, and all kinds of incomprehensible stuff. Thank goodness my mom's a normal person. Otherwise, he'd have driven us both crazy."
Zhang Yuan laughed along, remembering his own dad's bizarre ways.
Back then, he'd been playing with a Rubik's Cube on the sofa when his dad suddenly got the urge to lecture a seven- or eight-year-old about group theory.
Yes, group theory—the paper Évariste Galois had written in a single night.
"It's just math from five hundred years ago. It's easy. Learn this, and the other kids will be impressed by you!"
Zhang Yuan had been thrilled. "I want to learn! I want to!"
"...The group formed by all the possible moves is called the Rubik's Cube group. Obviously, it's a non-abelian group... If we can decompose it into the product of simpler subgroups, then construct the generators for each subgroup, we can prove that it's solvable. It has already been proven that any Rubik's Cube can be solved in 20 moves or fewer."
Throughout the lecture, Zhang Qiming had been beaming, thoroughly enjoying the satisfaction of being a teacher.
But eventually, he noticed that his son was just staring at him blankly, unable to follow.
Unable to follow?
Zhang Qiming blurted out a curse. "What an... idiot!"
It wasn't clear whether he meant his son or himself.
Zhang Yuan sighed. Looking back on those memories, he no longer felt the resentment he'd felt at the time. Instead, he rather missed those days.
It had already been three years since his father passed away, hadn't it?
Time really did fly. Open your eyes, close them, and three years were gone. The dead were gone, leaving only memories behind.
Seeing that Zhang Yuan was in low spirits, Li Zhendong turned on the TV and switched to the children's channel. An animated show was playing: Wolf Out: Bears Turn Into Sheep.
"Don't look down on me just because I'm a bear..."
It was a very childish cartoon, but the little girl beside them was enjoying it.
Zhang Yuan asked, "Won't your parents be sad when you leave?"
"They won't be. They still have my sister, don't they?" He pointed at the girl beside him, who looked to be in her early teens, and said nonchalantly, "They can have a few more kids later, anyway. Technology's advanced these days. They can have as many as they want, and they can afford to raise them."
He went on, "Think about it. If I don't get on the ship and stay on the Moon to work, I'll come home once a year for Spring Festival. Three days each time, and two hours with them each day... Over 60 years, that'd only add up to 360 hours together..."
"Right now, I'm home every day, eating and drinking, and I spend seven or eight hours with them each day. That's over 200 hours a month. I've spent half a lifetime's worth of time with them over this whole vacation. What is there to regret?"
Zhang Yuan scratched his head. What kind of lousy logic was that?
But somehow, it also made a bit of sense...
Li Mama smiled and cut up some fruit for them. She seemed to be used to Li Zhendong's eccentric remarks. "Zhang Yuan, don't go home tonight. Stay with us. We have a spare room, anyway."
"Okay."
Zhang Yuan nodded, sighing inwardly.
Li Zhendong's situation was a lot like his own, but unlike Zhang Yuan, he had both parents and a happy family.
As for Zhang Yuan, he was a test-tube baby. His father had provided the sperm, while the egg had come from an anonymous female donor in the human gene bank. Even now, he had no idea who his biological mother was, and there was no need to find out...
But who wouldn't want a kind, gentle mother?
Back in college, the two of them had earned similar grades. But Li Zhendong was a genius who could fool around and still score over 90 on exams, while Zhang Yuan was merely a top student who had to work much harder to get good grades.
It was really a difference in intelligence...
But that was okay!
Thinking this, Zhang Yuan took out his phone and started browsing the Super Brain app. As he looked at the mathematical symbols, a strange sense of happiness rose in his mind.
There was no need to envy anyone else. Learning made me happy, and learning helped me grow!
As long as I could learn, I had the whole world!
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