"Given the current level of technology development and restrictions from relevant policies and regulations, it's quite difficult for us to exploit faith on Earth on a large scale anymore. Since the 'sink' strategy is already blocked, the company's only option left is to go overseas."
Xu Mengyuan said, "Next, let's have Hephaestus introduce you to the basic theoretical knowledge related to cross-dimensional travel."
"Happy to serve," the handsome half-blood found a chair to sit in, rubbed his hands together and said, "Where shall we start, hmm... You've heard of string theory, buddy?"
"I've heard some."
"Good, then I'll try to keep a long story short. According to the theory of eternal inflation proposed by Soviet physicists Alexander Vilenkin and Andre Linde, our universe is like a bubble caused by quantum fluctuations."
"And there are infinitely many similar bubbles. They keep forming and then vanishing, never having a beginning or an end. To help you understand this theory better, you can think of a bottle of Coke being shaken madly, where one bubble represents our universe, and the other bubbles are other universes."
"Most of the time, our universe is very stable and solitary, growing and expanding on its own. But there are times when we collide with other bubbles, a phenomenon we researchers call 'interference'."
"Normally, interference is imperceptible, with the vast majority of creatures in both universes completely unaware of its occurrence, not knowing when it started or when it ended. Interference has almost no effect on the universes."
"Not until the founders of the Third Era uncovered the secrets hidden behind those ancient myths, and discovered that we can use interference to travel to another universe. This technology is now also called 'The Descent.'"
"In the early days, The Descent was an extremely dangerous affair, akin to sticking your head into a crocodile-infested pool. This is because the Calabi-Yau Manifolds differ, and the physical laws of different universes might vary greatly."
"Venturing into a universe with a different Calabi-Yau Manifold was basically the same as suicide. Luckily, since there are enough bubbles, later researchers gradually figured out how to find universes with the same Calabi-Yau Manifold after many trials and errors and at a great cost."
"Then the selection criteria were further narrowed down, and eventually, we picked out new worlds that weren't too different from ours."
"What do you mean by 'not too different'?" Li Yu asked.
"Quantifying it, the deviation would be worlds within 5% difference, with climates, geographical environments, flora and fauna we're familiar with... Most importantly, classical physics is completely applicable," Hephaestus said, "We call these worlds 'Clean Lands.'"
"However, just finding the right planes and mastering the technology of The Descent isn't enough," Xu Mengyuan interjected, "It's like setting a destination and preparing a ship for navigation; in the end, you still need someone to steer it."
"—The Captain, that's the key to it all."
"Exactly, only a very small number of people in this world possess the ability to cross universes, to descend from one universe to another," Hephaestus continued, "I'd give anything to see another universe, even if it means dying there the next second, I'd have no regrets. But it looks like I'll never get that chance in my lifetime."
The handsome half-blood sighed, looking quite remorseful, "Ordinary people like me are doomed to rely on our meager imaginations and others' descriptions to experience its magnificence, praying to encounter it in our dreams."
"That place is indeed quite beautiful," Li Yu said, "a bit like medieval Europe with a dash of fantasy elements. The most powerful Empire there is built by Half-Beasts, humans, and Dwarves together, though there's no Magic or Magicians."
"Half-Beast? Like the ones in 'Lord of the Rings' or..."
"The kind with beast ears, not much different in appearance from humans."
"Damn!!!" Hephaestus let out a rare curse, "The only thing in this world I can't refuse is furry! Now a world full of furries is laid out before me, yet I can't even glance at it, it's not fair! It's not fair at all!!!"
"We can discuss your fetish later," Xu Mengyuan glanced at the time, "The next descent is about to begin, you'd better focus on the important points."
"Alright." The half-breed hunk reluctantly suppressed his urge, "Next, I'll introduce you to some of the rules related to the descent, but I believe you've already noticed some of them."
"First, you can take things from this world over there."
"But only those my body can touch?" Li Yu asked.
"Bingo! Wow, dude, you have pretty good observation skills," Hephaestus praised, "And for now, the total weight of what you can bring cannot exceed five kilograms. No living things, and uncooked seeds are also not allowed."
The half-breed hunk's words also explained why, on Li Yu's first descent, his cellphone, watch, and clothes were all there, but his wallet and tissue in his pockets vanished.
Fortunately, the last two items were still in the room when he returned.
"What about bacteria," Li Yu asked, "the bacteria and viruses I carry on me can't possibly disappear too, can they? What impact would they have over there?"
"That's an interesting question. I've seen similar discussions on many forums before. I think most people somewhat overestimate the power of modern bacteria, even though many like to use the Native Americans of the American Continent as an example."
"However, these people overlook a premise, that is, the smallpox brought by the European colonizers was one of the most destructive diseases in human history, and similar to the influenza virus, the Black Death, as well as the current raging coronavirus, our old friend AIDS, and so on..."
"But if it's a healthy person, the bacteria they carry have very limited impact on a similar new environment. In fact, Eurasians reached America before the Age of Discovery, and the bacteria they brought didn't destroy it."
Seeing that Li Yu had no further questions, Hephaestus continued.
"Second, you can't bring anything back from that world, neither physical objects nor photo images, and each time your stay in that world can't exceed seven and a half hours of real-time.
"Of course, you've probably realized that time flows at different rates in different universes. Our seven and a half hours is not the same as seven and a half hours over there..."
"Three to one," Li Yu said.
"What?"
"The time flow rate between the two sides is roughly three to one. I spent almost a day there on my first descent."
"You went to a universe with more time? That's great, it means you have more time to act. Although there is not enough comprehensive research yet to prove why this happens, your watch and phone will still display the real world's time. If you use this to your advantage, you can master the timing of your return."
"Is the return something that happens naturally, or..." Li Yu asked again.
"It happens naturally. In that universe, you're like a guest. Once the visit time is over, you'll be kindly asked to leave by the host."