“If you remember one of our first interactions…” Lera said, drawing out a 2x2 square on the blackboard in front of them, “We had typically assessed one’s ability to interact with the Wave through the measures of Wave affinity and capacity, depending on how one's natural talents are, the paths of their development are then suggested.”

“But that's not really the full story...Channelers and Manifesters have far more intricate and complex abilities that stem from their natural abilities.” Wu said, pointing at Lera, “But Casters generally interact with the Wave through more external means than anybody else, and the kinds of abilities are also far more common across people than any of the other groups. Hell, I am a bit of a Caster.”

Lera nodded, spreading open her book of Casts and turning to the page of the Lighting Cast, one of the simpler of Casts as Wu leaned forward, and his big head got in the way to the point that Lera had to lightly push that noggin back.

“At the Academy, I spent a long time breaking my old Casts into smaller segments…” Lera said, “by making more of the Cast segments with specific functions, creation of new Casts became a lot easier for me. But for what's next...we are pushing further, right?”

Wu nodded, and he placed his hand on the very first Cast segment of the lighting Cast, the segment that draws in and pools the Wave.

“I want to know what this is.” He asked.

"You know what this is from before though?" Lera asked.

"I know what it does, but not how and why." Wu smiled, "That's called a black box approach, where you understand how the box interacts with the outside world, but not its inner workings."

Lera nodded, and she concentrated some Wave at the tip of her fingers before she rubbed against the corner of the page, tearing off a semi-transparent cover that was used to seal the page of Casts and revealing a dried-up spiraling pattern of Cast making ink around the Cast segment of interest.

“So…what would you actually do if you plan to activate the Lighting Cast?” Wu continued.

Lera looked away for a moment, and she pressed her finger at the very first node of the Cast segment before sending forth a single injection of the Wave. Immediately, the ink became lit up as the blue light was extracted from Lera’s fingers and injected straight into the spiral. Then, as she maintained her output, the spiraling circle became brighter and brighter.

“A reservoir with singular direction flow?” Wu asked, gesturing for Lera to lift her finger as she did, and the bright blue Wave maintained its form and intensity within the spiral, “Cool!”

“What’s the matter?” Lera asked when Wu leaned on the table and poked the slightly warm Cast segment with his finger.

“The ink. Do you have more of it?”

It turned out Lera had always carried a small pouch of Cast ink on her, and it was a dark brown powder made from a mix of soil and ground-up grass. With some drops of water on Wu’s fingertips, he then drew a pair of lines formed in a T position with two inputs, one on top and one on the left. Then, he drew a circle with regular ink at the right and just have the lines branch out at the very bottom.

“What’s…this?” Lera asked when Wu drew the triangle-shaped gauge that was used at the start of the spiral before finally wiping his hands.

“It’s a circuit diagram.” Wu said, “The most important thing with the spiral Cast segment turned out to be the very start of it…The diode…”

“Right…?” Lera asked, “But what’s the point of this new Cast segment that you drew?”

“To turn the input into the opposite.” Wu said, scratching the back of his head when Lera looked at him funny, “Here, put both fingers at the two inputs, one on the top, and the other on the left.”

Lera nodded and followed through, then Wu pointed at the finger on the left input, “That’s the true input. A signal input, and one where information is conveyed. The one at the top…it’s a power input, and you will keep injecting Wave into it while not doing anything with your left finger.”

Lera did exactly as he said, and the circle started to glow with Wave pooling within it.

“Ok…?” Lera looked at Wu, “So what…I put in Wave, and it glowed?”

“Not quite.” Wu shook his head, “Your signal input finger isn’t doing anything, so what’s really happening is that you are receiving a signal of one, or on, at the output, despite having nothing at the input. Now, try to inject Wave with your finger on the left input.”

Lera looked down as she directed her Wave through both fingers, and the direction of flow of the Wave instantly changed, now moving through the downward branch of the T-shaped channels and escaping at the bottom instead of pooling a the output circle.

“Woah.” Lera opened her mouth, “It turned off when I injected with both hands!”

“Yes!” Wu snapped his finger, “When you send something in the true input, it turns off, and when you don't send anything, it stays on! And all of that is by manipulating how much resistance the diode provides to the flow of the Wave and knowing how this segment behaves!”

“So…what will this accomplish?” Lera lifted her hand off the page, “This is all very cool…but what can we even do with something like this?”

“That is referred to as a NOT gate in computer science.” Wu said, “I had hoped that we can interact with the Wave at a far more fundamental level, but at our current level of technology, it’s not possible, so we just have to treat it like electricity, and work off the principles of computer science…Logic.”

"I am logical, I think."

"Yes yes, but also Logic as a series of...things like the NOT gate, but doing different things."

Lera opened her eyes when Wu hopped on the blackboard and started writing down a list of short words.

“NOT gates, just means that if the true input is on, the output is off, and vice versa.” Wu first said, “What we just made is the simpler of the logic gates. Another example is AND gates, which only turn on if both of the two true input signals are on.”

“What if we need three to turn on?” Lera raised her hand.

“Excellent question, my lovely wife.” Wu said, “We can just stack two of the AND gates.”

“I feel stupid now…”

“That’s how I felt in my second year of university.” Wu smiled, “We also have the OR gate, care to guess what it does?”

“It turns on…if either true inputs are on?”

“Bingo!” Wu kissed her on the forehead as the reward, “And we can make also make the opposites of AND and OR gates, the same way we add in the extra part to the NOT gates. And here we have all of the basic logic gates. All it takes are some ink lines and the diodes which it turned out can just be literal triangles drawn with the Cast making ink.”

“Right…but how are any of these used further?”

“When you stack and organize a large number of these gates together, you are then able to create an array of logic where information can be conveyed and stored in the forms of a series of on's and off's.” Wu said, “For example, remember the bases I talked about before? So long as we have a way of translating information into the formats of on's and off's, we can store them and extract them whenever we want..”

"And how are we supposed to remember what’s what?”

“We need a mapping of information or some way to make that information be presented in a way that’s readable by us. We can start writing it down, that's not too hard.” Wu explained, “But the main strength of this whole system is that the information storage device is now independent of the information that’s stored within it. We can store practically any information from it, and we can also encode any information in a similar way by noting down additional layers of mapping!”

“But for us to use it…we need other Casts connecting to this, right?” Lera asked, “Like a Cast to transmit the Wave a long distance, or to project what we have?”

“Yes! And those things already exist, thanks to the good work of the Casters of the past!” Wu smiled, “All I am changing here is the way information is stored at the lowest, and the most fundamental layer!"

The next few hours consisted of Wu and Lera making tons of logic gates of all sorts, while Lera quickly learned to be the one operating the Cast printer and was able to make the individual logic gates smaller and smaller as she became more skilled. Wu also retrieved one of the fuel rocks and used it as their power supply while putting together the ‘flip flops’.

“Like the disgusting things you wear on your feet?” Lera asked when Wu looked at her and paused before bursting out laughing.

“Will you divorce me if I say I enjoyed those?” Wu joked, “No…they are called that because their state can be flipped with specific inputs, and that information will be stored if nothing’s happening. And when you arrange multiple of these together, you store information!”

“Right…” Lera nodded blandly before continuing with her handy work. The logic gates were already too much for her to learn in one day, so as Wu hummed his little song and continued his electrical engineering lego project, Lera’s just going to focus on what she could already do.

The hours quickly went by, and the digging projects done by the three travelers were partially complete, where small stations were set up, and they returned only to see a large map of logic gates being connected in intricate ways and Lera passing out on the ground with froths in her mouth while Wu was stuck in the zone of checking the connections of the circuits.

“What’s going on here?” Tonya asked when Ver poked Lera in the cheeks as her head rolled to the side.

“I was explaining to her the fundamentals of computer science.” Wu said excitedly, “The arguably greatest invention that humans had ever done. Complete and full abstraction of the physical world.”

Augen, in the meanwhile, stood at the side of the puzzle pieces and started probing into the flow of the Wave as the countless number of circuits and switches also started to crowd his mind before he had to take a step back and a breather.

“I just hope this isn’t just some cool-looking puzzle.” Ver said, picking up Lera by the waist and heading out, “We are going to eat dinner now! Hurry up!”

“One sec!” Wu waved them off before he continued his debugging project and finally took a step back to fully check every step of the process.

Then, he went to the very beginning where the input is supposed to be, and he inputted a series of on's and off’s.

As far as computers go, this monstrosity in front of him isn’t capable of anything apart from the most basic of information storage and extraction, and he quickly realized that due to the size limitations of the ‘Wave transistors’ that they could make, it’s not only unlikely but also unwise for them to use the transistors to achieve all of the higher level computational functions.

He very much enjoyed the dive back into computer science as much as the next nerd in line to save the world, but he’s also smart and flexible enough to realize their limitations, being a classically trained engineer.

As the corresponding bits of glowing Wave showed up all along the circuits even as Wu let go of the inputs, he rushed to the output end where the same signals were shown and held there.

“This is the very beginning…” Wu murmured, “The start of it all…No more hard coding from here…”

He ended up writing down and attaching the mapping of the bits of information to basic characters overnight and missing the dinner.

When Lera walked out with a bowl full of stews with some roasted breadsticks floating above it, she saw Wu sleeping by the table with small scribbles of glowing text floating at the output end.

‘LOVE YOU’

Lera turned and looked at the series of switches at the input and smiled. Then, she picked up Wu with her strengthening Cast and carried him back to their bedroom.