Chapter 5: The Furnace That Wouldn't Hold

The morning light in the Heavenly Domain had a texture Liu Yang didn't trust.

It poured through the windows of his workshop like honey — thick, golden, and wrong. Back on Earth, light scattered. Particles hit the atmosphere, bounced around, filled a room evenly. Here, it pooled. It settled in corners like sediment. The physics of it made his teeth ache.

He'd been awake for three days.

The Immortal Smith, a man named Feng Bo who looked seventy but claimed to be twelve thousand years old, had delivered the furnace specifications on scrolls that smelled of sulfur and regret. The drawings were beautiful. Ink brush strokes danced across rice paper, showing a cauldron of impossible elegance, its surface etched with qi-conduction arrays that curved like living vines.

The structural engineering was a disaster.

"This support beam," Liu Yang said, tapping the scroll with his pen. "It's decorative. It does nothing."

Feng Bo's beard twitched. "It channels celestial fire through the heartstone."

"The heartstone's here." Liu Yang drew a circle on the paper. "The beam terminates three hand-widths away. The fire has to jump across a gap that weakens the thermal transfer by—" he did the math in his head, "—roughly forty-seven percent."

"Forty-seven percent?"

"Give or take." Liu Yang pulled out his calculator. The plastic casing had started to warp from exposure to ambient qi. He'd need to reinforce it soon. "And the base plate is too thin. The pressure differential between the molten qi-steel and the cooling chamber will crack it within a hundred cycles. Maybe fifty."

Feng Bo stared at him.

Then he laughed.

"Young man," the smith said, wiping a tear from his eye. "I have forged the weapons of three Celestial Wars. I have tempered blades that cut through fate itself. Do you think I do not understand my own furnace?"

"I think," Liu Yang said, "that you understand fire and metal and qi. I think you don't understand stress tolerances and thermal expansion coefficients. Those are different things."

The laughter stopped.

The silence that followed had weight. It pressed against Liu Yang's ears, made his skin prickle. Feng Bo's eyes narrowed, and for a moment, Liu Yang saw something ancient and dangerous looking out through those wrinkled lids.

But then the old man sighed.

"Show me."

---

They rebuilt the furnace together.

Liu Yang drew up new specifications on graph paper he'd managed to synthesize from cloud fiber and ink berries. The equations were the same ones he'd used on Earth — basic thermodynamics, material science, stress analysis. The numbers just meant different things now. Tensile strength in qi-units instead of megapascals. Thermal conductivity measured in spirit-flow rather than watts per meter-kelvin.

The principles held.

Feng Bo watched over his shoulder, grunting occasionally. He didn't ask questions. Just watched. When Liu Yang finished the calculations for the support beam relocation, the old smith picked up his hammer and started breaking down the existing furnace.

"My ancestors built this design," Feng Bo said, hammer ringing against stone. "For twelve thousand years, we have passed it down. Father to son. Master to apprentice. No one questioned it."

"Maybe you should have."

Feng Bo stopped. Turned. His face was unreadable.

"Maybe you're right."

They worked for three days. The other immortals came to watch. Word had spread — the mortal engineer was rebuilding the Grand Furnace. They stood in the doorway of the forge, their robes rustling, their ancient eyes tracking Liu Yang's every move.

He ignored them.

On the second day, a problem emerged.

The qi-conduction arrays were etched into the furnace walls in a spiral pattern. Beautiful. Elegant. Completely inefficient for uniform heat distribution. Liu Yang redrew them as a grid system, each node connected by parallel channels that would distribute thermal load evenly.

Feng Bo looked at the new pattern.

"This is ugly."

"It works."

"It's a grid."

"Yes."

Feng Bo picked up his etching tool. He carved the first line into the furnace wall. The immortals in the doorway gasped.

Liu Yang didn't gasp. He just checked his measurements and told Feng Bo to deepen the channels by half a finger-width.

On the third day, they tested it.

Feng Bo fed the furnace with heartstone — chunks of crystallized celestial fire that pulsed with trapped starlight. Liu Yang had measured their energy density at roughly the equivalent of a small nuclear reactor. Per stone.

The furnace hummed.

Heat built. The temperature rose evenly across the chamber, the grid pattern distributing thermal energy exactly as the calculations predicted. Feng Bo's face went through a journey — skepticism to surprise to something that looked almost like joy.

"It's holding," he whispered.

"It's supposed to."

Feng Bo threw in more heartstone. The furnace roared. Steam vented from the pressure-release valves Liu Yang had added, pipes that bled off excess qi like safety vents on an industrial boiler. The temperature hit optimal forging range and stayed there. Rock steady. Perfect.

"We can start the first batch," Liu Yang said.

He reached for the control panel he'd built — a series of levers and dials that regulated qi flow, temperature, pressure. Simple analog systems. Nothing that could fail if the power fluctuated.

His hand stopped.

Something was wrong.

The numbers on his gauges were drifting. Not much. A degree here, a half-degree there. Within normal variance. But the pattern was wrong. They weren't fluctuating randomly. They were oscillating. A sine wave moving through the system, growing wider with each cycle.

"Shut it down," Liu Yang said.

"What?"

"The furnace. Shut it down. Now."

Feng Bo grabbed the main lever and pulled. It didn't move. The heat had warped the mechanism, swelling the metal in its housing. Liu Yang threw himself at the emergency release — a valve he'd designed specifically for this failure mode — and cranked it open.

Steam exploded from the vents.

The furnace screamed.

It was a sound Liu Yang had heard before. On a bridge in Henan province, three years ago, when a support cable had snapped and the whole structure had started to sing. A warning frequency. Metal telling you it was about to die.

He grabbed Feng Bo's arm.

"Run."

They made it to the doorway. The furnace didn't explode — it ruptured. A split appeared in the side wall, exactly where the old support beam had been. The original design's flaw, the gap Liu Yang had identified but not fully corrected. The thermal stress had found the weak point.

The split widened.

Qi-steel slag poured out, molten and white-hot, eating through the stone floor. The furnace walls buckled. The roof sagged.

And then, just as suddenly, it stopped.

The slag solidified. The furnace went dark. The immortals in the doorway stared at the wreckage, their faces blank with shock.

Liu Yang's hands were shaking.

He looked at the ruined furnace. At the calculations still pinned to his workbench. At the smoke rising from a structure he'd designed, built, and watched fail.

Twelve thousand years of tradition.

Three days of his math.

He'd missed something.

"Liu Yang."

Feng Bo's voice was quiet. Not angry. Something worse than angry.

"You said the design was fixed."

"I thought it was."

"You thought."

The old smith turned away. His shoulders were set, rigid. When he spoke again, his voice carried to every immortal in the forge.

"The mortal has broken the Grand Furnace. Three thousand heartstone ingots, melted into slag. A structure that has served the Heavenly Domain since before the First Emperor ruled the mortal realm."

He faced Liu Yang.

"Destroyed."

Liu Yang opened his mouth to explain. To talk about thermal oscillation, about the sine wave pattern, about the flaw he'd missed but could still fix.

He never got the chance.

The doors of the forge slammed open. A figure stood in the entrance — tall, armored, radiating authority like heat from a fire. The Celestial Inspector. The woman who had first summoned him to the Heavenly Domain.

Her face was stone.

"Liu Yang of Earth. By order of the Jade Emperor, you are charged with sabotage against the Heavenly Domain. The punishment is dissolution."

She raised her hand.

And the world went white.