The mountain path curved like a ribbon through the highlands of Quanta. Mist clung to the air as Luma followed Elder Ion up the ridge, each step harder than the last. Her legs burned. Her breath came in sharp gasps.
"Why does this mountain feel heavier than yesterday?" she muttered.
Elder Ion, walking calmly ahead, only chuckled. "The weight is the same, child. But your body is resisting change. The steeper the path, the more force you need to keep moving."
They paused beside a fallen tree halfway up the slope. Below them, the valley stretched out like a green sea. Wind whispered through the branches.
Elder Ion turned and picked up a small sack from under his robe. "Come," he said, "help me with this."
It was filled with stones—heavy ones.
"Try to throw this down the hill," he said.
Luma staggered slightly under the weight but managed to toss it. The sack rolled slowly at first, then gained speed as it bounced and tumbled down the slope.
"Did you notice something?" Ion asked.
"It started slow, then sped up," she said. "Gravity pulled it, I guess."
"Correct. The force of gravity caused it to accelerate. Now watch this."
He picked up a feather and let it go. It floated gently, drifting side to side.
"That's lighter," Luma said.
"Yes. And because it has less mass, it doesn't need much force to move it. But look closer—it's not just about light or heavy. It's about how much mass something has, and how much force you apply. The more mass, the more force you need to get it moving—or to stop it."
He drew a symbol In the dirt: F = m × a
"This is the Second Law," he said. "Force equals mass times acceleration."
Luma furrowed her brow. "So… if I push something heavy, and I want it to go fast, I need to push really hard?"
"Exactly," Ion said. "And if it's light, a small push will do. The world responds in proportion."
Suddenly, a distant rumble echoed from farther up the mountain. Birds burst from the trees. Luma tensed.
"What was that?"
Ion's eyes narrowed. "An imbalance of forces," he said. "Come. Quickly."
They moved upward, this time at a brisk pace. The air grew colder. The path narrowed, the trees thinner. As they climbed, they came upon a broken cart, wheels shattered, crates scattered.
Luma knelt beside one. It was filled with chunks of black stone.
"Obsidian," she whispered. "But why bring so much up here?"
Ion studied the path ahead. "Somebody is trying to change the natural balance of motion. They are forcing nature to bend."
Luma looked up at him, her mind racing. "Then… if they use too much force, with too much mass—"
"—the acceleration will be unstoppable," Ion finished. "And that is why we must keep moving."
They pressed forward into the unknown, wind rising, and the mountain rumbling once more beneath their feet.