Page 48 of The Sunlit Man

“I’m not what you think, Contemplation,” he said. “I’mreallynot. But right now, if it will keep you all moving, then you can call me whatever you storming want.”

The elderly woman smiled. “I’m pleased I got to see you.” She retreated then, leaving him alone with a glowing madwoman. Well, that and his semifunctional conscience.

Do you really think you can do this? the hero asks, dubious but curious.

Nomad settled down at the desk, but continued watching Elegy, who had stopped thrashing and instead devoted herself to glaring at him. “I think,” he said to Auxiliary, “that I don’t have any other options. Fortunately they have the difficult part solved.”

They do?

He opened a blank notebook. “Sure. They have a compact, powerful, renewable energy source. Something most developing societies can only dream about.That’sdifficult. Travel has always been about the power supply. Creating energy—well, releasing it—is easy. Just throw a match into a pile of dried-out wood and you’ll see that. But harnessing it? Making itportable? That’s the problem.”

If it’s so easy,Auxiliary replied as Nomad started writing and sketching,then what happens when they get into those mountains? Why do their engines stop working?

“The engines don’t stop working,” he said. “They keep right on releasing energy, but there’s nothing for them todowith it. Most conventional travel involves one basic principle: equal and opposite reactions. From jet engines to horse-drawn carriages, it’s all about the primary laws of motion.”

And a jet engine needs air to provide thrust?

“Yes,” he said. “It’s more complicated, but in general, a jet engine works by forcing air through a small nozzle. In most cases, it’s superheated air that has passed through a turbine, and the resultingthrustis what moves the ship. Air shooting out the back of the engine.”

So…no more air…no more thrust?

“Exactly,” he said, pointing at the small engine. “I suspect these sides here are air intakes. They draw in a great deal of it, then the sunheart superheats it in this structure here—some kind of compressor—maybe even generatesplasma, which would be wild. Look at this. See these nozzles in here? That’s where the superheated air—and perhaps even some Investiture turned to raw energy—bursts out. That gives us the lift and the fiery glow we see.”

And what about space flight, where there is no air? How do other ships do it?

That was still relatively new. Well, the science was old, depending on which parts of the cosmere you visited. But few had ever experimented with it until the last hundred years or so. Why take all the effort to travel the void of space when there were easier ways to travel between planets?

Trick was, most of those were slow, usually involving months or even years of walking through another dimension. You could fly there too, but could only get out at specific points. Faster methods that could go anywhere were just starting to be explored, but they were proportionally more difficult in their own ways. Either that, or they had some storming terrible side effects. His own experience proved that.

Even so, more and more people in the cosmere inched toward understanding the difficult, but plausible, methods that had been out of reach until scientific practicality matched theoretical dreaming.

“For space flight,” he said to Aux’s question, “you usually bring your own propellant. A rocket engine will often mix a fuel and an oxidizer—but the point is that the mass of those two is ejected from the back of the engine at high speed. Mass and energy expelledout the back makesyougo forward. These sunheart-powered engines don’t carry fuel with them.”

So we do that.

“How much liquid oxygen you got handy?” he asked. “How about kerosene? Rocket fuel is not common stuff, Aux. I doubt we could put anything together in time, and I know of no sources of zephyr aether on this planet. Do you?”

Then…we’re ruined?

“No,” he said, beginning work on a diagram. “They’ve got plenty of one thing: water. It’s pounding on the rooftop right now. Plus they have, as I said, the hard part in hand: supercompact, energy-rich fuel. It can heat things without needing oxygen. So if we get a boiler working and steam jets coming out the bottom…”

Wait. You’re going to power space flight with a steam engine?

“I guess I am,” he said. “Though I’d call it high-atmosphere flight rather than proper space flight. Anyway, you’d be surprised how many modern sources of energy rely on the same principle. The problem with traditional steam engines—well, one of the big ones—has always been the fact that the fuel is outrageously bulky and heavy. Not practical for much beyond a large-scale engine on rails with a lot of towing capacity. I’m telling you, though, this is how all motion works.”

All motion? the knight asks hesitantly. What about when we’d fly together in the past?

Nomad froze. Thathadbeen different. He’d misspoken, of course. Not all motion was due to the factors he’d indicated. There were other kinds, like fundamental laws of attraction. One body to another. Forces that held all matter together, at the level of the axon.

“That was different,” he admitted.

I used to love that,Aux said.Before…

Nomad breathed out heavily, squeezing his eyes shut.

It wasn’t your fault.

“I said yes to Hoid. And I bonded you.”

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