"Wheelchairs are easy enough to get for you, then," he says, smiling.

"Great."

He gets the phone and requisitions a wheelchair, and after a couple of minutes someone knocks at the door with it.

And when they've stood back enough she gets into it and rolls a bit experimentally.

It rolls very smoothly! And is actually pretty comfortable.

"This is great. How will people know to stay far enough back, can you handle that -?"

"I probably can but—can you keep that fire circle without much trouble? They might just ignore me, or the sidewalk might be too densely packed with people."

"Yeah, I can do that - it won't freak people out?"

"A little bit at first but when you're just okay and followed by me they'll be fine."

"Okay." The ring flares into place.

And then they can go down the elevator and out, walk down the large bridge connecting the forcefielded HQ to the Boardwalk, and onto the actual Boardwalk! People gawk.

Kiri looks around, keeping her heat sense attuned to anyone getting too close to her fire ring apart from her helper, who can be within the ring.

"I don't suppose you have steam engines yet?"

"No."

"So, when you heat water up it becomes vapor and expands, right? So the principle behind that is that you heat a lot of water, usually with coal, to make it expand a lot and push into a piston which is connected to something else that's connected to yet another thing, and so on so forth, to create machines that move without having to be pulled by horses or people or anything like that. These vehicles," he says, pointing at a car, "work by a similar principle except it involves explosive fuels instead of water."

"Gosh. I can sort of feel some of it in motion but couldn't have figured out how it worked just from that."

"I don't remember, were you able to feel electricity inside the computer or the lamps or the phone? The cars should have some, too."

"No, not really, just temperature."

He nods. "So, electricity is—wait, I didn't ask, do you have the atomic model? Uh, like, the model of what matter is made of?"

"No, we don't have that."

"Alright, so electricity is—sort of like stored lightning. That's a bit simplified, really—all matter is made of very very small things, and some of those small things have positive charge and are many many times bigger than the even smaller things that have negative charge. The small things with negative charge are electrons, and the slightly less small things with positive charge are protons, and there are neutrons, which have no charge, and are the same size as protons. Electrons fly around a nucleus made of protons and neutrons, but they never hit the protons—I'm not sure why, I'm not a physicist—and all matter is composed of trillions upon trillions of those tiny things in different quantities. A single group of electrons and protons and neutrons is called an atom.

"So, lightning, like electricity, happens when the electrons stop just roaming around the atom's nucleus and go in a direction. And when they do that they generate energy that can be used to do bunches of things. Make sense so far?"

"Only because you're in range, but sure."

"That's helpful! So electricity was sort of an insight that really changed everything. If a lot of it goes through wire really fast, the wire gets very hot and starts emitting light, so we made electrical lamps. And we learned how to make lots of other things out of electricity, including sending data through long distances—a burst of electricity is a one, a space without electricity is a zero, and you can send lots of zeros and ones in sequence if they all last the same time and transmit information that way. That's how the computer and telephones and lots of things in cars work."

"That's cool!"

"It is! I think most recent technological advancements have involved electricity in one way or another, but since your world's approximate tech level there were other things that were very useful, like some materials science or the production line."