"I heard something about verifying that objects fall at the same speeds?"

"Yeah, they do. Okay, so we need two or more objects of different weight and roughly equal air resistance, and somewhere good to drop them. Finding a patch of roof shouldn't be hard."

"Somebody tried this once in my world and now there's a patch of desert or something somewhere that no longer has a down," volunteers Milan.

"Well, when we do it it's not going to have any effect whatsoever on down, but if it did I wonder if the patch would stick to Genosha or to the random bit of ocean we're over."

"You know, Atennesi was wondering the same thing."

"Great minds think alike, if I may so flatter myself."

Giggle.

She collects a pen and a couple of different sizes of rock from the garden and then she looks at Milan. "D'you mind if I fly us both onto the roof?"

"Go for it."

And once they are on the roof Odette hands him a pair of objects to confirm that they totally weigh different amounts.

Yep, those sure are differently weighted objects.

And she drops them from the same height at the same time and they hit the ground at the same moment.

Milan applauds.

She repeats this with all the other objects. They all hit the ground at the same time as their partner.

"And nothing is exploding and down still functions correctly!"

"The city's moving fast enough that I guess if the spots of malfunctioning down were anchored to the ocean instead we might be moving away from them too fast to notice, but that seems like the kind of loophole your world would object to."

"Yeah, you're getting the idea."

"Of course, having spots of no down anchored to a flying city might not be the worst thing in the world. I expect something nastier than that would happen, probably."

"Probably the city would fall out of the sky."

"Because I was dropping shit. Nnnnot impressed by your universe's sense of proportion."

"Oh, it wouldn't knock down the city until you'd been dropping things for longer than this. Not that that excuses it."

"I'm probably going to be on-and-off annoyed every now and then about how long it's going to take us to get powerful enough to fix it until we're there."

"I don't blame you. But I think I'll take a more optimistic attitude, myself."

"Oh, I'm fully confident we'll do it. It's just one of those things that bothers me, like the thing with my grandparents."

"Mm, maybe 'optimistic' isn't the word I wanted then."