Then he will detach a corded wand from the backpack and line it up with various parts of her body and cause it to make sharp clicking noises!  The other one returns pretty early in the process, holding some sort of glass sculpture that Rubelite can't get a good look at from the floor.

"...Huh.  Yeah you've got some stuff in there, at least."

"This is not hollow." She continues to lie there.

"Some stuff that I wouldn't expect in a normal human," he amends.

"I'm not a human."

"And this is evidence of that, so we're more likely to believe you even though in the overwhelming majority of cases when someone says that you shouldn't believe them!"

"Humans are the only people with bodies known to our society!  And the part of you we can see looks like one."

"I know!"

"Was there something confusing about what he last said?"

"No."

"Okay!  I have here a representation of part of our universe and I hope it will make it easier for us to understand differences between where you come from and where we are now."  He angles the sculpture so she can see; the main piece is not unlike a large test tube, but hung upside down and with artful wobbles at the bottom instead of a rim.  The glass is clear but the inside is varnished with a glittery and mostly-transparant dark blue.  It's mostly hollow inside, but a core of opaque material is suspended in the middle, swirling brown and gray with occasional pockmarks.

"So we're up here on the flat part," he points, tipping the piece fully over and holding the inside so it doesn't clink against the outer shell, "and here's the sun and the moon and Polaris - and all of this," he tries to gesture at the spot between the core and the outside, "has air in it, and we think it all might go down infinitely.  And from things you've said I have the impression that you travel through vacuum and between celestial bodies and aren't from farther down than we've been able to measure, so I think you're from a different universe, but on the information I have I'm not able to imagine very well what things look like there."

"I think it might be harder to draw than a self portrait."

"Can you try to explain verbally?"

"I can! The universe I am from and most of me is hopefully still in is principally vacuum. Stars vary more than an order of magnitude in size but are typically nonillions of kilograms in mass and average about five light years from their nearest neighbor. A light year is the distance light can travel in one year at its conventional speed of 299,792,458 meters per second. Many stars are orbited in elliptical patterns by some number of planets, asteroids, comets, and other items, these being various terms for various kinds and sizes of rock. Some planets are suitable for human life, or alien life, though many are not. Traveling between them requires vessels with propulsion systems adequate to escape planetary gravitational pull, with gravity being a force affecting all matter with all other matter in proportion to the product of their masses and inverse proportion to the square of the distance between them. Such vessels may or may not also be capable of traveling faster than light, which is a necessity in human polities that span multiple star systems."

This temporarily renders them both speechless.

"Do stars still merge up in your universe?  Not necessarily the physical parts, but - are they each individually involved with running their own set of planets, are the physical stars even dead people in the first place, do people - merge immediately with the rest of themselves after death but otherwise stay separate??  Or what?"

"I don't understand the question. Can you explain your universe the same way in case that helps?"

"I don't have numbers handy and even if I did I'm not familiar with most of your units, but, stars are dead people, here, or at least a new one appears every time a person dies, and although I can't be sure it sounded like yours are much much bigger and farther apart than ours.  So the thing where, here, dead people fuse into each other more and more over time seems - potentially logistically complicated, in your universe?  Even though physical stars and dead-people stars aren't necessarily tied together."

"Stars are not, predate, and have no partial relationship whatsoever to, people in my universe."

"...Huh."

"What are your dead people, then?"

"If they are anything it is not a thing that makes contact with consensus reality."

"Wow."

"What's 'alien' life?"

"Life originating from a biome other than the one of the planet where humans originated. Multiple planets have native ecosystems and several have given rise to people and civilizations."