She grows and falls over a lot and maintains her orange coiffure and reads books and is generally precocious. The veganism and the aversion to salt and lipids persist.
Her fifth basketday approaches.
"Yes," says Lynn. "And me, and the chairs, and the walls, and the trees outside. But we're so used to it that it feels like nothing at all."
"Well, it would be bad for you, because the things that make up you are used to pushing back against the air and wouldn't know how to stop. It would also mean that you wouldn't be able to breathe, which would be bad for - obvious reasons. That's why astronauts wear space suits, because there is no air pressure in space."
Astrid has not breathed again - or for that matter passed out - a couple of minutes later.
"If you're curious, by this point in time I would have passed out with so long without air," she informs Astrid. "It's probably different, for you. That's not bad or alarming, it's actually useful to have."
"Swimming. You could stay underwater without coming up for air longer. If you were to take up mountain climbing, you'd do better there, too. More able to withstand the lack of air."
"They do, but they don't have as much. The higher up you go, the less air there is, until eventually you reach space and there's none at all except for what you trap and take with you."
"You can, but I don't think it could withstand the vacuum - that's the term for no air pressure - of space. As you saw, balloons are rather fragile. You would trap it in something sturdier, but the concept is the same."
"The no-air doesn't break the balloon, the helium or air inside it would. Because it can push the balloon completely unchecked. And it's likely to push it to the point where the balloon breaks from the strain."
"Why does the helium in a balloon push just the right amount against the air so it doesn't squish in from the air pushing or break open from the helium pushing?" She gestures at the remaining intact balloons.
"Well, the person who filled it was in charge of just how much helium went into the balloon. And they chose an amount that would result in an inflated balloon, but not a broken one."
"I would be very disappointed in the world if it didn't make sense," agrees Lynn, sagely. "I'm of the opinion that the things that seem like they don't make sense are things that we don't know everything about. So of course they don't make sense, we're missing half of the required information to understand them."
"Like why I look like a human but I can hold my breath and my hair does the thing and stuff."
"Exactly. Humans can hold their breath, too, just not as long as you can. Though maybe you can hold yours indefinitely, I'm not sure."
"It varies, from person to person. Usually it's around one minute, longer if they practice. I think the record for holding one's breath above water is ten minutes or so."