Why is the sky blue?

I'm fortunate in that my daughter is not yet old enough to ask me any tough questions. The most complex interaction we have goes a little something like this:

Melly: "What's this?"

Me: "A butterfly."

Melly: "OH!"

Yes, I am the All Knowing All Powerful Mama.

My husband, however, is (unintentionally?) training me for the more complicated questions she might ask someday. He seems to go under the assumption that I know everything about the physiology of every animal. Some questions he's asked me recently:

"How long does a mouse live?"

"Where does lymph come from?"

"Would you still create poop if you didn't eat any food?"

(Yes, you read that right. My husband asked me this.)

He also has some very pointed questions about being a doctor, including:

"Why do you have to work 30 hours in a row?"

"Aren't you too tired to take care of patients after being up all night?"

"Why don't they just hire more residents and then you wouldn't have to work as many hours, right?"

Recently, he came across an article about how some huge percentage of doctors are unhappy with their careers and regret having gone to med school.

Husband: "If they regret it, why don't they just quit?"

Me: "It's not that simple."

Husband: "Why not?"

Me: "Well, the average med school tuition is more than $30,000 per year. With housing and other costs, you can end up borrowing at least $50,000 per year. So at the end of med school, when you're nearly a quarter of a million dollars in debt, you can't just quit right before your salary goes up. You're forced to continue, even if you're unhappy. You're locked in."

Husband: "My god, do people know about this?? You have to tell them!!"

Me: "I think they know."

Man, I am so much better at fielding questions about butterflies.