I had been drinking. And thinking, and remembering Einstein once said no scientific theory was any good unless you could explain it to a barmaid. Well, Albert, good luck with special relativity on a napkin, but Milankovitch?
A barmaid brought me another glass and it was slow and she was bored. “What do you know about Milankovitch?” I queried.
“The guy who proposed that the earth’s wobble caused the ice ages,” I suggested.
“Burrr.” She looked around as to see if someone had left a door open, but it was really, really slow.
“Ok, so tell me about this Milanko guy,” she grudgingly offered.
I drew eccentricity on my napkin.
“The earth’s orbit around the sun changes from this to that every hundred thousand years.”
“Reelee, do you ever have any fun?”
“Of course,” I parried, “but this is really important and Einstein said if it was any good I should be able to explain it to you.”
I drew the variation in obliquity.
“Why is the earth tipped?”
“Because it rotates around the sun leaning like the guys leaving here at closing time. And it wobbles like them too.”
“Ahguuh, you’re crazy.”
“You’re crazy and you’re a nerd!”
“Or you could think of it as summer arriving 19 days early and leaving 19 days later.”
Now I was faced with explaining precession. Napkin would be no help. It’s not like I was going to say, “The earth’s spin has phase relative to its orbit around the sun so that sometimes winter and other times summer is closest to the sun.”
The clock read 3:42 PM and the first regular walked in. The barmaid was visibly relieved. I knew that I had failed to explain it and those Milankovitch theories were no good.