Assume a Spherical Cow

Well, it's taken a while, but I've finally decided on an avatar. "What is it?" you ask? Read the damn title or look over at it! If it doesn't make sense, maybe the following joke I heard a while ago will help:

One day, a farmer's sole cow stops giving milk. He calls in a biologist, chemist, and physicist to see if they can solve the problem.

The biologist first looks and the cow, and after some consideration declares, "It must be the cells!" The farmer is completely dissatisfied with this answer, so he asks the chemist his opinion.

Next, the chemist takes a look at the cow, and after thinking for a while exclaims, "No, the problem is that the cow has an imbalance of biochemicals!"

"Well, how do we fix it?" the farmer asks.

"Beats me. That part's up to the pharmacists," the chemist replies.

Finally, the physicist takes a look at the cow, and after careful contemplation says, "I think I have a solution. There's just one little problem."

Exasperated, the farmer asks, "What's the problem?"

"It only works for spherical cows in a vacuum."