bookmacpro

> Thinking about it reminds me of a quantum mechanics prof who once explained the way a physicist would model a person skiing through the forest. The person would be either a sphere or a box, depending on what's most convenient. The trees in the forest would be cylinders or boxes. The person skiing would then be something like a sphere bouncing around through all these cylinders.

This way of thinking is a bit flawed.

Convenience is an important aspect, but it's not the entire reason. A physicist who wants to study how skiers might cause avalanches by modeling/simulation doesn't care about the details of the people they model because that's just not important. For what they want to study, it doesn't matter if they model the human as a sphere or as a real-life model with limbs and so on. It won't affect the grand picture.

On the other hands, a physicist who wants to study how an avalanche would crush a person? Then yes, modeling the limbs and the person's physical properties become much more important.

In modeling, you choose the model that best fits and represents what you aim to study. You start off with a complex system of equations and then you slowly go through and remove the parts that would be irrelevant. You don't need to account for turbulence if you know that you will never reach the high Reynolds numbers that require it. You don't need to model cellular biology if you're just trying to modeling how a piece of tissue stretches.