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> 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 wou
by bookmacpro 8y ago
> 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.
- macawfish 8y agoAll great points. But yeah it was a joke! And basically I remember his joke having a tangential quip about choosing the shape based on the coordinate system you wanted to stay in. And the point I got from it was that in modeling we often use crass approximations that are oversimplified in order to get a rough picture of what's going on with respect to certain dynamics, and that one shouldn't assume that the model resembles the full complexities of real life. By the way, he was a cosmologist, if that helps you understand a little better why he was so flippant with the shapes.
- deleted 8y ago[deleted]
- FakeComments 8y ago> 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. The exact claim is that such modeling, eg, fails to find avalanche dangers that truly exist in the world of skiers moving their body on physical skies, due to their shifting and localized weight, which is missing in the spherical skier model. Your post does nothing to address this. The simplifications you call out are all cases of decreased accuracy in exchange for easier computations: that is, for less accurate results that are “good enough”. But the intersection of many such simplified models may fail to accurately model reality.