Computational Physics and a group of 1000 8th graders

I like computers, really I do. Computational physics is a good thing. However, there is a small problem. The problem is that there seems to be a large number of people out there that treat numerical methods and simulations as something different than theoretical calculations. You can tell who these people are because they refer to simulations as “experiments”. But what do these simulations really do in science? What is science really all about?

**Science**

To me, science is all about models. Making models, testing models, upgrading models. Models. Some examples are the model of gravity. One such model is that there is a gravitational force between any two objects with mass. This force is inversely proportional the square of the distance between them. (This is Newton’s model). Is this model perfect? No. Is this model the truth? No. How did this model come about? Experimental evidence.

**Models**

Well, how do you make models and what form can they take? To make a model, you collect some observations. The model should agree with these observations. This model could be a physical model (like the globe). It could be a mathematical model (like V=IR). It could be a numerical model – like a [vpython](http://vpython.org) program of a baseball trajectory with air resistance. These are all models.

**8th graders**

What does any of this have to do with 8th graders? I claim that any numerical calculation or simulation could be done with a group of 1000 8th graders rather than a computer. What does a computer do? (a computer program really) A program takes a problem and breaks it into a bunch a really small steps. It then does each of these steps and combines them together in some way. Just like a group of 8th graders with TI-89 calculators. Clearly, they are just computing something – they are not a separate type of science (other than theory and experiment).

Hurricane models and the nature of science

Here I am, at my parents house. There is no power at my house and Louisiana in September with no power is really a whole bunch of no-fun. But maybe I can use this time to talk about science.

**The Nature of Science**

Here is a review. What is science all about? (I am pretty sure I talked about this before) Science is about making observations and from those observations creating models. If the model predicts other things that are confirmed, then that is good. If not, the model must be changed. Really, it’s that simple.

**Hurricane Models**

It is somewhat interesting that forecasting hurricanes is quite similar. To do this, they (hurricane people) start with a model of how a storm behaves. In this model they input the current weather conditions and run the model. Not everyone agrees on how a storm would behave given some initial conditions and not everyone agrees on what the initial conditions even are. The result is that there are several models (as shown below):
![hurricane models](http://blog.dotphys.net/wp-content/uploads/2008/09/hurricane-models.jpg)
(from [Weather Underground – a great weather site](http://www.wunderground.com))
Notice that the models do not agree. Everyone knows the models are not perfect, so multiple models are good. If the models are close in agreement, then there is more certainty in the track.

On a somewhat related note, I remember for a previous hurricane a weatherman said the following:
>The models say the hurricane will hit HERE. So, it’s NOT going to do that. It will either hit to the left or the right because the model is never correct.

I still find that quote to be quite funny. This would be the same as a person with a gun that is a bad shot. It is ok to aim at someone because the WILL miss.