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12 October 2001
A Pure Point-of-View
by George E. Hrabovsky, President of MAST
News from MAST
Hello all, it looks like the final supplies I need to begin the microbiology experiments will be arriving today or tomorrow. I should have some initial results in a week or two. I look forward to sharing them with all of you.
I look back over the last few weeks and I see that only one of the last nine columns have really been about science! I can talk (and hence write) about mathematical concepts and methods till we are all blue in the face. Indeed, mathematics is a vital part of all of science. I thought that I would talk about a little physics this time.
What is a Particle?
We have all heard about particles. There are electrons, protons, etc. The real mystery comes about when we think about where the idea of a particle comes from. In short, "What is a particle?"
As is so often the case when dealing with total generalizations, it is useful to think about a specific example. This, not to put too fine a point on it, is the basis of all theoretical work. Let us say you want to study the motion of a complicated object, a car for example. Think about the motion of a car...
There are the components of the engine, the wheels, people inside the car, the fluid moving through different systems in the car, the car itself moving on the road and creating turbulence in the air as it passes. This is very complicated.
Imagine that you can zoom out so that you can avoid some of this complexity. You no longer see the internal workings of the car, indeed you may not even be able to see the motion of the passengers or the wheels. You have the same vehicle, but it is a simpler picture.
Imagine that you zoom out further. Now all you see is a speck in the distance. This speck still has all of the properties of the car we started with. All of the internal systems are still there. We just don't need to worry about them.
Now we have tomake a leap of faith. We have to have some reason to believe that we can treat an object as if we were zooming out. We have to have some reason to treat it as a speck. But what is that reason?
Think about what we are losing by treating the object as a speck. The first thing we lose is all of the internal complexities of the object. The second thing is the shape of the object. Whenever we have an object where we do not need to worry about its shape or its internal workings we can look at it as if it were a speck. Such a simplified object is called a particle. Indeed, what we normally think of as particles (electrons and the like) are not really particles at all, they are bundles of waves that are neither particles nor waves in their entirety, but something that look alarmingly like either one depending upon what we are looking for, but this is the subject for another column...
What we are doing is generalizing the motion of the car so that we can make it simpler. The technical term for such a generalization is abstraction. We abstract (take from) the specific example those parts that are common to all similar problems. Since we are looking at motion,we look to see what the car has in common with a leaf falling from a tree, a ball thrown thorugh the air, a boat on a river, etc.
The highest level of abstraction for an object of any kind is to treat it as a particle.
The drawback is that by removing the complexities you also remove reality. So what is the point of the abstraction? It makes the problem simple enough to start. Once you understand that level of the problem, you can begin to put the complexity back into your model.
This is the heart of theoretical science.
Books That I Like
There really aren't too many books that cover this material in any meaningful way.
Converted by Mathematica October 11, 2001
