Scientific Models
Many scientists use models to understand and explain ideas. Models are representations
of objects or systems. Simpler than the real life system, models may be manipulated and
adjusted far more easily. Models can help scientists to understand, analyze and make pre-
dictions about systems that would be impossible without them.
Models are extremely useful but they have many limitations. Simple models often look at
only a single characteristic and not at the myriad conditions other aspects of a system. Since
the scientists who construct a model often do not entirely understand the system they are
modeling, the model may not accurately represent reality. Models are very difficult to test.
One way to test a model is to use as its starting point a time in the past and then have the
model predict the present. A model that can successfully predict the present is more likely
to be accurate when predicting the future.
Many models are created on computers because only computers can handle and manipulate
such enormous amounts of data. For example, climate models are very useful for trying
to determine what types of changes we can expect as the composition of the atmosphere
changes. A reasonably accurate climate model would be impossible on anything other than
the most powerful computers.
There are three types of models and each type is useful in certain ways.
Physical Models
Physical models are physical representations of whatever subject is being studied. These
models may be simplified by leaving out certain real components, but will contain the im-
portant elements. Model cars and toy dinosaurs are examples of physical models. Drawings
and maps are also physical models. They allow us to see and feel and move them, so that
we can compare them to one another and illustrate certain features.
We can use a drawing to model the layers of the Earth (Figure8.13). This type of model
is useful in understanding the composition of the Earth, the relative temperatures within
the Earth, and the changing densities of the Earth beneath the surface. Yet there are many
differences between a cut-away model of the Earth and the real thing. First of all, the size
is much different. It is difficult to understand the size of the Earth by looking at a simple
drawing. You can’t get a good idea of the movement of substances beneath the surface by
looking at a drawing that does not move. The model is very useful but has its shortcomings.
Conceptual Models
A conceptual model is not a physical model, but rather a mental explanation that ties
together many ideas to attempt to explain something. A conceptual model tries to combine