Observing Earth through a Scientific Lens - Geology - page 19

It's never “just a theory”
Most people use the word theory to refer to an educated guess — a hypothesis. But sci-
entifically speaking, a theory explains how some complex process works in the natural
world. For example, the theory of plate tectonics that I cover in detail in Chapter 10 ex-
plains how crustal plates on the earth move around, forming mountains and volcanoes
and causing earthquakes. The theory explains how all those geologic processes and res-
ulting features are related to one another through the movement of crustal plates.
A theory does not, however, explain why something occurs. The theory of
plate tectonics does not answer the question of why the surface of the earth is
broken into plates that move around. It only describes how.
When a scientist describes something as a theory, she has come to the end of a long
series of experiments and hypothesis testing. She is able to explain something so well
(and to have that something accepted by other scientists as true) that it can be called a
theory.
In other words, a theory is a hypothesis that has been thoroughly tested
through multiple experiments and is accepted as true by the scientific community.
Scientific theory versus scientific law
Scientific theories are not waiting to blossom someday into scientific laws. Laws and
theories in science are two very different things.
A scientific law describes an observed action that, when repeated many times, is
always the same. For example the law of gravity states that two objects will move
toward one another. This movement is observed every time you drop something.
The object you drop is attracted to the earth. The law of gravity simply describes
this action, which is demonstrated to be the same in every test.
A scientific theory explains how a set of observations are related. For example,
the theory of gravity seeks to explain how the relationship of two objects (their rel-