Theory
[Chapter 1 Objectives]
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"Theories are schemes of thought with assumptions
chosen to fit experimental knowledge, containing the speculative
ideas and general treatment that make them grand conceptual
schemes." E. M. Rogers, Physics for the Inquiring
Mind (Princeton University Press, Princeton, NJ, 1966).
"Once we grant that any physical theory is essentially only a model for the world of experience, we must renounce all hope of finding anything like the correct theory ... simply because the totality of experience is never accessible to us." Hugh Everett III (originator of the "many worlds" interpretation of quantum mechanics), quoted from the conclusion of his doctoral dissertation in Scientific American, December 2007, p. 105. Emphasis in the original.
A Scientific Theory
According to the text, a
scientific theory is:
"... a synthesis of a large body of information that
encompasses well-tested and verified hypotheses about certain
aspects of the natural world." (p. 3)
Huh?
Suppose that, in thinking about the behavior of gases, it occurs
to you that all of the facts and laws
about the pressure, volume, and temperature of a gas could be
explained if gases were made of very tiny, independent particles
moving about at high speeds. This is an interesting hypothesis
which produces several experimental tests. Suppose that the
predictions of this hypothesis all seem to indicate that the
hypothesis is correct. Scientists begin to call your hypothesis a
theory.
Characteristics of Scientific Theories
"Theory" is probably the most misused and ambiguous word in
science - misused and ambiguous in its use by scientists as well as
nonscientists! Some characteristics of a theory are:
- A physical theory is explanatory. A theory attempts to explain
why nature behaves as it does. Theories are sometimes called
"models" for this reason. Boyle's Law describes how nature
behaves, while the Kinetic Theory of Gases explains why nature
behaves that way. Unfortunately, this is not a "hard and fast"
distinction - Quantum Theory, one of the most powerful and
successful theories of physics, is not explanatory, it is
descriptive. Quantum Theory does not provide a
"model" of how the atom works!
- A physical theory is well tested. When someone says "I have a
theory..." or "...but that's only a theory..." they are almost
certainly confusing a theory with a hypothesis. Scientific
theories are generally supported by a considerable body of
evidence. Unfortunately, the word "theory" is often nowadays
attached to things that have not been thoroughly tested - that are
more properly classified as hypotheses. Such powerful ideas as
"String Theory" and "Supersymmetry Theory" are called theories
anyway - even though it may not be possible to test them, at least
in the foreseeable future.
- A physical theory is mathematical in nature. For instance,
starting with some basic hypotheses (or axioms), such as "gases
are made of tiny, independent particles," one can derive, in a
purely deductive way, Boyle's Law as well as the Ideal Gas Law.
(Science isn't purely inductive, after all...)
Practice quiz on laws and theories:
[Chapter 1
Objectives]
BHS
-> Mr. Stanbrough -> Physics
-> About Science ->
this page
last update August 31, 2009 by
JL Stanbrough