* Any physical theory is always provisional and may not account for
single measurement outcomes in a deterministic way *


According to Stephen Hawking in A Brief History of Time, "a theory is
a good theory if it satisfies two requirements: It must accurately
describe a large class of observations on the basis of a model that
contains only a few arbitrary elements, and it must make definite
predictions about the results of future observations." He goes on to
state, "any physical theory is always provisional, in the sense that
it is only a hypothesis; you can never prove it. No matter how many
times the results of experiments agree with some theory, you can never
be sure that the next time the result will not contradict the theory.
On the other hand, you can disprove a theory by finding even a single
repeatable observation that disagrees with the predictions of the
theory."

An example of how theories are models can be seen from theories on the
planetary system. The Greeks formulated theories that were recorded by
the astronomer Ptolemy. In Ptolemy's planetary model, the earth was at
the center, the planets and the sun made circular orbits around the
earth, and the stars were on a sphere outside of the orbits of the
planet and the earth. Retrograde motion of the planets was explained
by smaller circular orbits of individual planets. This could be
illustrated as a model, and could even be built into a literal model.
Mathematical calculations could be made that predicted, to a great
degree of accuracy, where the planets would be. His model of the
planetary system survived for over 1500 years until the time of
Copernicus. So one can see that a theory is a model of reality, one
that explains certain scientific facts; yet the theory may not be a
true picture of reality. Another, more accurate, theory can later
replace the previous model. (1)

Sahotra Sarkar was asked: "Can evolution be proved or only supported
by circumstantial evidence?" He replied by pointing out that a
scientific theory is always based on circumstantial evidence, but
there are aspects of evolution that are observable facts. Thus, some
aspects are proved and other aspects are not provable. In general, we
can reconstruct evolutionary history in the same way we reconstruct
any other type of history; we can never be 100% certain but we can
have a high degree of confidence in our findings. (2)

The Big Bang theory is just a theory. Couldn't it be wrong? Yes, it
could be wrong. In science, no theory is ever absolutely proved true.
Some theories, however, are stronger and better supported than others.
This depends on many factors, including how well the theory explains
observed facts, whether the theory has made successful predictions
later borne out by observation, how long the theory has been around,
and whether there are alternate theories that do almost as well. The
Big Bang theory is one of the most strongly supported theories in all
of science. It explains the observed facts; it has made successful
predictions; it has stood the test of time; and there is no alternate
theory that the professional scientific community deems valid. (3)

During the last century, quantum theory has proved to be a successful
theory, which describes the physical reality of the mesoscopic and
microscopic world. Up to now, no method is known which contradicts the
predictions made by quantum theory. This is remarkable, since
measurement accuracy has increased, and the size of the systems under
consideration has decreased at a fast pace. Quantum mechanics was
developed with the aim to describe atoms and to explain the observed
spectral lines in a measurement apparatus. During the development of
quantum mechanics the fact that quantum theory allows for an accurate
description of reality is obvious from many physical experiments, and
has probably never been seriously disputed. Quantum theory and quantum
mechanics do not account for single measurement outcomes in a
deterministic way. (4)

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1. en.wikipedia.org/wiki/Theory
2. www.atheist-community.org/library/articles/read.php?id=718
3. map.gsfc.nasa.gov/m_help/h_faq.html
4. en.wikipedia.org/wiki/EPR_paradox


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