So far, in the story about man’s curiosity concerning the fundamental
nature and structure of matter, the development of ideas about
_structure_ has been emphasized. We will now take a brief look at a
development which strongly influenced our ideas about the fundamental
_nature_ of matter.
In 1887 reports appeared on a famous study, often referred to as the
Michelson-Morley experiment, which was aimed at determining the earth’s
speed through absolute space. The entirely unexpected results of the
experiment had a great impact on the concepts of space and time. We will
here concern ourselves with just one outcome of the experiment.
In 1905, a young German-born physics student named Albert Einstein, who
was working as a patent examiner in Switzerland, published three papers,
each of which had a profound effect on a different field of physics.
One of the papers dealt with some peculiar speculations about space and
time which began to interest him when he was studying the
Michelson-Morley experiment. The contents of the paper are now referred
to as the Special Theory of Relativity. This paper contains several
predictions that seemed incredible to the average physicist of that day.
These predictions have, however, long since been proved valid.
[Illustration: _Albert Einstein in 1905._
Courtesy Lotte Jacobi, Hillsboro, New Hampshire]
One of Einstein’s predictions had to do with the equivalence of matter
and energy. Until 1905 _matter_ had been considered as something that
has mass or inertia; _energy_, on the other hand, had been regarded as
the ability to do work. It was believed that the two were as different
from each other as, say, a square yard is different from an hour.
Einstein’s theory, however, implies that matter and energy are merely
two different manifestations of the same fundamental physical reality,
and that each may be converted into the other according to the famous
equation: