Redefining Reality - The Intellectual Implications of Modern Science

In 1873, James Clerk Maxwell published a paper called “Molecules,”
in which he derived the ideal gas law from a mechanical picture of
gases—a picture in which a gas is a collection of atoms. It would
have been a massive coincidence if the law accidentally fell out
of the atomic picture. Everything in the results is macroscopically
measurable except one thing—the number of molecules. The
anti-atomistic chemists would have to say that it was a lucky but
meaningless occurrence that assuming atoms generates a world that
behaves exactly like this one.
From Avogadro’s work, it follows that the number of molecules in
or .
To determine Avogadro’s number would be to make a statement
about the reality of atoms. Such physicists as Albert Einstein
and Jean Perrin became serial derivers of Avogadro’s number
and found it everywhere—in the study of gases, liquids, alpha
particles, cathode rays, and so on.
Einstein proposed a way to experimentally determine
to do. Perrin took up the challenge and, through painstakingly
delicate work, determined Avogadro’s number and showed it
to be a constant across many different situations. Perrin’s work
In 1897, the British physicist J. J. Thomson discovered that the
cathode rays physicists had been investigating were actually
negatively charged particles, what we now know as electrons.
Scientists eventually realized that these were pieces of atoms that
were capable of being stripped out. Atoms had parts and structure.
Because atoms were electrically neutral and electrons were
negative, there had to be a positive part of the atom to balance out
the electrons. But there didn’t seem to be a positive correlate to the
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