Redefining Reality - The Intellectual Implications of Modern Science

eams, we also knew that there were particles called protons.
But when we added up the masses of the protons and electrons,
the atom was heavier than the result. There was something else
heavy inside the atom.
Further, we knew that elements come in different forms,
called isotopes, which have the same number of electrons and
the same number of protons but different masses. Because
the mass of the atom is in the nucleus and all isotopes are
electrically neutral, there must be something else in the
nucleus that contributed mass but not charge. This was
the .
Eventually, we were able to isolate neutrons and observe their
decay, which resulted in an electron and a proton.
If electrons and protons get too close, then their opposite
charges ought to bring them together into a single electrically
neutral object. The combined mass matched what the proton
had to weigh given the atomic masses of the various isotopes,
but there was a problem.
We had conservation of charge, energy, and momentum but
not , a measure of spin, which must remain
constant overall. Thus, a third component was proposed to
account for the discrepancies before and after the decay, a
particle with no charge and virtually no mass, the .
When there was a heavy-positive/light-negative image of the
atomic world, things were simple. But the neutrino suggested that
the subatomic realm was more complicated, and physicists began to
try to see what the world inside of atoms looked like.
Here, two more problems emerged.
If the nucleus is small and is populated by protons, which
share the same positive charge, how does it remain stable?
Like charges repel, and the closer they get, the stronger the
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