Familiar substances
such as wood, metal or meat are composed of molecules. Molecules are
themselves composed of atoms, of which there are approximately a hundred different sorts,
such as hydrogen, carbon or sulphur. We are intermediate in size between the Sun (a billion
metres in diameter) and a molecule (a billionth of a metre).
Atoms are composed
of particles. At the sub-atomic level particles are of two sorts - 'building-
block' particles named fermions, and 'gluing' or 'cementing' particles named bosons.
Starting with the
building-block particles and following them 'downwards', the highest level of
sub-atomic organisation is the 'massive building-block' particles known as baryons. They are of
two sorts - protons and neutrons, which form the nucleus of the atom.
At a 'lower' level,
we find 'light building-blocks', from which protons and neutrons are
themselves constructed. These are of two sorts, namely quarks of the up/ down variety, and
leptons which exist in three families. From the electron family come the electron particles which
may link to an atomic nucleus and, according to the number of electrons doing so, help to
create different sorts of atom.
What holds the
particles together? What is the binding force? The exerting of 'force' is a
transferring of energy from one particle to another. Particles which do this are called bosons.
They 'glue' or 'cement' particles together. Which particles do this depends on the properties of
the boson and whether the building-block particles have electric charges or not.
Tracing the bosons
back in conjunction with the blocks that they glue together there are four
sorts of particle collectively known as intermediate mesons at the level of quarks and leptons.
These are called gluons, photons, massive vector bosons and gravitons.
The gluons
are carriers of the very strong force known as the 'colour' force. They operate on
quarks, binding them together in groups of three to make massive building-blocks, baryons.
Photons
are particles which transfer energy to and from electrons, and carry the
electromagnetic force which holds them around the atomic nucleus and which also binds
separate atoms together.
Massive vector
bosons is the collective name for three particles which carry the weak nuclear
force, namely W plus, W minus and the neutral Z boson particles. They have a role in the
behaviour of neutrino particles and radioactivity, but this is outside the scope of the present
brief summary.
Gravitons
are the particles which transfer gravitational force to all matter. All matter is
attracted by their action, which, though weak, operates over immense distances, and
collectively with great force.
Rising now to the
level of the massive building-blocks, the J protons and neutrons, we find
particles collectively known as L, mesons. Of these the pion is of vital importance, since it
is
this particle which binds together protons and neutrons to form a stable nucleus of the atom.
Such is the strange
world of particles. It seems a thousand years removed from the seventeenth
century when Descartes and Henry More debated the omnipotence of God, stating that 'as
matter is always divisible, it is clear that God will never be able to bring this division to its end
and that there will always be something which evades His omnipotence. Whether the quark can
or cannot itself be divided into something smaller cannot perhaps be known with absolute
certainty. The inputs of energy used today may be inadequate and in future centuries may seem
quite trivial. A theory is always tentative. A huge readjustment in living and thinking, however, is
now inevitable, as a result of the quantum theory which led on to the 'uncertainty principle' first
formulated by Heisenberg in 1926. We ourselves are concerned with only a minute part of all
that is, minute in time as well as in space. The sheer size and grandeur of the thing is
intimidating. What saves us from despair is the fact that throughout the universe there appears
to be a pattern. This pattern is underpinned by mathematical laws.
