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.
