# A Classical Perspective

Again,
this section is not intended to be a physics tutorial, but rather a
review of the classical perspective of physics. While there are aspects
of the classical model that are still relevant today, it is possibly
true to say that this model is more reflective of scientific thinking
prior to the 20^{th} century. At this time, the Church was
still a powerful social institution, which undoubtedly influenced many
areas of scientific thinking. Even so, by this time, science had essentially
embraced what might be called a deterministic philosophy, which
is sometimes referred to as the `*clockwork universe*`. This idea
embodied a model of the universe that essentially ran by a process
of *`cause and effect*` as described by Newton’s laws of motion.
However, we shall start this discussion with the premise
that everything in science, and the rest of the universe,
can be described in terms of 4 basic quantities:

- Length
- Time
- Charge
- Mass

In a wider context, we might recognise that our understanding of
these quantities reflects our experience of the world, which in-turn
reflects the sensory and intellectual evolution of *
homosapiens*,
as a species. As such, the initial understanding of the real nature
of these quantities is often intuitive, subjective and wrong. Therefore,
we will start this aspect of the discussion by introducing these basic
quantities in a little more detail, first within the constraint of
a classical model, but then followed by latter day notes in*
italics*
suggesting a possibly different nature. However, in some respects, many
of the arguments in modern science today still relate to the conflicts between
our interpretation of the physical and mathematical reality of these
quantities:

## Length

We normally perceive length as a comparative measure, i.e. x=1 metre. The concept of length is one that natural selection has evolved to help us intuitively understand distance, albeit in the limited scope of length extending in 3 perpendicular directions, i.e. essentially a Cartesian model involving xyz directions. As a consequence, the concept of area, i.e. xy, and volume, i.e. xyz, are also intuitively understood based on the same caveat.

*Note: While we might feel that
we have a good grasp of these various manifestations of length, science
has come to challenge some of these intuitive perceptions when considering
the true nature of space between sub-atomic particles or the light-year
distances between galaxies. However, for the moment, we shall simply
flag this complexity for later discussion - see link in inset right. *

## Time

The concept of time is possibly less tangible than length, simply because it cannot be sensed directly, although it could be argued that we do have some in-built sense of the passage of time. However, without any concise definition of the mechanism of time, we might simply define time as a fourth dimension through which objects in xyz space can passed from one second to the next.

*Note: Again, we might flag
that subsequent ideas, such as special relativity,
suggest a far more profound relationship between space and time, but
again, we are trying not to run too far ahead of the classical model at
this point. However, the following discussion related to
the idea of time might provide some food
for thought for those interested in this aspect.*

## Charge

In evolutionary terms, we probably have had little need for an intuitive
understanding of the concept of charge, although we may have observed
static charge effects, e.g. lighting storms and static charge on a cat’s
fur. However, the notion of charge has come to be described as a fundamental
property of some particles, such as protons and electrons, which is
expressed in multiple units of the elementary charge [e] on an electron.
Electrons are said to have a charge of [e^{-}], while protons have
the opposite charge of [e^{+}]. Normally, the charge of a macroscopic object
is typically zero, as the number of electrons in every atom is typically
equal to the number of the protons, so their charge cancels out.

*Note: It is possibly
important to make a couple of clarifications so as not to lose sight
of the current scientific model. During the 20*^{th}*
century, the particle model divided the structure of a proton into
quarks, which were considered to have a fractional charge of −1/3
or +2/3, but which can be combined to form either the positively charged
proton, i.e. 2/3+2/3-1/3=+1, or the neutron, i.e. 2/3-1/3-1/3=0. Also,
there is a sense that describing a single particle, in isolation, as
having a charge may be essentially meaningless, because charge is said
to only exist between two charged particles. There is also a fundamental
relationship between an accelerating charge and electromagnetic radiation,
which is encrypted into Maxwell’s equations. Again, more speculative
ideas on the idea of charge will be
deferred to subsequent sections. *

## Mass

Our intuitive understanding of mass is normally considered in terms of the weight of an object, which is specific to the force of gravity on the surface of Earth, but mass is not weight. This situation is compounded because the units of mass and weight are both measured in kilograms [kg]. In space, where the effects of gravity are minimal, a mass would have no apparent weight, but still require a force [F=ma] to overcome its inertial mass. This complexity is linked to what really amounts to two different definitions of mass, i.e. gravitational and inertial.

*Note: Today, Einstein’s
famous equation E=m*_{0}c^{2}*
suggests the rest mass [m*_{0}*] is proportional
to energy divided by the speed of light squared [c*^{2}*].
This equation can also be combined with Planck’s equation E=hf to give
m*_{0}c^{2}*=hf,
where [h] and [c] are constants. On this basis, it would also
appear that mass is a manifestation of energy, which in-turn is related to frequency, but more on this aspect in
a later section entitled the idea of
energy.*

## Comment

So while these quantities are still considered to be fundamental
units within a basic particle model; the subsequent development of
*quantum theory* might suggest
that all notions of particles must ultimately disappear into a
probability wave function. In fact, there are number of alternative
theories that suggest that matter is only a manifestation of scale
and that
the fundamental units, as described, are only an emergence property
of the underlying *wave structure of matter*. However, irrespective of
whether this is the case, or not, developments in science have always
proceeded by making *models* that allow behavioural predictions to be
made, which have then been subsequently proved to be only an approximation
of reality. In many respects, the classical model has stood the test
of time better than most.