Chapter 2: Understanding the Universe
Section 2.1: Different views
Section 2.2: The common base
Section 2.3: Scientific investigation
Section 2.4: Key elements of a broad approach
Section 2.5: The basic understanding attained
References for Chapter 2
This chapter considers the basis
of the scientific approach to understanding the physical universe, and how this
can be broadened into an approach to understanding in general. This provides a
good background for what follows..
Section 2.1: Different views
The scientific viewpoint is but one
of the various ways humanity has tried in the quest for understanding and the
search for a pattern of meaning [7-10]. We cannot attain understanding without
such a search because of one of the fundamental aspects of the situation that
confronts us: namely, the hidden nature of reality. I assume this
reality exists, and can to some extent be discovered. There are of course
various viewpoints that deny one or other of these assumptions. While they may
be philosophically amusing, they cannot be sustained in a serious search for a
satisfying overall view of the nature of the world, precisely because they deny
that that quest can have any meaning.
Many of the scientific aspects of
the world are far from obvious; we cannot without considerable effort and
perspicacity deduce the nature of the chemical elements, the fundamental forces
that bind matter together, and so on. We can easily appreciate the majesty of
mountains and the beauty of flowers, but only with skilled experimentation
determine that they are made of a combination of carbon, nitrogen, oxygen, and
other elements. Furthermore when we do succeed in understanding physical
aspects of reality, its nature may be quite unexpected (for example, the
essence of relativity theory and the nature of quantum mechanics).
Thus one of the prime issues is
determining the essence and scope of the hidden nature of reality. The initial
attempts to relate to this hidden aspect of nature may be broadly characterised
as magical or superstitious approaches: it is assumed either that
if one wishes hard enough for something it will happen, or that if one adopts
various ritual practices intended to bring about an effect, it will occur,
whereas in fact they have no causal relation to it and cannot influence it. The
evident inefficacy of this approach, coupled with obvious injustices that have
often resulted from its practice (witch-hunts leading to the death of innocent
people, for example) have then led to development of two diverging world views.
On the one hand the religious
view has evolved serious approaches to moral issues and to possible
understandings of ultimate reality, although often in a faulty and misleading
manner; and on the other the scientific view has with tremendous success
tackled the issue of immediate causes, leading to an extraordinarily effective
understanding of how things work in terms of physical cause and effect. Indeed
one of the major triumphs of science is precisely the understanding that
because the sequence of natural events is governed by regular laws of
behaviour, each physical event has causes that can be determined by appropriate
investigation; and desired final effects can be achieved by organising an
appropriate set of initial conditions. This establishes the firm relation
between physical cause and effect.
The achievements of science are
undeniable: it has led to discovery of the physical basis of nature and laid
the foundations for the huge explosion of technology enabling us to order our
lives and control our environment in ways previously unimaginable. In the face
of this enormous success, other world views, and in particular the theological
one that held sway for many hundreds of year, have been forced to retreat: they
have had to modify their truth claims, abandoning to science much previously
claimed territory. However there has recently also been a reaction against
science in many quarters, on the one hand because of its perceived contribution
to environmental degradation and the development of weapons of mass
destruction, and on the other because many see it as based on an outlook that
dehumanises and denies the value of the individual [2]. In many cases this has
led to what is essentially a return to magic, in the form of astrology, arcane
effects ascribed to pyramids or crystals, and so on. These are bound to
disappoint eventually, as they are not based on real cause and effect relations;
however the fact that people turn to them is evidence that many are seeking a
world view with elements of humanity and hope not provided by the present
dominant scientific one. Sometimes the effort is dressed in pseudo-scientific
terms, wanting to inherit some of the mantle of scientific success but avoiding
the kind of logic and indeed hard work demanded to make good that hope.
We will here follow the scientific
method, adopting a specific set of values that underlie the approach. Broadly
speaking, the values adopted here are that we try to find a description that
reflects the truth insofar as we are able to achieve that aim, in particular
therefore taking seriously the discoveries and viewpoint of modern science.
This does not prevent us also acknowledging the worth and significance of the
broad range of human activity (including aesthetic and moral choices, personal
life decisions and experiences), but investigating them is a separate project.
We can then argue strongly we have
determined in a culture-free way some invariant aspect of underlying reality.
This does not mean we can describe the ultimate nature of that reality,
but rather that we can characterise its effective nature, which as far
as we are concerned is absolute; for example, if we let go of an object we hold
in our hand, it will fall; if people have no food, they will die.
Section 2.2: The common base
In each area of understanding, whether
we make the fact explicit or not, our understanding is based on mental
models of reality that will to a greater or lesser degree reflect
accurately the nature of some aspect reality. They may be simple ideas, perhaps
comprised in a single label (the word "cat", for example, conjures up
a whole model of appearance and behaviour), or complex theories (e.g. the
theory of relativity, or Jungian psychology). Each such model will have a range
of applicability, specifying both the set of phenomena that are its
concern, and a (usually restricted) set of conditions within that domain
it is supposed to explain. For example Newtonian mechanics explains the motion
of physical bodies, provided they do not move at speeds close to the speed of
light; a theory of psychology may describe the ordinary behaviour of people at
work, but not that of psychopaths.
Theories can never be absolute:
indeed the understanding they give will always be partial, because no model can
circumscribe within itself the full nature of reality. Thus theories are always
subject to revision. Hence the key element underlying the approach proposed is
that, whatever the field of application, growth in understanding is based on a
creative proposal of theories to explain reality}, but always founded on
the combination of skepticism, i.e. the willingness to doubt the current
orthodoxy, and testing, i.e. checking that orthodoxy, or any proposed
alternatives, against reality in the whole variety of ways that is practical.
Indeed this is the foundation of all learning, through the basic learning
cycle [11]: in essentials, we
1: set up a hypothesis on the basis of present knowledge;
2: work out its consequences, in the process checking that it is
coherent, making logical sense,
and then
3: test its consequences against evidence,
- if possible performing new
experiments that can check if it is true or not.
Then we return to step 1, if the agreement is not satisfactory
4: reconsidering the hypothesis and modifying the theory on the basis
of the new evidence available
- and on the basis of any new
ideas that may have come up.
Of course in reality life is more
complicated than this: the hypotheses are set up within a pre-existing
framework of understanding that will be based on a cultural and temporal
viewpoint; and a theory is made up of a complete set of interlocking hypotheses
and assumptions, which are tested as a whole. Thus it will in general not be
obvious what it is that needs altering to make a better theory than the present
one. Nevertheless the power of observational tests underlies the examination
and improvement of theories, whatever their domain of application, and is the
basis of all our knowledge of the real nature of the world and the Universe.
Section 2.3: Scientific investigation
The scientific method is nothing other than the basic learning cycle just discussed, but applied in a rather systematic manner; for discussions of how science is carried out, see Chapter 1 of [6] or the Rutgers internet notes [webpage] "Philosophy of Science - How do we know what we know?". The way it works out in the specific case of biology is nicely described in [webpage] and for the case of astronomy see [webpage].
The power of science as a method of investigation arises from two features it has practised to perfection: firstly, the use of the analytic method, i.e. dividing a system into its parts and understanding how the parts work in isolation from each other; and secondly, the systematic application of quantitative analysis, based on accurate measurement and used in conjunction with measuring instruments of ever increasing accuracy, so that the regularities underlying nature are formulated as mathematical laws. These features have been employed together in formulating theories and devising precise experimental tests of the theories proposed, leading both to the ability to predict to great accuracy the behaviour of simple isolated systems, and also to considerable knowledge about the nature of the constituent parts of matter.
One of the remarkable features that
has emerged is the amazing power of mathematics [12,13] in describing the
nature and behaviour of matter; it is something of a puzzle as to why this
should be so (see Barrow and Davies in [6]). It should be emphasized that this
has become particularly apparent in recent times, due to the dramatic
improvements in measurement technology: we can now measure times, distances,
masses, and other properties of objects to incredible accuracy, due to enormous
improvement in imaging and measurement techniques, often through use of
entirely new processes (scanning microscopy, Nuclear Magnetic Resonance
imaging, laser interferometry, CAT scanners, Charge Coupled Devices (CCD's),
and so on).
In searching for scientific laws, we
are looking for invariant behaviour common to many systems, providing a
unifying explanation of different generic and specific cases. We do so by
separating out their behaviour into a universal part, "laws of
nature" applicable to all similar systems, and specific information
determining the response of a particular system to those laws, usually in the
form of "initial conditions" and "boundary conditions"
specifying the nature and state of the specific system under investigation.
Thus for example general laws of motion describe how any falling object moves;
the particular place and speed with which a ball is propelled, together with a
specification of wind conditions, determines its particular path and pace of
motion. Experimental tests function by varying some of the initial conditions
of the system, keeping the rest fixed, and then seeing if the response to these
new conditions follows the universal pattern described by the laws we suppose
are applicable to that situation. Thus we may release projectiles with various
velocities from a tower, and verify if the way they fall complies with our
theories of wind-resistance and gravity; the test confirms the theory if they
move precisely as predicted (within the experimental error). By carrying out
such tests, we have successfully been able to confirm that physical laws that
do indeed describe accurately the behaviour of a large variety of physical
systems, and enable us to predict their future behaviour with precision.
2.3.1 Different kinds of science
While the characterisation just
given describes the nature of a large part of the natural sciences, including
the fundamental sciences of physics and chemistry, it is important to realise
there are other forms of "hard" science with major differences in
their practice.
Firstly, there are the purely logical
sciences, specifically logic itself and most of mathematics, which are not
susceptible to experimental test or proof (The exception here is recent use of computers
to determine the nature of mathematical systems, and in particular to examine
the behaviour of chaotic and fractal systems, where some of mathematics has
begun to take on aspects of an experimental science). Rather they are based on
pure analysis and examination of the satisfactoriness of that analysis. The
other sciences build their theories on the basis of the logical sciences (the
analysis of physics is based on mathematics, for example).
Next there are the natural
sciences, comprising the analytic sciences, as outlined above, and
the integrative (or synthetic) sciences: for example
ecology, where the emphasis is not on the behaviour of the parts of a system,
but rather on the behaviour of a complex system made up of many interacting
parts (the behaviour of each of these parts being susceptible to analysis by
the analytic method). The applied sciences, such as engineering and
computer science, fit into this category, and in many cases remarkable success
has been achieved; for example we can now use computer simulations to predict
the behaviour of aircraft before they have been made, on the basis of Newtonian
dynamics and the theory of fluid flow. As in the case of the analytic approach,
these understandings of how complex systems function are open to experimental
test (provided we can isolate the system adequately from outside interference).
One of the main differences from simple systems is that usually there is no way
we can test all possible types of initial configurations of a complex system;
we can only check its behaviour under a representative sample of initial
conditions, and hope this gives us sufficient insight into its behaviour in the
face of all the conditions that will be encountered in reality (for example we
test the computers that control aircraft in a way we believe will adequately
reflect the whole range of conditions they will encounter in practice; however
we cannot test all conditions that might occur).
Clearly the synthetic sciences build
on the analytic sciences, in that as we attain a better understanding of the
behaviour of the components of a complex system, we are in a better position in
our attempts to comprehend the whole. However they cannot be reduced to the
analytic sciences: it is precisely the relations between the parts of a human
body that enable the whole to function, and this cannot be understood by
examining the parts in isolation. This is why physiology is of necessity an
integrative science. Furthermore one should note that while the objects of
study in the reductive sciences may often be identical to each other (each
proton is identical to every other proton, similarly form electrons and
neutrinos), in the case of the integrative sciences there will, despite major
similarities, always be some differences (each human body is different from
each other one; each ecosystem has its own individuality).
Finally there are the historical
and geographical sciences, such as geology and astronomy, where we examine
the nature, history, and origin of unique systems (a particular mountain range,
the Earth, the Local Cluster of galaxies, and so on). Major examples are the
investigation of the creation of the Solar System, of the history of
continental drift on Earth, and of the evolution of life on Earth. In these
cases, we cannot set initial data so as to repeat the situation that occurred
in the past: experimental tests in the sense implied above are not possible,
because we are concerned with specific events that have only happened once in
the Universe. However we can on the one hand look at properties of similar
systems or events, hoping they will help us understand this particular one (the
issue of course being just how similar or different all these other examples
are); and on the other hand we can today make observations of many kinds of
data that tell us much about the specific historical event of concern,
representing features that would be necessary consequences if our theory is
correct (for example we can search for similarities in the DNA patterns of
animals we believe to be closely related through evolution, or we can compare
ages of different fossils as determined by measurements of radioactive decay).
Thus we can try to predict the
results of observations that have not yet been made, on the basis of our
current best theories about the specific historical event in question (we may
predict that various rocks must be similar in South America and South Africa if
continental drift is indeed true, and then go out and verify if this is so or
not). We may also be able to measure present behaviour that tends to confirm
our ideas about the past because it is the same process going on at the present
time (we can for example measure the present rate of change of distances
between the continents, and observe mutations presently occurring in population
species).
All of this provides corroborative
evidence which may be very convincing, but is still not the same as observing
the unique course of events that took place in the past, finding out the effect
of altering initial conditions at that time, or carrying out experiments that
repeat the same course of events. The historical sciences build on the analytic
and integrative sciences in that these give guidelines as to the kinds of
behaviour to expect, and put strict limits on the kinds of things that could
have happened in the past, assuming the fundamental laws were the same then as
now. This basic assumption is to a certain extent susceptible to test.
|
The Sciences: |
|||
|
|
Natural |
|
|
|
Logical |
Analytic |
Synthetic |
Historical |
|
Mathematics |
Physics |
Ecology |
Geology |
|
Statistics |
Chemistry |
Astrophysics |
Evolution |
|
Logic |
Molecular biology |
Physiology |
Astronomy |
Table 2.1: A classification of the different kinds of
sciences, with examples of each listed [Note that applied sciences and social
sciences are not shown here]. The Natural Sciences and Historical sciences
together comprise the observational sciences.
Table 2.1 shows this classification
of sciences (apart from applied sciences and the social sciences), reflecting
the relation of each to testing and confirmation. I use the latter word
advisedly; it is not possible to verify any theory in the sense of proving without
doubt that it is correct, but we can confirm it by providing more and more
evidence that supports its correctness (for example no one seriously doubts
that Newton's laws of motion adequately describe how a motorcar moves). The use
of Bayesian statistics gives such confirmation a solid logical foundation
[14-16]; in this approach we always regard knowledge as incomplete, but with
each new bit of positive evidence adding to the previous evidence for believing
a theory is true.
We can sometimes disprove theories,
including historical theories, in a decisive way, when observations clearly
contradict some of their predictions (for example, the finding of a human skull
that radioactive dating proved came from the era of the dinosaurs would
confound the present theory of evolution).
2.3.2 The invariant underlying nature
The point that now needs to be made,
in the face of much recent writing emphasizing the sociological basis of
scientific activity and suggesting that all scientific understanding is
therefore culturally bound and relative (see e.g. [9]), is the efficacy of
physical laws. Social and cultural issues do indeed play an important part in
shaping science, for they help determine what is regarded as an important issue
at any time, and therefore help shape what questions are asked by the working
scientist; and to some extent they shape the kinds of theories proposed to
provide explanation. However the fundamental point is that provided these
questions and theories are then refined and developed appropriately to lead to
true scientific tests, the answers obtained (in the logical and natural
sciences) are not relative: on the contrary, they reveal some aspect of the
working of nature that is universal: it is independent of the time and place
where the experiment takes place, and of the cultural and sociological nature
of society. Irrespective of these factors, when I release a weight it drops to
the ground; water is always made of hydrogen and oxygen; electric waves
propagate at the speed of light; and so on. There is a trivial relativisation
in terms of the language used to describe reality, for example
"oxygen" and "sauerstoff" are the same thing; I assume we
are able to handle such issues of multiple representation without getting misled
by them. Indeed the functioning of the world around is rigorously determined by
the laws of physics and chemistry, whatever we may wish or do, and no matter
what our life view may be; inter alia these laws determine the
functioning of our own bodies and minds, the physiological nature of that
functioning also being completely determinate (we breath oxygen; DNA determines
our genetic inheritance; calcium and sodium ions are the basis of signal
transmission in our nervous systems; and so on).
This is the triumph of natural
science: it has been able to locate an underlying reality that is invariant and
universal, despite the differing social and cultural positions from which
different scientists operate. The impression that relativity theory has done
away with such a reality is incorrect: that theory emphasizes both the
relativity of different observer's views of that reality, and the possibility
of characterising its nature in an invariant way [31]. We expect motor cars,
television sets, refrigerators to work in a specific way that results from
their design; and they do so completely reliably (unless defective) precisely
because the laws of physics govern their behaviour in a reliable and repeatable
way.
While the implications of the
natural sciences may be absolutely firm in many cases, the description we use
may not be rigidly specified. Indeed there may be different viewpoints and even
different mathematical descriptions that describe the same processes equally
well, and give the same results. For example, there are different ways of
formulating Newton's theory of gravity: in terms of a potential (the field
view), in terms of action at a distance (the force view), or in terms of a
variational principle (a Lagrangian or Hamiltonian view). In the case of
quantum mechanics, apparently different mathematical descriptions (the
Heisenberg, Schrödinger, and Feynman descriptions) have been shown to represent
the same physical behaviour: they are equivalent descriptions, although this is
far from obvious. In these cases we may prefer one or other of the alternative
views of the same phenomenon on cultural or aesthetic grounds; this will in no
way alter the solid nature of the predictions obtained from them.
Furthermore it is important to realise there are simple effective theories we may employ, even when we know that they are fundamentally wrong, because they may indeed be effective in a specific domain of application. Thus for example even though we know the rotation of the Earth is responsible for the daily appearance and disappearance of the Sun, it is still useful in everyday life to talk about the Sun rising and setting (in essence a completely wrong theory - but still a very practical viewpoint in daily life). Similarly we may apply the Newtonian theory of gravitation to predict the motion of planets in the Solar System unless we need very high accuracy predictions, when we need to use the correct theory (Einstein's theory of gravitation); and we can apply the Galilean theory of gravitation in engineering construction on Earth, even though it derives form the more fundamental Newtonian theory. Thus such effective (non-fundamental) theories are very useful; the real question is a meta-question: when can we usefully apply such theories, and when not?
2.3.3 Criteria of choice for theories
The situation is not so clear cut in
the case of the historical sciences (as defined above), such as geology,
evolutionary theory, archaeology, and astronomy. Here there may well be a
cultural or sociological bias influencing the conclusions we derive (as well as
the description we use), for in the face of our inability to perform the
experiments we would like to carry out, we have to make assumptions determining
what kind of theory we regard as reasonable, and the shape of what we find is
biased by these assumptions.
Thus a key issue then is what are
appropriate criteria for a satisfactory theory, that can help us choose amongst
possible alternative explanations. The primary candidates are,
Criteria for
scientific theories:
* simplicity - the Occam's
razor idea that one uses the simplest possible theory that can accommodate the
facts;
* beauty, on the face of it a
very subjective criterion, but there is remarkably good consensus about it in
many cases;
* prediction and verifiability - the ability to confirm the
theory by a variety of observations or tests; in particular,
- verified predictions of
a new kind provide major support for correctness of a theory.
- the converse is the Popper
criterion that a good theory should be clearly falsifiable by experimental
test;
* overall explanatory power and unity of explanation, in
particular congruence with the rest of our current body of knowledge.
These are the key requirements for a
"good" theory; the problem is that in general these criteria will not
agree, and differing emphasis on which of them is important may lead to
different choice of theory (see [10] for a discussion of the case of
cosmology).
Nevertheless in many cases we may
attain a high degree of certainty because these criteria concur, selecting
uniquely as preferred a theory with high explanatory power that also fits into
the body of established theory in a satisfying way, particularly when it makes
new predictions (such as the existence of anti-matter, the bending of light by
the sun, or the transformation of matter into energy) that are then verified.
2.3.4 Reasonable certainty in historical sciences
There will however be historical
situations where we are destined to always remain in doubt about the true
course of events, because of the fragmentary nature of the evidence available
to us; for example many cases in archaeology, and many of the details of
evolutionary history. Thus we will attain various degrees of certainty,
according to the quantity and quality of evidence available to us.
However in particular cases, there
is a vast interlocking array of facts that are explained in a unitary way if we
adopt one particular explanation of a complex phenomenon, but remain a set of
disconnected features that have common aspects by pure chance if we do not. By
marshalling evidence in this way, we can be virtually certain for example that
continental drift and evolution did in fact take place, and that carbon dating
gives correct estimates of ages of archaeological finds. It is possible to put
forward logically consistent alternatives that explain the same historical
facts differently, such as the so-called "creationist" view; the
problem is their incongruence with the rest of scientific knowledge, together
with the small number of features they explain. They provide a consistent
scheme, but considered as a scientific scheme of interpretation and
understanding, it is one of narrow scope and small vision, with low integrative
power. As far as possible we demand consistency with present day scientific
theory and understanding, together with the requirement of broad explanatory
power. This will in many cases lead to a unique interpretation of specific
events that fits in with present scientific theory in a mutually reinforcing
way, so that an unrivalled interpretation is both attainable and in effect
required: for example, the evolutionary principle not merely becomes an
explanation of past events but becomes a central feature and profound
organising principle of biological theory, explaining also many events
occurring today.
It is interesting to view this whole
discussion from the experience gained in law courts, for the examination of
evidence as undertaken there is nothing other than applied historical research;
and it is taken most seriously because people's freedom and livelihood hang on
the outcome of the verdict. The crucial point is that in many cases we believe
that, despite all the pitfalls, we are indeed able to arrive at a verdict
"beyond all reasonable doubt". The cautionary remark is that
sometimes such a verdict is wrong.
Section 2.4: Key elements of a broad approach
Whatever the field of concern, the
basic learning cycle discussed above is the way we obtain and extend our
understanding. Employing this method consciously will increase its
effectiveness. This demands
2.4.1 Setting the scene: Reflection, Observation, and Openness
The start is a reflection on issues,
principles, and data, with an openness to possibilities, the readiness to
search out grains of truth that may be hidden in alternative viewpoints and a
willingness to test them for possible validity. Thus a key question one can ask
oneself is, What am I prepared to question, and what am I not prepared to
question?
The answer lays down the fundamental
parameters within which one is willing to learn. Those issues that one is
unprepared to question are those domains where one has chosen to proceed on the
basis of preconception and dogmatic assertion, rather then reflective
investigation. As an example, Einstein's dramatic progress in understanding
space and time came because he was willing to query the nature of space
measurements, of time, and of simultaneity - which everyone else did not
question because they took them for granted.
The adoption of ideologies of
various kinds is a common way of protecting oneself from questioning what one
holds dear. The aim of the approach suggested here is that one will try to
avoid having a closed mind. This means in particular, emphasizing freedom of
information and freedom to support other ideas than the current dogmatism;
indeed that the basis of progress and understanding is an enquiring atmosphere
[11].
In developing a consistent theory
based on this approach, one is engaged in integrating the possibilities
considered into a coherent and logical scheme; our logical and creative skills
come into play as we fashion a satisfactory whole. A fundamental point here is
2.4.2 Identifying Main Issues and Causal effects
Next is identifying the important
issues and concepts, naming them, and characterising them. We can then show
how they relate to each other and to the extant wider body of theory and
knowledge.
The point is not only to state what
is fundamental and what is less important (from a causal viewpoint), but also
to consider what may have been left out, perhaps because it is so obvious that
it is taken for granted and therefore not taken into consideration.
Having set up a theory (or set of
competing theories) our task is to separate the wheat from the chaff by
suitable testing. The key point here is
2.4.3 Testing
Next is determining valid methods
of testing theories and of assessing the results of the tests. This will
vary greatly from area to area. We have to ask, What is acceptable data for
this area and how is its quality assessed? We can then review existing
data, and if possible, set up new experiments or observations to test the
theories.
If some feature regarded as key by
some is not admitted as data at all by others, agreement cannot be reached.
However often the disagreement is not over the general admissibility of a class
of data, but the quality of specific data. These problems apply particularly to
historic records.
2.4.4 Evaluation
Finally, having analysed the competing
theories and considered the evidence for and against them, we need to use our
chosen criteria for good theories to choose between them, asking how good is
each theory relative to alternatives, in terms of our criteria?
2.4.3 Real Observations
Two final comments relating to
realistic observations:
Firstly, we must realise that in
real-life situations, serious counter-evidence to some theory does not often by
itself lead to dropping a theory, but rather to investigating various perturbing
influences we have not taken into account so far (the wind, a temperature
gradient, an electric field, that may have affected the path of a falling
object; an unknown person entered the room and interfered with the murder scene
before the deed was discovered). The point here is that even if we are
investigating identical systems (say electrons), each experiment is in fact an
individual experiment that is in detail different from every other experiment.
We have to take this difference into account in interpreting the experiment.
Secondly, whenever observations are
made in support of a theory, we should always be aware not only of possible
distortion of the data but also of the various possible selection effects
that might be in action, distorting the appearances of what happened by
effectively preventing a whole segment of data getting through (for example,
they determine what galaxies we detect in photographic plates of distant
regions of the sky, because many are too faint to be detected). Thus a
particular question we need to always ask is, What is the information that
is not getting through? Furthermore, as emphasized in the famous Sherlock
Holmes comment on the strange incident of the dog in the night (the dog did not
bark), The absence of a signal may convey vital information. But we must
also remember that absence of evidence is not evidence of absence. Just because
we can't see it does not mean it is not there (cf. the celebrated case of the
preponderance of dark matter in the universe).
Overall, the essential feature advocated
here, in line with one of the major movements in methodology of the last
half-century, is that our concern ultimately must be an emphasis on process
rather than the particular presently available data and knowledge; for if the
process is right, then in due course errors in our understanding will be
corrected. Thus
* The basic need is a process of
learning that continually checks theories and models for incongruities and
problems in all possible ways, and corrects the errors found.
This chapter has briefly set out the nature of such a process - which is nothing but the scientific method. Its implications will be developed in the following Chapters in considering the nature of the physical Universe.
Section 2.5: The basic understandings attained
The rest of the book gives summaries
of understandings attained by this approach in various important areas. Here we
preview what follows by giving the following summary of the main findings of
science.
2.5.1 The Main Themes
1: Everything is changing
Contrary to our expectations, we have discovered that the universe is changing, stars evolve, the mountain chains and continents on earth are changing, and new life forms have come into being on earth while others have become extinct.
2: The way things are changing can be understood as the result of a regular relation between cause and effect which can be determined by scientific investigation
The changes do not happen randomly, but result from systematic and reliable causal relationships. We can determine the nature of those causal relationships by careful observation and experiment.
3: The relation between cause and effect can be understood as due to the interplay between (i) an unchanging constant part (physical laws) and (ii) variable circumstances (boundary conditions and initial conditions) that will lead to different outcomes even though the underlying laws of behaviour are the same.
The causal relationships can be characterised as the interplay between chance, the contingent set of circumstances that just happened to be, and necessity, the inviolable set of physical laws that characterise how all matter behaves - both living and non-living.
4: The behaviour of complex systems, including life, is grounded in the behaviour of the fundamental particles that are their ultimate components.
Complex systems can behave the way they do because they are made up of interacting simpler systems. Laws underlying the micro-behaviour, such as energy conservation, result in limits on how macro-bodies can behave, for example the First and Second laws of Thermodynamics (which follow from energy conservation at the micro level). However their structural relations also give them higher level behaviour:
5: Complex systems derive their essential properties from the hierarchically ordered structural relationships between their component parts that are set up by their physical structure.
It is these basic theses that will be explored and illustrated in what follows.
2.5.2 Summary Tables
There are three main kinds of tables in the Chapters that follow.
Firstly, there are tables setting out the hierarchical relationships that exist between components of the various structures around us. Understanding these hierarchies is an essential component of understanding each subject.
Secondly there are tables setting out some of the vast variety of objects that have come into being as a result of these relationships - the specifics of the world as we know it, as discovered by scientific investigation. This enormous variety of existence partly reflects the `chance' component of existence - giraffes happen to be because of the vagaries of evolutionary development. But they also exist because they are allowed to exist by the underlying laws of physics and chemistry.
Thirdly there are tables summarising important invariant underlying principles that have given rise to this variety of existence - that is they summarise essential features of the `necessity' component of existence. The contrast between the relatively few basic principles and the vast variety of resulting structures that is one of the fascinating features facing one in a comprehensive view of the nature of science, such as is attempted here.
Finally there are some tables setting out theoretical options in cosmology.
As noted above, these representations are all under review: they may be improved as comments are received.
References for Chapter 2: Understanding the Universe
Philosophical analysis is discussed in
[7] T Nagel: What does it all
mean? A very short introduction to philosophy (Oxford University Press,
1987)
[8] J Hospers: An introduction to
philosophical analysis. (Routledge and Keegan Paul, 1959)*
(and see also [1]). Philosophy and
science is discussed in
[9] W H Newton-Smith, The
Rationality of Science (Routledge, 1991)*
with the special issue of philosophy
and cosmology presented in
[10] G F R Ellis: "Major Themes
in the Relation of Philosophy and Cosmology", Memoirs Italian
Astronomical Society, 62: 553 (1991).
The learning cycle, and
organisational structure conducive to learning, is discussed in
[11] G F R Ellis: Organisation and administration
in a democratic era} (Book draft, University of Cape Town, 1991).
The nature of mathematics and
mathematical descriptions of nature is discussed in
[12] L A Steen (Ed.): Mathematics
Today (Vintage Books, 1980)
[13] M Kline: Mathematics: The
loss of certainty (Oxford University Press, 1980)*.
Use of Bayesian statistics in
analysing theories is presented in
[14] H Jeffreys: The Theory of
Probability (Oxford University Press, 1939)*
[15] R T Cox: American Journal of
Physics, 14: 1 (1946)*
[16] A J M Garrett: Ockham's Razor. Physics World (May 1991), 39-42.
[Version 2002-07-29].
Chapter 2 of The Universe Around Us by George Ellis.