Physical Reality – Construction or Discovery?: An Introduction to the Methodology and Aims of Physics

339 Pages·2021·7.862 MB·English

by  Michael Grodzicki

Michael Grodzicki
Physical
Reality –
Construction
or Discovery?
An Introduction to the Methodology and
Aims of Physics
–
Physical Reality Construction or Discovery?
Michael Grodzicki
–
Physical Reality
Construction or Discovery?
An Introduction to the Methodology and Aims
of Physics
123
Michael Grodzicki
Department ofChemistry andPhysics
of Materials
SalzburgUniversity
Salzburg, Austria
ISBN978-3-030-74578-3 ISBN978-3-030-74579-0 (eBook)
https://doi.org/10.1007/978-3-030-74579-0
Translation from the German language edition: Physikalische Wirklichkeit – Konstruktion oder
Entdeckung?,©LivingEdition/STARNA2015.AllRightsReserved.
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Preface
Physics owes its numerous practical successes largely to the fact that it seg-
regated from its philosophical roots during the seventeenth century and sub-
sequently developed a self-contained, generally accepted methodology. The
preoccupation with questions about this methodology and the legitimacy of
its foundations (“meta”-physics), as well as considerations about the struc-
ture of physical knowledge, are not a prerequisite for gaining and producing
physicalknowledge,andareconsideredasunnecessaryballastbymanywork-
ing physicists. However, for anybody who has to teach physics (whether at
school, university, or any other educational establishment), these issues can-
not be ignored if an appropriate view of physics and its methodology is to
be imparted which represents a more current understanding. This concerns
primarily the following issues:
• Factualknowledge:whatisaphysicallaw(constitutiveproperties,method-
ological function) and what is a physical theory (structure, function)?
• Procedural knowledge: what are the characteristic features of physical
methodology, in particular, whose methods can be used to obtain struc-
tured, secured, and reality-relevant knowledge?
• How can the relations between theory and experience be described in an
appropriate fashion?
• What are the aims of physics?
Thereisnogeneralagreementamongphysicistsconcerningtheseissues,most
likely because these problems are rarely discussed in physics. Rather the
competence to study and to answer these questions is generally claimed by
philosophers of science. Nevertheless, they have not yet succeeded in devel-
oping an authoritative conception of theory which provides an appropriate
description of the structure of physical theories, and nor have they provided
an adequate representation of the relationships between theory and experi-
ence.
It is precisely for this reason that this book has come about. In the early
1980s, I started to hold seminars on the methodology of physics that supple-
v
vi Preface
mented my courses on theoretical physics, primarily for future high-school
teachers. A search of the available literature about the structure of phys-
ical theories and the relationships between theory and experience did not
yield material relevant to physics, so I was forced to develop my own ideas
abouttheoreticalconceptformation,thestructureofphysicalknowledge,and
the objectives of physics. Initially planned merely as material for the semi-
nar talks with the students, it eventually became a detailed treatise on the
methodological issues of physics. Due to this historical origin, the book is
a combination of textbook and original contributions. The third and fourth
chapters in particular contain material that cannot be found in the available
literaturetothebestofmyknowledge.Thesechaptersarebasedalmostexclu-
sively on concrete examples from physics taken directly from my lectures on
theoretical,molecular,andsolidstatephysics.Theseexampleseitherprovide
the starting point for the derivation and discussion of more abstract issues,
or elucidate the general conclusions. Moreover, this extensive use of concrete
examplesfromphysicsshowsthatathoroughunderstandingofphysicallaws
and theories and of the relationships between theory and experience cannot
be acquired via formal considerations, as is usually attempted in philosophy
of science.
Although there are several connections with philosophical considerations,
this book is definitely about the issues of physics itself. It is the translation
of the German edition (Physikalische Wirklichkeit – Konstruktion oder En-
teckung?), which was edited in 2015 by the publishing house Living Edition,
Starna GmbH. Note that translations of quotes from other sources are also
my own.
Duetothepositiveresonanceamongstudentsandcolleagues,Iwasencour-
aged to prepare an English translation in order to make the text available to
abroaderaudience.Inthiscontext,myspecialthanksgotomyeditorAngela
Lahee at Springer and also to Stephen Lyle for his assistance in improving
the style and occasionally clarifying ambiguous formulations.
University of Salzburg, Michael Grodzicki
February 2021
Contents
1 The World View of Physics I: Presuppositions ............ 1
1.1 Introduction ........................................... 1
1.2 Constructive Realism ................................... 6
1.3 Factual Knowledge: The Structure of Bohr’s Theory ........ 15
1.4 Procedural Knowledge: The Method of Consistent Adjustment 23
1.5 The Evolution of Thought Patterns....................... 27
1.6 Tacit Assumptions...................................... 31
References ................................................. 40
2 Methodology of Physics .................................. 43
2.1 Scientific Methodology .................................. 43
2.2 Empirical Basis ........................................ 54
2.3 Experimental Methodology .............................. 65
2.4 Empirical-Inductive Methodology......................... 75
2.5 Theoretical Concept Formation........................... 87
2.6 Theoretical Orders...................................... 98
2.7 Modeling .............................................. 109
References ................................................. 119
3 The Structure of Physical Theories ....................... 121
3.1 Descriptive Theories .................................... 121
3.2 Formation of Hypotheses ................................ 135
3.3 Explanatory Theories ................................... 149
3.4 Axiomatization......................................... 169
3.5 Unification ............................................ 184
References ................................................. 201
4 Theory and Experience ................................... 203
4.1 The Structure of Physical Knowledge ..................... 203
4.2 Physical Laws.......................................... 212
4.3 Theory–Experiment Comparisons......................... 223
vii
viii Contents
4.4 The Duhemian Theses .................................. 234
4.5 Consistent Adjustment: Examples ........................ 245
4.6 Consistent Adjustment: Methods ......................... 253
References ................................................. 265
5 The World View of Physics II: Implications............... 269
5.1 Aims of Physics ........................................ 269
5.2 The Problem of Causality ............................... 281
5.3 Explanation and Prediction.............................. 291
5.4 The Problem of Truth................................... 301
5.5 Physical Reality........................................ 315
References ................................................. 332
Chapter 1
The World View of Physics I:
Presuppositions
Thebasicrequirementsforanappropriaterepresentationofthepropertiesof
physicalmethodsandknowledgearebrieflydescribed,andshowntobeindis-
tinctcontrasttoempiricistviews.Acomprehensiveunderstandingofphysics
requires one to include metaphysical and sociological elements in addition to
factual and procedural knowledge. The philosophical basis of physics is de-
fined as a “constructive realism” that is subsequently specified and extended
by a number of implicit or “tacit” assumptions. A preliminary explication
of the conception of a theory is exemplified by Bohr’s theory. The method
of consistent adjustment, which is of crucial importance to understanding
the relations between theory and experience, is elucidated using a simple
mathematical example.
1.1 Introduction
Since the foundations of physics as a mathematical natural science were laid
in the seventeenth century, the achievements of science have exerted an ever
increasing influence on our view of the world. In establishing the scientific
world view, physics has played the leading role, and it still does, irrespective
of the developments in other branches of science. Firstly, the most striking
indications are the directly perceptible technical advances based on physical
knowledge.Secondly,physicsprovidesthebasisformostoftheothernatural
sciences and influences them accordingly. Finally, the methods of working
and reasoning in physics are regarded as paradigmatic for the scientific at-
titude and rationality. As a result, these methods do not just establish the
standard view of scientific methodology, but also constitute the basic pat-
tern for numerous modes of thinking and working in extra-scientific areas.
Consequently,thesemethodsareappliedtoissuesforwhichtheywerenotde-
velopedandarenotwellsuited.Thishasattractedcriticismwhichisjustified,
at least partially, because such applications are frequently based on concep-
The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 1
M. Grodzicki, Physical Reality – Construction or Discovery?,
https://doi.org/10.1007/978-3-030-74579-0_1
2 1 TheWorld ViewofPhysics I:Presuppositions
tions of physical methodology dating back to the seventeenth and eighteenth
centuries and do not even properly accord with the methodology of classi-
cal physics. Certainly, the most widespread prejudice is that (experimental)
experience in relation to theory has the distinct priority in the process of
gaining and corroborating physical knowledge, as shown by representative
textbook citations:
Observingnatureonesoonarrivesattheinsightthatitisgovernedbystrictly
valid laws. [...] In physics one attempts to read out of experiences relations
ofasgeneralaspossibleimportance,andthensinglelawsbeingvalidwithina
subareatoassembletoawholesystemwithoutleavingagaporcontradiction.
[...]Theexperimentallyobtainedfactsareuntouchableforthephysicistasfar
astheappliedobservationalprocedurewithstandsallcriticism.Atheorymust
bechangedassoonasasinglesecuredexperimentisincontradictionwiththis
theory. [...] Fundamental physical laws can be extracted from nature only by
observation(Fleischmann1980).
[Physicalaxioms]areempiricalfundamentallawswhosecorrectness[...]emerges
solelyfromimmediately givenfacts(Stroppe1981).
Newton’s equations [...] were initially empirical formulations of immediately
observablequantities(Dransfeldetal.1974).
[Physical axioms] emerge as generalization of a finite number of observations.
[...]Anaturallawonceestablishedcanberefuted(falsified)byasingleobser-
vationorasingle experiment(Fließbach1996).
Experimentisthe solejudgeofscientifictruth(Feynman etal.1964).
Physics is an experimental science. Everything we know about the physical
world and about the principles that govern its behaviour has been learned
throughexperiment,thatis,throughobservationsofthephenomenaofnature.
The ultimate test of any physical theory is its agreement with experimental
observations(Searsetal. 1987).
Theviewofphysicsemergingfromthesequotationsisasfollows.Physicsisan
empiricalsciencebecauseobservationsandexperimentsarethesole,trustwor-
thy source of knowledge and the sole criterion for corroborating theoretical
results. Nature is governed by strictly valid laws (“natural laws”) discovered
throughcarefulobservationofnatureorbygeneralizationofdirectlyaccessi-
ble facts. The physicist “asks” nature and obtains unequivocal answers that
may, in principle, be scrutinized by any other person. As the aggregation of
these laws, physical theories are void of speculative and subjective elements,
so that physical knowledge is objective and value-free. Neither the histori-
calprocessofacquiringknowledgenorindividual,social,oreconomicfactors
play any role.
Amodernphilosophicalcounterpartofthisconceptionisneopositivismor
logical empiricism (Haller 1993), developed during the 1920s. Understanding
itself as an empiricism supplemented with the results of modern logic, it is
characterized by the following assumptions: