Bodies and Media: On the Motion of Inanimate Objects in Aristotle’s Physics and On the Heavens

130 Pages·2015·2.25 MB·English

by  Ido Yavetz (auth.)

SPRINGER BRIEFS IN HISTORY OF SCIENCE
AND TECHNOLOGY
Ido Yavetz
Bodies and Media
On the Motion of
Inanimate Objects
in Aristotle’s
Physics and
On the Heavens
123
SpringerBriefs in History of Science
and Technology
More information about this series at http://www.springer.com/series/10085
Ido Yavetz
Bodies and Media
On the Motion of Inanimate Objects
’
in Aristotle s Physics and On the Heavens
123
Ido Yavetz
CohnInstitute for History of Science
andIdeas
TelAviv University
TelAviv
Israel
ISSN 2211-4564 ISSN 2211-4572 (electronic)
SpringerBriefs inHistory ofScience andTechnology
ISBN978-3-319-21262-3 ISBN978-3-319-21263-0 (eBook)
DOI 10.1007/978-3-319-21263-0
LibraryofCongressControlNumber:2015943847
SpringerChamHeidelbergNewYorkDordrechtLondon
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Foreword
The purpose of this essay is to present a theory of the motion of inanimate bodies
based exclusively on principles laid down by Aristotle in his Physics and On the
Heavens.Astheintroductionwillexplainingreaterdetail,thereisnopretensehere
to capture the definitive reconstruction of Aristotle’s theory of bodies in motion—
animpossibletaskinmyopinion,giventheinformationwecurrentlypossess.Itis,
however, a plausible reconstruction, albeit not the only one possible. The essay is
meantprimarilyforhistoriansofscienceinterestedintheevolutionofphysicsfrom
antiquity to the scientific revolution of the seventeenth century, and to students of
Aristotle’s natural philosophy. In order to keep a sharp focus on Aristotle’s texts,
andtoremainwithintheusefulformatoftheSpringerBriefsSeries,discussionsand
references that pertain to the vast literature on Aristotle’s natural philosophy have
been cut down to a bare minimum.
Initial motivation forthisprojectoriginatedinagraduateseminar Igavejointly
withProf.RivkaFeldhayonGalileo’sDeMotuattheCohnInstituteforHistoryand
Philosophy of Science and Ideas in Tel Aviv University. In his De Motu, Galileo
attempted to formulate principles of locomotion irrespective of more general ideas
regarding natural change. Aristotle’s Physics discusses nature as the realm of all
material changes, of which locomotion is but one form. On the Heavens discusses
aspects of locomotion to the extent that they pertain to general cosmology.
Aristotle’s surviving works do not contain a separate treatise dedicated to locomo-
tionalone.Bycontrast,Galileo’sstudyofterrestrialmotion,fromtheDeMotutoits
finalevolvedformintheDiscoursesonTwoNewSciences,revealsnointerestinthe
wider scope of Aristotle’s terrestrial natural philosophy. Instead, he developed a
theoryoflocomotionforitsownsake.However,inthecourseofformulatinghisown
ideas, he found numerous occasions to comment at length on various aspects of
Aristotle’stheory oflocomotion. Onsome ofthese occasions, Galileo’s comments
vii
viii Foreword
seemed to us either misguided, or somewhat careless, or not representative of a
decent interpretation of Aristotle’s texts as we currently know them. The more we
discussed these issues in the seminar, the clearer it became that before we could
properlyaddressGalileo’sremarks,weneededtodevelopourownunderstandingof
Aristotle’s theory of locomotion. This resulted in an outline for a theory of loco-
motion with fair capacity to account for a large class of locomotive phenomena,
often in mathematical form that Aristotle’s own text indicates. Viewed from this
theoretical perspective, Galileo’s law offree fall remains a highly original contri-
bution, exposing connections between basic Aristotelian parameters that were pre-
viouslytreatedasindependentwithinthetheory.Itisnot,however,aprinciplethat
requireswholesaleabandonmentoftheAristoteliantheory.Infact,itcanbeseenasa
great new discovery that refines the theory’s ability to account for locomotive
phenomena.
Developmentoftheideasthatgerminatedduringthejointseminarwasaidedby
discussionswithasmallgroupofscholarsandstudentsattheMinervaHumanities
Center’s project on migrating knowledge at Tel Aviv University, headed by Prof.
Feldhay, to whom I owe my first gratitude. Without her constant encouragement
and support this essay would never have developed beyond my lecture notes and
PowerPoint presentations. Particular thanks go to Dr. Michael Elazar, for his
endless patience and constructively critical examination of this essay’s various
aspects.Dr.IvorLudlumhelpedwithsomedifficultiesinvolvingAristotle’sGreek,
and Appendix B on the threshold of motion in time would not have been possible
without Mr. Avi Aroesti’s generous help.
Final shaping of the understandings gained during these years into the present
essay was made possible by two scholarships at Department 1 of the Max Planck
InstitutefürWissenschaftsgeschichteinBerlin,undertheleadershipofProf.Jürgen
Renn, to whom I am indebted for this opportunity. Professor Matteo Valleriani of
Department 1 read the entire manuscript, and suggested many useful corrections
andimprovements.IhavealsobenefittedfromDr.JoycevanLeeuwen’sextensive
familiarity with the pseudo Aristotelian Mechanical Problems. At an advanced
stage,selectaspectsofthisworkwerepresentedattheExcellenceClusterTOPOIin
Berlin. I thank the informed audience I met there for the relevant feedback.
Contents
1 The Three Levels of Aristotle’s Theory of Material Bodies
in Forced Motion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Level 1: The Basic Relationship Between Mover, Load, and Speed. . . 1
Level 2: The Medium and Resistance to Motion . . . . . . . . . . . . . . . . 6
Level 3: Why Motion Persists After the Initial Moving Cause
Has Been Removed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2 Heaviness, Lightness, Sinking and Floating . . . . . . . . . . . . . . . . . . 15
Summary: The Main Features of Aristotle’s Theory of Terrestrial
Locomotion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3 Some Refinements of the Basic Theory . . . . . . . . . . . . . . . . . . . . . 29
The Threshold of Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Segments of Time, Instants of Time, and the Concept of Speed. . . . . . 31
Formal and Dynamical Objections to Motion of Unlimited Extent . . . . 34
Reversal of Motion and Collisions. . . . . . . . . . . . . . . . . . . . . . . . . . 36
Heaviness, Lightness, and “the Dense Is Heavy
and the Rare Light”. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
The Geometry of Heaviness: On Projectiles that Reach
Peak Speed at Midflight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4 The Dynamics of Balance: The Winch and the Lever
in the Pseudo Aristotelian Mechanical Problems. . . . . . . . . . . . . . . 55
How to Balance a Winch Using Aristotle’s Physics, VII.V . . . . . . . . . 55
The Winch in the Pseudo-aristotelian Mechanical Problems. . . . . . . . 59
ix
x Contents
5 Hipparchus on the Theory of Prolonged Motion . . . . . . . . . . . . . . 67
Appendix A: Do Heavy Objects Become Heavier as they
Approach Their Natural Place?. . . . . . . . . . . . . . . . . . . 71
Appendix B: A Threshold of Motion in Time, as well as in Force? . . . 73
Appendix C: A Mathematical Formulation of Aristotle’s
Theory of Forced Horizontal Motion. . . . . . . . . . . . . . . 81
Appendix D: A Mathematical Formulation of Aristotle’s
Theory of Natural and Forced Vertical Motion . . . . . . . 85
Appendix E: A Mathematical Formulation of Hipparchus’s
Theory of Vertical Motion. . . . . . . . . . . . . . . . . . . . . . . 91
Appendix F: Alternative Translations of the Quotations Used
in the Main Text. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117