Space, Time and the Limits of Human Understanding

524 Pages·2017·10.114 MB·English

by  Shyam Wuppuluri, Giancarlo Ghirardi (eds.)

T H E F R O N T I E R S C O L L E C T I O N
Shyam Wuppuluri
Giancarlo Ghirardi
(Eds.)
SPACE , TI M E
A N D TH E LI M ITS
OF HUM A N
U N DER STA N DI NG
Foreword by John Stachel and
Afterword by Noam Chomsky
123
THE FRONTIERS COLLECTION
Series editors
Avshalom C. Elitzur
Iyar The Israel Institute for Advanced Research, Rehovot, Israel
e-mail: [email protected]
Laura Mersini-Houghton
Department of Physics, University of North Carolina, Chapel Hill,
NC 27599-3255, USA
e-mail: [email protected]
T. Padmanabhan
Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, India
e-mail: [email protected]
Maximilian Schlosshauer
Department of Physics, University of Portland, Portland, OR 97203, USA
e-mail: [email protected]
Mark P. Silverman
Department of Physics, Trinity College, Hartford, CT 06106, USA
e-mail: [email protected]
Jack A. Tuszynski
Department of Physics, University of Alberta, Edmonton, AB T6G 1Z2, Canada
e-mail: [email protected]
Rüdiger Vaas
Center for Philosophy and Foundations of Science, University of Giessen,
35394 Giessen, Germany
e-mail: [email protected]
THE FRONTIERS COLLECTION
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⋅
Shyam Wuppuluri Giancarlo Ghirardi
Editors
Space, Time and the Limits
of Human Understanding
123
Editors
ShyamWuppuluri Giancarlo Ghirardi
R. N.PodarSchool(CBSE) Abdus Salam International Centrefor
PodarEducational Complex TheoreticalPhysics
Mumbai Trieste
India Italy
ISSN 1612-3018 ISSN 2197-6619 (electronic)
THEFRONTIERS COLLECTION
ISBN978-3-319-44417-8 ISBN978-3-319-44418-5 (eBook)
DOI 10.1007/978-3-319-44418-5
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Vox audita perit litera scripta manet,
The thing heard perishes but the written
word remains
—Latin Maxim.
Foreword
First of all, let me thank Mr. Shyam Wuppuluri for his years of effort devoted to
inspiring,assembling,andeditingthisvolume.Ratherthanattemptingtocomment
onthepapersinit,Ishalltrytooutlinemyapproachtosomeissuesthatthereader
may find helpful to bear in mind when reading these papers. Unfortunately, the
concepts needed to discuss these issues are so interrelated that I have not found it
possibletoprovideasimple,sequentialintroductiontotheseconcepts.Indeed,they
are inextricably intermingled in my presentation.
Everyhumancommunityisbasedonaninterrelatedcomplexoflaborprocesses
that enable the community not just to survive but that, if successful, enable it to
grow and thrive. Each such labor process involves three elements: the labor of a
group of people using some tools to act upon the initial objects of labor (the “raw
materials”). The goal of this process is action upon these initial objects in such a
way as to produce final objects (the “finished products”) that will benefit at least
some members of the community.
But not all tools and initial objects are external to the members of the com-
munity. Language—and other symbolic systems that language enables people to
create—allows them to form conceptual systems, some of which in turn become
intellectual tools that can be used to modify the initial conceptual systems and to
create new ones.
Inother words, notall labor need tobe manual.Justasimportant is intellectual
labor. Like all forms of labor, intellectual labor starts from some object—in this
caseaconceptualobject—andworksonthisobjectwiththeaimofmodifyingitto
produceanewconceptualobject(seemypaper“ProblemsnotDisciplines”).There
aremanytypesofintellectualtools(art,literature,religion,etc.)butmostimportant
for the questions discussed in this volume are the scientific disciplines, including
boththeso-callednaturalandsocialsciences(bettercalledthehumansciences—the
Geisteswissenschaften in German).
Why include the social sciences? As in all other forms of labor, a successful
intellectuallaborprocessisultimatelytheresultofthecollectivelaborofmorethan
one individual: knowledge is our name for such results. Rather than being an
vii
viii Foreword
individual problem, as it has been treated in Western philosophy since the time of
Descartes, the problem of knowledge is a social problem (see my paper Where is
Knowledge?). And it should always be borne in mind that the ultimate goal of all
intellectual labor is to provide additional resources to some human community for
action upon the material world and, intended or not, to produce changes in the
community itself.
As noted already, in the case of intellectual labor the objects of labor are
complexesofconcepts;andthecollectivelaboractinguponthesecomplexesisthat
ofsomeintellectualcommunity.Whenitissuccessful,newknowledgeisourname
for theresultsofsuch aprocessof intellectuallabor. And it isimportanttobear in
mind that knowledge itself is indeed a process that will never end as long as
intellectual communities continue to exist. So one should be suspicious of any
proposed axiomatization of some realm of human knowledge, especially if it is
accompaniedbyclaimsoftheclosureofwhatshouldbeanopen,unendingprocess.
An important philosophical issue is the distinction between the conceptual
objects that constitute our knowledge and the objects of that knowledge, and the
relationbetweenthesetwo.Suchphilosophicaldoctrinesasconflictsasempiricism,
rationalism, naturalism, materialism and idealism depend on the answer to this
question. Suffice it to say that I regard the goal of action on the objects of
knowledge as primary. The introduction of a new conceptual object, or the modi-
fication of an existing one, must make clear its relation to some object(s) of
knowledge.Inthecaseofphysicalconcepts,suchasspaceandtime,thismeansthat
their definition must be accompanied by some account of the means by which an
ideal measurement of this quantity can be carried out.
Let me emphasize: I am not maintaining that it is meaningful because it is
measurable;ratherthatbecauseitismeaningfulitmustinprinciplebemeasurable.
No one has stated this lesson more eloquently than Gaston Bachelard:
In order to embody new experimental evidence, it is necessary to deform the original
concepts,studytheconditionsofapplicabilityoftheseconcepts,andaboveallincorporate
theconditionsofapplicabilityofaconceptintotheverymeaningoftheconcept.…The
classic division that separates a theory from its application ignores this necessity to
incorporatetheconditionsofapplicabilityintotheveryessenceofthetheory(Laformation
del’espritscientifique.Paris:Vrin.1938,pg.61;transl.byJ.S.).
Like all tools, intellectual tools themselves may become the object of a labor
process aimed at improving their effectiveness—indeed one tool may even be set
aside totally in favor of some new tool. The prime example is relation between
language, the first intellectual tool, and logic. Logic is a tool created for the
improvementoflanguagewhenitisappliedtocertainsubjects.Indeed,oneshould
rathersay“logics,”sincemorethanoneconsistentlogicalsystemmaybeemployed
in the critical reconstruction of a language. So one might say that logic is about
languageandlanguageisabouttheworld.Oftenthistwo-steprelationisreducedto
a one-step relation: logic is about the world—a view I have criticized for decades
[A]logicalwayshassomelanguageasitsobject.Themoreformalizedonewantsthelogic
tobe,themoreformalizedthelanguagemustbe.…Sincealogicpresupposesalanguage,
Foreword ix
theobjectslogicstudiesmustbelinguisticobjects.Ibelieveintheexistenceofotherobjects
whicharequiteindependentoflanguage;butsuchobjects,incontrast tolinguisticrefer-
encestothem,cannothavealogic.Lestthisbethoughtamereverbalquibble,letmepoint
out that someone who believed that all reality was fundamentally conceptual in nature
couldmeaningfullyandnon-metaphoricallyspeakofthelogicoftheworld.
Thedoctrinethatallrelationsarefundamentallylogicalrelationsandthatthereishenceno
basicdistinctionbetweenlogicandontologyisnotunknowninthephilosophicalliterature.
…Ithasevenbeengivenaname,“panlogism”…However,ifonedoesadoptthisposition,
it should be done with full awareness, and not tacitly through acceptance of a certain
approachtoquantumlogic”(excerptsfrom“DoQuantaNeedaNewLogic?”).
I maintain that, in this respect, mathematics is similar to logic. Mathematical
structuresdonotapplydirectlytotheworld,buttootherconceptualstructuresthat
have been created to apply to some aspects of the world. Again this two-step
relationisoftenshort-circuitedwiththeassertionthatmathematicalstructuresapply
directlytotheworld(seeWhereisKnowledge?).Inthecaseofphysicalstructures,
theeasiestwaytoseethefallacyofsuchanassertionisbylookingthequestionof
units.Inordertoquantifyanyphysicalconcept,asystemofappropriateunitsmust
be introduced; andit isonly theratio ofsome physical quantity toits unit that isa
pure number, and the usual mathematical relation between two such physical
conceptscanonlybeappliedtopurenumbers.Todefinethedistancebetween two
points,onemustfirstspecifysomeunitofdistance,andthenumerical valueofthe
distance between these points is then the ratio of that distance specified in these
unitsdividedbythisunitofdistance. Givenasetofsuchprimary units,secondary
unitsmaythenbecomputed.Forexample,inordertospecifythevelocityofsome
object one must divide a spatial distance by a temporal interval; so units of space
and time must first be specified.
Finally, let me turn to the concepts of space and time. If we now consider the
objects of the dynamical natural sciences, their objects themselves are processes
(e.g., mechanical, electromagnetic, quantum, etc.). As long as the Newtonian
worldview prevailed, it made sense to consider such processes as composed of a
sequence of states, one for each value of the absolute time. But with the advent
of the special theory of relativity, and even more the general theory of relativity, a
viewpointbasedonstatesisnolongertenable.Theprocessesareprimary;andany
introduction of a temporal sequence of states—to the extent that it is possible—is
quite secondary and dependent on additional definitions. A number of theoretical
physicists have emphasized the primacy of process, including Lee Smolin:
Relativitytheoryandquantumtheoryeach.tellus—no,better,theyscreamatus—thatour
worldisahistoryofprocesses.Motionandchangeareprimary.Nothingis,exceptinavery
approximateandtemporarysense.Howsomethingis,orwhatitsstateis,isanillusion.It
maybeausefulillusionforsomepurposes,butifwewanttothinkfundamentallywemust
notlosesightoftheessentialfactthat‘is’isanillusion.Sotospeakthelanguageofthenew
physicswemustlearnavocabularyinwhichprocessismoreimportantthan,andpriorto
stasis(ThreeRoadstoQuantumGravity.BasicBooks,2001).
x Foreword
Toputitanotherway,thefour-dimensionalconceptofspace–timeisprimary,its
possible division into three-dimensional space and one-dimensional time is quite
secondary and depends on the introduction of additional concepts.
What about time, the reader may object? Surely this is a primary concept. Here
onemustmakeadistinctionbetweentwoconceptsoftimethatareoftenconflated:
betweenwhatIhavecalledlocaltimeandglobaltime(see“AlbertEinstein:AMan
for the Millennium”). To clarify what I mean by the concept of the local time
betweentwoevents,Ioftendrawananalogybetweenthisconceptandtheconcept
of the spatial distance between two places. It is well known that the distance
between two different places depends on the spatial path between them. The
shortestdistanceisalongthestraightestpathbetweenthem.Thelocaltimebetween
two non-coincident events in space–time depends on the spatiotemporal path
between them. That is the analogy; the difference is that the longest local time
interval between thetwoeventsisalong thestraightest pathinspace–time has.As
alluded to above in the discussion of units, it is the local time that is measured by
clocks and the spatial distance that is measured by rulers (“measuring rods”).
Clearly, when one speaks of two non-coincident events as “taking place at the
sametime,”itcannotbetheconceptoflocaltimethatisinvolved.Indeeditishere
that the concept of global time enters the story. When the Newtonian worldview
prevailed, the additional concept of the absolute time provided such a definition
oftheglobaltime.Twonon-coincidenteventseitheroccurredatthesameabsolute
time or one preceded the other, and clocks measured this absolute time in a
path-independent way. Once the concept of absolute time was abandoned, clocks
measuredonlythepath-dependentlocaltime,andtwonon-coincidenteventsmight
ormightnotbeconnectedbyatemporalpath.Givenaninitialevent,alleventsnot
connectedtoitbyatimelinepathformanentireregionofspace–timethathasbeen
called the elsewhere of the event. The concept of global time amounts to some
definition of a three-dimensional slice of this four-dimensional elsewhere; and in
general nothing physically significant can depend on this definition.
The great divide between general relativity and all previous dynamical theories
isthattheywereallbasedonfixedandgivenspace–timestructures.Alldynamical
processes took place on the fixed and given stage provided by these structures. In
contrast, general relativity has no such fixed structures. All space–time structures
arethemselvesdynamicalentities,subjecttofieldequations.Sothatuntilasolution
to these field equations is specified, no answers to questions about space–time
structures can be given. As I have put it elsewhere: in all the rest of physics,
“where” and “when” are parts of the question; in general relativity, “where” and
“when” are parts of the answer.
I do not expect the reader to uncritically accept my viewpoint on these issues;
but hope that he or she will bear in mind the need for adopting some standpoint
about them when confronting many of the questions discussed in this volume.
John Stachel