23.3. THE”CLASSIC”VIEWS(I):VONNEUMANN 363
23.3 The ”Classic” Views (I): von Neumann
ThesimplestanswerwasgivenbyvonNeumann,whourgesustofollowthechain
ofeventsintothebrainoftheobserver. Thedetectorisinasuperpositionof”red
light/greenlight”states,anditemitsphotonsinasuperpositionofthecorresponding
frequencies. Thephotonsreachtheretinaoftheobserver,andcertainneuronsare
leftinasuperpositionof excited/un-excited states. The messagefromthe retina
travelstothecerebralcortex;verylargecollectionsofneuronsarenowinquantum
superpositions,andthebrainremainsinsuchasuperpositionuntil,atsomepoint,a
sensationoccurs. Attheinstantofconsciousperception,theobserver,thedetector,
andeventheparticle,jumpintooneortheotherofthe”up/down,red/green”states.
WhatvonNeumannissuggestingisthathumanconsciousnesscausesthewave-
functionto”collapse,”withacertainprobablity,intooneoranotherofthepossible
neuralstates; thecollapseof thewavefunction occursduetothe awareness ofthe
observer. Itfollows,sincetheSchrodingerequationcannevercauseawavefunction
tocollapse(i.e. causeapurestatetogoto amixture),that thementalfunction
describedas”awareness”or”conciousness”cannotbedescribedbytheSchrodinger
equation;itisnotaphysicalprocessintheusualsense.
Thenotionthatthereissomethingspecialaboutconciousness,andthatitcannot
beexplainedbythedynamicallawsthatgovernallotherphysicalprocesses,isanath-
ematomostscientists. Itisreminiscentofvitalism;atheorywhichheldthatone
mustlookbeyondtheusuallawsofphysicsandchemistrytoexplaintheprocesses
whichoccurinlivingorganisms. Thistheorywas,ofcourse,longagodiscreditedby
spectacularadvancesinmolecularbiology.
Still,vonNeumann’sideashouldnotberejectedoutofhand.Philosophershave
arguedforcenturiesabouttheso-calledmind/bodyproblem,andthereexistsophisti-
catedargumentstotheeffectthat,e.g.,acomputerfollowingacomplicatedalgorithm
tosimulatesomeaspectofhumanbehaviorcanneveractually”understand”whatit
isdoing.^1 Intheabsenceofanywell-established”TheoryofConsciousness,”itisnot
entirelyobviousthatawarenesscanbeexplainedentirelyintermsofthedynamics
of moleculesobeyingtheSchrodingerequation. von Neumannarguesthat mental
processessimplycannotbeexplainedinthisway,duetotheabsenceofsuperimposed
mentalstates. His argument,although obviouslyradical, cannot be immediately
dismissed.
23.4 The ”Classic” Views (II): Bohr
NielsBohrs’view(a.k.a.”theCopenhagenInterpretation”)isthatthewavefunction
whichrepresentsthephysicalstateofamicroscopicobjectdoesnotrefertothestate
(^1) AfascinatingandrecentexpositionofthispointofviewisfoundinthebookShadowsofthe
Mind,byRogerPenrose.