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Ernst Mach

if one merely sceks a convcnient symbolic tool, and not understanding, much less a common sense interpretation, then that should sufticc. Bohr and Heiscnbcrg may havc thought their interpretation permanent, but even if one is inclined to doubt this, one should not confusc either their mcthodological narrowness or any kind ot “physical mcaning” with the mathcmatical system itsclf. The latter will surcly be cxtendcd and perhaps sonie of its multidimensional geometry moclified or abandoncd, but total revision is probably much less likcly than for “the thousand ycar Copcnhagcn interpretation" itsclf.

Planck argued “By their fruits ye shall know them,” but should the currcnt “physical meaning” of quantum theor-y be blamcd on Ernst Mach? Or perhaps even on Max Planck himself? Or has this particular fruit rotted only sińce its stay in Dcnmark? Ilamlct wondered “to be or not to be," a vcry profound qucstion. Niels Bohr and Polonius Heiscnbcrg have laborcd long and skillfully to find a solution. But in spite of all their mathcmatical and methodological wisdom is particle-wavc duality really the finał answer?

A ppendix

DID MACH FINALLY ACCEPT THE REAL1TY OF ATOMS?

Until 1950 it was gcncrally belicvcd that Mach ncvcr altcrcd his op-position to the reality of atoms. Many pcoplc tried to persuade him, but hc would always answer: “Havc you seen one¹” And that ended the discussion.¹ But Stefan Meyer, a former assistant of Boltzmann, published an article in that year in which hc elaimed to have been present when Mach changed his mind 3nd acccpted the reality of atoms.

According to Meyer, shortly after the invention of the spinthariscope, an instrument that detccted alpha ray scintillations, hc invitcd Ernst Mach, who was then retired, to tako a look through tiie instrument and judge the reality of what hc saw for himself. Mach entered the darkened room and then leoked at the scrcen. Stefan Meyer continucd: “It remains one of my most striking remcmbranccs, when Mach after the introduction of the spinthariscope did not make obstinatc objcc-tions, but simply dcclared: 'Now I bclicvc in the e.sistcnce of atoms.' An entire world vicw had changed in a fcw minutes.""

Did Mach rcally change his mind? In the rest of this appcndix I marshal evidcnce pro and eon and then add my own analysis and eon clusion.

To help corroborate Meycr's story I have tried to contact pcoplc who knew him. This is part of a letter from a wcll-known Yiennesc scicntist, Karl Przibram:

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