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Ernst Mach

Mach apologizcd in a lcttcr datcd July 21, 1914: “Your telegram camc yesterday cvening and your card today. l'm sorry that it was no longer possiblc for mc to arrange my departure. You and Dr. Dinglcr must aefinitely discuss the matter at your leisurc."

The war brokc out and Petzoldt nevcr saw Ernst Mach aga i n.⁶¹ Later hc believed that hc could havc talkcd Mach into acccpting the theory of rcladvity if in fact hc did not already acccpt it at that timc.^0ł In arguing this way, hc blamcd Ludwig Mach for bcing ovcrly protcc-uve with rcspect to his father, and hc appealed to the foliowing letter from Ernst Mach, dated scvcral wceks later, which expresscd disap-pointment that Petzoldt had bcen unablc to visit him: "When 1 asked my son whether he had bcen ablc to mcct you, he told me that you had uncxpectcdly departed ...lam very sorry that you lcft without visiting me. I wanted to say something to you.” ⁰⁵

This letter stiongly suggested to Petzoldt that cithcr Ludwig or Ernst Mach had not bcen telling the truth. Petzoldt condudcd that it was Ludwig Mach.⁰⁶ From our pcrspcctivc too much has remained con-ccalcd to givc a finał answer. Noncthclcss, we might do wcll to kccp in mind that Joseph Petzoldt was already publicly committed to link-ing Mach with Einstcin's theory of rclativity, and in this sense had a vcstcd interest in the matter, that Ernst Mach was willing to go to great lcngths not to alienate influcntial parciał allics such as Joseph Petzoldt, and that Ernst Mach’s only known attacks spccifically dircctcd against Einstcin’s theory of rclativity (he ncvcr criticizcd Einstein by name) wcrc both published posthumously under the super-vision of Ludwig Mach. In other words, thcrc is cnough evidcncc to raisc suspicions against the vcracity of all thrcc men, but not cnough evidencc cither to settle the matter or to justify undermining the repu-tation of any of thcsc able and wcll-intcntioncd gcntlcmen. Let it suf-fice for our purposes simply to mention that a problem docs exist, namcly, whether Mach acccpted, or was vulnerable to bcing pcrsuaded to acccpt, the theory of relativity during latc 1913 and carly 1914, and the jury is still out on the entire situation, induding the vcracity of the participants.

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All the meager c.videncc available from latc 1914 until MadTs dcath a year and a half later has suggested that hc continucd to opposc Ein-

stcin’s theory. Thrcc letters from Mach to Petzoldt in the fali of 1914 emphasized Mach’s rcspcct for Hugo Dinglcr, and again, Petzoldt was requested to talk to Dingler."⁷ Ludwig Mach in his foreword to the ninth cdition of his fathcr’s Science of Mcchunics (1933) rcmcmbcrcd: “I [Ludwig Mach] can only refer to the situation as it cxistcd at the end of 1915 and only in so far as his writings on the subject arc avail-ablc to mc. ... ‘I [Ernst Mach] do not consider the Newtonian Principles as complctcd and perfeer; yet in my old age, I can acccpt the theory of rclativity just as littlc as 1 can acccpt the existcncc of atoms and other such dogma.’ ’’^,itl

Our last piece of significant evidcncc comcs in a letter from Ćcnćk Dvorak dated August 19, 1915, clcarly in reply to one by Mach: "The best contcmporary physicists would agrec with you about the cxag-gerated speeulation, mass suggestion, and modish tendencics in modern physics.”

Six months later, during a luli on the Western Front, Ernst Mach died, to the end a pacifist who had hcard about the outbreak of World War I only belatedly, and who ncver commentcd on it, cithcr in public or in his known correspondencc/¹⁹

Paul Carus picturcd the crcmation ccremony in lasting chiaroscuro: "Lying amoug the branchcs of the fir-trees under which of latc he had loved to spend his timc, in his lcft hand his canc which was his faiih-ful companion for sutccn ycars, and on his head 3 laurcl wreath wovcn by the hands of his daughter, Professor Machs body was givcn to the flame in utter stillncss on the morning of February 22." "^J

XI

After the war was ovcr, Joseph Petzoldt, who was still trying to find a theoretical way to provc that the constancy of the \cIocity of light was “relatiYc,” continucd to publish books and articles emphasizing the elose epistemological and scicntific relation betwccn the ideas of Mach and Einstein.⁷¹ He was evcn able to add a rclativistic "after-word” to the 1921 cdition of Mach*s Mcchanics, which hc titled "1 hc Relation of Machs Ideas to the Theory of Rdatmiy."⁷²

lii carly 1914 Ludwig Mach had expressed his agreement with Petzoldt’s understanding and acceptancc of Einsteins theory of rela-tivity, but sometimc betwccn 1014 and 1919 hc turncd dccidcdly against it.⁷⁸ Ludwig Mach wrotc the following letter to Petzoldt from Augs

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