IMG63

Ernst Mach

‘'mcchanical" explanation to a mcrc affair o£ scnsations, idcas, and numbcrs. Both Mach and Popper-Lynkcus wcrc strongly intlucnced by PylMajrcr's idcas on thermodynamics.¹⁵ Mayer, likc Mach, oppmed -_ln_

/ fcrencc bcyond the appcarances: "the attempt to pcnctratc by hypoth-eses to the inner rcccsscs of the world order is of a piece with the efforts of the alchcmists.” ¹⁶

Since the cflicicncy of steam engines working betwccn the same temperaturę levcls had bccn presumed to be the same (i.c., sińce Sadi Carnot), “irrcspcctivc of their modę of operation or the materiał used to transport the hcat and do work," many phenomcnalistically and idcalistieally inclined physicists supposcd that theory of hcat, ihat is, thermodynamics, could be dcvclopcd without any rcfercncc at all to materiał particlcs or mcchanistic “force" explanation. Thermodynamics had no need of “atomistic hypothcscs." It was a "purc” science bascd only on observation, expcrimcnt, and generał laws. It was a truć “posi-tivistic” science. Indced, thcrc arc still physicists today who retain and advocatc ideals of this sort.

A most telling argument against the kinctic theory of gases as dc-veloped up to that time came from Boltzmann’s friend, Loschmidt (1876, 1877), who suggested that sińce all mechanical motion was supT posed to be rcversible and entropy was not rcvcrsiblc, thereforc, ncither hcat nor entropy consistcd of mechanical motion. This rcasoning sup-ported Mach’s attempt to restrict the scope of mcchanics and to “frcc" hcat and optical theory from the notions of "atoms” and “molccules.” Also, if cvcry rcal process contained irrevcrsiblc components and all mechanical motion were revcrsible, then mcchanics was confincd to indircct dcscription of naturę, and hencc, should be considered less scientific than dircct phenomenalistic thermodynamics. Mach speeulated further that the sccond law of thermodynamics, far from mcasuring time, was itself a definition of time.

Ludwig Boltzmann was not prepared to mect speculative and philo-sophical objections at this time, but in 1877, through mathcmatical and statistical reasoning, hc appeared to mect the objections of Loschmidt. Bohzmann argued that the irreversibility of entropy Dow was mercly a statistical probability of what was to be cxpected of a hugc number of particlcs. The entropy of individual particlcs of the group, howcvcr, might vcry wclj dccrcasc rather than inerease, and hencc, heat might iruJccrl consist of the mechanical motionsof atorns and molccules.

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Bul Boltzmann was plowing a field of dragons teeth wiih scientific and philosophical opponents sprouting up cvcrywhcrc. Mach in 1872, Gustav Kirchhoff in 1874, and Richard Avcnarius in 1876 alfvoiccd a major philosophical objcction. Thcy argucd that science should de-,/ scribc and relate ihc appearanccs in ihc simplcst way possiblc, and M.ich kept hammering homclKc point that the atomie theory was notf * the simplcst way to dcscribc and relate the appearanccs, and that a simplcr approach was nccdcd.    —■—\

Wilhelm Ostwald sccmcd to find that approach in the early 1890S with his philosophy of energeticism. He attempted to substitute the notion of “cnergy" for that of discretc "ultimatc” particles such as atonis and molccules. Many physicists acccptcd this philosophy as in-troducing a gcnuinc simplification.¹⁷

Boltzmann was now up against the wali. It had becomc obvious that if he was to refute his opponents and succcssfully defend his kinctic theory of gases he would havc to learn cnough philosophy to mect and vanquish his opponents on their own grounds. Could a middlc-agcd physicist who dislikcd philosophy tum the trick? It was quitc a challenge. But was he simply too late?

How Mach’s situation had changed! As a refugee from “atomistic Vicnna” in 1864 with fcw if any physicist allies he had now twenty years latcr found numerous fcllow “antiatomists." Opposition to atom-ism was once again coming into fashion, at least within physics. But why? Was it the disappointingly slow progress of the atom-bascd physics of Ilclmholtz and Du Bois-Rcymond? Was it the rcvival of neo-Kantianism under Friedrich Lange which mcrely condescendingly acceptcd a watered version of atomism within the scopc of his form of “scientific” phenomenalism? Was it the result of a camouflaged return to Natnrphilosophie? Or was it the search for a ncw approach in the face of frustrating complexitics?

We do not know the answer, but if there was a single turning point in physics which symbolized this fin-de-siccle opposition to atomism it was the publication of Ernst Mach's The Science of Mcchanics in 1883. Ilcnceforth, the tide increasingly sccmed to run against Boltz mann. There is every cvidence, however, in spite ot the growing ser iousness of the philosophical confrontation between Mach and the harassed atomist, that both men continued to remain on good pcrsonal terms. Nonethclcss, Boltzmann had an c.\pression for Mach; he caited