the nineteenth century drew to a close； scientists could reflect with satisfaction thatthey had pinned down most of the mysteries of the physical world： electricity； magnetism；gases； optics； acoustics； kinetics； and statistical mechanics； to name just a few； all had falleninto order before them。 they had discovered the x ray； the cathode ray； the electron； andradioactivity； invented the ohm； the watt； the kelvin； the joule； the amp； and the little erg。
if a thing could be oscillated； accelerated； perturbed； distilled； bined； weighed； or madegaseous they had done it； and in the process produced a body of universal laws so weightyand majestic that we still tend to write them out in capitals： the electromagnetic field theoryof light； richter’s law of reciprocal proportions； charles’s law of gases； the law ofbining volumes； the zeroth law； the valence concept； the laws of mass actions； andothers beyond counting。 the whole world clanged and chuffed with the machinery andinstruments that their ingenuity had produced。 many wise people believed that there wasnothing much left for science to do。
in 1875； when a young german in kiel named max planck was deciding whether to devotehis life to mathematics or to physics； he was urged most heartily not to choose physicsbecause the breakthroughs had all been made there。 the ing century； he was assured；would be one of consolidation and refinement； not revolution。 planck didn’t listen。 he studiedtheoretical physics and threw himself body and soul into work on entropy； a process at theheart of thermodynamics； which seemed to hold much promise for an ambitious young man。
1in 1891 he produced his results and learned to his dismay that the important work on entropyhad in fact been done already； in this instance by a retiring scholar at yale university namedj。 willard gibbs。
gibbs is perhaps the most brilliant person that most people have never heard of。 modest tothe point of near invisibility； he passed virtually the whole of his life； apart from three yearsspent studying in europe； within a three…block area bounded by his house and the yalecampus in new haven； connecticut。 for his first ten years at yale he didn’t even bother todraw a salary。 （he had independent means。） from 1871； when he joined the university as aprofessor； to his death in 1903； his courses attracted an average of slightly over one student asemester。 his written work was difficult to follow and employed a private form of notationthat many found inprehensible。 but buried among his arcane formulations were insightsof the loftiest brilliance。
in 1875–78； gibbs produced a series of papers； collectively titledon the equilibrium ofheterogeneous substances ； that dazzlingly elucidated the thermodynamic principles of； well；1specifically it is a measure of randomness or disorder in a system。 darrell ebbing； in the textbook generalchemistry； very usefully suggests thinking of a deck of cards。 a new pack fresh out of the box； arranged by suitand in sequence from ace to king； can be said to be in its ordered state。 shuffle the cards and you put them in adisordered state。 entropy is a way of measuring just how disordered that state is and of determining thelikelihood of particular outes with further shuffles。 of course； if you wish to have any observationspublished in a respectable journal you will need also to understand additional concepts such as thermalnonuniformities； lattice distances； and stoichiometric relationships； but thats the general idea。
nearly everything—“gases； mixtures； surfaces； solids； phase changes 。 。 。 chemical reactions；electrochemical cells； sedimentation； and osmosis；” to quote william h。 cropper。 in essencewhat gibbs did was show that thermodynamics didn’t apply simply to heat and energy at thesort of large and noisy scale of the steam engine； but was also present and influential at theatomic level of chemical reactions。 gibbs’s equilibrium has been called “the principia ofthermodynamics；” but for reasons that defy speculation gibbs chose to publish theselandmark observations in the transactions of the connecticut academy of arts and sciences；a journal that managed to be obscure even in connecticut； which is why planck did not hearof him until too late。
undaunted—well； perhaps mildly daunted—planck turned to other matters。
2we shall turnto these ourselves in a moment； but first we must make a slight （but relevant！） detour tocleveland； ohio； and an institution then known as the case school of applied science。 there；in the 1880s； a physicist of early middle years named albert michelson； assisted by his friendthe chemist edward morley； embarked on a series of experiments that produced curious anddisturbing results that would have great ramifications for much of what followed。
what michelson and morley did； without actually intending to； was undermine alongstanding belief in something called the luminiferous ether； a stable； invisible； weightless；frictionless； and unfortunately wholly imaginary medium that was thought to permeate theuniverse。 conceived by descartes； embraced by newton； and venerated by nearly everyoneever since； the ether held a position of absolute centrality in nineteenth…century physics as away of explaining how light traveled across the emptiness of space。 it was especially neededin the 1800s because light and electromagnetism were now seen as waves； which is to saytypes of vibrations。 vibrations must occur in something； hence the need for； and lastingdevotion to； an ether。 as late as 1909； the great british physicist j。 j。 thomson was insisting：
“the ether is not a fantastic creation of the speculative philosopher； it is as essential to us asthe air we breathe”—this more than four years after it was pretty incontestably establishedthat it didn’t exist。 people； in short； were really attached to the ether。
if you needed to illustrate the idea of nineteenth…century america as a land of opportunity；you could hardly improve on the life of albert michelson。 born in 1852 on the german–polish border to a family of poor jewish merchants； he came to the united states with hisfamily as an infant and grew up in a mining camp in california’s gold rush country； where hisfather ran a dry goods business。 too poor to pay for college； he traveled to washington； d。c。；and took to loitering by the front door of the white house so that he could fall in besidepresident ulysses s。 grant when the president emerged for his daily constitutional。 （it wasclearly a more innocent age。） in the course of these walks； michelson so ingratiated himself tothe president that grant agreed to secure for him a free place at the u。s。 naval academy。 itwas there that michelson learned his physics。
ten years later； by now a professor at the case school in cleveland； michelson becameinterested in trying to measure something called the ether drift—a kind of head windproduced by moving objects as they plowed through space。 one of the predictions ofnewtonian physics was that the speed of light as it pushed through the ether should vary with2planck was often unlucky in life。 his beloved first wife died early； in 1909； and the younger of his two sonswas killed in the first world war。 he also had twin daughters whom he adored。 one died giving birth。 thesurviving twin went to look after the baby and fell in love with her sisters husband。 they married and two yearslater she died in childbirth。 in 1944； when planck was eighty…five； an allied bomb fell on his house and he losteverything…papers； diaries； a lifetime of accumulations。 the following year his surviving son was caught in aconspiracy to assassinate hitler and executed。
respect to an observer depending on whether the observer was moving toward the source oflight or away from it； but no one had figured out a way to measure this。 it occurred tomichelson that for half the year the earth is traveling toward the sun and for half the year it ismoving away from it； and he reasoned that if you took careful enough measurements atopposite seasons and pared light’s travel time between the two； you would have youranswer。
michelson talked alexander graham bell； newly enriched inventor of the telephone； intoproviding the funds to build an ingenious and sensitive instrument of michelson’s owndevising called an interferometer； which could measure the velocity of light with greatprecision。 then； assisted by the genial but shadowy morley； michelson embarked on years offastidious measurements。 the work was delicate and exhausting； and had to be suspended fora time to permit michelson a brief but prehensive nervous breakdown； but by 1887 theyhad their results。 they were not at all what the two scientists had expected to find。
as caltech astrophysicist kip s。 thorne has written： “the speed of light turned out to bethe same inall directions and at all seasons。” it was the first hint in two hundred years—inexactly two hundred years； in fact—that newton’s laws might not apply all the timeeverywhere。 the michelson…morley oute became； in the words of william h。 cropper；“probably the most famous negative result in the history of physics。” michelson was awardeda nobel prize in physics for the work—the first american so honored—but not for twentyyears。 meanwh