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ages have to be historical； apparently； as it takes the atomssome decades to bee thoroughly redistributed； however much you may wish it； you arenot yet one with elvis presley。）so we are all reincarnations—though short…lived ones。 when we die our atoms willdisassemble and move off to find new uses elsewhere—as part of a leaf or other human beingor drop of dew。 atoms； however； go on practically forever。 nobody actually knows how longan atom can survive； but according to martin rees it is probably about 1035years—a numberso big that even i am happy to express it in notation。
above all； atoms are tiny—very tiny indeed。 half a million of them lined up shoulder toshoulder could hide behind a human hair。 on such a scale an individual atom is essentiallyimpossible to imagine； but we can of course try。
start with a millimeter； which is a line this long： …。 now imagine that line divided into athousand equal widths。 each of those widths is a micron。 this is the scale of microorganisms。
a typical paramecium； for instance； is about two microns wide； 0。002 millimeters； which isreally very small。 if you wanted to see with your naked eye a paramecium swimming in adrop of water； you would have to enlarge the drop until it was some forty feet across。
however； if you wanted to see the atoms in the same drop； you would have to make the dropfifteen miles across。
atoms； in other words； exist on a scale of minuteness of another order altogether。 to getdown to the scale of atoms； you would need to take each one of those micron slices and shaveit into ten thousand finer widths。 that’s the scale of an atom： one ten…millionth of amillimeter。 it is a degree of slenderness way beyond the capacity of our imaginations； but youcan get some idea of the proportions if you bear in mind that one atom is to the width of amillimeter line as the thickness of a sheet of paper is to the height of the empire statebuilding。
it is of course the abundance and extreme durability of atoms that makes them so useful；and the tininess that makes them so hard to detect and understand。 the realization that atomsare these three things—small； numerous； practically indestructible—and that all things aremade from them first occurred not to antoine…laurent lavoisier； as you might expect； or evento henry cavendish or humphry davy； but rather to a spare and lightly educated englishquaker named john dalton； whom we first encountered in the chapter on chemistry。
dalton was born in 1766 on the edge of the lake district near cockermouth to a family ofpoor but devout quaker weavers。 （four years later the poet william wordsworth would alsojoin the world at cockermouth。） he was an exceptionally bright student—so very brightindeed that at the improbably youthful age of twelve he was put in charge of the local quakerschool。 this perhaps says as much about the school as about dalton’s precocity； but perhapsnot： we know from his diaries that at about this time he was reading newton’s principia in theoriginal latin and other works of a similarly challenging nature。 at fifteen； stillschoolmastering； he took a job in the nearby town of kendal； and a decade after that hemoved to manchester； scarcely stirring from there for the remaining fifty years of his life。 inmanchester he became something of an intellectual whirlwind； producing books and paperson subjects ranging from meteorology to grammar。 color blindness； a condition from whichhe suffered； was for a long time called daltonism because of his studies。 but it was a plumpbook called a new system of chemical philosophy； published in 1808； that established hisreputation。
there； in a short chapter of just five pages （out of the book’s more than nine hundred）；people of learning first encountered atoms in something approaching their modernconception。 dalton’s simple insight was that at the root of all matter are exceedingly tiny；irreducible particles。 “we might as well attempt to introduce a new planet into the solarsystem or annihilate one already in existence； as to create or destroy a particle of hydrogen；”
he wrote。
neither the idea of atoms nor the term itself was exactly new。 both had been developed bythe ancient greeks。 dalton’s contribution was to consider the relative sizes and characters ofthese atoms and how they fit together。 he knew； for instance； that hydrogen was the lightestelement； so he gave it an atomic weight of one。 he believed also that water consisted of sevenparts of oxygen to one of hydrogen； and so he gave oxygen an atomic weight of seven。 bysuch means was he able to arrive at the relative weights of the known elements。 he wasn’talways terribly accurate—oxygen’s atomic weight is actually sixteen； not seven—but theprinciple was sound and formed the basis for all of modern chemistry and much of the rest ofmodern science。
the work made dalton famous—albeit in a low…key； english quaker sort of way。 in 1826；the french chemist p 。j。 pelletier traveled to manchester to meet the atomic hero。 pelletierexpected to find him attached to some grand institution； so he was astounded to discover himteaching elementary arithmetic to boys in a small school on a back street。 according to the scientific historian e。 j。 holmyard； a confused pelletier； upon beholding the great man；stammered：
“est…ce que j’ai l’honneur de m’addresser à monsieur dalton？” for he couldhardly believe his eyes that this was the chemist of european fame； teaching a boyhis first four rules。 “yes；” said the matter…of…fact quaker。 “wilt thou sit downwhilst i put this lad right about his arithmetic？”
although dalton tried to avoid all honors； he was elected to the royal society against hiswishes； showered with medals； and given a handsome government pension。 when he died in1844； forty thousand people viewed the coffin； and the funeral cortege stretched for twomiles。 his entry in the dictionary of national biography is one of the longest； rivaled inlength only by those of darwin and lyell among nineteenth…century men of science。
for a century after dalton made his proposal； it remained entirely hypothetical； and a feweminent scientists—notably the viennese physicist ernst mach； for whom is named the speedof sound—doubted the existence of atoms at all。 “atoms cannot be perceived by the senses 。 。
。 they are things of thought；” he wrote。 the existence of atoms was so doubtfully held in thegerman…speaking world in particular that it was said to have played a part in the suicide of thegreat theoretical physicist； and atomic enthusiast； ludwig boltzmann in 1906。
it was einstein who provided the first incontrovertible evidence of atoms’ existence withhis paper on brownian motion in 1905； but this attracted little attention and in any caseeinstein was soon to bee consumed with his work on general relativity。 so the first realhero of the atomic age； if not the first personage on the scene； was ernest rutherford。
rutherford was born in 1871 in the “back blocks” of new zealand to parents who hademigrated from scotland to raise a little flax and a lot of children （to paraphrase stevenweinberg）。 growing up in a remote part of a remote country； he was about as far from themainstream of science as it was po