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tweezers； one atom at a time； you would produce amound of fine atomic dust； none of which had ever been alive but all of which had once beenyou。） yet somehow for the period of your existence they will answer to a single overarchingimpulse： to keep you you。
the bad news is that atoms are fickle and their time of devotion is fleeting…fleeting indeed。
even a long human life adds up to only about 650；000 hours。 and when that modestmilestone flashes past； or at some other point thereabouts； for reasons unknown your atomswill shut you down； silently disassemble； and go off to be other things。 and thats it for you。
still； you may rejoice that it happens at all。 generally speaking in the universe it doesnt； sofar as we can tell。 this is decidedly odd because the atoms that so liberally and congeniallyflock together to form living things on earth are exactly the same atoms that decline to do itelsewhere。 whatever else it may be； at the level of chemistry life is curiously mundane：
carbon； hydrogen； oxygen； and nitrogen； a little calcium； a dash of sulfur； a light dusting ofother very ordinary elements…nothing you wouldnt find in any ordinary drugstore…and thatsall you need。 the only thing special about the atoms that make you is that they make you。
that is of course the miracle of life。
whether or not atoms make life in other corners of the universe； they make plenty else；indeed； they make everything else。 without them there would be no water or air or rocks； nostars and planets； no distant gassy clouds or swirling nebulae or any of the other things thatmake the universe so usefully material。 atoms are so numerous and necessary that we easilyoverlook that they neednt actually exist at all。 there is no law that requires the universe to fillitself with small particles of matter or to produce light and gravity and the other physicalproperties on which our existence hinges。 there neednt actually be a universe at all。 for thelongest time there wasnt。 there were no atoms and no universe for them to float about in。
there was nothing…nothing at all anywhere。
so thank goodness for atoms。 but the fact that you have atoms and that they assemble insuch a willing manner is only part of what got you here。 to be here now； alive in the twenty…first century and smart enough to know it； you also had to be the beneficiary of anextraordinary string of biological good fortune。 survival on earth is a surprisingly trickybusiness。 of the billions and billions of species of living thing that have existed since thedawn of time； most…99。99 percent…are no longer around。 life on earth； you see； is not only brief but dismayingly tenuous。 it is a curious feature of our existence that we e from aplanet that is very good at promoting life but even better at extinguishing it。
the average species on earth lasts for only about four million years； so if you wish to bearound for billions of years； you must be as fickle as the atoms that made you。 you must beprepared to change everything about yourself…shape； size； color； species affiliation；everything…and to do so repeatedly。 thats much easier said than done； because the process ofchange is random。 to get from 〃protoplasmal primordial atomic globule〃 （as the gilbert andsullivan song put it） to sentient upright modern human has required you to mutate new traitsover and over in a precisely timely manner for an exceedingly long while。 so at variousperiods over the last 3。8 billion years you have abhorred oxygen and then doted on it； grownfins and limbs and jaunty sails； laid eggs； flicked the air with a forked tongue； been sleek；been furry； lived underground； lived in trees； been as big as a deer and as small as a mouse；and a million things more。 the tiniest deviation from any of these evolutionary shifts； and youmight now be licking algae from cave walls or lolling walrus…like on some stony shore ordisgorging air through a blowhole in the top of your head before diving sixty feet for amouthful of delicious sandworms。
not only have you been lucky enough to be attached since time immemorial to a favoredevolutionary line； but you have also been extremely…make that miraculously…fortunate in yourpersonal ancestry。 consider the fact that for 3。8 billion years； a period of time older than theearths mountains and rivers and oceans； every one of your forebears on both sides has beenattractive enough to find a mate； healthy enough to reproduce； and sufficiently blessed by fateand circumstances to live long enough to do so。 not one of your pertinent ancestors wassquashed； devoured； drowned； starved； stranded； stuck fast； untimely wounded； or otherwisedeflected from its lifes quest of delivering a tiny charge of genetic material to the rightpartner at the right moment in order to perpetuate the only possible sequence of hereditarybinations that could result…eventually； astoundingly； and all too briefly…in you。
this is a book about how it happened…in particular how we went from there being nothing atall to there being something； and then how a little of that something turned into us； and alsosome of what happened in between and since。 thats a great deal to cover； of course； which iswhy the book is called a short history of nearly everything； even though it isnt really。 itcouldnt be。 but with luck by the time we finish it will feel as if it is。
my own starting point； for what its worth； was an illustrated science book that i had as aclassroom text when i was in fourth or fifth grade。 the book was a standard…issue 1950sschoolbookbattered； unloved； grimly hefty…but near the front it had an illustration that justcaptivated me： a cutaway diagram showing the earths interior as it would look if you cut intothe planet with a large knife and carefully withdrew a wedge representing about a quarter ofits bulk。
its hard to believe that there was ever a time when i had not seen such an illustrationbefore； but evidently i had not for i clearly remember being transfixed。 i suspect； in honesty；my initial interest was based on a private image of streams of unsuspecting eastboundmotorists in the american plains states plunging over the edge of a sudden 4；000…mile…highcliff running between central america and the nort