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e interior melting…or is it？ and when the core at last burns itself out； will some ofthe earth slump into the void； leaving a giant sinkhole on the surface？ and how do you knowthis？ how did you figure it out？
but the author was strangely silent on such details…indeed； silent on everything butanticlines； synclines； axial faults； and the like。 it was as if he wanted to keep the good stuffsecret by making all of it soberly unfathomable。 as the years passed； i began to suspect thatthis was not altogether a private impulse。 there seemed to be a mystifying universalconspiracy among textbook authors to make certain the material they dealt with never strayedtoo near the realm of the mildly interesting and was always at least a longdistance phone callfrom the frankly interesting。
i now know that there is a happy abundance of science writers who pen the most lucid andthrilling prose…timothy ferris； richard fortey； and tim flannery are three that jump out froma single station of the alphabet （and thats not even to mention the late but godlike richardfeynman）…but sadly none of them wrote any textbook i ever used。 all mine were written bymen （it was always men） who held the interesting notion that everything became clear whenexpressed as a formula and the amusingly deluded belief that the children of america wouldappreciate having chapters end with a section of questions they could mull over in their owntime。 so i grew up convinced that science was supremely dull； but suspecting that it needntbe； and not really thinking about it at all if i could help it。 this； too； became my position for along time。
then much later…about four or five years ago…i was on a long flight across the pacific；staring idly out the window at moonlit ocean； when it occurred to me with a certainunfortable forcefulness that i didnt know the first thing about the only planet i was evergoing to live on。 i had no idea； for example； why the oceans were salty but the great lakeswerent。 didnt have the faintest idea。 i didnt know if the oceans were growing more saltywith time or less； and whether ocean salinity levels was something i should be concernedabout or not。 （i am very pleased to tell you that until the late 1970s scientists didnt know theanswers to these questions either。 they just didnt talk about it very audibly。）and ocean salinity of course represented only the merest sliver of my ignorance。 i didntknow what a proton was； or a protein； didnt know a quark from a quasar； didnt understandhow geologists could look at a layer of rock on a canyon wall and tell you how old it was；didnt know anything really。 i became gripped by a quiet； unwonted urge to know a littleabout these matters and to understand how people figured them out。 that to me remained thegreatest of all amazements…how scientists work things out。 how does anybody know howmuch the earth weighs or how old its rocks are or what really is way down there in thecenter？ how can they know how and when the universe started and what it was like when itdid？ how do they know what goes on inside an atom？ and how； e to that…or perhapsabove all…can scientists so often seem to know nearly everything but then still cant predict anearthquake or even tell us whether we should take an umbrella with us to the races nextwednesday？
so i decided that i would devote a portion of my life…three years； as it now turns out…toreading books and journals and finding saintly； patient experts prepared to answer a lot ofoutstandingly dumb questions。 the idea was to see if it isnt possible to understand andappreciate…marvel at； enjoy even…the wonder and acplishments of science at a level thatisnt too technical or demanding； but isnt entirely superficial either。
that was my idea and my hope； and that is what the book that follows is intended to be。
anyway； we have a great deal of ground to cover and much less than 650；000 hours in whichto do it； so lets begin。
PART I LOST IN THE COSMOS
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they鈥檙e all in the same plane。
they鈥檙e all going around in the same direction。 。 。 。
it鈥檚 perfect； you know。
it鈥檚 gorgeous。
it鈥檚 almost uncanny。
…astronomer geoffrey marcy
describing the solar system
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1 HOW TO BUILD A UNIVERSENO MATTER
灏忥紲璇达紲t锛渪t锛炲ぉ锛煛峰爞
how hard you try you will never be able to grasp just how tiny； how spatiallyunassuming； is a proton。 it is just way too small。
a proton is an infinitesimal part of an atom； which is itself of course an insubstantial thing。
protons are so small that a little dib of ink like the dot on this i can hold something in theregion of 500；000；000；000 of them； rather more than the number of seconds contained in halfa million years。 so protons are exceedingly microscopic； to say the very least。
now imagine if you can （and of course you can鈥檛） shrinking one of those protons down to abillionth of its normal size into a space so small that it would make a proton look enormous。
now pack into that tiny； tiny space about an ounce of matter。 excellent。 you are ready to starta universe。
i鈥檓 assuming of course that you wish to build an inflationary universe。 if you鈥檇 preferinstead to build a more old…fashioned； standard big bang universe； you鈥檒l need additionalmaterials。 in fact； you will need to gather up everything there is every last mote and particle ofmatter between here and the edge of creation and squeeze it into a spot so infinitesimallypact that it has no dimensions at all。 it is known as a singularity。
in either case； get ready for a really big bang。 naturally； you will wish to retire to a safeplace to observe the spectacle。 unfortunately； there is nowhere to retire to because outside thesingularity there is no where。 when the universe begins to expand； it won鈥檛 be spreading outto fill a larger emptiness。 the only space that exists is the space it creates as it goes。
it is natural but wrong to visualize the singularity as a kind of pregnant dot hanging in adark； boundless void。 but there is no space； no darkness。 the singularity has no 鈥渁round鈥�
around it。 there is no space for it to occupy； no place for it to be。 we can鈥檛 even ask how longit has been there鈥攚hether it has just lately popped into being； like a good idea； or whether ithas been there forever； quietly awaiting the right moment。 time doesn鈥檛 exist。 there is no pastfor it to emerge from。
and so； from nothing； our universe begins。
in a single blinding pulse； a moment of glory much too swift and expansive for any form ofwords； the singularity assumes heavenly dimensions； space beyond conception。 in the firstlively second （a second that many cosmologists will devote careers to shaving into ever…finerwafers） is produced gravity and the other forces that govern physics。 in less than a minute theuniverse is a million billion miles across and growing fast。 there is a lot of heat now； tenbillion degrees of it； enough to begin the nuclear reactions that create the lighter elements鈥攑rincipally hydrogen and helium； with a dash （about one atom in a hundred million） oflithium。 in three minutes； 98 percent of all the matter there is or will ever be has beenproduced。 we have a