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癳mbroiled in controversy for most of his life”
and “put his name to much rubbish。” he claimed； for instance； and without evidence； that thenatural history museum’s treasured fossil of an archaeopteryx was a forgery along the linesof the piltdown hoax； causing much exasperation to the museum’s paleontologists； who had tospend days fielding phone calls from journalists from all over the world。 he also believed thatearth was not only seeded by life from space but also by many of its diseases； such asinfluenza and bubonic plague； and suggested at one point that humans evolved projectingnoses with the nostrils underneath as a way of keeping cosmic pathogens from falling intothem。
it was he who coined the term “big bang；” in a moment of facetiousness； for a radiobroadcast in 1952。 he pointed out that nothing in our understanding of physics could accountfor why everything； gathered to a point； would suddenly and dramatically begin to expand。
hoyle favored a steady…state theory in which the universe was constantly expanding andcontinually creating new matter as it went。 hoyle also realized that if stars imploded theywould liberate huge amounts of heat—100 million degrees or more； enough to begin togenerate the heavier elements in a process known as nucleosynthesis。 in 1957； working withothers； hoyle showed how the heavier elements were formed in supernova explosions。 forthis work； w。 a。 fowler； one of his collaborators； received a nobel prize。 hoyle； shamefully；did not。
according to hoyle’s theory； an exploding star would generate enough heat to create all thenew elements and spray them into the cosmos where they would form gaseous clouds—theinterstellar medium as it is known—that could eventually coalesce into new solar systems。
with the new theories it became possible at last to construct plausible scenarios for how wegot here。 what we now think we know is this：
about 4。6 billion years ago； a great swirl of gas and dust some 15 billion miles acrossaccumulated in space where we are now and began to aggregate。 virtually all of it—99。9percent of the mass of the solar system—went to make the sun。 out of the floating materialthat was left over； two microscopic grains floated close enough together to be joined byelectrostatic forces。 this was the moment of conception for our planet。 all over the inchoatesolar system； the same was happening。 colliding dust grains formed larger and larger clumps。
eventually the clumps grew large enough to be called planetesimals。 as these endlesslybumped and collided； they fractured or split or rebined in endless random permutations；but in every encounter there was a winner； and some of the winners grew big enough todominate the orbit around which they traveled。
it all happened remarkably quickly。 to grow from a tiny cluster of grains to a baby planetsome hundreds of miles across is thought to have taken only a few tens of thousands of years。
in just 200 million years； possibly less； the earth was essentially formed； though still moltenand subject to constant bombardment from all the debris that remained floating about。
at this point； about 4。5 billion years ago； an object the size of mars crashed into earth；blowing out enough material to form a panion sphere； the moon。 within weeks； it isthought； the flung material had reassembled itself into a single clump； and within a year it had formed into the spherical rock that panions us yet。 most of the lunar material； it isthought； came from the earth’s crust； not its core； which is why the moon has so little ironwhile we have a lot。 the theory； incidentally； is almost always presented as a recent one； butin fact it was first proposed in the 1940s by reginald daly of harvard。 the only recent thingabout it is people paying any attention to it。
when earth was only about a third of its eventual size； it was probably already beginning toform an atmosphere； mostly of carbon dioxide； nitrogen； methane； and sulfur。 hardly the sortof stuff that we would associate with life； and yet from this noxious stew life formed。 carbondioxide is a powerful greenhouse gas。 this was a good thing because the sun wassignificantly dimmer back then。 had we not had the benefit of a greenhouse effect； the earthmight well have frozen over permanently； and life might never have gotten a toehold。 butsomehow life did。
for the next 500 million years the young earth continued to be pelted relentlessly byets； meteorites； and other galactic debris； which brought water to fill the oceans and theponents necessary for the successful formation of life。 it was a singularly hostileenvironment and yet somehow life got going。 some tiny bag of chemicals twitched andbecame animate。 we were on our way。
four billion years later people began to wonder how it had all happened。 and it is there thatour story next takes us。
part ii the size of the earthnature and nature’s laws lay hid innight；god said； let newton be！ and allwas light。
…alexander pope
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5THE STONE…BREAKERS
小说
at just the time that henry cavendish was pleting his experiments in london； fourhundred miles away in edinburgh another kind of concluding moment was about to take placewith the death of james hutton。 this was bad news for hutton； of course； but good news forscience as it cleared the way for a man named john playfair to rewrite hutton’s work withoutfear of embarrassment。
hutton was by all accounts a man of the keenest insights and liveliest conversation； a delightin pany； and without rival when it came to understanding the mysterious slow processesthat shaped the earth。 unfortunately； it was beyond him to set down his notions in a form thatanyone could begin to understand。 he was； as one biographer observed with an all but audiblesigh； “almost entirely innocent of rhetorical acplishments。” nearly every line he pennedwas an invitation to slumber。 here he is in his 1795 masterwork； a theory of the earth withproofs and illustrations ； discussing 。 。 。 something：
the world which we inhabit is posed of the materials； not of the earth whichwas the immediate predecessor of the present； but of the earth which； in ascendingfrom the present； we consider as the