万物简史英文版_比尔·布莱森-第4章
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ations； and that we simplylive in one that bines things in the way that allows us to exist。 he makes an analogy witha very large clothing store： 鈥渋f there is a large stock of clothing； you鈥檙e not surprised to find asuit that fits。 if there are many universes； each governed by a differing set of numbers； therewill be one where there is a particular set of numbers suitable to life。 we are in that one。鈥�
rees maintains that six numbers in particular govern our universe； and that if any of thesevalues were changed even very slightly things could not be as they are。 for example； for theuniverse to exist as it does requires that hydrogen be converted to helium in a precise butparatively stately manner鈥攕pecifically； in a way that converts seven one…thousandths ofits mass to energy。 lower that value very slightly鈥攆rom 0。007 percent to 0。006 percent；say鈥攁nd no transformation could take place： the universe would consist of hydrogen andnothing else。 raise the value very slightly鈥攖o 0。008 percent鈥攁nd bonding would be sowildly prolific that the hydrogen would long since have been exhausted。 in either case； withthe slightest tweaking of the numbers the universe as we know and need it would not be here。
i should say that everything is just right so far。 in the long term； gravity may turn out to be alittle too strong； and one day it may halt the expansion of the universe and bring it collapsingin upon itself； till it crushes itself down into another singularity； possibly to start the wholeprocess over again。 on the other hand it may be too weak and the universe will keep racingaway forever until everything is so far apart that there is no chance of material interactions； sothat the universe bees a place that is inert and dead； but very roomy。 the third option isthat gravity is just right鈥斺�渃ritical density鈥潯s the cosmologists鈥櫋erm for it鈥攁nd that it willhold the universe together at just the right dimensions to allow things to go on indefinitely。
cosmologists in their lighter moments sometimes call this the goldilocks effect鈥攖hateverything is just right。 （for the record； these three possible universes are known respectivelyas closed； open； and flat。）now the question that has occurred to all of us at some point is： what would happen if youtraveled out to the edge of the universe and； as it were； put your head through the curtains？
where would your head be if it were no longer in the universe？ what would you find beyond？
the answer； disappointingly； is that you can never get to the edge of the universe。 that鈥檚 notbecause it would take too long to get there鈥攖hough of course it would鈥攂ut because even ifyou traveled outward and outward in a straight line； indefinitely and pugnaciously； you wouldnever arrive at an outer boundary。 instead； you would e back to where you began （atwhich point； presumably； you would rather lose heart in the exercise and give up）。 the reasonfor this is that the universe bends； in a way we can鈥檛 adequately imagine； in conformance witheinstein鈥檚 theory of relativity （which we will get to in due course）。 for the moment it isenough to know that we are not adrift in some large； ever…expanding bubble。 rather； spacecurves； in a way that allows it to be boundless but finite。 space cannot even properly be saidto be expanding because； as the physicist and nobel laureate steven weinberg notes； 鈥渟olar systems and galaxies are not expanding； and space itself is not expanding。鈥潯ather； thegalaxies are rushing apart。 it is all something of a challenge to intuition。 or as the biologist j。
b。 s。 haldane once famously observed： 鈥渢he universe is not only queerer than we suppose； itis queerer than we can suppose。鈥�
the analogy that is usually given for explaining the curvature of space is to try to imaginesomeone from a universe of flat surfaces； who had never seen a sphere； being brought toearth。 no matter how far he roamed across the planet鈥檚 surface； he would never find an edge。
he might eventually return to the spot where he had started； and would of course be utterlyconfounded to explain how that had happened。 well； we are in the same position in space asour puzzled flatlander； only we are flummoxed by a higher dimension。
just as there is no place where you can find the edge of the universe； so there is no placewhere you can stand at the center and say： 鈥渢his is where it all began。 this is the centermostpoint of it all。鈥潯e are all at the center of it all。 actually； we don鈥檛 know that for sure； wecan鈥檛 prove it mathematically。 scientists just assume that we can鈥檛 really be the center of theuniverse鈥攖hink what that would imply鈥攂ut that the phenomenon must be the same for allobservers in all places。 still； we don鈥檛 actually know。
for us； the universe goes only as far as light has traveled in the billions of years since theuniverse was formed。 this visible universe鈥攖he universe we know and can talk about鈥攊s amillion million million million （that鈥檚 1；000；000；000；000；000；000；000；000） miles across。 butaccording to most theories the universe at large鈥攖he meta…universe； as it is sometimescalled鈥攊s vastly roomier still。 according to rees； the number of light…years to the edge ofthis larger； unseen universe would be written not 鈥渨ith ten zeroes； not even with a hundred；but with millions。鈥潯n short； there鈥檚 more space than you can imagine already without going tothe trouble of trying to envision some additional beyond。
for a long time the big bang theory had one gaping hole that troubled a lot of people鈥攏amely that it couldn鈥檛 begin to explain how we got here。 although 98 percent of all thematter that exists was created with the big bang； that matter consisted exclusively of lightgases： the helium； hydrogen； and lithium that we mentioned earlier。 not one particle of theheavy stuff so vital to our own being鈥攃arbon； nitrogen； oxygen； and all the rest鈥攅mergedfrom the gaseous brew of creation。 but鈥攁nd here鈥檚 the troubling point鈥攖o forge these heavyelements； you need the kind of heat and energy of a big bang。 yet there has been only onebig bang and it didn鈥檛 produce them。 so where did they e from？
interestingly； the man who found the answer to that question was a cosmologist whoheartily despised the big bang as a theory and coined the term 鈥渂ig bang鈥潯arcastically； as away of mocking it。 we鈥檒l get to him shortly； but before we turn to the question of how we gothere； it might be worth taking a few minutes to consider just where exactly 鈥渉ere鈥潯s。
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2 WELE TO THE SOLAR SYSTEMAS
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tronomers these days can do the most amazing things。 if someone struck a matchon the moon； they could spot the flare。 from the tiniest throbs and wobbles of distant starsthey can infer the size and character and even potential habitability of planets much tooremote to be seen鈥攑lanets so distant that it would take us half a million years in a spaceshipto get there。 with their radio telescopes they can capture wisps of radiation so preposterouslyfaint that the total amount of energy collected from outside the solar system by all of themtogether since collecting began （in 1951） is 鈥渓ess than the energy of a single snowflakestriking the ground；鈥潯n the words of carl sagan。
in short； there isn鈥檛 a great deal that goes on in the universe that astronomers can鈥檛 findwhen they have a mind to。 which is why it is all the more remarkable to reflect that until 1978no one had ever noticed that pluto has a moon。 in the summer of that year； a youngastronomer named james christy at the u。s。 naval observatory in flagstaff； arizona； wasmaking a routine examination of photographic images of pluto when he saw that there wassomething there鈥攕omething blurry and uncertain but definitely other than pluto。 consulting acolleague named robert harrington； he concluded that what he was looking at was a moon。
and it wasn鈥檛 just any moon。 relative to the planet； it was the biggest moon in the solarsystem。
this was actually something of a blow to pluto鈥檚 status as a planet； which had never beenterribly robust anyway。 since previously the space occupied by the moon and the spaceoccupied by pluto were thought to be one and the same； it meant that pluto was much smallerthan anyone had supposed鈥攕maller even than mercury。 indeed； seven moons in the solarsystem； including our own； are larger。
now a natural question is why it took so long for anyone to find a moon in our own solarsystem。 the answer is that it is partly a matter of where astronomers point their instrumentsand partly a matter of what their instruments are designed to detect； and partly it鈥檚 just pluto。
mostly it鈥檚 where they point their instruments。 in the words of the astronomer clarkchapman： 鈥渕ost people think that astronomers get out at night in observatories and scan theskies。 that鈥檚 not true。 almost all the telescopes we have in the world are designed to peer atvery tiny little pieces of the sky way off in the distance to see a quasar or hunt for black holesor look at a distant galaxy。 the only real network of telescopes that scans the skies has beendesigned and built by the military。鈥�
we have been spoiled by artists鈥櫋enderings into imagining a clarity of resolution thatdoesn鈥檛 exist in actual astronomy。 pluto in christy鈥檚 photograph is faint and fuzzy鈥攁 piece ofcosmic lint鈥攁nd its moon is not the romantically backlit； crisply delineated panion orbyou would get in a national geographic painting； but rather just a tiny and extremelyindistinct hint of additional fuzziness。 such was the fuzziness； in fact； that it took seven yearsfor anyone to spot the moon again and thus independently confirm its existence。
one nice touch about christy鈥檚 discovery was that it happened in flagstaff； for it was therein 1930 that pluto had been found in the first place。 that seminal event in astronomy waslargely to the credit of the astronomer percival lowell。 lowell； who came from one of theoldest and wealthiest boston families （the one in the famous ditty about boston being thehome of the bean and the cod； where lowells spoke only to cabots； while cabots spoke onlyto god）； endowed the famous observatory that bears his name； but is most indeliblyremembered for his belief that mars was covered with canals built by industrious martians for purposes of conveying water from polar regions to the dry but productive lands nearer theequator。
lowell鈥檚 other abiding conviction was that there existed； somewhere out beyond neptune；an undiscovered ninth planet； dubbed planet x。 lowell based this belief on irregularities hedetected in the orbits of uranus and neptune； and devoted the last years of his life to trying tofind the gassy giant he was certain was out there。 unfortunately； he died suddenly in 1916； atleast partly exhausted by his quest； and the search fell into abeyance while lowell鈥檚 heirssquabbled over his estate。 however； in 1929； partly as a way of deflecting attention awayfrom the mars canal saga （which by now had bee a serious embarrassment）； the lowellobservatory directors decided to resume the search and to that end hired a young man fromkansas named clyde tombaugh。
tombaugh had no formal training as an ast
