万物简史英文版_比尔·布莱森-第43章
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light。 breaking up atomic nuclei； however； requires quite a lot of money and agenerous supply of electricity。 getting down to the level of quarks鈥攖he particles that make upparticles鈥攔equires still more： trillions of volts of electricity and the budget of a small centralamerican nation。 cern鈥檚 new large hadron collider； scheduled to begin operations in 2005；will achieve fourteen trillion volts of energy and cost something over 1。5 billion toconstruct。
1but these numbers are as nothing pared with what could have been achieved by； andspent upon； the vast and now unfortunately never…to…be superconducting supercollider； whichbegan being constructed near waxahachie； texas； in the 1980s； before experiencing asupercollision of its own with the united states congress。 the intention of the collider was tolet scientists probe 鈥渢he ultimate nature of matter；鈥潯s it is always put； by re…creating as nearlyas possible the conditions in the universe during its first ten thousand billionths of a second。
the plan was to fling particles through a tunnel fifty…two miles long； achieving a trulystaggering ninety…nine trillion volts of energy。 it was a grand scheme； but would also havecost 8 billion to build （a figure that eventually rose to 10 billion） and hundreds of millionsof dollars a year to run。
in perhaps the finest example in history of pouring money into a hole in the ground；congress spent 2 billion on the project； then canceled it in 1993 after fourteen miles oftunnel had been dug。 so texas now boasts the most expensive hole in the universe。 the siteis； i am told by my friend jeff guinn of the fort worth star…telegram； 鈥渆ssentially a vast；cleared field dotted along the circumference by a series of disappointed small towns。鈥�
1there are practical side effects to all this costly effort。 the world wide web is a cern offshoot。 it wasinvented by a cern scientist； tim berners…lee； in 1989。
since the supercollider debacle particle physicists have set their sights a little lower； buteven paratively modest projects can be quite breathtakingly costly when pared with；well； almost anything。 a proposed neutrino observatory at the old homestake mine in lead；south dakota； would cost 500 million to build鈥攖his in a mine that is already dug鈥攂eforeyou even look at the annual running costs。 there would also be 281 million of 鈥済eneralconversion costs。鈥潯 particle accelerator at fermilab in illinois； meanwhile； cost 260 millionmerely to refit。
particle physics； in short； is a hugely expensive enterprise鈥攂ut it is a productive one。
today the particle count is well over 150； with a further 100 or so suspected； butunfortunately； in the words of richard feynman； 鈥渋t is very difficult to understand therelationships of all these particles； and what nature wants them for； or what the connectionsare from one to another。鈥潯nevitably each time we manage to unlock a box； we find that thereis another locked box inside。 some people think there are particles called tachyons； which cantravel faster than the speed of light。 others long to find gravitons鈥攖he seat of gravity。 atwhat point we reach the irreducible bottom is not easy to say。 carl sagan in cosmos raised thepossibility that if you traveled downward into an electron； you might find that it contained auniverse of its own； recalling all those science fiction stories of the fifties。 鈥渨ithin it；organized into the local equivalent of galaxies and smaller structures； are an immense numberof other； much tinier elementary particles； which are themselves universes at the next leveland so on forever鈥攁n infinite downward regression； universes within universes； endlessly。
and upward as well。鈥�
for most of us it is a world that surpasses understanding。 to read even an elementary guideto particle physics nowadays you must now find your way through lexical thickets such asthis： 鈥渢he charged pion and antipion decay respectively into a muon plus antineutrino and anantimuon plus neutrino with an average lifetime of 2。603 x 10…8seconds； the neutral piondecays into two photons with an average lifetime of about 0。8 x 10…16seconds； and the muonand antimuon decay respectively into 。 。 。鈥潯nd so it runs on鈥攁nd this from a book for thegeneral reader by one of the （normally） most lucid of interpreters； steven weinberg。
in the 1960s； in an attempt to bring just a little simplicity to matters； the caltech physicistmurray gell…mann invented a new class of particles； essentially； in the words of stevenweinberg； 鈥渢o restore some economy to the multitude of hadrons鈥濃�攁 collective term used byphysicists for protons； neutrons； and other particles governed by the strong nuclear force。
gell…mann鈥檚 theory was that all hadrons were made up of still smaller； even morefundamental particles。 his colleague richard feynman wanted to call these new basicparticles partons； as in dolly； but was overruled。 instead they became known as quarks。
gell…mann took the name from a line in finnegans wake： 鈥渢hree quarks for mustermark！鈥潯。╠iscriminating physicists rhyme the word with storks； not larks； even though thelatter is almost certainly the pronunciation joyce had in mind。） the fundamental simplicity ofquarks was not long lived。 as they became better understood it was necessary to introducesubdivisions。 although quarks are much too small to have color or taste or any other physicalcharacteristics we would recognize； they became clumped into six categories鈥攗p； down；strange； charm； top； and bottom鈥攚hich physicists oddly refer to as their 鈥渇lavors；鈥潯nd theseare further divided into the colors red； green； and blue。 （one suspects that it was not altogethercoincidental that these terms were first applied in california during the age of psychedelia。） eventually out of all this emerged what is called the standard model； which is essentially asort of parts kit for the subatomic world。 the standard model consists of six quarks； sixleptons； five known bosons and a postulated sixth； the higgs boson （named for a scottishscientist； peter higgs）； plus three of the four physical forces： the strong and weak nuclearforces and electromagnetism。
the arrangement essentially is that among the basic building blocks of matter are quarks；these are held together by particles called gluons； and together quarks and gluons formprotons and neutrons； the stuff of the atom鈥檚 nucleus。 leptons are the source of electrons andneutrinos。 quarks and leptons together are called fermions。 bosons （named for the indianphysicist s。 n。 bose） are particles that produce and carry forces； and include photons andgluons。 the higgs boson may or may not actually exist； it was invented simply as a way ofendowing particles with mass。
it is all； as you can see； just a little unwieldy； but it is the simplest model that can explainall that happens in the world of particles。 most particle physicists feel； as leon ledermanremarked in a 1985 pbs documentary； that the standard model lacks elegance and simplicity。
鈥渋t is too plicated。 it has too many arbitrary parameters；鈥潯ederman said。 鈥渨e don鈥檛 reallysee the creator twiddling twenty knobs to set twenty parameters to create the universe as weknow it。鈥潯hysics is really nothing more than a search for ultimate simplicity； but so far all wehave is a kind of elegant messiness鈥攐r as lederman put it： 鈥渢here is a deep feeling that thepicture is not beautiful。鈥�
the standard model is not only ungainly but inplete。 for one thing； it has nothing at allto say about gravity。 search through the standard model as you will； and you won鈥檛 findanything to explain why when you place a hat on a table it doesn鈥檛 float up to the ceiling。 nor；as we鈥檝e just noted； can it explain mass。 in order to give particles any mass at all we have tointroduce the notional higgs boson； whether it actually exists is a matter for twenty…first…century physics。 as feynman cheerfully observed： 鈥渟o we are stuck with a theory； and we donot know whether it is right or wrong； but we do know that it is a little wrong； or at leastinplete。鈥�
in an attempt to draw everything together； physicists have e up with something calledsuperstring theory。 this postulates that all those little things
