3 THE REVEREND EVANS’S UNIVERSE

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    WHEN THE SKIES are clear and the Moon is not tht, the Reverend Robert Evans, aquiet and cheerful man, lugs a bulky telescope onto the back deck of his home in the BlueMountains of Australia, about fifty miles west of Sydney, and does araordinary thing. Helooks deep into the past and finds dying stars.

    Looking into the past is of course the easy part. Gla the night sky and what you see ishistory and lots of it—the stars not as they are now but as they were when their light leftthem. For all we know, the North Star, our faithful panion, might actually have bur last January or in 1854 or at any time sihe early fourteenth tury and news of it justhasn’t reached us yet. The best we  say— ever say—is that it was still burning on thisdate 680 years ago. Stars die all the time. What Bob Evans does better than anyone else whohas ever tried is spot these moments of celestial farewell.

    By day, Evans is a kindly and now semiretired minister in the Uniting Chur Australia,who does a bit of freelance work and researches the history of eenth-tury religiousmovements. But by night he is, in his unassuming way, a titan of the skies. He huntssupernovae.

    Supernovae occur when a giant star, one much bigger than our own Sun, collapses and theacularly explodes, releasing in an instant the energy of a hundred billion suns, burningfor a time brighter than all the stars in its galaxy. “It’s like a trillion hydrogen bombs going offat once,” says Evans. If a supernova explosion happened within five hundred light-years of us,we would be goners, acc to Evans—“it would wreck the show,” as he cheerfully puts it.

    But the universe is vast, and supernovae are normally much too far away to harm us. In fact,most are so unimaginably distant that their light reaches us as no more than the faiwinkle. For the month or so that they are visible, all that distinguishes them from the otherstars in the sky is that they occupy a point of space that wasn’t filled before. It is theseanomalous, very occasional pricks in the crowded dome of the night sky that the ReverendEvans finds.

    To uand what a feat this is, imagine a standard dining room table covered in a blacktablecloth and someohrowing a handful of salt across it. The scattered grains  bethought of as a galaxy. Now imagine fifteen hundred more tables like the first one—enough tofill a Wal-Mart parking lot, say, or to make a single liwo miles long—each with a randomarray of salt across it. Now add one grain of salt to any table a Bob Evans walk amongthem. At a glance he will spot it. That grain of salt is the supernova.

    Evans’s is a talent so exceptional that Oliver Sacks, in An Anthropologist on Mars, devotesa passage to him in a chapter on autistic savants—quickly adding that “there is no suggestionthat he is autistic.” Evans, who has not met Sacks, laughs at the suggestion that he might beeither autistic or a savant, but he is powerless to explain quite where his talent es from.

    “I just seem to have a knaemorizing star fields,” he told me, with a franklyapologetic look, when I visited him and his wife, Elaine, in their picture-book bungalow on atranquil edge of the village of Hazelbrook, out where Sydney finally ends and the boundlessAustralian bush begins. “I’m not particularly good at other things,” he added. “I don’tremember names well.”

    “Or where he’s put things,” called Elaine from the kit.

    He nodded frankly again and grihen asked me if I’d like to see his telescope. I hadimagihat Evans would have a proper observatory in his backyard—a scaled-downversion of a Mount Wilson or Palomar, with a sliding domed roof and a meized chair thatwould be a pleasure to maneuver. In fact, he led me not outside but to a crowded storeroomoff the kit where he keeps his books and papers and where his telescope—a whiteder tha<big></big>t is about the size and shape of a household hot-water tas in a homemade,swiveling plywood mount. When he wishes to observe, he carries them in two trips to a smalldeck off the kit. Between the  of the roof and the feathery tops of eucalyptustrees growing up from the slope below, he has only a letter-box view of the sky, but he says itis more than good enough for his purposes. And there, when the skies are clear and the Moonnot tht, he finds his supernovae.

    The term supernova was ed in the 1930s by a memorably odd astrophysicist namedFritz Zwicky. Born in Bulgaria and raised in Switzerland, Zwicky came to the CaliforniaInstitute of Te<bdo>藏书网</bdo>ology in the 1920s and there at once distinguished himself by his abrasivepersonality aic talents. He didn’t seem to be outstandingly bright, and many of hiscolleagues sidered him little more than “an irritating buffoon.” A fitness buff, he wouldoften drop to the floor of the Caltech dining hall or other public areas and do one-armedpushups to demonstrate his virility to anyone who seemed ined to doubt it. He wasnotoriously aggressive, his manually being so intimidating that his closestcollaborator, a gentle man named Walter Baade, refused to be left aloh him. Amongother things, Zwicky accused Baade, who was German, of being a Nazi, which he was not. Onat least one occasion Zwicky threateo kill Baade, who worked up the hill at the MountWilson Observatory, if he saw him on the Caltech campus.

    But Zwicky was also capable of insights of the most startling brilliance. In the early 1930s,he turned his attention to a question that had long troubled astronomers: the appearan thesky of occasional unexplained points of light, ars. Improbably he wondered if theron—the subatomic particle that had just been discovered in England by JamesChadwick, and was thus both novel and rather fashionable—might be at the heart of things. Itoccurred to him that if a star collapsed to the sort of densities found in the core of atoms, theresult would be an unimaginably pacted core. Atoms would literally be crushed together,their eles forced into the nucleus, f rons. You would have a ron star.

    Imagine a million really weighty onballs squeezed down to the size of a marble and—well, you’re still not even close. The core of a ron star is so dehat a single spoonfulof matter from it would weigh 200 billion pounds. A spoonful! But there was more. Zwickyrealized that after the collapse of such a star there would be a huge amount of energy leftover—enough to make the biggest bang in the universe. He called these resultant explosionssuperhey would be—they are—the biggest events iion.

    On January 15, 1934, the journal Physical Review published a very cise abstract of apresentation that had been ducted by Zwicky and Baade the previous month at StanfordUy. Despite its extreme brevity—one paragraph of twenty-four lihe abstratained an enormous amount of new sce: it provided the first refereo supernovaeand to ron stars; vingly explaiheir method of formation; correctly calculatedthe scale of their explosiveness; and, as a kind of cluding bonus, ected supernovaexplosions to the produ of a mysterious new phenomenon called ic rays, which hadretly been found swarming through the universe. These ideas were revolutionary to say theleast. ron stars wouldn’t be firmed for thirty-four years. The ic rays notion,though sidered plausible, hasn’t been verified yet. Altogether, the abstract was, in thewords of Caltech astrophysicist Kip S. Thorne, “one of the most prest dots iory of physid astronomy.”

    Iingly, Zwicky had almost no uanding of why any of this would happen.

    Acc to Thorne, “he did not uand the laws of physics well enough to be able tosubstantiate his ideas.” Zwicky’s talent was f ideas. Others—Baade mostly—were leftto do the mathematical sweeping up.

    Zwicky also was the first that there wasn’t nearly enough visible mass in theuniverse to hold galaxies together and that there must be some ravitational influence—what we now call dark matter. Ohing he failed to see was that if a ron star shrankenough it would bee so dehat even light couldn’t escape its immense gravitationalpull. You would have a black hole. Unfortunately, Zwicky was held in such disdain by mostof his colleagues that his ideas attracted almost no notice. When, five years later, the greatRobert Oppenheimer turned his attention to ron stars in a landmark paper, he made not asingle refereo any of Zwicky’s work even though Zwicky had been w for years onthe same problem in an office just down the hall. Zwicky’s dedus ing dark matterwouldn’t attract serious attention for nearly fou<mark></mark>r decades. We  only assume that he did alot of pushups in this period.

    Surprisingly little of the universe is visible to us when we ine our heads to the sky. Onlyabout 6,000 stars are visible to the naked eye from Earth, and only about 2,000  be seenfrom any one spot. With binoculars the number of stars you  see from a single locatioo about 50,000, and with a small two-inch telescope it leaps to 300,000. With a sixteen-inch telescope, such as Evans uses, you begin to t not in stars but in galaxies. From hisdeck, Evans supposes he  see between 50,000 and 100,000 galaxies, each taining tensof billions of stars. These are of course respectable numbers, but even with so much to take in,supernovae are extremely rare. A star  burn for billions of years, but it dies just ondquickly, and only a few dying stars explode. Most expire quietly, like a campfire at dawn. In atypical galaxy, sisting of a hundred billion stars, a supernova will occur on average onceevery two or three hundred years. Finding a supernova therefore was a little bit like standingon the observation platform of the Empire State Building with a telescope and seargwindows around Manhattan in the hope of finding, let us say, someone lighting a twenty-first-birthday cake.

    So when a hopeful and softspoken minister got in touch to ask if they had any usable fieldcharts for hunting superhe astronomical unity thought he was out of his mind.

    At the time Evans had a ten-inch telescope—a very respectable size for amateur stargazingbut hardly the sort of thing with which to do serious ology—and he roposing tofind one of the universe’s rarer phenomena. In the whole of astronomical history before Evansstarted looking in 1980, fewer than sixty supernovae had been found. (At the time I visitedhim, in August of 2001, he had just recorded his thirty-fourth visual discovery; a thirty-fifthfollowed three months later and a thirty-sixth in early 2003.)Evans, however, had certain adva<dfn></dfn>ntages. Most observers, like most people generally, are inthe northern hemisphere, so he had a lot of sky largely to himself, especially at first. He alsohad speed and his uny memory. Large telescopes are cumbersome things, and much oftheir operational time is ed with being maneuvered into position. Evans could swinghis little sixteen-inch telescope around like a tail gunner in a dogfight, spending no more thana couple of seds on any particular point in the sky. In sequence, he could observeperhaps four hundred galaxies in an evening while a large professional telescope would belucky to do fifty or sixty.

    Looking for supernovae is mostly a matter of not finding them. From 1980 to 1996 heaveraged two discoveries a year—not a huge payoff for hundreds of nights of peering andpeering. Once he found three in fifteen days, but aime he went three years withoutfinding any at all.

    “There is actually a certain value in not finding anything,” he said. “It helps ologists towork out the rate at which galaxies are evolving. It’s one of those rare areas where theabsence of evidenceis evidence.”

    On a table beside the telescope were stacks of photos and papers relevant to his pursuits,and he showed me some of them now. If you have ever looked through popular astronomicalpublications, and at some time you must have, you will know that they are generally full ofric<samp>..</samp>hly luminous color photos of distant nebulae and the like—fairy-lit clouds of celestial lightof the most delicate and moving splendor. Evans’s w images are nothing like that. Theyare just blurry blad-white photos with little points of haloed brightness. One he showedme depicted a swarm of stars with a trifling flare that I had to put close to my face to see.

    This, Evans told me, was a star in a stellation called Fornax from a galaxy known toastronomy as NGC1365. (NGC stands for New General Catalogue, where these things arerecorded. O was a heavy book on someone’s desk in Dublin; today, needless to say, it’sa database.) For sixty million silent years, the light from the star’s spectacular demise traveledunceasingly through spatil one night in August of 2001 it arrived at Earth in the form ofa puff of radiahe ti brightening, in the night sky. It was of course Robert Evans onhis eucalypt-sted hillside who spotted it.

    “There’s something satisfying, I think,” Evans said, “about the idea of light traveling formillions of years through spad just at the right moment as it reaches Earth someonelooks at the right bit of sky and sees it. It just seems right that a of that magnitudeshould be witnessed.”

    Supernovae do much more than simply impart a sense of wohey e in severaltypes (one of them discovered by Evans) and of these one in particular, known as a Iasupernova, is important to astronomy because it always explodes in the same way, with thesame critical mass. For this reason it  be used as a standard dle to measure theexpansion rate of the universe.

    In 1987 Saul Perlmutter at the Lawrence Berkeley lab in California, needing more Iasuperhan visual sightings were providing, set out to find a more systematic method ofsearg for them. Perlmutter devised a nifty system using sophisticated puters andcharge-coupled devices—in essence, really good digital cameras. It automated supernovahunting. Telescopes could now take thousands of pictures a a puter detect thetelltale bright spots that marked a supernova explosion. In five years, with the eique,Perlmutter and his colleagues at Berkeley found forty-two supernovae. Now even amateursare finding superh charge-coupled devices. “With CCDs you  aim a telescope atthe sky and go watch television,” Evans said with a touch of dismay. “It took all the roma of it.”

    I asked him if he was tempted to adopt the eology. “Oh, no,” he said, “I enjoy myway too much. Besides”—he gave a nod at the photo of his latest supernova and smiled—“I still beat them sometimes.”

    The question that naturally occurs is “What would it be like if a star exploded nearby?” Our stellar neighbor, as we have seen, is Alpha tauri, 4.3 light-years away. I hadimagihat if there were an explosion there we would have 4.3 years to watch the light ofthis magnifit event spreading across the sky, as if tipped from a giant . What would itbe like if we had four years and four months to wat inescapable doom advang towardus, knowing that when it finally arrived it would blow the skin right off our bones? Wouldpeople still go to work? Would farmers plant crops? Would anyone deliver them to the stores?

    Weeks later, ba the town in Neshire where I live, I put these questions to JohnThorstensen, an astro Dartmouth College. “Oh no,” he said, laughing. “The news ofsu event travels out at the speed of light, but so does the destructiveness, so you’d learnabout it and die from it in the same instant. But don’t worry because it’s not going to happen.”

    For the blast of a supernova explosion to kill you, he explained, you would have to be“ridiculously close”—probably within ten light-years or so. “The danger would be varioustypes of radiation—ic rays and so on.” These would produce fabulous auroras,shimmering curtains of spooky light that would fill the whole sky. This would not be a goodthing. Anything potent enough to put on such a show could well blow away themagosphere, the magie high above the Earth that normally protects us fromultraviolet rays and other ic assaults. Without the magosphere anyone unfortunateenough to step into sunlight would pretty quickly take on the appearance of, let us say, anovercooked pizza.

    The reason we  be reasonably fident that su event won’t happen in our erof the galaxy, Thorstensen said, is that it takes a particular kind of star to make a supernova inthe first place. A didate star must be ten to twenty times as massive as our own Sun and“we don’t have anything of the requisite size that’s that close. The universe is a mercifully bigplace.” The  likely didate he added, is Betelgeuse, whose various sputterings havefor years suggested that something iingly unstable is going on there. But Betelgeuse isfifty thousand light-years away.

    Only half a dozen times in recorded history have supernovae been close enough to bevisible to the naked eye. One was a blast in 1054 that created the Crab Nebula. Another, in1604, made a star bright enough to be seen during the day for over three weeks. The mostret was in 1987, when a supernova flared in a zone of the os known as the LargeMagellanic Cloud, but that was only barely visible and only in the southern hemisphere—andit was a fortably safe 169,000 light-years away.

    Supernovae are signifit to us iher decidedly tral way. Without them wewouldn’t be here. You will recall the ological drum with which we ehe firstchapter—that the Big Bang created lots of light gases but no heavy elements. Those camelater, but for a very long time nobody could figure out  how they came later. The problem wasthat you needed something really hot—hotter even than the middle of the hottest stars—te carbon and iron and the other elements without which we would be distressinglyimmaterial. Supernovae provided the explanation, and it was an English ologist almostas singular in manner as Fritz Zwicky who figured it out.

    He was a Yorkshireman named Fred Hoyle. Hoyle, who died in 2001, was described in anobituary in Nature as a “ologist and troversialist” and both of those he most certainlywas. He was, acc to Nature ’s obituary, “embroiled in troversy for most of his life”

    and “put his o much rubbish.” He claimed, for instance, and without evidehat theNatural History Museum’s treasured fossil of an Archaeopteryx was a fery 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 projegnoses with the nostrils underh as a way of keeping ic pathogens from falling intothem.

    It was he who ed the term “Big Bang,” in a moment of facetiousness, for a radiobroadcast in 1952. He pointed out that nothing in our uanding of physics could atfor why everything, gathered to a point, would suddenly and dramatically begin to expand.

    Hoyle favored a steady-state theory in which the universe was stantly expanding andtinually 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 togee the heavier elements in a process known as nucleosynthesis. In 1957, w 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.

    Acc to Hoyle’s theory, an exploding star would gee enough heat to create all thenew elements and spray them into the os where they would faseous clouds—theiellar medium as it is known—that could eventually coalesto new solar systems.

    With the heories it became possible at last to struct plausible sarios 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—99.9pert 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 ception for our pla. 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 plaesimals. As these endlesslybumped and collided, they fractured or split or rebined in endless random permutations,but in every enter there was a winner, and some of the winners grew big enough todomihe orbit around which they traveled.

    It all happened remarkably quickly. To grow from a tiny cluster of grains to a baby plasome 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 stant 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 ih,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 hadformed 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, ially, is almost alresented as a ret one, butin fact it was first proposed in the 1940s by Reginald Daly of Harvard. The only ret thingabout it is people paying any attention to it.

    Wheh was only about a third of its eventual size, it robably already beginning toform an atmosphere, mostly of carbon dioxide, nitrogehane, and sulfur. Hardly the sortof stuff that we would associate with life, a from this noxious stew life formed. Carbondioxide is a powerful greenhouse gas. This was a good thing because the Sun wassignifitly dimmer back then. Had we not had the be of a greenhouse effect, the Earthmight well have frozen over permaly, and life might never have gotten a toehold. Butsomehow life did.

    For the  500 million years the youh tio be pelted relentlessly byets, meteorites, and alactic debris, which brought water to fill the os and thepos necessary for the successful formation of life. It was a singularly hostileenviro a 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 akes us.

    PART  II THE SIZE OF THE EARTHNature and Nature’s laws lay hid innight;God said, Let on be! And allwas light.

    -Alexander Pope

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