Philip Ball
Can the tevatron steal the LHC’s thunder?
Recently, I went on a visit to Cern (the European Organisation for Nuclear Research) in Geneva, site of the Large Hadron Collider (LHC). The LHC, whose much heralded opening last September ended in tears just nine days later, is due back in action this September. The LHC could transform scientists’ understanding of the particles and forces from which the universe is made. Two beams of subatomic particles will be forced to collide at very high speed inside the circular accelerator, creating conditions similar to those just after the big bang.
One of the LHC’s key assignments is finding the Higgs particle. The Higgs, thought to be responsible for giving other fundamental particles their mass, is the last piece in the jigsaw of the “standard model,” the theoretical framework used to understand all known particles and forces. The Higgs is thought to have too much mass to be made in existing accelerators—the bigger this (still unknown) mass, the more energetic particle collisions have to be to spawn a Higgs. The mightiest accelerator until the LHC, the Tevatron at Fermilab in Illinois, lacks the necessary oomph.
The LHC’s failure happened when an electrical short circuit caused a leak of the liquid helium coolant, which in turn ripped from its moorings one of the immense magnets used to accelerate particles through the 27km tunnels, blasting a hole in the ring and contaminating it with debris. The clean-up and installation of new safeguards have been going on ever since.
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Pedro Ferreira
It’s like a page torn from a Dan Dare comic strip, where the undeveloped world meets the ultra future: a barren landscape of rock and bush, peppered with radio antennae so sophisticated they have yet to be invented. But it won’t be on another planet, or involve space travel. Rather, it will be the world’s most sophisticated telescope—a series of hundreds of antennae stretching across thousands of kilometres of Australian or southern African desert.
The planned square kilometre array, or SKA, is a giant camcorder scanning the sky in all directions to pick out every galaxy visible on the earth’s cosmic horizon. Its many separate dishes will simulate a single giant telescope, with a central “collecting area” of one square kilometre capable of capturing electromagnetic waves from the outer reaches of space.
The current generation of telescopes pick up only about 5 per cent of the universe’s energy and matter; the vast majority remains invisible or dark. Cosmologists think that unravelling this dark world will allow us to understand both the history of the universe and the formation of galaxies such our own. A range of new projects aim to help to solve this central problem of modern cosmology, namely establishing what, and where, dark matter and energy is. The SKA, originally conceived in the 1990s by a group of scientists from 19 countries, has become the poster child for such “big astronomy.” Today’s telescopes can provide different windows on the universe, but not a single picture. The SKA, if built, could turn this incomplete vision into a new map of the universe.
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Philip Ball
Of cosmic rays and dark matter
Physicists’ understandable embarrassment that we don’t know what most of the universe is made of prompts an eagerness, verging on desperation, to identify the missing ingredients. Dark matter, which is thought to comprise around 85 per cent of tangible material, is very much on the experimental agenda. This invisible substance is inferred on several grounds, especially that galaxies ought to fall apart without its gravitational influence. The favourite idea is that dark matter consists of unknown fundamental particles that barely interact with visible matter—hence its elusiveness.
One candidate is a particle predicted by theories that invoke extra dimensions of spacetime beyond the familiar four. So there was excitement at the recent suggestion that the signature of these particles has been detected in cosmic rays, which are electrically-charged particles (mostly protons and electrons) that whizz through space. Cosmic rays can be detected when they collide with atoms in the Earth’s atmosphere. Some are probably produced in high-energy environments like supernovae and neutron stars, but their origins are poorly understood.
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Stephen Eales
My Very Easy Method Just Speeds Up Naming Planets. Since 24th August 2006, children have had to find a new mnemonic for the names of the planets in the solar system, because on that day the International Astronomical Union voted to remove Pluto from the list of planets. The peculiar story of the fall of Pluto shows how human nature and politics can interfere even in astronomy, the most ethereal and beautiful of sciences.
The story starts over 200 years ago, in the back garden of a house in Bath, when William Herschel discovered a new planet—the first in modern times. In an act of spectacular grovelling, Herschel tried to call the planet Georgium sidus (George’s star). The name didn’t stick—the planet was named Uranus—but George III took the point; he granted Herschel a pension that allowed him to give up teaching music to young ladies and take up astronomy full time.
Herschel hadn’t stumbled on Uranus by chance. He was one of the first astronomers to realise the importance of systematic surveys, and over several thousand cold nights, he surveyed the whole sky five times. During the second of these surveys, he discovered Uranus, which he knew must be a planet because it slowly moved across the sky from night to night, unlike stars, which stay fixed in position.
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Geoffrey Miller
Sometime in the 1940s, Enrico Fermi was discussing the possibility of extraterrestrial intelligence with other physicists. They argued that our galaxy holds 100bn stars, that intelligent life evolved quickly on earth and that therefore extraterrestrial intelligence must be common. Fermi listened patiently, then asked, “So where is everybody?” That is, if extraterrestrial intelligence is so common, why haven’t we met any bright aliens yet? This conundrum became known as Fermi’s paradox.
The paradox has become ever more baffling. Over 150 extra-solar planets have been identified in the last few years, suggesting that life-hospitable planets orbit most stars. Paleontology shows that organic life evolved very quickly after the earth’s surface cooled. Given simple life, evolution shows progressive trends towards larger bodies, brains and social complexity. Evolutionary psychology reveals several credible paths from simpler social minds to human-level creative intelligence. Yet 40 years of intensive searching for extraterrestrial intelligence has yielded nothing. No radio signals, no credible spacecraft sightings.
It looks as if there are two possibilities. Perhaps our science has overestimated the likelihood of extraterrestrial intelligence evolving. Or perhaps evolved technological intelligence has some deep tendency to be self-limiting, even self-exterminating. After Hiroshima, some suggested that any aliens bright enough to make spaceships would also be bright enough to make thermonuclear bombs, and would use them on each other sooner or later. Fermi’s paradox became, for a while, a cautionary tale about cold war geopolitics.
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Michio Kaku
The universe is out of control, in a runaway acceleration. Eventually all intelligent life will face the final doom—the big freeze. An advanced civilisation must embark on the ultimate journey: fleeing to a parallel universe.
In Norse mythology, Ragnarok—the fate of the gods—begins when the earth is caught in the vice-like grip of a bone-chilling freeze. The heavens themselves freeze over, as the gods perish in great battles with evil serpents and murderous wolves. Eternal darkness settles over the bleak, frozen land as the sun and moon are both devoured. Odin, the father of all gods, finally falls to his death, and time itself comes to a halt.
Does this ancient tale foretell our future? Ever since the work of Edwin Hubble in the 1920s, scientists have known that the universe is expanding, but most have believed that the expansion was slowing as the universe aged. In 1998, astronomers at the Lawrence Berkeley National Laboratory and the Australian National University calculated the expansion rate by studying dozens of powerful supernova explosions within distant galaxies, which can light up the entire universe. They could not believe their own data. Some unknown force was pushing the galaxies apart, causing the expansion of the universe to accelerate. Brian Schmidt, one of the group leaders, said, “I was still shaking my head, but we had checked everything… I was very reluctant to tell people, because I truly thought that we were going to get massacred.”
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Ian Stewart
Light from distant galaxies tells us that the universe is expanding-one of the main pieces of evidence that space, time and everything came into existence a little over 12bn years ago in the big bang. In 1998 astronomers, trying to find out whether the expansion will continue forever, or grind to a halt and reverse itself in a big crunch, discovered something much more puzzling. The expansion is speeding up. To explain this baffling acceleration, the cosmologists invented dark energy, a mysterious force that pushes the universe apart.
Does dark energy exist? No one knows. At present nothing known to physics can explain it, so something unknown to physics must be the cause. It’s like something out of Star Wars.
In February this year, American cosmologists Gia Dvali and Michael S Turner put forward a different theory, one in which dark energy does not exist. Instead, gravity is leaking out of our universe into an extra dimension. With less gravity to hold the universe together, it is coming apart faster than expected. It also sounds like something out of Star Wars.
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Martin Rees
Over the past few centuries, the earth has aged spectacularly. Its creation has been moved back from 6pm on Saturday, 22nd October, 4004 BC, as calculated by the 17th-century scholar and Archbishop of Armagh, James Ussher, to a time and date some 4.5 billion years earlier. The story of life has been stretched back almost as far, and the story of complex, multicellular life-forms-relative newcomers-has itself been almost a billion years in the making. As a result, the way we see the world has changed profoundly. Not only can we now have some sense of the millions of years it takes to raise and then level mountains, or to open and then close oceans, we also have the clearest evidence of humanity’s absence throughout those ages. To Ussher’s mind, the creation of the world and the creation of humanity were within a week of one another; to our modern minds, the two events are unimaginably far apart. There was a vast absence before us, a physical and biological world untouched by introspection, and its record stares out at us from every rock.
If the earth’s past has been stretched, what of its future? To those of Ussher’s faith, the end of the world was a certainty and to some of his contemporaries history was already nearing its close. Sir Thomas Browne wrote, “the world itself seems in the wane. A greater part of Time is spun than is to come.”
To look forward, we must turn from geology to cosmology. Current cosmology suggests a future that, if not infinite, dwarfs the past as much as the depths of time we now accept dwarf Ussher’s exquisite estimates. What it cannot tell us, though, is whether these vast expanses of time will be filled with life, or as empty as the earth’s first sterile seas. In the aeons that lie ahead, life could spread through the entire galaxy, even beyond it-and outlast it too. But life could also snuff itself out, leaving an eternity as empty as the space between the stars.
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Hilary Lawson
The notion that we might uncover the nature of the world through a combination of careful observation and logic goes back to the inception of the scientific project. It was the dream of the Enlightenment and it could even be said that this vision has defined modern western culture. A motivating and liberating force, it has given us a sense of progress, a sense that unlike previous cultures and other societies we are on the road to truth. Nevertheless, it is profoundly mistaken.
In the closing pages of A Brief History of Time Stephen Hawking took a sideswipe at contemporary philosophy, arguing that it has been reduced to an analysis of language. In his haste to dismiss philosophy he allowed himself to misunderstand not only language but the nature of the world. Hawking makes the simple error of assuming that the world and our descriptions of it might be one and the same. In our descriptions of the world we divide it into things: trees and houses, people and events, stars and planets, atoms and molecules. But the world is not a thing or a combination of things, for these categories-these closures, as I call them-are the outcome of our descriptions. Instead, the world is open and it is we who close it. Through our closures we grasp the openness of the world as things, and out of these things we build stories and models through which we are able to intervene. But these stories and models are not the world, nor could they in principle come close to being the world.
The world does not come pre-packaged and divided into its parts. We are not in a cosmic supermarket identifying cling-wrapped items of reality. Instead we find ourselves in openness, and in order to make sense of it, to have some means of intervening to certain effect, we realise closure. We do not form our closures in a vacuum. We find ourselves in a network of linguistic closures already realised and handed down by our culture from generation to generation. As biological organisms, we are already set up, through evolution, to generate certain types of sensory closure. These biological and cultural systems of closure have been adopted because they prove useful, not because they are true.
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prospect
These days most people know that the universe began with a bang-a big bang. But as soon as they try to imagine this event, an awkward question presents itself: what happened before the big bang? Since the idea of something happening without any prior cause is alien to us, the question seems to demand an answer. Yet many cosmologists insist that there is no answer to the question of what happened before the big bang, not because the origin of the universe must forever lie beyond the scope of human inquiry, but because the question itself is meaningless.
It is a subject charged with emotion. Books and lectures on the big bang often provoke a passionate response. Religious people see the scientific attempt to explain how the universe came into existence as a move to finally abolish God the creator. Atheists are also alarmed, because the notion of the universe coming into being from nothing looks suspiciously like the creation ex nihilo of Christianity.
Today, few cosmologists doubt that the universe did have an origin at a finite moment in the past. The alternative-that the universe has always existed in one form or another-runs into a basic paradox. The sun and stars cannot keep burning forever: sooner or later they will run out of fuel and die. The same is true of all irreversible physical processes; the stock of energy available in the universe to drive them is finite, and cannot last for eternity. This is an example of the so-called second law of thermodynamics, which, applied to the entire cosmos, predicts that it is stuck on a one-way slide of degeneration and decay towards a final state of maximum entropy, or disorder. As this final state has not yet been reached, it follows that the universe cannot have existed for an infinite time.
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