The Best Australian Science Writing 2013 (16 page)

In the auditorium a retired nuclear theorist sits to one side of me; a youngish Spaniard with a mop of curly hair checks his
email on the other. The retired theorist isn't quite sure why the press need be here at all: to him it's strictly a scientific affair. Above the stage a screen shows a similar auditorium at CERN, the scene of the main event. The camera scans for something to look at: a Higgs boson soft toy on a desk, popular in certain quarters around the time the Large Hadron Collider (LHC), CERN's gargantuan particle accelerator, was first switched on in 2008; a woman snapping a phone photo of herself with the stage in the background. The assembled physicists have come with a legitimate professional interest in the results from the LHC. I've come to satisfy what Wittgenstein called ‘one of the lowest desires of modern people, namely the superficial curiosity about the latest discoveries of science'.

Scientists always bemoan the simplifications and outright errors endemic to science journalism, though it's easy to see why they occur. You'd need to cover at least quantum field theory, electroweak unification and symmetry breaking in the early universe before you could give an explanation of the Higgs boson that's neither inaccurate nor at the level of a just-so story. Add to that the necessary mathematical scaffolding, and it's no wonder journalists write articles ‘intended to make you believe that you understand a thing which actually you don't understand' (Wittgenstein again). Tomorrow's papers will be full of ‘God particle' this and ‘cosmic molasses' that; the headline will be ‘ORIGIN OF UNIVERSE REVEALED', not ‘HIGGS MASS 125.3 ± 0.6 GeV'.

Geoff Taylor, the dapper head of Australia's Large Hadron Collider contingent, takes the stage briefly to announce that the presentations will be longer than planned. On screen, Peter Higgs enters the room at CERN to cheers.

In late June, physics blogs had lit up with rumours that LHC scientists had some news. It could only mean one thing: the Higgs. Last December they had released what a physicist
would describe unwinkingly as ‘highly suggestive' results, but had refrained from making definite claims. The word was there were now enough data to cross the line into certainty, or what passes for it given the distressingly probabilistic nature of quantum mechanics. People were talking 5-sigma significance.

Eventually there is a hush in the auditorium, and Rolf-Dieter Heuer, CERN's avuncular director general, appears on screen. ‘Today is a special day,' he begins, before trotting out a couple of diligently constructed jokes and introducing Joe Incandela, a slick American from the Compact Muon Solenoid LHC experimental team. Incandela walks us through the experimental set-up, the data-processing arrangements and the statistical methodology before getting down to graphs and numbers. The statement that inspires the crowd to frenzied applause: ‘If we combine the Z–Z and the gamma–gamma, this is what we get. They line up extremely well in the region of 125 GeV. They combine to give us a combined significance of five standard deviations'. He stumbles and stutters getting the words out.

From a physicist's point of view, particle hunting is the extreme sport. There's a rakish disregard for common sense in the lengths to which they will go. Take the IceCube neutrino telescope, a kilometre-a-side cubic grid of detectors buried deep in the Antarctic ice, or Holland's MiniGRAIL (Gravitational Radiation Antenna In Leiden), a perfect 1400-kilo copper sphere chilled to just above absolute zero in the hope of observing tiny ripples in the fabric of the universe caused by far-off stellar cataclysms. The LHC is the wildest of all: a particle accelerator whose 27-kilometre circumference takes the better part of a day to walk around, built by thousands of scientists from across the world at a cost of US $9 billion (a month's worth of US spending in Afghanistan, by comparison) to hunt truly exotic game – dark matter, extra dimensions, magnetic monopoles, the Higgs.

After Incandela has said the magic words, the rest is
appendices. He hands over to Fabiola Gianotti from the ATLAS experiment (A Toroidal LHC ApparatuS), which runs in parallel with Incandela's team so that the two can cross-check each other's results. Gianotti's data provide further confirmation of the Higgs's existence. After she finishes, Heuer returns to the stage. ‘I think we have it,' he says. ‘You agree?' The rooms at CERN and in Melbourne erupt with affirmative cries. ‘It's a historic milestone today, but we are only at the beginning.' It's the approved take-home message.

The retired nuclear theorist is dubious. He'll allow that they've found a boson; he's not convinced it's the Higgs. It's sad science is going this way, he says – releasing results before publishing in a peer-reviewed journal, courting media coverage, dumbing it down for popular consumption. Later, an unidentified American on screen puts the contrasting view: ‘It's wonderful to be at a physics event where there's applause like there is at a football game'. He too has a point: is there harm in celebrating a scientific discovery? Accurate or not, the media coverage will at least remind people for a moment that they live in a universe.

Paradigm shifters

Writer as flâneur

Here come the übernerds: Planets, Pluto and Prague

Fred Watson

I wonder if you heard the sad news that on 30 April 2009 Venetia Phair died, at the grand old age of 90. Despite her strikingly beautiful name, I can imagine you may be hardpressed to remember who Mrs Phair was. But she was famous – especially in the last few years of her life – as the only woman ever to have named a planet.

Back in March 1930, when 11-year-old Venetia lived in Oxford and was still Venetia Burney, she heard from her grandfather that a planet had been newly discovered by an astronomer in the far-off USA and that they were trying to think of a name for it. Young Venetia was not only rather cluey about astronomy but also hooked on Greek and Roman mythology. She suggested that the Roman god of the Underworld, Pluto, might be an appropriate alter ego for the planet.

Such a suggestion made by most 11-year-olds would go no further, but Venetia's grandfather happened to be friendly with Herbert Hall Turner, the Professor of Astronomy at Oxford University. Turner thought the idea was a cracker, although, being an Oxford professor, he probably didn't put it quite like that. Fired with enthusiasm, he telegraphed his colleagues at the Lowell
Observatory in Flagstaff, Arizona, from where the planet had been discovered, and they agreed it was a splendid suggestion. Thus, on 1 May 1930, the name Pluto was formally adopted for the newly discovered planet, and Venetia was naturally rather pleased with herself. Throughout her long life, she was at pains to point out that Walt Disney's cartoon dog was named after her planet rather than the other way around.

It seems that naming celestial objects was something of a family tradition. A little more than half a century before the Pluto episode, Venetia's Great-Uncle Henry had suggested the names Phobos and Deimos (fear and dread) for the two tiny moons of Mars, which had just been discovered by scientists in the USA. They, too, were duly adopted in the world of astronomy, but sadly Great-Uncle Henry was long dead by the time Venetia's turn came around.

Why was it only in the last few years of her life that Venetia's contribution to modern astronomy became well known? The answer lies in the controversy that has surrounded Pluto in recent years as the true nature of this remote Solar System object has become the subject of intense debate. Indeed, as the discussion has descended into increasing acrimony and farce, Venetia's gentle composure has been depressingly missed.

When is a planet a star?

It was back in August 2006 that the celestial cat was set among the world's pigeons, at a General Assembly of the International Astronomical Union (IAU) in Prague. You may not have encountered the IAU before, but this venerable organisation is the governing body of world astronomy. Of necessity, it sits at the tedious end of the excitement spectrum, since someone has to dot the i's and cross the t's of all the astonishing new discoveries made by the world's astronomers and space scientists. That sort of thing isn't everyone's cup of tea, but it's an important function, and
it includes responsibility for providing definitions of the various celestial objects, as well as the exclusive right to name them. (Which, incidentally, gives the lie to star registry companies offering to name a star for you or your loved one on receipt of your hard-earned cash.)

Anyway, every three years the IAU has a General Assembly, in which matters of great cosmic weight are debated. Its 40 commissions and 76 working groups tackle such esoteric matters as extrasolar planets, high-energy astrophysics, and the origin of the Universe. Most of it is completely unintelligible to the outsider, but it's terribly exciting if you're part of the action. And part of the action in August 2006 was sorting out one particularly burning question: ‘What, exactly, is a planet?'

Yes, I know. You'd think that after 400 years of looking at the sky through telescopes, astronomers would have worked out what planets are. You may also wonder whether it actually matters how the word is defined. But there's real mystery attached to this question, and it's nowhere near as daft as it sounds. It comes about because astronomy, like all the sciences, is constantly evolving as new discoveries challenge established ideas. It's just one of the things that makes science exciting – you never know quite what's around the corner.

When I was a lad, everyone knew what a planet was. It was an object orbiting the Sun and shining by reflected sunlight rather than by its own luminosity. Stars like the Sun radiate heat and light because of energy-producing nuclear reactions in their interiors, whereas planets were thought to have no energy sources of their own. There were nine planets, and their order could be recalled using various loopy mnemonics like ‘My Venomously Eccentric Mother Just Served Up Napalm Pudding'. The biggest of them was Jupiter, and then, rather smaller but bedecked with a beautiful set of rings, was Saturn. Two more large planets, Uranus and Neptune, completed the quartet known eloquently as ‘gas
giants' – since they are big and are made mostly of gas. The rest of the planets were smallish rocky worlds, and the whole thing was very neat and tidy. Except, that is, for occasional comets and a decidedly untidy place called the Asteroid Belt, where myriads of mountain-sized boulders rolled around between the orbits of Mars and Jupiter.

I think it's fair to say that there was no single startling discovery that served to change this orderly picture. Rather, a gradual sequence of events arose from subtle new findings about both the Solar System and the planetary families of other stars in our celestial neighbourhood. To begin with, measurements made by the
Pioneer 10
and
Pioneer 11
spacecraft in the early 1970s showed that Jupiter actually gives off 70 per cent more energy than it receives from the Sun when measurements are extended beyond the red end of the rainbow spectrum of visible light, and into the invisible zone of infrared (redder-than-red) light – which is heat radiation. This put into question the idea that planets only shine by reflected light and raised the notion that a giant gas-ball planet like Jupiter might in some ways be viewed as a failed star – one that hadn't become big enough to switch on the nuclear reactions required for true stardom. And this led to a further blurring of the definitions.

In a genuine star, like our Sun, the central temperature is sustained by continuous H-bomb-like reactions in which hydrogen – the raw material of all stars – is turned into helium. The process is called nuclear fusion, and involves small atomic nuclei (of hydrogen) sticking together to make bigger ones (of helium), and releasing prodigious amounts of energy as a by-product. That's where the Sun's heat and light come from. The reactions are kicked off at the star's birth by a cloud of hydrogen being compressed, as it is pulled into a ball shape by its own gravity, and therefore getting hotter, just as the air in a bicycle pump becomes warmer as it is compressed. But if the hydrogen cloud is less
massive than it needs to be to form a true star, then the resulting object is something different.

Incidentally, when astronomers discuss the masses of celestial objects, they usually lump things into convenient bundles rather than measuring everything in tonnes. There's really no future in talking about the masses of planets, stars or galaxies in tonnes – you end up with far too many zeroes. For example, the Sun's mass is about 2 × 10
²⁷
tonnes in mathematical notation – or 2 followed by 27 zeroes for the rest of us. Which is pretty meaningless, really. It's far more convenient (and meaningful) to think about the masses of celestial objects like planets and stars in relation to the mass of Jupiter. The Sun, for example, is roughly 1000 times the mass of Jupiter. ‘Jupiter-masses' are therefore the units of choice for streetwise astronomers.

Back to the plot, then. Supposing that instead of being 1000 times the mass of Jupiter, like the star that became our Sun, a much smaller baby star – say, under 75 Jupiter-masses – began to form. What would happen? The smaller size would reduce the gravitational compression of the collapsing gas cloud, and its temperature wouldn't become high enough for hydrogen burning to begin. Thus, no star? Well, not quite. It turns out that if the baby star were between about 13 and 75 Jupiter-masses, a less energetic type of nuclear reaction would kick in, involving something called ‘deuterium', or ‘heavy hydrogen'. The resulting star would shine, but only dimly, and in infrared rather than visible light. It would become something to which astronomers have given the particularly uninspiring name of ‘brown dwarf '. It's not terribly PC, but that's the way it is.