Does it exist? Does it not exist? From the moment you jettison the first teddy bear from your pram to see it return, you are playing the "gone, come back again game" that underpins much popular science. More comment from July 2002 Media Monitor.
Like those who say there are only five different plots, scientists have their standard storylines too. Among their favourites are the "This ought to exist but doesn't - why?" story, the "This seems to exist but shouldn't - why?" story, the "We thought this existed but couldn't find it until yesterday, whoopeedoo" story, and the "We always thought this existed, but on closer inspection find it doesn't" story.
Picture: Poor Archibald. Little did he know.
Most of these tales, science journalists would say, fall into another group - namely, the "Here's an answer to a problem you never knew was a problem" story. They abound in science, for obvious reasons – but for science journalists they are, well, a problem. And though scientists think them interesting, they more often than not give rise to another familiar tale, the "we thought we’d get coverage for this but didn’t" story.
Take, as a bad example, the problem of the mysterious missing sulphur. "What missing sulphur?" you ask. As Keller, Hony, Bradley, Molster, Waters, Bouwman, de Koter, Brownlee, Flynn, Henning and Mutschke explained in Nature (May 9), iron sulphides are a major component in meteorites. The problem was that until their research, sulphides had escaped detection in celestial objects similar to the early solar nebula – whence meteorites are thought to derive.
So where was it? Keller et al. showed how a broad feature in infrared spectra (that of iron sulphide grains from meteorites and interplanetary dust) did (after all) match another feature in Infrared Space Observatory spectra of those apparently sulphide-free Young Stellar Objects. What a relief! And what had caused this sudden spectral apparition? Nothing. It had been there all along, misattributed to iron oxide. Problem solved.
So, as a result of discovering that the thing we thought was there wasn't, Keller et al. made room for the thing that should have been there, but apparently wasn’t – thus solving the problem (that you never knew was a problem). "The missing sulphur has been found" Keller et al. concluded, triumphantly.
This kind of yarn is usually wearisome to all except those who already know about the problem – and they are all co-authoring the paper. Usually, that is, unless said problem is something really compelling – something utterly fantastic – or more often, some new and horrible way to die. New, not-nice ways to go are a sure-fire way of getting people’s attention, which is why scientists (especially geologists) spend so much time frightening folk to get them to listen. The nature of storytelling, combined with the structure of typical scientific plot-lines, impose it. And try as he or she might to resist the temptation of scaring the pants off Joe Public, sometimes a hack just can’t help it.
However there are times when the subject is just so odd, so weird, so intrinsically fascinating, as not to need the lurid edge. If the Earth moved for you late last year, and if you believe what you read in the Sunday Telegraph, you may have felt the planet being pierced by a million-mile-per-hour pollen grain that weighs as much as a truck – and not once, but twice. Two paired and unusual seismic signatures, one recorded on October 22 and the other on November 24 last year, are thought to represent the entry and exit wounds inflicted on the Earth by super-heavy cosmic particles called "strange quark nuggets" or "strangelets".
They sound like fast food, and they are. Travelling at close to a million miles an hour, they pass through planets without even slowing up. According to reports, this remarkable conclusion was presented to the Seismological Society of America (SSA) in May by a multidisciplinary team of geologists and physicists.
Strangelets were formed in the Big Bang, and are still being born inside very dense stars. They are ten million million times more dense than lead. Until recently, they were also pretty much entirely theoretical (though of course in physics, where certain magic rules apply, the boundary between what is real and what is imaginary is not as most folk understand it). However, this was perhaps the confirmation that theory had been demanding for 20 years.
The investigative team, from Southern Methodist University, Austin, Texas, went hunting the seismic records for pairs of sharp signatures that might denote a strangelet passing through the planet. They analysed millions of reports, and found two.
In the first, seismometers in Bolivia and Turkey registered a violent event in Antarctica that suggested an explosion equivalent to thousands of tons of TNT. The event was followed by another, somewhere offshore Sri Lanka, 26 seconds later – suggesting a travel time of 900,000 miles per hour. The other event saw the strangelet enter the Earth in Australia and exit over Antarctica after a similar travel time.
The authors of the SSA report plan to look for more. However, because seismic records routinely filter out non-earthquake noise, they have to look at the raw data, said Prof. Eugene Herrin. Seismologists, it seems, have been throwing the strangelets out with the bathwater.
This was not the first public outing for strangelets. In 1999, a standard frightener story suggested that they may devour the Earth completely – and it might be our fault. The suggestion was that the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (Long Island) could put the Earth in peril by creating them. They might, so the story went, begin eating the nuclei of ordinary matter, converting them into strange matter - eventually consuming the entire Earth. Bummer!
In an attempt to reassure the public, Arnon Dar, Alvaro De Roejula and Ulrich Heinz of CERN calculated the maximum probability of the Brookhaven collider creating a dangerous strangelet during its lifetime. The result was less than 20 chances in a billion, which the team called "a safe and stringent upper bound". Thus the Brookhaven lab set the RHIC running in June.
For some of those who love to quote the odds, this was far from acceptable, however. Radiological protection policy in Britain deems it unacceptable for solid nuclear waste to pose more than a one-in-a-million chance of killing around five people a year on average. To achieve the same level of risk, global annihilation by a strangelet would have to have a probability of 1 in 10-15 or less, because it has the potential to wipe out all six billion people on the planet. At such moments MM can only shake his head and wonder at strong persuasive power that figures seem to exert over the otherwise non-feebleminded. But anyway, back to strangelets.
Whatever the potential dangers of anthropogenic quark nuggets, you have to admit that the idea of natural-born killer strangelets bashing into the planet with the force of many kilotons of TNT lends the arcane world of subatomic physics a refreshingly non-cerebral kind of glamour. Hell, these things could kill you! However, the sober-minded Robert Matthews, author of the Sunday Telegraph piece, evidently felt he did not need to speculate on what it might be like to get in the way of one of these things.
MM, who shares the public’s taste for gore, felt this reticence rather regrettable. But although this was a classic "We always thought this existed but didn’t know until yesterday" story, it didn’t need it. We might never have heard of strangelets, nor have been aware that their apparent absence posed a problem. But finding out that the universe is riddled by million-mph ten-ton pollen is simply compelling enough on its own.
Related reading: New Scientist, 28 August 1999, p 24; Physics Letters B, v470, p142; New Scientist 13 April 2002, p50; Identification of iron sulphide grains in protoplanetary disks, Nature 417, 148-150, 9 May 2002; Sunday Telegraph 12.5.02, p19. Seismological Society of America