ANTI GRAVITY

  Attack of the Killer Neutrinos

  Incoming asteroids, nuclear war, deadly viruses--how many ways are there to
destroy life on Earth? Thanks to physics, obsessive apocalyptists now have
another possibility: lethal neutrinos. Neutrinos are those ghostly little
rascals that appeared in experiments in the 1930s but were invisible, that
might have some mass but then again might not, that can shift from one form to
another but might not, and that hardly react with anything but--guess
what?--sometimes do.

  That last feature is why physicists must resort to unusual detection methods
such as filling up tanks with nearly half a million liters of dry-cleaning
fluid. Not that neutrinos leave unsightly stains; rather a huge target is
necessary for that rare occasion when a neutrino bangs into a
dry-cleaning-fluid atom and thus reveals its elusive presence. And if you think
that some neutrinos might be killers, as does Juan I.  Collar of the University
of Paris, you need to know how frequently they interact with other kinds of
matter.

  Here's Collar's argument. The vast numbers of neutrinos produced by the sun
and other celestial bodies generally pass through Earth each day without a
peep. Yet once every 100 million years, a massive star collapses "silently"
within a couple dozen light-years of Earth. (It just so happens that everything
in space happens silently, but Collar is referring to a stellar collapse that
does not produce any visible supernova.)

  The silent ones may be the deadly ones. As the star collapses, it releases
prodigious quantities of hyperactive neutrinos. These energetic neutrinos could
ricochet off atoms in organic tissue, causing the atoms to tear through cells,
rip apart DNA, and thereby induce cancer and cellular mutations severe enough
to wipe out many species of animals.

  Collar even derives specific figures. He calculates that for every kilogram
of tissue, the neutrinos would send 19,000 atoms flying, leading to 12 tumors.
That's about six cancer sites for the average turtle, 350 for the typical dog,
800 for the adult human--in short, enough to wipe out many species. To bolster
his case, Collar also deduced that the 100-million-year period of these stellar
collapses is consistent with the known extinctions in Earth's historical
record.

  Paleontologists do not take Collar's theory too seriously, because there are
plenty of other, more likely killing mechanisms (including some that actually
leave evidence). But neutrino bombardment does provide another source of
consternation.  Other apocalyptic scenarios at least leave hope for salvation.
Asteroids could be diverted; nuclear war could be avoided; viruses could be
contained. But with neutrinos, even the dry cleaners won't be spared.