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 .

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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. )

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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 .

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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 wo not be spared .

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