| THE END-OF-THE-WORLD MIGHT HAPPEN BECAUSE OF..
from "20 ways the world could end" by Corey S. Powell, on Discover Vol. 21 No. 10 (October 2000) © Copyright 2000 The Walt Disney Company (!!!) - with additional research by Diane Martindale
NATURAL DISASTERS: asteroid impact, gamma-ray burst, rogue black holes, giant solar flares, reversal of Earth's magnetic field, flood-basalt volcanism, global epidemics
HUMAN-TRIGGERED DISASTERS: global warming, ecosystem collapse, biotech disaster, particle accelerator mishap, nanotechnology disaster, environmental toxins
WILLFUL SELF-DESTRUCTION: global war, robots take over, mass insanity
A GREATER FORCE IS DIRECTED AGAINST US: alien invasion, divine intervention
Vedi anche: La fine del mondo e/o scarica il manuale-base di sopravvivenza (in inglese)
.. The current rate of extinctions is, by some estimates, 10,000 times the average in the fossil record. .. But the next statistic on the list could be us.
NATURAL DISASTERS
Asteroid impact
.. There is no question that a cosmic interloper will hit Earth. .. In 1908 a 200-foot-wide comet fragment slammed into the atmosphere and exploded over the Tunguska region in Siberia, Russia, with nearly 1,000 times the energy of the atomic bomb dropped on Hiroshima. Astronomers estimate similar-sized events occur every one to three centuries. .. One killed 10,000 people in the Chinese city of Chi'ing-yang in 1490. .. Impacts are most likely to occur over the ocean, and small ones that happen over land are most likely to affect unpopulated areas. But with big asteroids, it doesn't matter much where they land. Objects more than a half-mile wide - which strike Earth every 250,000 years or so - would touch off firestorms followed by global cooling from dust kicked up by the impact. Humans would likely survive, but civilization might not. An asteroid five miles wide would cause major extinctions, like the one that may have marked the end of the age of dinosaurs. For a real chill, look to the Kuiper belt, a zone just beyond Neptune that contains roughly 100,000 ice-balls more than 50 miles in diameter. The Kuiper belt sends a steady rain of small comets earthward. If one of the big ones headed right for us, that would be it for pretty much all higher forms of life, even cockroaches.
Gamma-ray burst
.. Once a day or so, .. gamma-ray bursts, .. originate[d] in distant galaxies and .. unfathomably powerful (as much as 10 quadrillion - a one followed by 16 zeros - times as energetic as the sun), .. outshine everything else, then vanish. .. The bursts probably result from the merging of two collapsed stars. .. At a distance of 1,000 light-years - farther than most of the stars you can see on a clear night - it would appear about as bright as the sun. Earth's atmosphere would initially protect us from most of the burst's deadly X rays and gamma rays, but at a cost. The potent radiation would cook the atmosphere, creating nitrogen oxides that would destroy the ozone layer. Without the ozone layer, ultraviolet rays from the sun would reach the surface at nearly full force, causing skin cancer and, more seriously, killing off the tiny photosynthetic plankton in the ocean that provide oxygen to the atmosphere and bolster the bottom of the food chain. ..
Rogue black holes
Our galaxy is full of black holes, collapsed stellar corpses just a dozen miles wide. How full? Tough question. After all, they're called black holes for a reason. Their gravity is so strong they swallow everything, even the light that might betray their presence. .. Researchers guesstimate there are about 10 million black holes in the Milky Way. These objects orbit just like other stars, meaning that it is not terribly likely that one is headed our way. But if a normal star were moving toward us, we'd know it. With a black hole there is little warning. A few decades before a close encounter, at most, .. the black hole wouldn't have to come all that close to Earth to bring ruin; just passing through the solar system would distort all of the planets' orbits. Earth might get drawn into an elliptical path that would cause extreme climate swings, or it might be ejected from the solar system and go hurtling to a frigid fate in deep space.
Giant solar flares
Solar flares - more properly known as coronal mass ejections - are enormous magnetic outbursts on the sun that bombard Earth with a torrent of high-speed subatomic particles. Earth's atmosphere and magnetic field negate the potentially lethal effects of ordinary flares. But .. Bradley Schaefer of Yale University found .. that some .. sunlike stars can brighten briefly by up to a factor of 20. Schaefer believes these stellar flickers are caused by superflares, millions of times more powerful than their common cousins. Within a few hours, a superflare on the sun could fry Earth and begin disintegrating the ozone layer (see #2). Although there is persuasive evidence that our sun doesn't engage in such excess, scientists don't know why superflares happen at all. .. And while too much solar activity could be deadly, too little of it is problematic as well. [If the sun gets] nearly 1% dimmer, [that] could send us into another ice age. .. Decreased solar activity contributed to 17 of the 19 major cold episodes on Earth in the last 10,000 years.
Reversal of Earth's magnetic field
Every few hundred thousand years Earth's magnetic field dwindles almost to nothing for perhaps a century, then gradually reappears with the north and south poles flipped. The last such reversal was 780,000 years ago, so we may be overdue. Worse, the strength of our magnetic field has decreased about 5% in the past century. .. The magnetic field deflects particle storms and cosmic rays from the sun, as well as even more energetic subatomic particles from deep space. Without magnetic protection, these particles would strike Earth's atmosphere, eroding the already beleaguered ozone layer (see "Giant solar flares"). Also, many creatures navigate by magnetic reckoning. A magnetic reversal might cause serious ecological mischief. ..
Flood-basalt volcanism
In 1783, the Laki volcano in Iceland erupted, spitting out three cubic miles of lava. Floods, ash, and fumes wiped out 9,000 people and 80% of the livestock. The ensuing starvation killed a quarter of Iceland's population. Atmospheric dust caused winter temperatures to plunge by 9 degrees in the newly independent United States. And that was just a baby's burp compared with what the Earth can do. Sixty-five million years ago, a plume of hot rock from the mantle burst through the crust in what is now India. Eruptions raged century after century, ultimately unleashing a quarter-million cubic miles of lava - the Laki eruption 100,000 times over. Some scientists still blame the Indian outburst, not an asteroid, for the death of the dinosaurs. An earlier, even larger event in Siberia occurred just about the time of the Permian-Triassic extinction, the most thorough extermination known to paleontology. At that time 95% of all species were wiped out. Sulfurous volcanic gases produce acid rains. Chlorine-bearing compounds present yet another threat to the fragile ozone layer. .. The last big pulse of flood-basalt volcanism built the Columbia River plateau about 17 million years ago. ..
Global epidemics
If Earth doesn't do us in, our fellow organisms might be up to the task. Germs and people have always coexisted, but occasionally the balance gets out of whack. The Black Plague killed one European in four during the 14th century; influenza took at least 20 million lives between 1918 and 1919. .. From 1980 to 1992, reports the Centers for Disease Control and Prevention, mortality from infectious disease in the United States rose 58%. Old diseases such as cholera and measles have developed new resistance to antibiotics. Intensive agriculture and land development is bringing humans closer to animal pathogens. International travel means diseases can spread faster than ever. ..
HUMAN-TRIGGERED DISASTERS
Global warming
.. It's easy to see how global warming could flood cities and ruin harvests. .. A balmier planet could also assist the spread of infectious disease by providing a more suitable climate for parasites and spreading the range of tropical pathogens (see #8). That could include crop diseases which, combined with substantial climate shifts, might cause famine. .. There could [also] be a bad feedback effect, with water evaporating faster, freeing water vapor, .. which traps more heat, which drives carbon dioxide from the rocks, which drives temperatures still higher. ..
Ecosystem collapse
.. Billions of years of evolution have produced a world in which every organism's welfare is intertwined with that of countless other species. .. To meet the demands of the growing population, we are clearing land for housing and agriculture, replacing diverse wild plants with just a few varieties of crops, transporting plants and animals, and introducing new chemicals into the environment. At least 30,000 species vanish every year from human activity, which means we are living in the midst of one of the greatest mass extinctions in Earth's history. .. Pollinating insects might become extinct, leading to widespread crop failure. ..
Biotech disaster
While we are extinguishing natural species, we're also creating new ones through genetic engineering. .. The genes from modified plants can leak out and find their way into other species. Engineered crops might also foster insecticide resistance. .. The resulting superweeds and superpests could further destabilize the stressed global ecosystem (see "Global warming"). Altered microbes might prove to be unexpectedly difficult to control. [Also,] a terrorist group or rogue nation might .. put together, say, an airborne version of the Ebola virus. Now there's a showstopper.
Particle accelerator mishap
.. Recently .. London's Sunday Times reported that the Relativistic Heavy Ion Collider (RHIC) on Long Island, New York, might create a subatomic black hole that would slowly nibble away our planet. Alternately, it might create exotic bits of altered matter, called strangelets, that would obliterate whatever ordinary matter they met. To assuage RHIC's jittery neighbors, the lab's director .. rejected both scenarios as pretty much impossible. .. The RHIC physicists did not, however, reject the fundamental possibility of the disasters. They argued that their machine isn't nearly powerful enough to make a black hole or destabilize the vacuum. Oh, well. We can always build a bigger accelerator.
Nanotechnology disaster
.. Within a few decades, maybe sooner, it should be possible to build microscopic robots that can assemble and replicate themselves. They might perform surgery from inside a patient, build any desired product from simple raw materials, or explore other worlds. .. After an industrial accident, .. bacteria-sized machines, "could spread like blowing pollen, replicate swiftly, and reduce the biosphere to dust in a matter of days." ("Engines of Creation", by K. Eric Drexler). .. Bill Joy, a cofounder of Sun Microsystems, envision nano-machines as the perfect precision military or terrorist tools.
Environmental toxins
.. In major cities around the world, the air is thick with .. carcinogen .. diesel particulates. .. Heavy metals from industrial smokestacks circle the globe, even settling in the pristine snows of Antarctica. Intensive use of pesticides in farming guarantees runoff into rivers and lakes. In high doses, dioxins can disrupt fetal development and impair reproductive function - and dioxins are everywhere. Your house may contain polyvinyl chloride pipes, wallpaper, and siding, which belch dioxins if they catch fire or are incinerated. .. Every year NIH adds to its list of cancer-causing substances - the number is up to 218. ..
WILLFUL SELF-DESTRUCTION
Global war
Together, the United States and Russia still have almost 19,000 active nuclear warheads. .. Political situations evolve; the bombs remain deadly. There is also the possibility of an accidental nuclear exchange. And a ballistic missile defense system, given current technology, will catch only a handful of stray missiles - assuming it works at all. Other types of weaponry could have global effects as well. Japan began experimenting with biological weapons after World War I, and both the United States and the Soviet Union experimented with killer germs during the cold war. Compared with atomic bombs, bioweapons are cheap, simple to produce, and easy to conceal. They are also hard to control. [Also,] genetic engineering might permit the creation of "ethnic" biological weapons that are tailored to attack primarily one ethnic group (see "Biotech disaster").
Robots take over
.. Hans Moravec, one of the founders of the robotics department of Carnegie Mellon University, .. predicts [that sooner or later] machines will match human intelligence, and perhaps human consciousness. Then they'll get even better. He envisions an eventual symbiotic relationship between human and machine, with the two merging into "postbiologicals" capable of vastly expanding their intellectual power. Marvin Minsky, an artificial-intelligence expert at MIT, foresees a similar future: People will download their brains into computer-enhanced mechanical surrogates and log into nearly boundless files of information and experience. Whether this counts as the end of humanity or the next stage in evolution depends on your point of view. ..
Mass insanity
While physical health has improved in most parts of the world over the past century, mental health is getting worse. The World Health Organization estimates that 500 million people around the world suffer from a psychological disorder. By 2020, depression will likely be the second leading cause of death and lost productivity, right behind cardiovascular disease. Increasing human life spans may actually intensify the problem, because people have more years to experience the loneliness and infirmity of old age. Americans over 65 already are disproportionately likely to commit suicide. Gregory Stock, a biophysicist at the University of California at Los Angeles, believes medical science will soon allow people to live to be 200 or older. .. Perhaps 200 years of accumulated sensations will overload the human brain, leading to a new kind of insanity. .. One possible solution - promoting a certain kind of mental well-being with psychoactive drugs such as Prozac - heads into uncharted waters. Researchers have no good data on the long-term effects of taking these medicines.
A GREATER FORCE IS DIRECTED AGAINST US
Alien invasion
.. The most likely danger is not direct conflict. Aliens might want resources from our solar system .. and swat us aside if we get in the way, as we might dismiss mosquitoes or beetles stirred up by the logging of a rain forest. Aliens might unwittingly import pests with a taste for human flesh, much as Dutch colonists reaching Mauritius brought cats, rats, and pigs that quickly did away with the dodo. Or aliens might accidentally upset our planet or solar system while carrying out some grandiose interstellar construction project. [Also,] contact with extraterrestrial visitors could also be socially disastrous. "Advanced western civilization has had a destructive effect on all primitive civilizations it has come in contact with, even in those cases where every attempt was made to protect and guard the primitive civilization".
Divine intervention
Judaism has the Book of Daniel; Christianity has the Book of Revelation; Islam has the coming of the Mahdi; Zoroastrianism has the countdown to the arrival of the third son of Zoroaster. .. But the underlying concept is similar: God intervenes in the world, bringing history to an end and ushering in a new moral order. .. More worrisome, to the nonbelievers at least, are the doomsday cults that prefer to take holy retribution into their own hands. In 1995, members of the Aum Shinri Kyo sect unleashed sarin nerve gas in a Tokyo subway station, killing 12 people and injuring more than 5,000. Had things gone as intended, the death toll would have been hundreds of times greater. A more determined group armed with a more lethal weapon - nuclear, biological, nanotechnological even - could have done far more damage.
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inimmaginabile!!!!! Seviper e' unico ed inimitabile!!!!!!! 
....ecco...adesso mi dite che cavolo ho postato?