Now many of you have probably seen this.. pretty scary.. pretty funny.. i laughed.. i cried.. whatever. Does anyone have any alternate ways that the human race could be brought to an end? Summarised from an article by Corey S. Powell, entitled 'Twenty ways the world could end suddenly', in Discover magazine (October 2000). Monitored for the Institute by Roger Knights. The odds of being one of the people to witness the end of the world are highest when there is the largest number of witnesses around - at present, about one fifth of all the people who have ever lived are alive today. When it is also considered that ninety-nine percent of all species that have ever lived have become extinct, it is not so unlikely that humans could feature among the next statistics. Twenty ways in which this could possibly happen, ranging from the frighteningly likely to the frankly absurd, are detailed below. Asteroid Impact There is now little doubt that a comet or asteroid, or a fragment of them, will hit the Earth in the future. In 1908, a 200-foot-wide comet fragment exploded over a region of Siberia with nearly 1,000 times the energy of the Hiroshima atomic bomb. More recently, comets and asteroids have passed close by the Earth, watched with trepidation by astronomers and governments alike. And if an asteroid does hit us, it will not matter where, for the force of the impact will cause firestorms, global cooling, and probable major extinctions. A ten-mile asteroid is thought to have done for the dinosaurs; without taking the problem seriously, the human race could be next. [For a related article on this subject in the Global Ideas Bank, see 'Using lasers to deflect earth-bound asteroids'] Gamma-ray burst Gamma-ray bursts, which are thought to be caused by the merging of two collapsed stars, could conceivablycompletely destroy the ozone layer of the Earth, and civilisation with it. With each burst being as much as ten quadrillion (10,000,000,000,000,000) times as energetic as the sun, a burst bombarding Earth would cook the atmosphere and allow ultraviolet rays to reach the surface at full force. This would not just mean an increase in skin cancer, but the extermination of photosynthetic plankton which provide oxygen to the atmosphere. The chance of a burst near us may be rare, but scientists believe that such a burst might eb completely undetectable until it starts. [For a related article on this subject in the Global Ideas Bank, see 'Gamma-ray bursts wipe out galactic life before spacefaring evolves'] Collapse of the vacuum According to some cosmologists, there was a false vacuum (an empty space full of energy) that existed in the very early history of the universe, which was subsequently replaced by more stable kind of vacuum. The transition between the two unleashed a massive amount of energy and caused an expansion of the cosmos. It is feasible that an even more stable vacuum might appear and take over, which would result in the laws of physics changing in a split second, and everything being blown to pieces by a massive blast of energy. Rogue black holes There are estimated to be about ten million black holes in the Milky Way, all of which are difficult to find, observe and track. If a black hole were to pass through our solar system, it would distort the other planets' orbits. This, in turn, could mean the Earth becoming drawn into an elliptical path that would result in massive climate swings or, more catastrophically, the Earth could even be ejected from the solar system altogether and sent hurtling in to space. The good news is that black holes orbit like other stars, so one is unlikely to be headed our way. The bad news is that we would not know if one was. Giant solar flares Bradley Schaefer of Yale University recently discovered that solar flares which bombard the Earth, and which the Earth's atmosphere effectively defends against, may have cousin superflares which are potentially destructive. Such a superflare, or giant solar flare, emitted by the sun could fry the Earth, resulting in the complete destruction of the ozone layer. And if Mr Schaefer is wrong, Sallie Baliunas of the Harvard-Smithsonian Center forAstrophysics suggests an equally worrying opposite scenario. She has found that solar-type stars go through quiescent periods, in which they become one per cent dimmer. If the sun went through a similar period, another ice age could be upon us. Reversal of Earth's magnetic field The Earth's magnetic field decreases to almost nothing every few hundred thousand years, and then reappears with the north and south poles flipped. A decrease in the magnetic field could result in a decrease in the amount of particle storms, cosmic rays and subatomic particles that the field deflects on a daily basis. This would, again, erode the protective ozone layer. And if the poles were to flip, many creatures that navigate magnetically could be affected. A full magnetic reversal could cause massive ecological problems across the whole of the Earth. Flood-basalt volcanism Sixty-five million years ago, a huge volcanic explosion in what is now India unleashed a quarter-million cubic miles of lava;it is an eruption which some scientists believe may have caused the extinction of the dinosaurs. An earlier, even greater, eruption wiped out ninety-five per cent of the species living on Earth at that time. It might not be long before the planet is due another. Global epidemic As old diseases grow resistance to current antibiotics, and international travel allows diseases to spread much more quickly, another global epidemic might not be to far away. A new, unfamiliar strain, possibly encouraged by a generally warmer climate and our interference in ecological matters, could spread at such a rate as to defeat all preventative measures. Our worst enemies could once again prove to be the organisms with which we co-exist. Global warming Global warming is a well-documented problem now, but that does not lessen the potential for disaster which it brings. A warmer planet could encourage disease, possibly coupling with climate change to cause famine. Temperatures could be increased by evaporating water and carbon dioxide being driven from rocks. Meanwhile, the melting of ice caps and increase in sea levels could soon conceivably be flooding cities and washing out harvests. Some even say that a typical day on Earth could soon mirror that on Venus, with an average top temperature of 900 degrees fahrenheit. [For related articles on this subject in the Global Ideas Bank, see 'Mediterranean climate for UK for 1000 years, then glacial'; also 'Reducing cattle flatulence to combat global warming'; also 'Buy an acre of tropical forest'; and 'The Ecologist's Declaration on Climate Change'] Ecosystem collapse Evolution over the year has resulted in the fate of organisms on this planet becoming intertwined with one another. The overall loss of biodiversity could therefore be disastrous for Earth if it continues unabated, especially when one considers that humans are directly responsible for 30,000 species becoming extinct every year. As an example, a study of a park near Lake Superior discovered that colder snowy winters result in wolves hunting in larger packs. This leads to the wolves killing more moose. The reduction of the moose population leads, in turn, to more balsam fir trees surviving. The increase in the number of trees then results in more carbon dioxide being pulled out of the atmosphere which influences the climate. This subtle interlinking of co-existent organisms will be something that the human race continues to overlook at its own peril. Biotech disaster The hazardous effects of biotechnology range from the possible impact of genetically modified food on our natural ecosystems to deliberate misuse of its power. GM crops, it is thought, could engender insecticide resistance in other species, resulting in superweeds and superpests affecting our ecosystems. More frightening, pehaps, is the thought that a terrorist group or hostile nation might unleash disease upon the world. Anthrax might be controllable, but what about an airborne version of Aids or the Ebola virus? Particle accelerator mishap Some scientists have posited the theory that a particle accelerator experiment could set of a world-destroying chain reaction. It was recently reported in the Sunday Times that the Relativistic Heavy Ion Collider (RHIC) in New York could create a subatomic black hole that would gradually eat away at our planet. Or, with equally serious results, it might create 'strangelets' (bits of altered matter) that would destroy any ordinary matter they encountered. The RHIC's directors rejected these suggestions not by dismissing the fundamental possibility of such disasters, but by insisting that their machine was not big enough to cause them. Which begs the question: what if somebody builds a bigger particle accelerator? Nanotechnology disaster Nanotechnology is a burgeoning new field in which engineers are creating atomic-scale machines with miniaturised circuits and silicon chips. The technology could one day see robots which are capable of assembling and replicating themselves. While this could lead to robots performing surgery from inside a patient or exploring new worlds, it could also lead to a more frightening future. Eric Drexler of the Foresight Institute has suggested that if an industrial accident were to occur, then bacteria-sized machines could spread across the planet like pollen blowing in the wind. This would, says Drexler, simply "reduce the biosphere to dust in a matter of days." Environmental toxins Environmental pollution is a topic familiar to us all these days, particularly in the wake of the Bhopal and Chernobyl disasters. The sheer volume of pollutants that the human race now pumps into the air and the sea will cause problems for much longer than a few centuries. Carcinogenic diesel particulates hang in the air, while heavy metals emerge from industrial smokestacks daily. At the same time, rivers become more and more polluted by the hour. Potentially most seriously of all could be the massive increase in dioxins in the air. In sufficiently high doses, dioxins can impair foetal development and it has been suggested that they could seriously reduce fertility. If that proves to be the case, polluting our atmosphere could eventually threaten our survival. Global war Although the US and Russia are on relatively good terms today, the threat of war remains very real. There are now eight nuclear nations in the world, with over 20,000 active nuclear weapons, and politics change notoriously quickly. Added to that is the possibility of an accidental nuclear exchange, with current interception technology unable to prevent a significant number of missiles. Bioweapons could be an even more realistic threat, because they are cheaper, easier to produce, and simpler to conceal. This could prove attractive to hostile, no-nuclear nations wishing to wreak havoc. And as genetic engineering technology continues to progress, genetic warfare, in which particular ethnic groups are targeted, might not be far behind. [For a related article in the Global Ideas Bank, see 'Ideas for preventing war'] Robots taking over This may sound more like something out of a film, but serious scientists give credence to this possibility. Hans Moravec, a co-founder of the robotics department at Carnegie Mellon University, believes that by 2040 robots will match human intelligence and even human consciousness. He then foresees a 'postbiological' person evolving symbiotically, who will be a merging of human and machine. Some might say this is the next stage in evolution, but others will view it as the end of humanity itself. Mass insanity By 2020, it is thought that depression will be the second leading casue of death after cardiovascular disease. 500 million people around the world suffer from some sort of psychological disorder at the moment, and the number is increasing rapidly year on year. It is thought that ever-lengthening life spans could also see the number increase, as the brain is overloaded with 150 or even 200 years of problems, stresses and sensations. If that proves to be correct, depression and suicide among the elderly could well continue to increase. Alien invasion The great danger from extra-terrestrial visitors might not be conflict, but a wish for our resources or for Earth as part of some grand inter-stellar project. Just making contact with aliens could be disastrous as well: as the late physicist Gerald O'Neill pointed out, "Advanced western civilisation has had a destructive effect on all primitive civilisations it has come into contact with. I don't see any reason why the same thing would not happen to us." Divine intervention Judaism, Islam, and Christianity all have books containing predictions of divine intervention in which God brings history to an end and ushers in a new, more moral, order. Such apocalyptic thinking may seem far-fetched if you are a non-believer, but the doomsday cults that seem intent on fulfilling these prophecies themselves should provide enough food for thought for now. Someone wakes up and realises it was all a dream The possibility that we are living a shadow existence that fools us into thinking it is real has been dealt with countless times in books and films. This could also be compared to the possibility of vacuum collapse. In the same way that our empty space might not be the most stable form of the vacuum, so what we call reality might not be the truest, most stable form of the vacuum. To frame the question more poetically, one can refer to the Taoist philosopher Chuang Tzu who had a dream in which he was a butterfly with no awareness of his existence as a person. When he awoke, he said,"Was I before Chuang Tzu who dreamt about being a butterfly, or am I now a butterfly who dreams about being Chuang Tzu?"