Doomsday Scenarios?

Is the world going to end with a bang - or with a whimper? What about that bit in Revelations - The last trump?

The one thing we can assume is that the world will one day 'end' - even if that means waiting around for a few billion years until the sun expands to a red giant and swallows up the earth. But what do people mean when they speak of 'the end of the world'? Let's take a look at some doomsday scenarios.

• Impact events - The impact of a big enough asteroid or comet could create giant tsunamis, global fires, and cause a global winter from the dust it puts in the atmosphere. There is strong evidence that such an impact has occurred several times in the history of the Earth. It is highly probable that such an event was the cause of the extinction of the dinosaurs. The chances are that we would receive little or no warning of such an event. (Sorry Armageddon fans - it just wouldn't be noticed in time for Bruce Willis to go and blow it up). Astronomers have calculated, based on crators on the Moon, that during the last 600 million years the Earth has probably been struck by about 60 objects, 5 kilometers or more across. The smallest of these would release the equivalent of 10 million megatons of TNT, leaving a crater 95 kilometers across. Thats 200,000 times as powerful as the largest atom bomb ever detonated. Definitely a 'Bang' scenario.
  
  
• Volcanism - Throughout the history of the Earth there have been huge 'super volcano' volcanic eruptions which involve the outflow of millions of cubic kilometres of ejecta in a short period of time. By comparison the biggest volcanic explosions recorded by history are tiny. The dust and gasses would poison the atmosphere and oceans and bring on a global winter in a way that may cause extinctions. This cause has been proposed for the End Cretaceous, End Permian, End Triassic, and End Jurassic extinctions. There are supervolcanos at Yellowstone in the USA, Indonesia and New Zealand. Definitely a 'Bang' scenario.
• Nuclear war -Apart from the destruction and radiation, a global nuclear war could throw sufficient dust into the atmosphere to cause a nuclear winter which would prevent crops growing for up to two years and bring about mass starvation. Definitely a 'Bang' scenario.
• Climate change - Rapid changes of climate may be capable of stressing the environment to the point of causing mass extinction. Such a scenario is suggested in the film 'The day after tomorrow'. Whilst such a scenario would greatly inconvenience us, causing mass starvation and causing some species to become extinct, ice ages in the past seem to have had little effect on bio-diversity. Extinctions suggested to have this cause include: End Ordovician, End Permian, Late Devonian, and others. This one would be a shivering whimper.
  
  
  
  
  
  
  

• Gamma ray burst - A nearby gamma ray burst from a supernova within 6000 light years distance could cause enough radiation on the surface of the Earth to kill most of the larger animals living there and destroy the ozone layer in the process. Insects would probably survive. Astronomers tell us approximately 1 gamma ray burst can be expected every 540 million years. This has been suggested as an explanation for the End Ordovician extinction event. A whimper scenario with a spectacular display in the sky.
• A new disease. It's possible that a new disease could develop, either by natural means or by genetic manipulation. Humanity would have little or no resistance to it and only isolated communities would survive. There have been several natural pandemics in the past but none of them came close to wiping out humanity. They did have a dramatic effect on civilization however. The black death killed from 20 to 80% of the population of towns, 33% overall of the worlds population. Labour became in short supply and it caused the end of the feudal system. A whimper scenario.
• Simulation shutdown. I'm sure you've seen the 'Matrix' films. Science fiction huh? Well maybe not! It's possible that we are living in a simulation. Consider the way in which computers have advanced. It won't be too long before they advance to the point where it would be possible to create a society in simulation (Sims 2 game?). Given a sufficiently advanced technology it would be possible to simulate an entire world in incredible complexity. Think that's unlikely? We could in fact be in such a simulation and not know it. If that were the case then it would be possible for the simulation to be shut down. There's not a lot we could do about it. One second we are 'alive' and the next - off. No sound at all.
• Nanotechnology. This is in effect a man made equivalent to a biological plague. Whilst nanotechnology (the creation of microscopic machines) could have enormous potential for good it could also cause a 'gray death' where the nano-machines convert the entire mass of the Earth to more machines. An unlikely scenario? You would only need one of these nanobots to be created to start the process. Another 'whimper' scenario first proposed by Eric Drexler, in his book 'Engines of Creation' and was followed by Michael Chrichton's book 'Prey'.
• Magnetic pole reversal. Geological evidence shows us that the Earth's magnetic poles reverse every 200,000 years on average. The last one was 700,000 years ago so we would seem long overdue for this. When it happens it will have a dramatic effect on the Earth. The main cause for concern is that the Earth's magnetic field which creates the protective Van Allen belts will disappear and Earth will be exposed to very high levels of solar radiation. Some scientists think the magnetic field is already weakening. This would be a 'whimper' event - maybe a good time to invest in sun-screen manufacturer shares.
• Runaway Greenhouse. In this 'global warming' scenario, the level of greenhouse gases in the atmosphere reaches a point where more heat is trapped in the atmosphere than can be radiated back out into space. The result is an unstoppable temperature rise over a period of years or tens of years, which would be sufficient to wipe out most forms of life very quickly.Venus, where temperatures at the surface are high enough to melt lead, is affected by this phenomenon. It's possible that the release of carbon dioxide and methane into the Earth's atmosphere could trigger the release of trapped methane stored on the oceans floors and in permafrost causing this effect. The amount of greenhouse gases in the atmosphere has been much higher in the past however so this is very uncertain. It may be that the Earth's oceans will absorb whatever we release. Again a 'whimper' event.
• Superseded by technology. Eventually we will create an artificial intelligence which could replace us as the dominant intelligence on this planet. Something like the scenario on which the Terminator movies are based. The war between it and us would be a bang event. Of course we could carefully program such intelligences with something like the laws of robotics suggested by Isacc Asimov and it could go too far the other way with such intelligences stifling our future development by being over protective - a whimper event.
• Global Snowball. The very reverse of the runaway greenhouse. Dust from volcanoes, a decrease in solar output or impact events could cause a winter which freezes the oceans. This increases the amount of heat reflected and the temperature in summer is never enough to melt the ice. A very chilly 'whimper' event where we would desperately try to induce a greenhouse effect to solve it!
• Solar old age. As the Sun uses up all its hydrogen fuel, helium at it's core will start nuclear fusion causing an increase in solar temperature. The result is a gradual increase in size. This process will continue until, around 5 billion years from now, the Sun will be 100 million miles across - encompassing the entire orbit of the Earth. Life will have been extinguished on our planet long before that. The seas will boil off and all gas will be blown away from the Earth by solar storms. It is estimated that 1 billion years from now, the temperature of the Earth will be similar to present-day Venus making life untenable. Given a billion years this will be a long drawn out 'whimper' where our descendants (if we have any by then) will probably bear little resemblance to us today.
  
  
• Alien invasion. Could it be the might be an alien invasion on the lines of 'Independence Day', 'Battlefield Earth' or 'War of the Worlds'. If we were to face a hostile advanced intelligence would we really have any chance against them? Probably a 'Bang' event.
• Uploads. This is an alternative to developing artificial intelligence which supersedes us. It may be that we will develop the ability to transfer our consciousness to a computer by 'uploading our brains'. If that were the case then many would choose this as an alternative to death. Once this is the case human intelligence can evolve at an ever increasing rate as processors become more powerful, faster and storage capacities increase. The upload would be able to redesign itself and eventually uploads would swamp the 'normal' humans. The question here is whether an upload could count as being human? Humanity as we know it today would wither away. A whimper event.
• Divine intervention. Most religions suggest that there will come a time when Man's purpose on Earth is achieved and God/the Gods call an end where the good people are separated from the evil ones.
• In the Christian Biblical account of the Last Judgment, the End of the World is preceded by War, Conquest, Pestilence and Famine, the so-called "Four Horsemen of the Apocalypse" and the blowing of seven trumpets. It's been expected since about AD 60.
• Islam nails the Apocalypse down to a formula in the Qur'an, thanks to prophecies by Muhammad. It's the apocalypse when 'x' amount of famine is multiplied by 'y' amount of drought, divided by the square root of 'z' infidels. (It's any day now, in case you were wondering.) Only Allah will know the exact date however but we can watch out for: Fire, Floods, Pestilence, Wars, Rumours of wars, Strange lights in the skies, The Second Coming, A virgin birth, The birth of the Antichrist, A number of false Christs and/or Messiahs, Cloning, Identifying marks being placed on the population at large (embedded RFID chip anyone?), Famine, Earthquakes and The Rapture where true believers will be whisked away to heaven.
• The Hindus believe that the universe is running a cycle which will culminate in a Cosmic Reboot at the end of the Fourth Age (which we are currently enjoying). Currently the world exists in the Age of Kali, the god of destruction. Kali rules over an age of strife, anger and war on earth, which will end with the destruction of everything to pave the way for a new world. Unlike the Christians and Muslims, the Hindus don't believe this event is coming any time soon.
• Buddhists believe that the seeds of the ending of the universe are present in the creation of the universe. (Quite in tune with cosmology). The "Buddha of our time", Shakyamuni Buddha, did not say he was the first Buddha. He did speak of the end of illusion which would change how we see the universe. In Tibetan Buddhism, it is predicted that the physical universe will end with earth and air being subsumed into water and fire, and all will dissolve into space. Within this cosmology, the end is predicted to be a long way off in the future as there will be 1,000 Buddhas who appear in this fortunate kalpa (great eon).
• The Mayans too believed in a cyclic world. Their highly detailed and accurate calendar is a list of days in the Fourth Sun, the current cycle of the world. The calendar simply ends on Dec. 21, 2012 (the winter solstice), and the Mayans did not offer a calendar addendum to specify anything much happening after that. No doubt, had they still been around, they would be getting round to producing a new calendar for the next cycle now.
• The Jews believe they are God's chosen people and that the Messiah will arrive in the future and gather them into Israel. There will be a general resurrection of the (Jewish?) dead, and the Jerusalem Temple destroyed in 70 CE will be rebuilt. I'm not sure on what Jews believe will happen then or to the rest of the world. Perhaps someone more knowledgeable could enlighten me?
• Zoroastrians believe in a single supreme god Ahura Mazda and an evil spirit Angra Mainyu who opposes. At the end of time there will be a cosmic conflict involving the entire universe. Humanity will be required to choose which to follow. Evil, and the Spirit of Evil, will be completely destroyed at the end of time. Eventually, everything will be purified. Even the occupants of hell will be released.

Source: Google and Google images