History's greatest conspiracy theories

30. Chemtrails - Chemtrail conspiracy theorists believe that some contrails, which consist of ice crystals or water vapor condensed behind aircraft, actually result from chemicals or biological agents being deliberately sprayed at high altitude for some undisclosed purpose. The staple of right-wing radio shows in the US, there is fevered speculation that the chemicals being sprayed are part of a wider plot that involves the so-called New World Order and is being directed by shadowy forces within the government. The existence of chemtrails has been repeatedly denied by federal agencies and scientists.



29. Global warming is a hoax - Some climate change doubters believe that man-made global warming is a conspiracy designed to soften up the world's population to higher taxation, controls on lifestyle and more authoritarian government. These sceptics cite a fall in global temperatures since last year and a levelling off in the rise in temperature since 1998 as evidence.



28. The Aids virus was created in a laboratory - Based on the theories of Dr William Campbell Douglass, many believe that that HIV was genetically engineered in 1974 by the World Health Organisation. Dr Douglass believed that it was a cold-blooded attempt to create a killer virus which was then used in a successful experiment in Africa. Others have claimed that it was created by the CIA or the KGB as a means to reduce world population.



27. HAARP - More than 200 miles east of Anchorage, Alaska, is the Pentagon's High-frequency Active Auroral Research Program, officially an enormous experiment to heat the ionosphere with radio waves. But conspiracy theorists believe the project is a weapon to bring down aircraft and missiles by lifting sections of the atmosphere, cause earthquakes or even a huge weather modification machine.



26. Plastic coffins and concentration camps - Just outside Atlanta, Georgia, beside a major road are approximately 500,000 plastic coffins. Stacked neatly and in full view, the coffins are allegedly owned by the Federal Emergency Management Agency (Fema). Conspiracy theorists believe that Fema has also set up several concentration camps in the US in preparation for the imposition of a state of martial law and the killing of millions of Americans. They suggest that the financial crisis will be used to justify the imposition of a police state.



25. The 2004 Indian Ocean tsunami - A popular theory in the Muslim world is that the tsunami could have been caused by an Indian nuclear experiment in which Israeli and American nuclear experts participated. Several newspapers in Egypt and the Middle East alleged that India, in its heated nuclear race with Pakistan, has acquired sophisticated nuclear technology from the US and Israel, both of which "showed readiness to co-operate with India in experiments to exterminate humankind," beginning with the heavily populated Muslim regions of southeast Asia, where the bulk of casualties took place.



24. Fluoridation - Fluoride is commonly added to drinking water as a way to reduce tooth decay. However, there has been some evidence that there could be some harmful side effects from fluoride and conspiracy theorists believe that this information is known and recognised by those responsible for adding the fluoride, but that they continue the practice regardless. Drug companies have been targeted as possible beneficiaries, as they will profit from a population with ill-health. Another motive is that fluoride lowers mental abilities thereby "dumbing down" the entire population.



23. Pan Am Flight 103 - Pan Am Flight 103 was Pan American's third daily scheduled transatlantic flight from Heathrow to New York John F. Kennedy International Airport. On December 21, 1988, the aircraft flying this route - a Boeing 747 - was destroyed by a bomb, killing all 259 people on board and 11 people on the ground. The remains landed around Lockerbie in southern Scotland. A popular theory for which no evidence has been produced suggests that the US Central Intelligence Agency (CIA) had set up a protected drug route from Europe to the United States - allegedly called Operation Corea - which allowed Syrian drug dealers to ship heroin to the US using Pan Am flights. The CIA allegedly protected the suitcases containing the drugs and made sure they were not searched. On the day of the bombing, terrorists exchanged suitcases: one with drugs for one with a bomb. Another version of this theory is that the CIA knew in advance this exchange would take place, but let it happen anyway, because the protected drugs route was a rogue operation, and the American intelligence officers on the flight had found out about it, and were on their way to Washington to tell their superiors.



22. The Philadelphia Experiment - Popularised by the Charles Berlitz novel of the same name, conspiracy theorists believe that during an experiment at the Philadelphia Naval Shipyard in October 1943, the US Navy destroyer Eldridge was rendered invisible. According to some accounts, the scientists on the experiment found a way to bend light around an object but that the experiment went wrong and Eldridge was transported through space and time, reappearing at sea. Several sailors, it is said, were badly hurt when the experiment went wrong and some were melded into the ship's superstructure. The US Navy has denied that the experiment ever took place.



21. Pearl Harbor was allowed to happen - Theorists believe that President Franklin Roosevelt provoked the Japanese attack on the US naval base in Hawaii in December 1941, knew about it in advance and covered up his failure to warn his fleet commanders. He apparently needed the attack to provoke Hitler into declaring war on the US because the American public and Congress were overwhelmingly against entering the war in Europe. Theorists believe that the US was warned by the governments of Britain, the Netherlands, Australia, Peru, Korea and the Soviet Union that a surprise attack on Pearl Harbor was coming and that, furthermore, the Americans had intercepted and broken all the important Japanese codes in the run up to the attack.

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