Wednesday, June 25, 2008

Common misconceptions.

Some of my favorites:

Christopher Columbus's efforts to obtain support for his voyages were not hampered by a European belief in a flat Earth. In fact, sailors and navigators of the time knew that the Earth was spherical, but (correctly) disagreed with Columbus' estimates of the distance to the Indies (see Flat Earth). If the Americas did not exist, and Columbus had continued to the Indies (even putting aside the threat of mutiny he was under) he would have run out of supplies before reaching them at the rate he was travelling.

Entrapment law in the United States does not forbid police officers from going undercover, or from denying that they are police. It is a common misconception among persons engaged in low-level crime that if an undercover police officer is asked, "Are you a cop?" that they must reveal themselves to avoid entrapment.

The Coriolis effect doesn't determine the direction that water rotates in a bathtub drain or a flushing toilet. The Coriolis force is relatively small; it appears over large scales (like weather systems) or in systems such as the Foucault pendulum in which the small influence is allowed to accumulate over time. In a bathtub or toilet, the flow of the water over the basin itself produces forces that dwarf the Coriolis force. In addition, most toilets inject water into the bowl at an angle; the resulting spin is tens of thousands of times too fast to be overcome by the Coriolis effect.

Mount Everest is, indisputably, the highest point of land above sea level (8850 meters / 29035 feet) which, according to traditional measurements, means that it is the tallest mountain in the world. Given certain definitions, however, this can be challenged. One alternative method of measurement is the base-summit height. When this is applied, Mauna Kea (a dormant volcano in Hawaii) turns out to be much higher at 10,314 meters (33,480 feet). This takes into account Mauna Kea's base on the ocean floor, some 6000 meters below sea level. Its height above sea level is only 4,208 meters (13,796 feet). If the base-summit height is measured from land only, Mount Kilimanjaro is the tallest free-standing mountain in the world, meaning it does not belong to a mountain range or chain, measured from its base (at ground level) to the summit at 5,896 meters (19,344 feet). Another alternative method is to work out the furthest point of land as measured from the centre of the earth. Chimborazo, a volcano in Ecuador, takes this honor, because the Earth "bulges" at the equator. This peak is 2,100 meters "taller" than Everest.

Lots more here.

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