If we can't explain it simply, then we don't know it well enough.
Relativity is concerned with observing the same events from two different points of view. The key understanding concerns one point of view moving with respect to another; for example, comparing observations from a speeding airplane with those from the ground below the plane. If one point of view is moving steadily with respect to the other, time and space follow laws first derived by Albert Einstein in 1905 with additional ideas from Henri Poincare [French: 1854-1912] in 1906.
– May 28, 2010
From early times, sanitation relied on ditches or pits where human wastes could be disposed. Even today such pits, with wooden shacks built over them, provide toilets for camps, rustic weekend houses, and much housing in poorer nations. People living near rivers or lakes built toilets that permitted wastes to fall into the water.
– May 23, 2010
Aristotle provided reasons based on his own physics why a vacuum-a region containing no matter-cannot exit. His physics and conclusion were both incorrect, but medieval scholars cited Aristotle to explain that pumps work because “nature abhors a vacuum,” causing fluid to move upward to fill empty space. In 1643, however, Evangelista Torricelli showed that air pressure pushes fluid to rise into a vacuum. Torricelli’s barometer produced the first persistent vacuum, lying above a column of mercury supported by air pressure.
– May 21, 2010
The favorite student of Aristotle, Theophrastus was one of the first people known to have studied plants. He wrote two major works that influenced scientists for centuries.
Inquiry into Plants, consisting of nine books, described and classified plants. Theophrastus noted the great diversification among roots, leaves, flowers, and other plant parts. For instance, he saw that some kinds of plant have numerous roots while others have single taproots, and that some kinds have small insignificant flowers while others have large colorful flowers.
– May 20, 2010
When Spanish explorers arrived in Central and South America some 500 years ago, they found people playing with bouncing balls made from the dried sap of certain trees.
Scientific interest in the sap began with Charles de La Condamine [French: 1701-1774] and Francois Fresneau [French: 1703-1770], who traveled up South American rivers looking for trees that natives called caa-ochue (“weeping wood”). The material didn’t get the name “rubber” until 1770, when Joseph Priestley noticed that it rubbed pencil marks off paper.
– May 18, 2010
| Flags | Countries | V (%) |
|---|---|---|
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Singapore | 61 % |
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United States | 13 % |
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Myanmar [Burma] | 7 % |
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United Kingdom | 2 % |
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India | 2 % |
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Canada | 1 % |
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Malaysia | 1 % |
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Australia | 1 % |
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Germany | 1 % |
| Total Visits: | 9187 |
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