Encyclopaedia

In no other country on earth is my story even possible. —Barack Obama, July 27, 2004 On July 27, 2004, Illinois State Senator Barack Obama delivered the keynote speech at the Democratic National Convention. He said, “Tonight is a particular honor for me because, let’s face it, my presence on this stage is pretty unlikely.” When he finished his speech, the audience that listened with rapt attention excitedly waved their arms, hats, and signs, thrilled with what they had just heard. Afterward, those watching on television said that they had stood and cheered, many admitting they danced. Some wondered what had just happened. For many Democrats, the speech was electrifying and inspiring; for them, it was a joyful time. And those from the other side of the political aisle who watched and listened had to agree: this fresh face, this politico, unknown to nearly everyone in the count...

Cosmic body of extremely intense gravity from which nothing, not even light, can escape. A black hole can be formed by the death of a massive star. When such a star has exhausted its internal thermonuclear fuels at the end of its life it becomes unstable and gravitationally collapses inward upon itself. The crushing weight of constituent matter falling in from all sides compresses the dying star to a point of zero volume and infinite density called the singularity . Details of the structure of a black hole are calculated from Albert Einstein's general theory of relativity. The singularity constitutes the centre of a black hole and is hidden by the object's “surface,” the event horizon . Inside the event horizon the escape velocity ( i.e., the velocity required for matter to escape from the gravitational field of a cosmic object) exceeds the speed of light, so that not even rays of light can escape into space. The radius of the event hori...

S ome Uru and Aymara Indians on Lake Titicaca, South America, subsist through traditional agriculture and fishing. Inhabitants of floating totora islands are shown crushing grain with a saddle quern, embroidering wool cloth and other items for purchase by tourists, and finishing a small totora reed boat.

North Atlantic Ocean off North America in which more than 50 ships and 20 airplanes are said to have mysteriously disappeared. The area, whose boundaries are not universally agreed upon, has a vaguely triangular shape marked by the southern U.S. coast, Bermuda, and the Greater Antilles. Reports of unexplained occurrences in the region date to the mid-19th century. Some ships were discovered completely abandoned for no apparent reason; others transmitted no distress signals and were never seen or heard from again. Aircraft have been reported and then vanished, and rescue missions are said to have vanished when flying in the area. However, wreckage has not been found, and some of the theories advanced to explain the repeated mysteries have been fanciful. Scientific searches have revealed nothing to substantiate the storied peril of the r...

Diamond-making techniques have been embraced by Earth scientists in their efforts to simulate conditions in the Earth's deep interior. Of special significance were the high-pressure syntheses of two new forms of silicates. In 1960 Sergei Stishov, while at the Institute of High-Pressure Physics in Moscow, subjected ordinary beach sand (composed of the mineral quartz SiO 2 ) to more than 8 GPa of pressure and high temperatures. The form of silica that he produced was approximately 62 percent denser than quartz and was the first known high-pressure compound to contain silicon in six-coordination rather than the four-coordination found in virtually all crustal minerals. The natural occurrence of this new synthetic material was confirmed within a few weeks by careful examination of shocked material from Meteor Crater, Ariz., U.S. The mineral was named stishovite. In 1974 a second high-pressure discovery revolut...

Alfred Bernhard Nobel born Oct. 21, 1833, Stockholm, Sweden died Dec. 10, 1896, San Remo, Italy Swedish chemist, engineer, and industrialist, who invented dynamite and other, more powerful explosives and who also founded the Nobel Prizes . Alfred Bernhard Nobel was the fourth son of Immanuel and Caroline Nobel. Immanuel was an inventor and engineer who had married Caroline Andrietta Ahlsell in 1827. The couple had eight children, of whom only Alfred and three brothers reached adulthood. Alfred was prone to illness as a child, but he enjoyed a close relationship with his mother and displayed a lively intellectual curiosity from an early age. He was interested in explosives , and he learned the fundamentals of engineering from his father. Immanuel, meanwhile, had failed at various business ventures until moving in 1837 to St. Petersburg in Russia, where he prospered as a manufacturer of explosive mines and machine tools. The Nobel family left Stockholm in 1842 to join the father in...