To make certain the U.S. was aware of the danger, in July 1939, a few months before the beginning of World War II in Europe, Szilard and Wigner visited Einstein to explain the possibility of atomic bombs, which Einstein, a pacifist, said he had never considered. He was asked to lend his support by writing a letter, with Szilard, to President Roosevelt, recommending the U.S. pay attention and engage in its own nuclear weapons research. A secret German facility, apparently the largest of the Third Reich, covering 75 acres in an underground complex, was being re-excavated in Austria in December 2014 and may have been planned for use in nuclear research and development. The letter is believed to be "arguably the key stimulus for the U.S. adoption of serious investigations into nuclear weapons on the eve of the U.S. entry into World War II". In addition to the letter, Einstein used his connections with the Belgian Royal Family and the Belgian queen mother to get access with a personal envoy to the White House's Oval Office. President Roosevelt could not take the risk of allowing Hitler to possess atomic bombs first. As a result of Einstein's letter and his meetings with Roosevelt, the U.S. entered the "race" to develop the bomb, drawing on its "immense material, financial, and scientific resources" to initiate the Manhattan Project. It became the only country to successfully develop an atomic bomb during World War II. For Einstein, "war was a disease ... [and] he called for resistance to war." By signing the letter to Roosevelt he went against his pacifist principles. In 1954, a year before his death, Einstein said to his old friend, Linus Pauling, "I made one great mistake in my life--when I signed the letter to President Roosevelt recommending that atom bombs be made; but there was some justification--the danger that the Germans would make them ..."

What was arguably the key stimulus for the U.S. adoption of serious investigations into nuclear weapons on the eve of the U.S. entry into World War II?

The Golden Heian Era: The geomancers in 794 decided that Heian-kyo (modern Kyoto) would be an auspicious site for the imperial family. It was indeeduntil 1869. Grants of tax-free land over the years had been made to Buddhist temples and members of the court aristocracy. The most powerful families thus carved out for themselves whole regions that were to become the fiefdoms of Japanese feudalism. By the end of the eighth century the clans had created a hierarchy of shiki, or rights, from the highest to the lowest ranks of society. The aristocrat or court patron lent his prestige to a powerful provincial proprietor, who employed a competent estate-manager to oversee smallholders, who in turn worked their farms with dependent laborers. This elaborate structure of interdependent rights and obligations was to serve Japanese society right into the 20th century. Meanwhile, Heian court life blossomed in an effusion of aesthetic expression. Princes and princesses judged the merits of birds, insects, flowers, roots, or seashells. Literary party games held in ornate palace gardens required each guest to compose a small poem as his wine cup floated toward him along a miniature winding channel of water. Expeditions were organized to the best viewing points for the first spring cherry blossoms, and special pavilions were built to watch the rising of the full moon. Every gesture, from the most banal opening of an umbrella to the sublimest act of lovemaking, had its appropriate ceremonial. Conversation often took the form of elegant exchanges of improvised verse. The changing role of Chinese culture in Japanese life was epitomized in the language itself. In the absence of an indigenous alphabet, Japanese scholars had with the greatest difficulty tried to adapt the complex ideograms of monosyllabic Chinese to the essentially polysyllabic Japanese. Thus developed the katakana system used as a vehicle for writing Buddhist names and concepts. After rival Fujiwara factions had been struggling for years to gain control of the imperial throne, they turned to the Taira and Minamoto armies in 1156 to wage the four-year war that heralded the end of the golden age of the Heian court. The Taira, controlling the region along the Inland Sea, defeated the Minamoto armies based in the Kanto province east of the capital.

In Heian court life, princes and princesses judge merits of creatures and items based on what category?

From Babylon, Alexander went to Susa, one of the Achaemenid capitals, and captured its legendary treasury. He sent the bulk of his army to the Persian ceremonial capital of Persepolis via the Royal Road. Alexander himself took selected troops on the direct route to the city. He had to storm the pass of the Persian Gates (in the modern Zagros Mountains) which had been blocked by a Persian army under Ariobarzanes and then hurried to Persepolis before its garrison could loot the treasury. On entering Persepolis, Alexander allowed his troops to loot the city for several days. Alexander stayed in Persepolis for five months. During his stay a fire broke out in the eastern palace of Xerxes and spread to the rest of the city. Possible causes include a drunken accident or deliberate revenge for the burning of the Acropolis of Athens during the Second Persian War.
Alexander allowed his army to loot Persepolis after fighting against what army?