Only 12,000 years ago there was a species closely related to modern humans called Homo floresiensis that had been living on an Indonesian Island. They used fire and rather advanced tools, yet were only about 3 feet tall and weighed around 25kg.
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Because heat expands the metal, the Eiffel Tower always leans away from the sun.
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In Arizona, a solar wind energy tower has been proposed that would generate as much energy as the Hoover Dam.
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Columbia University has developed an artificial tree that passively soaks up carbon dioxide from the air using "leaves" that are 1,000 times more efficient than true leaves that use photosynthesis.
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One ragweed plant can release as many as one billion grains of pollen!
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Stephen Hawking once tried to find potential time travellers by throwing a party and only sending out invitations after the party.
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