Sleep paralysis is a phenomenon in which people, either when falling asleep or wakening, temporarily experience an inability to move. More formally, it is a transition state between wakefulnessand rest characterized by complete muscle atonia (muscle weakness). It can occur at sleep onset or upon awakening, and it is often associated with terrifying visions (e.g., an intruder in the…

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Nikola Tesla  was a Serbian born and later  inventor, electrical engineer, mechanical engineer, physicist, and futurist best known for his contributions to the design of the modernalternating current (AC) electricity supply system. Tesla gained experience in telephony and electrical engineering before emigrating to the United States in 1884 to work for Thomas Edison. He soon struck out on his own with financial backers, setting up laboratories and companies to…

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In the seventeenth century, the philosophy of space and time came as a central issue in epist and metaphysics. At its heart, Gottfried Leibniz, the German philosopher-mathematician, and Isaac Newton, the English physicist-mathematician, set out two opposing theories of what space is. Rather than being an entity that independently exists over and above other matter, Leibniz held that space is no…

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In 1905, Albert Einstein published a paper on a special theory of relativity, in which he proposed that space and time be combined into a single construct known asspacetime. In this theory, the speed of light in a vacuum is the same for all observers—which has the result that two events that appear simultaneous to one particular observer will not be simultaneous to another…

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