ACID RAIN

WHAT IS ACID RAIN? Acid rain is the common name for acidic deposits that fall to Earth from the atmosphere. The term was coined in 1872 by the Scottish chemist Robert Angus Smith (1817–1884) to describe the acidic precipitation in Manchester, England. In the twenty-first century scientists study both wet and dry acidic deposits. Even though there are natural sources of acid in the atmosphere, acid rain is primarily caused by emissions of sulfur...

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Quantum Theory

quantum theory quantum theory, modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity together form the theoretical basis of modern physics. Just as the theory of relativity assumes importance in the special situation where very large speeds are involved, so the quantum theory is necessary for the special situation where very...

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Global warming

Global warming Understanding the causes of and responses to global warming requires interdisciplinary cooperation between social and natural scientists. The theory behind global warming has been understood by climatologists since at least the 1980s, but only in the new millennium, with an apparent tipping point in 2005, has the mounting empirical evidence convinced most doubters, politicians, and the general public as well as growing sections of...

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French Revolution

French Revolution The French Revolution invented modern revolution —the idea that humans can transform the world according to a plan—and so has a central place in the study of the social sciences. It ushered in modernity by destroying the foundations of the “Old Regime”—absolutist politics, legal inequality, a “feudal” economy (characterized by guilds, manorialism, and even serfdom), an alliance of church and state, and created a vision...

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