Plasma is one of the four fundamental states of matter (the others being solid, liquid, and gas). Heating a gas may ionize its molecules or atoms (reducing or increasing the number of electrons in them), thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions.

In linguistics, the comparative method is a technique for studying the development of languages by performing a feature-by-feature comparison of two or more languages with common descent from a shared ancestor, as opposed to the method of internal reconstruction, which analyzes the internal development of a single language over time.

Six years ago, lawyer-banker-scholar Charles Morris wrote a prophetic book - 'Two-Trillion-Dollar Meltdown: Easy Money, High-Rollers and the Great Credit Crunch' - that foresaw the 2008 Great Recession before it clobbered America and the world. Now Morris has reversed course and sees good times ahead. His forthcoming book, 'Comeback,' predicts that surging U.S. energy independence will bring a buoyant rise in American manufacturing and jobs.

"Democracy's real test lies in its respect for minority opinions." - Ellery Sedgwick

The Vikings were seafaring north Germanic people who raided, traded, explored, and settled in wide areas of Europe, Asia, and the North Atlantic islands from the late 8th to the mid-11th centuries. The Vikings employed wooden longships with wide, shallow-draft hulls, allowing navigation in rough seas or in shallow river waters. The ships could be landed on beaches, and their light weight enabled them to be hauled over portages. These versatile ships allowed the Vikings to travel as far east as Constantinople and the Volga River in Russia, as far west as Iceland, Greenland, and Newfoundland, and as far south as Nekor. This period of Viking expansion, known as the Viking Age, constitutes an important element of the medieval history of Scandinavia, Great Britain, Ireland, Russia, and the rest of Europe.