The Hairy Ball theorem, proved by Henri Poincaré in 1885, demonstrates that it's impossible to create a perfectly smooth hair pattern on a spherical surface. The theorem states that any continuous ...

The roots of Russia's invasion of Ukraine go back decades and run deep. The current conflict is more than one country fighting to take over another; it is — in the words of one U.S. official — a shift ...

Matt Webber is an experienced personal finance writer, researcher, and editor. He has published widely on personal finance, marketing, and the impact of technology on contemporary arts and culture.