black hole

Everything in nature comes and goes—stars, planets, even our bodies—but what truly endures is repetition. The universe moves to a rhythm: the Sun brings the year’s shortest day on December 21 and its earliest sunset on December 7; the Moon cycles through fullness every 29½ days and repeats its elevation pattern every 18.6 years, reaching an extreme this year. Venus, fading from the morning sky, will return as a brilliant evening star later this winter—part of its elegant 8-year cycle. Saturn’s rings, now edgewise, won’t appear this way again until 2044. Even Earth’s poles follow a 26,000-year rhythm, and we’re now living in the rare moment when Polaris serves as the most perfectly placed North Star in that grand celestial cycle.

The Best of Our Knowledge explores topics on learning, education and research.Einstein theorized that at the center of a black hole, the laws of time and space break down. But quantum theory might allow researchers to further our understanding of the unknown.And an underground water source that feeds rivers in the Pacific Northwest could be much larger than previously thought.

Roundtable Panel: a daily open discussion of issues in the news and beyond.Today's panelists are WAMC’s Alan Chartock, Fran Berman - the Edward Hamilton…