Oxygen fills the air today, but for most of Earth’s early history it barely existed. Scientists say the atmosphere did not hold steady oxygen until about 2.

There are many levels at which a scientific question can be answered. An answer that is quite satisfying to a scientist from one discipline may be totally unsatisfactory to a scientist from another.

COLUMBUS, Ohio - When it comes to the fundamentals of making better materials - stronger-but-thinner glass for televisions or phone screens, for example - it almost always comes down to the building ...