This puzzle is known as the problem of time, and it remains one of the most persistent obstacles to a unified theory of ...

Tiny aerosol particles in the air play a big role in regulating how much sunlight our planet absorbs or reflects, and how clouds form above us. In a recent study, researchers found that extreme heat ...

Curious Kids is a series for children in which we ask experts to answer questions from kids. What is the smallest thing in the universe that actually exists? – Mimi, 12, Abeokuta, Nigeria To find an ...