The universe is a big place, but do we really know how big? Scientists think they do, and use an array of methods to figure it out. Here are our CliffNotes.

Five hundred million years following the Big Bang, when the universe was but three percent as old as it is now, a black hole ...

Conventional wisdom says that the age of the universe is 13.8 billion years old—but a recent paper disagrees. How do we decide?

In 1916, Albert Einstein discovered that his theory of general relativity predicted the existence of gravitational waves — ...

Some astronomers think one set of measurements or the other will turn out to be wrong. Others believe that the tension is a ...

Short answer: We don't really know how the universe was created, though most astrophysicists believe it started with the Big Bang.