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.

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

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

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

A big Hubble constant also means a young universe: if the cosmos is expanding quickly, it has gotten to its present size quickly, and the Big Bang is relatively recent. A Hubble constant of 100 ...

The limit of our vision extends more than 46 billion light years in all directions. But how big was the Universe when it was first born?

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

So how big is the universe in the inflation model? It begs the question of what is going on at the boundaries and whether information could be communicated across universes. We suppose not.