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.

The cosmos has been expanding since the Big Bang, but how fast? The answer could reveal whether everything we thought we knew about physics is wrong.

The universe is vast, beyond what we can truly comprehend. But how big is it, really? In this video, we explore the incredible size of the universe, from its observable limits to the theories that ...

What if the universe existed before the Big Bang? In this fascinating discussion, legendary physicist Roger Penrose explores ...

If we know how big the observable Universe is, why can't we figure out how big the unobservable part is?

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.

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 ...

But knowing how big the observable universe is doesn't tell us everything we know about how many atoms are in it. We also need to know how much matter, or stuff, is in it.

How can the universe be 95 billion light years across when it has only been in existence for approx 14.3 billion years? If nothing can travel faster than the speed of light shouldn't the universe ...