There are some interesting answers to this question, including that we live in a bubble multiverse!

On the twelfth day of advent we celebrate Stephen Hawking's contribution to cosmology.

On the eleventh day of advent we explore an unresolved puzzle concerning black holes which greatly intrigued Stephen Hawking.

Now we think we know all about black holes, here is another surprise: they are not completely black after all.

On the ninth day of advent we find out about the maths of black holes.

Behind door #8 we answer all the questions you've ever wanted to ask about the physical reality of black holes!

On the seventh day of advent we venture to a dark place we will never return from

On the sixth day of advent we find out why gravitational waves are so important in revealing the secrets of the Universe.

On the fifth day of advent we learn about the heroic effort that led to the detection of gravitational waves and the excitement of their discovery.

On the fourth day of advent, we remember one of our most exciting cosmological events, watching the announcement of the detection of gravitational waves in 2016.

Find out how an exploding Sun led Einstein to discover one of the most successful theories ever!

On this, the third day of advent, we explore some strange consequences of general relativity on our concept of time.