Brian Cox:

Did you know that if we could travel to each galaxy in one second, it would take us 63,376 years to visit just the two trillion galaxies in the observable universe? Scientists believe that the observable universe is only 5% of the whole universe. Our own Milky Way galaxy has 400 billion stars, and it takes light thousands of years to travel from one galaxy to another. What's even more astonishing is that the universe is expanding in all directions at a speed faster than the speed of light.