How would you calculate the size of the universe?
Well we can't calculate the size of the universe yet. But we can mesure the size of observable universe. We have to start with the age of the universe which is about 13.8 billion years and this is the time the light had to travel to reach us. This is universe's radius - it is about 46 billion light years. BUT IMPORTANT THING IS THAT THE UNIVERSE IS EXPANDING. If you would like to know how big is it you would have to know every moment in history of universe's expanding.