Because we are all living in a world that our mind is capable to perceive. But what is really oustide of this bubble? We go for grocery shopping while giant stars are born, galaxies collide. We read the history books of conquerors and kings of past ages and keep forgetting of the history that is just above us - perfectly coded into mysterious constellations. Although time scales are different on the lifespan of the universe, it still flows. Billions of photons are traveling through vacuum for hundreds, thousands or millions of years to generate history we are capable to understand.