Obstruction Theory offers an alternative to the Newton/Einstein theory for cosmology. Assuming a rarefied mass density in the universe, the redshift we observe in distant light sources can be explained without assuming that the sources are moving away from us at high speed, causing the universe to expand. The redshift can be easily explained by the average mass density of the universe.It is known that a mass slows down the velocity of time at a point in its vicinity. This slowdown turns out to be equal to the reduction of direct radiation from more distant space due to the presence of the mass. We show that the amount of direct radiation reaching an observer from the universe is always partially lost along the way through scattering by protons and other small particles. This translates into the velocity of time, which we observe as redshift. We find the size of our visible universe by stating that the observed time velocity of the light sources at the boundary of the universe is reduced to zero. The value for the size that we find via a simple calculation is close to the value found in the traditional way. Furthermore, with this theory, a value for the Hubbleconstante can be found using the mass density of the universe. According to Obstruction Theory, there can furthermore be no question of a bounded universe. Every observer is the center of their own universe. Beyond its own universe, the universe extends infinitely far.