Dark Night Sky. Why?

 The year is 2009. I went hiking mount Abang which is located in Kintamani, Bangli, Bali. Six people including me begin our hiking at 4 PM. We slowly ascending the mount, and finally reach the summit 6 hours after we started. It is really dark when we arrived since no light source available there other than our small lamp. But when I looked at the sky, I witnessed one of the most beautiful scenery I have ever seen in my life. For the first time, I saw countless white spot all over the dark sky without any interference from light pollution. What a dazzling view.

Now back to our main topic. It is already common knowledge that at night, the sky is dark, while at noon, the sky is bright. We also know that the sky change from bright to dark is due to earth rotation around its axis which causing the earth side which facing the sun changes at certain interval. In this case, 23 minutes and 56 seconds. The earth surface is experiencing noon when it is facing the sun, and experiencing night when it is not facing sun. 

But, sun is not the only source of light in the universe. There are countless stars other than sun out there. Each star has its own nuclear reactor in its core, generating heat and light which illuminate the universe. With so much stars, how come the sky is dark?

The stars are countless, but are they infinite in quantity?

To try to answer this question, lets start by assuming that the stars is infinite, uniformly distributed on the whole space of universe. If this is the case, then every parts of earth surface will receive infinite amount of light, accumulated from infinite stars. No matter how far the stars location, a small portion of its light will reach earth. If infinite light reach earth, then the sky should be bright, with or without sun. 

The fact that the night sky is dark contradicts our initial assumption. This is called Olbers paradox.

The dark sky is our evidence that the amount of light that reach earth is not infinite. What can we get with this information? at least three possibility can be deducted.

First possibility is, the star quantity is finite. If we define universe size as the farthest star position from earth, then we also can say that the universe is finite. That mean there is exist the edge of universe out there. But since space and time is contained inside universe, is there no space and time outside the edge of the universe?
Second possibility is, our universe is not yet reach infinity point, and will reach it someday. This mean our universe is expanding. Surprisingly, there is evidence that the universe is expanding. If we observe far galaxy, the spectra from the galaxy will show red shift pattern, which tell us that the galaxy is moving away from us, become further and further. The farther the galaxy, the larger the red shift, which is indicating that the universe is expanding at accelerating phase.

Third possibility is, the universe already reach infinity point, but at some point the space expansion rate is equal with the speed of light, causing the light to never be able to reach earth. 

Which one is correct? nobody can answer yet. Interested to find the answer? feel free to join the research.