WHY THE NIGHT SKY IS DARK?

When we gaze up at the celestial canvas, sprinkled with countless stars, a common query comes to mind: Despite the universe's supposed infinity, filled with billions of stars and galaxies, why is it that our night sky doesn't gleam with their brilliance in every direction we look? This bewildering phenomenon, known as Olbers' paradox, presents us with an intriguing photometric riddle that's not easily unraveled.

There are several theories associated with Olbers' paradox, but two lend themselves to a satisfactory explanation. It's common knowledge that light travels at a finite speed, and that the universe's scale is enormous. So vast, in fact, that the light from distant stars hasn't yet reached us. Moreover, both the universe's age and its expansion rate influence our perception of the star-strewn sky - as the universe ages, so increases the number of stars whose light we can observe.

The universe's age is an estimated 13 billion years, and based on what we perceive in the night sky, we might deduce that the universe is in its relative 'youth'. If the universe were 10,000 billion years old, the sheer abundance of stars formed would cause the sky to sparkle in every direction. We observe only a limited portion of the universe due to the finite speed of light.

Deep within space, galaxies are accelerating, continuously moving away from us because of gravitational interactions. Once they attain light speed, these galaxies hit the limit of our visible universe. Beyond this point, they exceed light speed and become invisible to us. These galaxies, filled with billions of stars, continue to exist - we simply can't see them. This theory suggests that while the visible universe is 13 billion years old, the actual size of the universe (visible and 'invisible') could be around 90 billion years, according to some calculations.

Written by Chatsonic