However, the above thinking is not true. The sky is dark; But how is this possible? Well, you might think that the nebulae or clouds of gas and dust in space are the cause of this darkness. These objects can block the light of distant stars and keep the sky dark. Unfortunately, such a mentality does not work, because clouds of gas and dust become hot due to the absorption of radiation and shine as much as other stars; So by adding nebula you can’t solve the problem, you just delay it.
The paradox of the dark sky is called the Albers paradox, which is derived from the name of the German astronomer, Heinrich Wilhelm Albers is In 1823, he mentioned this phenomenon in his treatise “On the Transparency of Space”. Of course, it should be noted that this phenomenon is called by this name in the western naming culture. In fact, Elbers was not the first person to mention this issue, and other astronomers had also discussed it in previous periods. For example Thomas Diggsthe 16th century astronomer mentioned the dark sky paradox in his theory about the infinite nature of the universe.
Various researchers investigated the problem of Albers paradox, but none of them reached an acceptable scientific solution for it. This trend changed in 1848. At that time, an American writer published a treatise titled “Eureka: A Prose Poem”. He writes in this work, the world is not infinite in terms of size and the light does not have enough time to reach us. Quoting from this book:
So the gaps that telescopes find in countless directions can only be understood if we assume that the distance of the invisible background is so great that no rays from it can reach us.
Although the mentioned work does not provide a mathematical solution, it is generally correct and has two key parts. The author of this treatise was none other than Edgar Allan PoeAmerican writer and poet. I bet you didn’t imagine that the discoverer of the mystery would be such a person. A few decades later, the famous British physicist Lord Kelvin also presented the mathematical solution to the problem.
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Another part of the answer suggests that the universe has not always existed. Astronomers in the early 20th century finally came up with clues that the universe could be far beyond the Milky Way. The discovery of cosmic expansion rejected the hypothesis of a static universe and the stability of the universe, and along with subsequent observations, paved the way for the current Big Bang model. The Big Bang model is not an obstacle to the infinity of the universe, but in addition to confirming the hypothesis of Alan Poe, it predicts a beginning and the first cosmic day for it.
Interestingly, if cosmic expansion occurred in a steady-state universe, it could still explain the cause of the dark sky. If the universe as a whole were growing, the expansion would pull the stars away from us at a high rate; so that their light does not reach us; So it’s not like the dark sky proves the Big Bang model, but the Big Bang is a key aspect to understanding what’s happening in the sky.
Today we know that the universe began its journey approximately 13.8 billion years ago, and our view of more distant objects is limited. The expansion causes the light of the stars to decrease, so that their energy is lost on the way to Earth and they undergo a so-called redshift. On the other hand, stars have a finite lifespan, and when all the nebular gas is consumed for their formation, the world will become dark and the dark sky today will become even darker.
Lord Kelvin says there is no contradiction in science; Rather, these contradictions are actually illusory inconsistencies that occur due to the limitation of our understanding. The more we learn about the world, the more contradictions disappear.
