The Origin of the Universe by Bilal Qureshi
Since the dawn of intelligent man, humanity has speculated about the origins of the universe. There is evidence, which indicates that the universe started around 15 billion years ago. This is probably the greatest discovery imaginable; however, the universe still seems to be a very controversial subject.
Most scientists agree that there was a beginning but there is a lot of speculation of how it (the universe) actually started. The much-celebrated Greek philosopher, Aristotle, denied the fact that there ever was a beginning. He and his associates believed in the eternal existence of the universe, they also tried to prove that the universe was static, and was unchanging in time. However, there is evidence, which suggests that the universe is changing with time. Geologists have discovered meteorites on the earth that have existed for many thousands of millions of years, way before the earth came into existence. A second principle, which concretises the beginning of the universe, is the second law of thermodynamics. As I quote the cosmologist Sir Arthur Eddington, said, "Don't worry if your theory doesn't agree with the observations, because they are probably wrong.' But if your theory does not agree with the 2nd law of thermodynamics then it is in serious trouble". The second law states that disorder (which is measured by entropy) always increases with time. Therefore, the idea that the universe existed forever is contradictory, because the second law implies that there was a beginning.
If the universe has an infinite number of stars then the night sky should be uniformly bright as the surface of the sun. This essentially is Olbers' paradox There are many possible explanations for Olbers' paradox. Here are just a few:
There's too much dust to see the distant stars.
The universe is expanding, so distant starts are red-shifted into obscurity. The universe is young. Distant light hasn't even reached us yet.
The first explanation does not make sense. The dust in a black body will heat up; this essentially acts like a radiation shield, exponentially damping the distant starlight. In addition, one cannot put enough dust into the universe to get rid of all the starlight, without obscuring your own sun. The last two possibilities are correct. There are numerical arguments that effect the finite age of the universe. Currently, we live inside an "observable universe", objects more than the age of 15 billion are too far away too ever reach us.
The question put forward by Newton was:
"If the universe is full of static then, why did the stars suddenly turn on?
This is where we turn to the Cosmological principal.
It states that the universe is homogeneous (the same everywhere) and isotropic. (The same in all directions) It is an extension of the Copernican principle, which states that we are not in a special place at the centre of the solar system, but just one of nine planets. In relation we can, according to Newton find a gravitational force between to objects of masses M1 and M2: FG= GM1 M2/d2
This equation indicates that each star in the universe is attracted to each other star. The problem with this equation is the Gravitational constant. In cosmological terms, how could the stars remain at a constant distance, wouldn't they end up falling? It is possible for the stars/galaxies to be attracted to each other but it is impractical to assume that the stars/galaxies are getting closer to each other. The correct procedure is to assume that there is a finite region of stars, which are distributed uniformly by more stars that are outside the finite region. Adding more stars outside will not...