The Big Bang

Alexander 1

Since the beginning of mankind, we have been in search of answers from, why is the sky blue? what makes the birds sing in the spring? all the way to what is that big yellow thing that moves about the sky every day? Throughout history, one of the most prodding questions of them all that we haven’t exactly been able to answer until now is: ‘How did the universe come to be?’ The study of cosmology, or the study of the universe, plays a significant role in the answer to this question. Scientists have many theories about the creation of matter, but one seems much more prominent than the rest of its competitors: the Big Bang theory.

In 1927, the Belgian priest George's Lemaоtre was the first to introduce the theory that the universe began with the explosion of a single atom. A Graduate of Cambridge University, Lemaоtre reviewed the general theory of relativity. As with Einstein’s calculations ten years earlier, Lemaоtre’s calculations showed that the universe had to be either shrinking or expanding. But while Einstein thought it was an unknown force, a cosmological constant which kept the world stable, Lemaоtre decided that the universe must have been expanding. He came to this conclusion after observing the reddish glow, known as a red shift, around objects outside of our galaxy. If interpreted as a Doppler effect, this shift in color meant that the galaxies were moving away from us.

Some years later, Edwin Hubble found experimental evidence to help justify Lemaоtre's theory. He found that distant galaxies in every direction are moving away from us with speeds proportional to their distance. That means that things farther away from earth were moving away faster. In other words, the universe must be expanding. He announced his findings in 1929. The ratio of distance to redshift was 170 kilometers/second per light year of distance, now called Hubble's constant. The numbers were not exactly right, and improvements in measuring techniques and technology have changed the formula, but the basic principle remains. Hubble kept working on the problem and collected data throughout his career.

So what exactly does the universe expanding have to do with the Big

Alexander 2

Bang? The Big Bang theory is the major scientific theory about the origin of the universe. According to this theory, the universe was created between 10 billion and 20 billion years ago from a cosmic explosion that sent matter flying in all directions, consequently creating the universe.

Before the Big Bang, every part of what the universe was, was tightly compacted together during a very dense phase. When the explosion occurred, every particle of all that our universe consists of shot out in every direction in that one instant. It is believed that the universe expanded rapidly in its first microseconds, but then slowed, a process called inflation. This process explains how the universe appears similar to a type of flat space. However, we see only a tiny region of the original universe, so we don't notice the curvature. The inflationary universe also shows why the universe appears so uniform. If the universe we observe was inflated from some small, original region, it isn’t surprising that it looks consistent.

Only one single force existed when the universe was still extremely hot from the explosion. As the universe expanded and cooled off, the one original force split into the four as we know them today: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force. There is a theory called the electroweak theory, that unifies electromagnetism and the weak forces. Scientists are also searching for what is called the grand unification theory, and the string theory. The grand unification theory would combine the strong nuclear force with the other two. The string theory would provide scientists a way to combine all four forces, and would be one step closer to the goal of simplicity.

At about 10,000 years after the Big Bang, the temperature had fallen so much that massive particles began to take form in the universe, rather than the