User:Traductoraplatense/ Origin of the Universe

According to Greek and modern cosmology, the origin of the universe is the instant where all the matter and energy currently existing in the universe originated as a result of a great expansion. The Big Bang Theory (great explosion) has been accepted by most scientists and posits that the universe may have been originated 13.800 billion years ago, at a definite moment. In the 1930s, the American astronomer Edwin Hubble found proof that the universe was expanding, a phenomenon that the priest and astrophysicist Georges Lemaître described in his research on the expansion of the universe (big bang), based on Albert Einstein's equations and theory of general relativity. However, Einstein did not believe in his results since it seemed absurd that the universe was constantly expanding, so he added the famous «cosmological constant» to his equations (such constant solved the problem of the infinite expansion), to which later on he called the biggest mistake of his life. For this reason, Hubble was recognized as the scientist who discovered the expansion of the universe.

Inflation
The Inflation Theory, proposed by Alan Guth and Andréi Linde during the 1980s, who tried to explain the first moments of the universe, is widely accepted in the scientific community. It is based on studies of gravitational fields that are too strong, as those that are near a black hole. Supposedly, there was nothing before the moment in which our universe had the size of a point with infinite density, known as «space-time singularity». All matter, energy, space and time were concentrated in that point. According to this theory, what triggered the first impulse of the big bang is an «inflationary force», exerted in a virtually inestimable amount of time. It is assumed that from that inflationary force the current fundamental forces were split.

This impulse, in an inconceivably short period, was so violent that the universe continues to expand even nowadays. A fact postulated by Edwin Hubble. It is estimated that in only 15 x 10-33 seconds this primordial universe multiplied its measurements.

Formation of matter
The Big Bang Theory states that the universe, which was previously an infinitely dense singularity, mathematically paradoxical, and had a very high temperature, at some point, began to expand, generating great amounts of energy and matter splitting everything to date.

The universe, after the big bang, began to cool and expand, and this cooling caused that a lot of energy started to stabilize. Protons and neutrons were «created» and stabilized when the universe had a temperature of 100 billion degrees, approximately a hundredth of a second after the beginning. Electrons had too much energy and interacted with neutrons that initially had the same ratio as protons. But due to their collision, neutrons become more protons than vice versa. Thus, when the universe had 30 billion degrees (one-tenth of a second), there were thirty-eight neutrons per every sixty-two protons, and twenty-four per seventy-six when it had 10 billion degrees (one second).

The atomic nucleus of the deuterium was the first thing to appear, almost forty seconds later, when the temperature of 3000 billion degrees allowed neutrons and protons to stay together. By the time these nuclei could be stable, the universe needed more than just three minutes when this glowing ball had cooled to 1000 billion degrees.

Dark Matter
For everything stated here to be officially valid, scientists need an additional matter to the one known (or specifically observed) by human beings. Many calculations have shown that all matter and energy that we know is very little in relation to what should exist for the big bang to be correct. Accordingly, the existence of a hypothetical matter was postulated to fill that void, which was called «dark matter», for it does not interact with any nuclear force (weak nuclear force and strong nuclear force) or with electromagnetism, only with the gravitational force. You can see the calculated ratios in the graph to the right.

Other scientific theories about its origin

 * Cosmología de branas
 * Multiverso