1- Basic Cosmology

Cosmology is the study of the universe as a whole, including theories about its origin, evolution, large-scale structure, and future. The more specific study of the origin of the universe and of astronomical systems, such as the solar system, is often called cosmogony.

Most people want to know what is the universe, what is our place in it, where do the universe and the human beings come from? Why is it like it is?

To try to answer these questions -and others- scientists and philosophers suggested theories. A long time ago people thought that events and natural phenomena were controlled by good and bad spirits living in rivers, mountains, lakes and seas, as well as on the sun, planets and stars. Offerings had to be given to them to keep them good. But it was finally discovered that if no offerings were given, nothing much changed: the sun went on rising every day in the east, the seasons came regularly, and the sun, moon and planets followed precise orbits that could be predicted with accuracy. In other words these celestial bodies may be gods, but they followed precise laws.

With knowledge improving, news laws were discovered and, in the 19th century, Laplace suggested that there were laws that would determine the global evolution of the universe if we knew its configuration at one time. This was named determinism. Laplace did not say what the laws were, and what the initial configuration of the universe was. The answers to these questions were left to God who, accordingly, imposed the laws and the initial universe configuration. However He would not interfere once the process was launched. In other words, God's intervention was limited to what the scientists did not know at that time.

The uncertainty principle discovered later on showed that Laplace's theory was far from perfect. It is true that the quantum theories are also determinist since they give laws for the evolution of waves with time and, if we know the state of the waves at one time, we can calculate it at another. But quantum theories introduce random elements when we try to describe the waves in terms of the positions and velocities of the particles -the alternative view of waves- that, according to the uncertainty principle, cannot be known exactly.

Science, in this case, aims to discover the laws that predict events in the limits set by the uncertainty principle. Gravity is probably the more important factor because it shapes the universe even if it is the weakest of the four known forces. As gravity is always attractive, the universe is either expanding or contracting. According to the general theory of relativity, there must have been a state of infinite density -a singularity- at the time of the big bang, the beginning of time as far as we are concerned. Conversely, if the universe should collapse in the future, there would be another state of infinite density at the time of the big crunch, and this would be the end of time for us human beings. Even if the whole universe does not collapse, there are singularities in localised regions of the universe leading to the formation of black holes. At the big bang, and in all the other singularities, all the physical laws broke down, and only God could manage these situations.

By combining quantum mechanics and general relativity, there is a possibility that space and time combine to form a finite four-dimensional space without singularity or boundary -something similar to a sphere, but in four dimensions. If this were true the universe would have no beginning and no end. A question arises: what could be the role of God as creator in this case?

The role of God in the creation of the universe and its configuration has always been important to all the religions. If we limit ourselves to Christianity, and more specifically to the Roman Catholic branch, it has gone through many phases.

Aristotle postulated that earth was made of four and only four elements: earth, air, fire and water. Earth was spherical and fixed -immobile- in the universe while the sun, the moon, the planets and the stars were rotating around it. The Church had no objection to his views.

Ptolemy, coming later on, thought that the immobile earth was at the centre of eight spheres on which the sun, the moon, the five planets known at that time and the stars were moving. The stars are on the eighth sphere and they remain at the same position in relation to each other and, in consequence, they move together on their sphere. Again the Church had no objection because the space outside the eighth sphere could be considered as god's domain.

The Church's problems started with Copernicus who suggested:
- That the planets -including the earth- rotate around the Sun, the fixed point, to which their motions are to be referred.
-That the Earth is a planet which, besides moving on a circular orbit around the Sun once a year, also turns once daily on its own axis. Saying that the earth was not the central point of the universe was taboo to the Church.

Galileo Galilei confirmed Copernicus theory that the earth was not the centre of the universe. This conflicted with the teachings of the Roman Catholic Church and Galileo was forced to recant publicly his findings. He was put under house arrest for the final eight years of his life for having "held and taught" Copernican doctrine. It took until 1992 for the church formally acknowledging that condemning Galileo was wrong.

Newton's discovery of the laws of gravitation showed definitely that the earth was not the centre of the universe, but only a planet like the others rotating around the sun.