Alternatives to the Big Bang

The Big Bang theory has a problem, which can be explained by the following set of questions:

• The farthest we can see is the cosmic microwave background radiation, which originated about 380,000 years after the Big Bang. We cannot see directly what happened before, because it is hidden behind that radiation.
• It is true that we cannot see, but we can deduce what happened in those first 380,000 years by applying the standard physical theory, i.e. general relativity. It is also possible to check those deductions, for they offer predictions, such as the average composition of the cosmos, which fit well with the experimental data.
• The problem is, general relativity does not take us to time zero, the Big Bang itself. This theory can be applied only from 5×10^-44 seconds after the Big Bang (the Planck time), as quantum effects were predominant before that time, and we do not have a physical theory that unifies quantum mechanics with general relativity.

Did the universe have a beginning?

Georges Lemaître

This question has fascinated scientists since 1931, when the Belgian astronomer, physicist and priest Georges Lemaître formulated the theory of the primordial atom, which since 1950 was known as the Big Bang theory. According to this cosmological theory, as the universe is expanding, if we move back in time we must come to a point (13,800 million years ago, the cosmologists tell us) when it would have gone through a singularity, with a volume tending to zero, while pressure and density would tend to infinity. Could this have been the beginning of the universe?

In 1951 Pope Pius XII, in a speech to the Pontifical Academy of Sciences, said the following words:

A mind illuminated and enriched by modern scientific knowledge, calmly evaluating this problem, is led to break the circle of a matter entirely independent and autochthonous, either uncreated, or because it has arisen by itself, and to rise to a creative Spirit... It seems really that present science, by jumping back over millions of centuries, has succeeded in being witness to that primordial “Fiat lux”, when out of nowhere burst forth, together with matter, a sea of light and radiation, while the particles of the chemical elements split and were reunited into millions of galaxies