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Interview with Javier Sánchez Cañizares on Lemaître and the Big Bang

Author: Javier Sánchez Cañizares
Published in: 98.3 Radio, programme "Pensar la fe".
Date of publication: 21 January 2018


Basic explanation of the physical model of the Big Bang, origin of the Big Bang model by Lemaître from the physical observations of the time. Projection of the future of the physical universe (big crunch, thermal death). The origin of the universe and the arrow of time.


Thinking about faith


Bosco: You are warmly welcome to think about faith. On this occasion we are going to talk about Georges Henry Lemaître who, apart from being an astrophysicist, a priest and known for enunciating the theory of the big bang, was perhaps a fighter against the commonly held view among his professional colleagues that the universe was stagnant in time. In all his talks and discussions, Lemaître professed his thinking, from which it can be deduced that the universe is expanding. Don Javier Sanchez, physicist and theologian visit in order to get to know this Belgian scientist better. How about Don Javier?

Javier Sánchez: Hello Bosco. So nice to be here with you today.

Bosco: We are delighted. I'm sure you can explain the Big Bang much better than I can, especially briefly.

Javier Sánchez: Yes, in reality the Big Bang is a physical theory, a model to try to explain the origin of the universe and above all its development origin from a big explosion. It was developed above all thanks to Einstein's equations, to that model of general relativity. What happens is that, curiously enough, Einstein, as he was rather in favour, along with many other scientists, of a model of a stationary universe, i.e. one that has always been the same and would always remain the same, did not take into account what is called the solutions of the Big Bang, the solutions of an expanding universe, i.e. one that would have been born from an initial singularity of energy from which all the galaxies, all the planets would be formed... This is what our protagonist Georges Lemaître would later develop.

Bosco: It's also interesting, that's why I cut, excuse me, it's interesting to know if this idea of the big bang is compatible with the idea of God the creator.

Javier Sánchez: Well, the truth is that the big bang does not strictly speaking explain the origin of the universe, that is, the big bang is a model from which we can more or less explain the development of the known universe. Of course, the big bang starts from an initial singularity, spacetime would be, so to speak, condensed, contained, all the energy of what will later be the subject of the universe. But, of course, it doesn't give a reason why this exists at the beginning. In that sense, there is a philosophical and religious question about this origin, why this initial structure is there. And this is compatible with the idea of creation in the Judeo-Christian tradition of a creator God who brings everything into existence and in particular wants the universe to develop in this natural, physical way.

Bosco: Basically, it doesn't explain whether there is a beginning, or even an end to the universe.

Javier Sánchez: Yes, the end of the universe according to the big bang theory depends on the ratio between subject, the total mass and energy of the universe, and, so to speak, the force of the explosion. Depending on whether one or the other won, the end of the universe would be a big crunch, i.e. the universe would either implode back on itself, or it would end up expanding continuously, it would continue to expand.

Bosco: The subject keeps insisting?

Javier Sánchez: In other models, if we take into account other effects, it would eventually come to an end. If the universe were to expand continuously, in the end there would be a process of what is called thermal death, where the only thing that would exist would be radiation, in which energy is conserved, although the subject could cease to exist.

Bosco: We are going a lot on the physics side. I would also like to ask you what are the religious questions that the future of this theory may raise, where it is drifting towards, or if it is still the same as it is now.

Javier Sánchez: One thing that I find interesting about the big bang is that it raises, effectively, an origin, that is, there is an origin of the universe, and it also raises a sense, what in physics is known as the arrow of time, that is, time moves in a certain direction, the laws of physics do not give the same in a sense of time towards the future as towards the past; This is one of the fundamental problems facing physics today, which cannot be explained well; so the question of the origin is very interesting because it is posed in a scientific way, and I would like to bring up here the words that Benedict XVI has often said in his pontificate: the question of the origin is very important because it asks philosophically, and also religiously, whether at the origin of everything there is reason, a creative reason, or pure chance; so this question is something that arises naturally with the big bang theory. And Christianity advocates that origin in a creative reason from which everything develops and which is superior to our intelligence, but we can know some of these plans of the divine design.

Bosco: Well, thank you very much, Don Javier, these spaces are short and we have to say goodbye.

Javier Sánchez: Well, I'm delighted to be with you.

Bosco: Thank you.

Javier Sánchez: A hug.


Bosco: Greetings Bosco Eguidazu for ninety-eight point three radio, have a nice day.