Father Dr. Manuel Carreira: "And what was there before? And the scientific answer is: there was not before. Because if there is no matter there is also no time. And where did the explosion occur? Nowhere and everywhere, because there was no space before, just as there was no time there was no space."
Dr. Ibáñez-Soto: It is ironic that this "Big Bang" theory, a pillar of modern cosmology and enemy of eternal materialism, was not born from atheistic minds, but from the intellect of a man of Christian faith.
Father Dr. Manuel Carreira: "This is the theory that was first proposed by a Belgian priest using Einstein's equations, the priest Lemaître. By solving Einstein's equations he came to the conclusion that the universe had to have begun with a huge explosion."
Dr. Ibáñez-Soto: Once we understand that the universe emerges from this colossal singularity, we find that matter is not an indeterminate chaotic entity, but rather obeys strict rules of behavior. How does modern physics describe these norms or modalities of interaction that shape the cosmos?
Father Dr. Manuel Carreira: "Matter has only four ways of activity and those are the four forces that physics accepts. The first is the gravitational force... the electromagnetic force... and with nuclear forces, one strong and one weak, it produces atoms."
Dr. Ibáñez-Soto: And this perfect balance between these forces is what sculpts galaxies. How did gravity intervene, for example, in the moments after the great primordial explosion to generate starlight?
Father Dr. Manuel Carreira: "After the big explosion the gravitational force slowed the expansion and in some places produced contractions... a star is a balloon of gas that, due to its own gravitation, contracts and heats up as it contracts until it reaches a temperature of millions of degrees in the center."
Dr. Ibáñez-Soto: Father, let's move from the immense architecture of the universe to another level of amazing order: life. Vague definitions of what it means to be alive are often proposed. In strictly thermodynamic and physical terms, what is the minimum that life demands in terms of resource management?
Father Dr. Manuel Carreira: "Life implies activity and if the living being is a material being and has activity, it necessarily spends energy. Where must it extract it? Well, it can only extract it from the environment. Therefore we can already say that the living structure has to be a material structure capable of activity and therefore capable of extracting energy from the environment and capable of using that energy for its own development and finally also to reproduce."
Dr. Ibáñez-Soto: Science fiction literature is full of fantasies about exotic life forms: beings based on interstellar gas, intelligences made of pure light, or mineral and crystalline creatures. If we apply strict physics, why is it materially impossible for a living entity to be constituted in a solid state?
Father Dr. Manuel Carreira: "Life cannot be based on the solid state. There cannot be a living crystal."
Dr. Ibáñez-Soto: And as for the hypotheses of life in a gaseous state or as a pure energetic entity floating in the cosmic void?
Father Dr. Manuel Carreira: "For a physicist, the perfect gas is one that has no structure whatsoever... How is it going to be a living structure if it cannot have structure? You could perhaps imagine a science fiction life that is pure energy... all that is science fiction talk."
Dr. Ibáñez-Soto: Thus, scientific rigor reduces the options. What is the only state of matter capable of sustaining the microscopic transfer and disposal reactions of an organism?
Father Dr. Manuel Carreira: "There can only be a living structure based on the liquid state. And a cell is a droplet of liquid with a semipermeable membrane through which it can interact with the environment and can extract materials from the environment and can dispose of it."
Dr. Ibáñez-Soto: Beyond the liquid state, the building of life needs specific "bricks." We have seen that not every element in the periodic table is suitable for assembling complex molecules that carry genetic information. What is the fundamental chemistry that makes life possible?