This piece may appear to many readers (that is, I imagine it might if there were many readers) to be an exercise better suited for a medieval theologian, an effort which most people today would deem a waste of mental energy spent elaborating a dubious odd abstraction having no relationship to the real world. Nonetheless, I am going to report my observation of interesting parallels between the Christian doctrine of the Holy Trinity, as envisioned by the great medieval poet Dante Alighieri in his Paradiso, and the picture modern physics presents of the fundamental nuclear particle called the proton. Structuralists may take some pleasure in seeing an unexpected example of the human mind’s convergence on certain images for representing conjectured interactions between entities which are not directly observable by means of our senses. Of course, the theoretical picture of the proton is based on objective experimental data and is in no sense arbitrary, though it may be incomplete; while theological consensus is that the Trinity can be known by revelation only.
First let us briefly review some important facts about protons. Protons are the electrically charged particles that, along with the electrically neutral particles of slightly higher mass, the neutrons, make up the nuclei of atoms, in which almost all of the atomic mass is concentrated. The number of protons in an atom’s nucleus determines how many electrons the atom has—the same number—and from this everything about the atom follows.
Given the laws of physics that govern the electrons in the atom, the mere number of protons in the nucleus determines the chemical properties of the atom of which it is a part. For example, the nucleus of the hydrogen atom consists of a single proton. Hydrogen thus has one electron; and, by virtue of that fact, two hydrogen atoms love to join with oxygen to make that extraordinary chemical compound that Life requires—water. Helium, on the other hand, has two protons in its nucleus and thus two electrons; it won’t combine with anything else. These are the two simplest elements, but their examples suffice to illustrate how definitive the number of protons in the nucleus is for establishing atomic properties.
Electrons can and do exist separately from nuclei and are freely exchanged among them. Protons do not spontaneously join together to form nuclei here on Earth. All atomic nuclei, except for that of hydrogen, which formed shortly after the Big Bang, and that of helium, much of which formed during a short time where conditions in the early universe resembled those in a star’s interior, have to be made in the furnace of the stars. Most of the matter of the universe (the normal matter, anyway, not the “dark” matter) is still in the form of the first-made element, hydrogen. The number of protons in the universe is estimated to be around 1079!
Born from the Big Bang, protons seem destined to last as long as the universe. All the other heavy particles (baryons), such as the neutron, are unstable and subject to decay into lighter particles. A free neutron (not bound in an atomic nucleus) will on the average last only around fifteen minutes before decaying into a proton, an electron, and an ultralight particle called the antineutrino.
Although theories have been put forth in which the proton would also decay, no one has ever observed proton decay, and not for want of carrying out experiments deep below the Earth’s surface that specifically look for such events. According to experiment, the lower limit on the average lifetime of the proton is around 1034 years! Considering that this is about 1024 times greater than the age of the universe, I’m comfortable calling protons as “eternal” as matter can be.
In summary, protons, which may be totally stable, make up most of the normal matter of the universe and by their mere number in the atomic nucleus determine the chemical properties of atomic elements. All of the complex chemical reactions that take place in the universe, though they involve most directly the electrons of the atoms, ultimately trace down to the number of protons in the nuclei of the atoms involved.
Now let us move from science to theology. One of the features of Christianity that sets it apart from the other major monotheistic religions—Islam and Judaism—is its peculiar notion of the Trinity, that somehow God, although one and indivisible, is also three persons (Father, Son, and Holy Spirit, traditionally). The idea of one God in three persons is different from that of multiple independent gods and goddesses in polytheistic religions, although Islam holds that Christianity is polytheistic because of the Trinity belief.
Now I want to consider Dante’s attempt to convey through poetry the mysterious concept of the Holy Trinity, which in his faith was a certainty. On reading the final canto of Dante’s Paradiso recently, I came across an image that immediately reminded me of something else I’d thought of before: the conceptual similarities between our scientific description of the proton and the Triune God; only now a particular detail of Dante’s description of what he had seen made the similarity appear stronger than I had realized before.
Near the end of his time in Heaven (Paradiso) Dante was finally empowered to behold God, his ability to comprehend mysteries directly by sight alone having been enabled by Divine grace. Here is the Singleton translation of lines 115-120 of Canto XXXIII of Paradiso.
“Within the profound and shining subsistence of the lofty Light appeared to me three circles of three colors and one magnitude; and one seemed reflected by the other, as rainbow by rainbow, and the third seemed fire breathed forth equally from the one and the other.”
This is far from being a clear picture, and Dante had said beforehand that description—even distinct memory—of what he had beheld was impossible. But I was struck this time by how much Dante’s word-painting resembles our own nebulous physical picture of the proton. The essentials of Dante’s vision were three equally sized circles (or spheres) of three colors and two distinguishable types, with some sort of continual interaction occurring among the circles. The image of the rainbows reflected in each other, with each circle yet of a different color, seems to my mind to be saying that the colors are changing, but in a co-ordinated way. I might add that Dante’s original description of God was as a point of blindingly bright white light.
Why does this vision of Dante’s make me think of the proton? Modern physics has discovered that the proton has within it three particles, whose existence a theoretical physicist had predicted and named quarks years before they were first experimentally observed. Two of the quarks in the proton are identical and are called “up” quarks. The other is a “down” quark. In this context, the terms up and down have no meaning except as a way of distinguishing the two types of quark. No directionality is implied by the names. Up and down are examples of what physicists call quark “flavor,” and of course there is nothing related to the sense of taste implied by the name flavor; it’s just a conventional way to designate this particular quantum number or characteristic.
Now, by probing the proton with high-energy particle collisions we can “see” that the quarks are inside the proton, but there is no way to observe an individual free quark, due to the peculiar nature of the force between quarks, which, contrary to the action of other known forces, actually gets stronger as the quarks are separated further from each other, making it impossible to pull or knock a single quark free from its mates. It is possible to break up a proton with a high-energy collision, but only by making new quark combinations, never in a way that makes a single quark visible.
Thus nature seems to present us with a stable and indivisible proton consisting of three quarks, two of which are identical, but no one of which can be seen apart from its union with the other two. What I hadn’t realized before re-reading Dante was that Catholic theology viewed the Holy Spirit as different in some way from the Father and the Son. The Son was “begotten” by the Father, whatever that might mean, and the Holy Spirit “proceeds” from the two other Persons, whatever that means. Thus in Dante’s vision two of the “circles” seemed reflected by each other, these being identified by commentators as the Father and the Son of the Trinity. For me it seems natural to mentally map this pair to the two up quarks. Dante clearly sees the third circle as being distinguishable from the other two, and this third circle would correspond to the down quark in my whimsical analogy.
Can we go further? There is more to the quark picture of the proton than the quark flavors. The quarks all have another quantum characteristic which physicists, for want of a better term, have called “color,” though, of course, without any real connection to what we mean by color in the world we perceive directly. The proton as a whole is colorless, however, meaning that proton states must be made up of one “red” quark, one “blue” one, and one “green” one, which taken together make for a colorless proton. However, the colors are not fixed on any given quark. The quarks are continually exchanging particles called “gluons” between each other. These gluons carry color, so that each quark is changing color continually, but always in a way so that there is one red, one green, and one blue quark at any time. This color exchange is the source of the force that binds the quarks together. I invite the reader to judge the extent to which Dante’s description resembles the picture of quarks held together through color exchange.
Do the similarities between Dante’s poetic vision of the Christian doctrine of the Triune God and our modern, well-established theory of the tri-quark proton amount to more than a curious historical coincidence? Does this analogy go beyond the merely amusing to the deeply significant?
Of course not.
It can’t, can it?
How could it not?
But that’s crazy.
Frederick Copleston, S.J., in the second volume of his superb work, A History of Philosophy, says in summarizing a fundamental teaching of the preeminent medieval theologian-philosopher, St. Thomas Aquinas, that God “creates the world as a finite imitation of His divine essence.” One aspect of this is that we human beings with our power of reason and our ability to appreciate beauty and to discern good are created “in God’s image,” as Genesis says. But can this finite imitation of God’s essence also be be seen in the most fundamental parts of the physical universe?
As one who has come to recognize God’s existence, but who has not embraced Christianity fully, partly because of the difficulty in affirming belief in “revealed truths” such as God’s Three Persons, I can’t help wondering if the protons of the universe (all the multitude of protons!) are not so many messages in bottles thrown into the sea of the cosmos, just waiting to be read once their language had been mastered: “Yes, doubting Scientist, here is a coherent image of the Trinity. Ponder my depths and believe.”