No one has ever seen one, but scientists are now sure they exist.
In fact, by definition it’s impossible to see a black hole—an object whose gravitational pull is so strong that not even light can escape its grasp. Black holes had long been just a theoretical possibility that stemmed from Albert Einstein’s general theory of relativity. But then, in 1971, scientists were sure they had found one.
But how could they observe what by definition was incapable of being seen?
The first hint was a blue supergiant star many times larger and brighter than our sun. As one astronomer observed its movement it seemed to wobble—an indication that another large object was nearby. At first, it was thought this hidden object might be merely a neutron star, another incredibly dense object. But further observation revealed a problem with this working hypothesis—the blue supergiant was orbiting its partner star at a speed that could only be explained if that partner was the even heavier black hole. (Read the full story of the discovery here.)
Black holes are more than just astronomical curiosities. Modern astronomers believe they are crucial to the development of galaxies. As one science site puts it,
They were essential to galactic evolution (they still are!) and, in the long run, to the creation of our Sun, our planet, and our very existence. They are both the universal omega and the cosmic alpha.
Think about that for a moment: the objects that scientists now believe drove the evolution of the entire visible universe—all the galaxies with their stars, including our galaxy with our sun—are essentially invisible and incapable of direct detection.
Black holes are hardly the only unseen thing scientists are certain exists.
On the other end of the scale there are quarks—the tiny particles that make up the larger particles like protons and neutrons in the nucleus of an atom.
We have actually seen an atom, but quarks, because of their extremely small size simply cannot be observed directly. Remember, light itself consists of particles, called photons, complicating efforts to observe subatomic particles. As another science site explains,
They can never be seen alone due to a property known as color confinement. The energy required to remove a quark from a proton or separate two quarks immediately produces an antiquark, which quickly turns a single quark back into a hadron [the term for larger particles like protons]. Computer models have to be used to determine their mass by simulating the interaction between quarks and gluons—the particles that glue quarks together.
As with black holes, scientists are confident that quarks—or something very much like them—do exist. Again, how do they ‘know’ this? Their observations of interactions among subatomic particles. (For example, see the discussion here.)
Now, it would be a mistake to say that what scientists say about black holes, quarks, and other unseen entities and forces is based on a form of belief identical to religious belief. But, the ‘discoveries’ of black holes and quarks does provide a useful analogy for how we come to belief in the transcendent unseen, that is God.
St. Augustine himself recognized this in his wonderful treatise, On Faith in Things Unseen:
Now as regards those whom folly has made so servile to the eyes of the body that they do not think they ought to believe anything which they do not perceive through those eyes, they ought, in the first place, to be reminded of how many things there are which cannot be seen with such eyes—things which they not only believe, but also actually know.
Just as black holes and quarks are detected indirectly through their effects, so also we know of the existence of God through His effects. (Augustine’s example was drawn from human interaction, such as friendship and love.) St. Thomas Aquinas—though he lived many centuries before modern cosmology and particle physics—also recognized this principle:
Although we cannot know in what consists the essence of God, nevertheless in this science we make use of His effects, either of nature or of grace, in place of a definition, in regard to whatever is treated of in this science concerning God; even as in some philosophical sciences we demonstrate something about a cause from its effect, by taking the effect in place of a definition of the cause.
The above comment appears in the Summa Theologica, at the very beginning, where Aquinas asks if theology is a science—science here being defined as any body of knowledge. (The word science comes from the Latin scire, to know.)
Needless to say, Aquinas answers in the affirmative.
Then, in the second question of the Summa, Aquinas outlines his famous ‘proofs’ for the existence of God—proofs not in the sense of direct detection, but conclusions based on indirect observation. All of his five arguments, in some way, depend on this kind of reasoning. Most obvious are his arguments based on the need for an unmoved Mover and a First Cause, but there is also his argument based on the order and purpose that is observable in the natural world—which suggest a divine designer.
Augustine took this line of reasoning further, arguing not just for the existence of God, but for the truth about Christ and divine grace. For Augustine, the signs that God’s grace is at work are in the visible Church:
But, just as by means of tokens or marks which we do see we believe the good will of our friends which we do not see, so the Church, which is now visible, is a token of all those past things and a harbinger of future things which are invisible to use, but which are pointed out in the very writings in which she herself is foretold.
Today we think of the longevity of the Church, the consistency of her doctrines, the persistence of the papacy, and the numerous saints she has nurtured over centuries as among the signs, or visible effects, of God’s hidden grace, unseen yet unmistakably there.