“Who indeed will set bounds to human ingenuity?” Galileo asked in his magnificent letter to the Grand Duchess of of Tuscany as he dethroned the human animal from the center of the universe. “Who will assert that everything in the universe capable of being perceived is already discovered and known?”

Half a millennium later, as we continue to make revolutionary discoveries that invite us to revise our understanding of the cosmos and reassess our place in it — discoveries like the detection of gravitational waves, perhaps the greatest breakthrough in astronomy since Galileo pointed his telescope at the heavens — we continue to struggle with the same discomfiting questions: How are we to live with any sense of importance and meaning if the more we find out about the universe, the less significant we seem to be and the more meaningless it becomes? What, then, is the human and humane value of knowing more at all?

That’s what Hannah Arendt (October 14, 1906–December 4, 1975) addresses with great subtlety and uncompromising intellectual rigor in a 1963 essay titled “The Conquest of Space and the Stature of Man,” later included in her altogether spectacular and timely book Between Past and Future: Eight Exercises in Political Thought (public library).

The essay’s title was inspired by a question posed by the editors of the magazine Great Ideas Today for a special feature focusing on “what the exploration of space is doing to man’s view of himself and to man’s condition” — the question of whether humanity’s so-called conquest of space has increased or diminished the existential stature of human beings.

Five years after she weighed the difference between how art and science illuminate the human condition, Arendt writes:

To understand physical reality seems to demand not only the renunciation of an anthropocentric or geocentric world view, but also a radical elimination of all anthropomorphic elements and principles, as they arise either from the world given to the five human senses or from the categories inherent in the human mind. The question assumes that man is the highest being we know of, an assumption which we have inherited from the Romans, whose humanitas was so alien to the Greeks’ frame of mind that they had not even a word for it. (The reason for the absence of the word humanitas from Greek language and thought was that the Greeks, in contrast to the Romans, never thought that man is the highest being there is. Aristotle calls this belief atopos, “absurd.”) This view of man is even more alien to the scientist, to whom man is no more than a special case of organic life and to whom man’s habitat — the earth, together with earthbound laws — is no more than a special borderline case of absolute, universal laws, that is, laws that rule the immensity of the universe. Surely the scientist cannot permit himself to ask: What consequences will the result of my investigations have for the stature (or, for that matter, for the future) of man? It has been the glory of modern science that it has been able to emancipate itself completely from all such anthropocentric, that is, truly humanistic, concerns. […] For the scientist, man is no more than an observer of the universe in its manifold manifestations. The progress of modern science has demonstrated very forcefully to what an extent this observed universe, the infinitely small no less than the infinitely large, escapes not only the coarseness of human sense perception but even the enormously ingenious instruments that have been built for its refinement.

Although science is, as astrophysicist Janna Levin has memorably noted, “a truly human endeavor,” Arendt argues that the task of the scientist is to stand outside and beyond human solipsism; that setting out to answer such questions as what man’s stature should be, how we differ from other other animals, and why we pursue knowledge at all would shackle science to constraining concerns, to a sort of smallness of curiosity. She reflects on the paradox of such questions:

All answers … whether they come from laymen or philosophers or scientists, are non-scientific (although not anti-scientific); they can never be demonstrably true or false. Their truth resembles rather the validity of agreements than the compelling validity of scientific statements. Even when the answers are given by philosophers whose way of life is solitude, they are arrived at by an exchange of opinions among many men, most of whom may no longer be among the living. Such truth can never command general agreement, but it frequently outlasts the compellingly and demonstrably true statements of the sciences which, especially in recent times, have the uncomfortable inclination never to stay put, although at any given moment they are, and must be, valid for all. In other words, notions such as life, or man, or science, or knowledge are pre-scientific by definition, and the question is whether or not the actual development of science which has led to the conquest of terrestrial space and to the invasion of the space of the universe has changed these notions to such an extent that they no longer make sense.

So if science ought to be concerned with questions far beyond the human scale, free of human ego, then the very notion of the “conquest” of space and man’s “stature” implies a sort of hunger for power antithetical to the real enterprise of science.

Fifteen years before the pioneering scientist Erwin Chargaff made his beautiful case for the poetics of curiosity, she considers the true animating force of scientists — amplified access to what Einstein famously called the human “passion for comprehension.” Arendt writes:

It is, I think, safe to say that nothing was more alien to the minds of the scientists, who brought about the most radical and most rapid revolutionary process the world has ever seen, than any will to power. Nothing was more remote than any wish to “conquer space” and to go to the moon… It was indeed their search for “true reality” that led them to lose confidence in appearances, in the phenomena as they reveal themselves of their own accord to human sense and reason. They were inspired by an extraordinary love of harmony and lawfulness which taught them that they would have to step outside any merely given sequence or series of occurrences if they wanted to discover the overall beauty and order of the whole, that is, the universe. […] It is, in fact, quite obvious that the scientists’ strongest intellectual motivation was Einstein’s “striving after generalization,” and that if they appealed to power at all, it was the interconnected formidable power of abstraction and imagination.

She turns to the particular case of space exploration and its immense humanizing value in enlarging not only our knowledge but our humility:

The magnitude of the space enterprise seems to me beyond dispute, and all objections raised against it on the purely utilitarian level — that it is too expensive, that the money were better spent on education and the improvement of the citizens, on the fight against poverty and disease, or whatever other worthy purposes may come to mind — sound to me slightly absurd, out of tune with the things that are at stake and whose consequences today appear still quite unpredictable. There is, moreover, another reason why I think these arguments are beside the point. They are singularly inapplicable because the enterprise itself could come about only through an amazing development of man’s scientific capabilities. The very integrity of science demands that not only utilitarian considerations but the reflection upon the stature of man as well be left in abeyance. Has not each of the advances of science, since the time of Copernicus, almost automatically resulted in a decrease in his stature? And is the often repeated argument that it was man who achieved his own debasement in his search for truth, thus proving anew his superiority and even increasing his stature, more than a sophism? Perhaps it will turn out that way. At any event, man, insofar as he is a scientist, does not care about his own stature in the universe or about his position on the evolutionary ladder of animal life; this “carelessness” is his pride and his glory.

Complement this particular portion of Arendt’s altogether indispensable Between Past and Future with physicist Sean Carroll on how “poetic naturalism” helps us wrest meaning from an impartial universe, then revisit Arendt on the crucial difference between truth and meaning, the power of being an outsider, how tyrants use isolation as a weapon of oppression, and our only effective antidote to the normalization of evil.