The first images of distant galaxies, nebulae, quasars and other exquisite space-treats were sent back from the James Webb Space Telescope on 12 July. Launched in December 2021, at a cost of $9.7bn, the Webb telescope, with 18 gold hexagonal plates making up its primary mirror, is itself a beautiful object. While the question of alien life is never far from our investigations of distant galactic structures, the device’s distinctive honeycomb structure seems emblematic of the organic complexity of our own planet, of what it has been capable of producing, and what it is capable of projecting out into space.
As usual with expensive astronomical projects, there are complaints about all the ways the money might have been better spent here on Earth. We are neglecting complex and fragile habitats, it is said, some of which we now risk losing through ecological crisis, yet instead we are seeking to discern the nature of objects so distant that they are unlikely to have any practical relevance for terrestrial life. This objection is reinforced by the fact that the Webb telescope was not conceived to deliver anything fundamentally different from what its predecessor, the Hubble, has been yielding since its launch in 1990 except a higher-quality version of the same – the Webb telescope has the power to detect distant objects up to 100 times fainter than anything Hubble can see.
What these complaints miss is that nothing could be more existentially urgent than knowing our place in the world, which means in part knowing the extent, the diversity, and the nature of the entities that make up the entire cosmos. This means making new discoveries – about the physics of black holes or the role of dark energy in the expansion of the universe, for example. But it also means sensitising the public to basic information about cosmological scale. Outer space needs PR, meaning projects like the Webb telescope are irreplaceable.
I imagine myself as somewhere in the top percentile of astronomical literacy, and yet, if you were to catch me unprepared and ask, “How many stars are there?” there is a good chance I would say something stupid like: “I don’t know. 300? 400?” The fact that I so consistently default back to a sort of spontaneous folk-cosmology, in which the observable night sky is taken for the entirety of the universe itself, is revealing of the limitations inherent to the human mind. And it is also a reminder of the peculiar and often paradoxical role that astronomy has played in shaping the modern world and the modern subject.
Reflecting on this role reveals a surprising connection between periods of contraction of what we can call “the astronomical imagination”, on the one hand, and other forms of parochialism, on the other. That is, to insist that outer space is “not important” because it is too far away to have any practical implications for our own lives is already the reflection of a certain myopia that is also expressed in thinking about other human societies or other living species.
“How many other kingdoms are ignorant of us!” Blaise Pascal wrote in his Pensées (1670). That we are not quite sure whether he is talking about Siam, say, or about an extraterrestrial civilisation orbiting another star, is just part of the genius of the French author’s terse exclamation. Pascal was writing at a moment of significant transformation in the concept of “world”, one that remains hard to grasp even today – are we talking about social reality (as in the title of the French newspaper of record, Le Monde)? Or about everything that is found on the surface of the planet Earth? Or is “world” a synonym of “universe”, so that by definition there can only be one of them, and everything is contained within it?
In its political meaning – the king of Siam did not spend his days thinking about court intrigues at Versailles – Pascal was extending the cultural relativism found in Michel de Montaigne’s essays a century earlier. But in questioning the idea of “the world”, he was processing the human implications of the heliocentric revolution in astronomy spearheaded by Copernicus and Galileo – the Earth, they discovered, was no longer the centre of the universe.
Pascal is sometimes said to have anticipated existentialism, which is characterised in part by a sustained reflection on the intrinsic meaninglessness and absurdity of human existence. Nowhere was this dimension of his thought more evident than in his reflections on the new cosmology. “The eternal silence of these infinite spaces horrifies me,” he wrote. The loss of geocentrism had not simply brought about the small shift of the Sun into the centre of the cosmos. More importantly, it opened up the new possibility that the Sun itself is just another star, and that each star is the centre of its own “world”, with planets circling it, and kingdoms on those planets that are ignorant of us. And between these worlds, untraversable distances, foreclosing any practical possibility of a unified cosmic community.
In antiquity things had been much cosier. Not only was the Earth believed to exist in the middle of the cosmos, but it was surrounded by a finite number of concentric spheres that remained in eternal and perfect circular motion around the Earth. The bodies that orbited in these spheres were conceived as intelligent, indeed more intelligent than human beings. They were closer to a god in their nature, and this entailed that they were not “organic”; that is to say, their nature was simple, made up of a single element sometimes called “the quintessence”, rather than depending for their existence on a special configuration of interfunctional parts, as is the case in our animal bodies.
One of the fundamental conceptual innovations of the 17th-century mechanical revolution was the idea that the universe is everywhere the same; there are no special laws that govern the growth and motion of terrestrial beings that don’t also apply to the celestial beings. This was the moment in history that the notion of the “extraterrestrial” was born and as it has been understood ever since: not a pure and quasi-divine being, but rather a humanoid or reptilian animal, with limbs and organs much like ours. The shift from the “closed world” to the “infinite universe”, to evoke the name of Alexandre Koyré’s classic 1957 study of the Copernican revolution, also saw the shift from the angel to the alien, as the prototype of the sort of being we might expect to find “out there” in the distant night sky.
As a science, astrobiology remained purely speculative until the late 20th century. The first efforts to gain empirical evidence of the existence of extraterrestrial life were mostly makeshift long shots. They relied on an array of presumptions about the cognitive abilities of the aliens whose signals we might pick up, or, as in the case of the representations of the human body and of the solar system etched on a plaque and sent into space on board the Pioneer 10 spacecraft in 1972, of the aliens who might pick up our signals in turn.
But then something remarkable began to happen in the 1990s, when the first confirmed exoplanets were detected. Three decades later, we have a list of more than 5,000 planets orbiting other stars, and a significant number of them are known to be in the “Goldilocks zone”: neither too hot nor too cold for life. Given this sizeable sample, we are now able to make some broad conjectures as to the total number of such planets relative to the number of stars in the observable universe. From here we are able to get a number for the so-called Drake equation, which seeks probabilistically to establish the number of extraterrestrial civilisations with communication technologies in the universe, that warrants much more confidence than anything we could have estimated prior to the 21st century.
The discovery of exoplanets has thus had two important epistemological consequences. One is that even without delivering concrete empirical evidence of life in other star systems, the study of these other systems, the simple tabulation of their features, is already a significant contribution to the search for extraterrestrial life and intelligence. The other is that, while the 20th-century belief in extraterrestrial life was mostly a matter of faith, and something asserted publicly only by people willing to risk being seen as a bit, well, “spacy”, today the existence of extraterrestrial life is generally taken, on probabilistic grounds alone, to be the most rational position one can hold.
There is a sense in which “it doesn’t matter” whether we are alone in the universe or not. Finding out will not solve the climate crisis, or end the war in Ukraine. But it is hard, at least for me, to see what the point of finding our way out of these scrapes might be, if not to enable us to continue asking the profound questions that make life worth living. And none is more profound than the question of our possible cosmic community with other beings like us.
While the Webb telescope does not directly pursue an answer to this question, what it does do is help reveal to us the stunning and incontrovertible reality of complex structures far beyond those in our immediate cosmic neighbourhood. To witness these structures in such a high resolution is at the same time to experience a sort of “cosmic reality check”.
It is to be taught again what is likely the greatest lesson of the Scientific Revolution, a lesson that was made possible most of all by the parallel disclosures made to us through the new technologies of the telescope and the microscope: that there are levels of detail in the world that were not “made for us”, that are not targeted at our natural and unaided perceptual range. That these levels are there, that they are real, is deeply destabilising. The invention of refracting telescopes, as much as the Protestant Reformation or the printing press, was likely one of the principal motors of the formation of the modern world, for better or worse, with all its crises and as-yet unfulfilled dreams.
It is important to be destabilised in this way, to face the same existential truths that Pascal discerned in the discoveries of Copernicus and Galileo. And if we forget then it is necessary to be destabilised again. To avoid such destabilisation, on the grounds that it is “irrelevant” or “impractical”, is in the end a reflection of the same fear that drives people into political dogmatism and cliché. In this respect there is no viable distinction between the “theoretical” and the “practical”. To adapt a well-known motto from Immanuel Kant, it is futile to seek to cultivate “the moral law within” if one is not simultaneously attuned to “the starry heavens above”.
Kant, writing in the late 18th century, did not have anything like the tools and resources we have today for observing our cosmos, yet he still understood the unity of the projects of human moral and political progress, on the one hand, and the need to take our cosmological bearings, on the other. What the Webb telescope delivers to us is a powerful tool for helping us with the latter part of our human project. Anyone who scoffs at this incredible gift is unlikely to make much progress in the former part of it either.
[See also: How to halt the space arms race]