Coming of Age in the Milky Way (21 page)

In much the same way that human beings could not investigate interstellar space until we understood that the sun is one among many stars, so the realization that we live in a universe of galaxies, scattered across immense gulfs of space, required that we first understand the nature of the nebulae. This involved comprehending not only the appearance of the nebulae but also their chemical composition, an effort that spawned the sciences of spectroscopy and astrophysics.

Science is said to proceed on two legs, one of theory (or, loosely, of deduction) and the other of observation and experiment (or induction). Its progress, however, is less often a commanding stride than a kind of halting stagger—more like the path of the wandering minstrel than the straight-ruled trajectory of a military marching band. The development of science is influenced by intellectual fashions, is frequently dependent upon the growth of technology, and, in any case, seldom can be planned far in advance, since its destination is usually unknown. In the case of the exploration of intergalactic space, the first step was taken by armchair theorists—by the philosopher Immanuel Kant and the mathematician Johann Lambert—followed by the observations of the prescient amateur astronomer William Herschel.

When Kant first wrote on cosmology he was not yet
Kant
, the intellectual titan whose unification of empiricism and rationalism was to illuminate and enliven philosophy throughout the world. The year was 1750, and he was but twenty-six years old. The death of his father four years earlier had obliged him to interrupt his education, and he was working as a private tutor in East Prussia. He had earned a bachelor’s degree (paying his tuition out of his earnings from gambling at billiards and cards) but five more years would pass before he was awarded his doctorate. He had not yet ruined his writing style by trying to satisfy the formal requirements
established by the philosophy faculty at the University of Königsberg, where, at the age of forty-six, he would finally be appointed professor of logic and metaphysics. He was a witty, outgoing man and attractive to women, though he could never bring himself to marry. A creature of habit, he ate one meal a day, always with friends, consulted a barometer and thermometer by his bedside each morning in order to determine how to dress, and took his evening walk so punctually that neighbors literally set their clocks by his appearance on the street. He taught mathematics and physics, revered Lucretius and Newton, and read everything from theological history to the actuarial tables.

One day Kant read, in a Hamburg journal, a review of a book titled
An Original Theory or New Hypothesis of the Universe
, by an English surveyor and natural philosopher named Thomas Wright. Wright in his piety had taught himself astronomy the better to appreciate the grandeur of God’s creation, and his books and lectures, freighted with moral and theological lessons, were popular in society circles. In the course of a variegated career, Wright proposed a number of models of the universe, many of them contradictory and all burdened with such concerns as the location of the throne of God, which he put at the center of the cosmos, and hell, which he relegated to the outer darkness.

The cosmological speculations of such a thinker might not normally have commanded the attentions of a Kant, but the summary of Wright’s book that Kant read distorted Wright’s theories, and, in the process, improved upon them. The result was one of journalism’s signal contributions to cosmology, the inadvertent promotion of a nonexistent hypothesis that Kant then turned into this world’s first glimpse of the universe of galaxies.

Wright, following the same erroneous route that had misled Plato, Aristotle, Ptolemy, and Copernicus, assumed the universe to be spherical. But where his pre-Copernican predecessors had put the sun at the center of the universe, Wright suggested that the sun instead belongs to the celestial sphere. What he had done, really, was to resurrect the starry sphere of Aristotle and Ptolemy, but with the sun as one of its stars. Wright’s cosmos was hollow, like an orange with the pulp sucked out and with the sun and other stars in the skin. Wright noted that the appearance of the Milky Way as a band of stars in the sky might be explained as our view of this starry shell from our location within it: When we
look along a line tangential to the sphere we see many stars—the Milky Way—and when we look along the sphere’s radius we see relatively few stars.

The synopsis that Kant read in the newspaper stressed this last point—happily, the most felicitous part of Wright’s theory—and was vague about the rest. Consequently, Kant got the mistaken impression that Wright’s universe consisted of a flattened disk of stars, like a thumbnail-sized slice cut tangentially from the skin of an orange. Kant therefore supposed (as he thought Wright had also) that the stars of the Milky Way are arrayed across a disk-shaped volume of space. So excited was Kant about this idea that he wrote a book on it. He stated its thesis this way:

From this precarious foothold Kant made a cat’s leap to the universe of galaxies. He knew from reading of the observations of the French astronomer Pierre-Louis de Maupertius that elliptical nebulae had been found here and there in the sky. One of these, the Andromeda nebula, could be seen with the unaided eye; others were discernible through telescopes. Kant realized that if the universe were composed of many disk-shaped aggregations of stars—galaxies, as we would say today—then the elliptical nebulae could be other galaxies of stars like our Milky Way. “I come now to that part of my theory which gives it its greatest charm, by the sublime idea which it presents of the plan of the creation,” he wrote.

Wright envisioned the universe as a bubble, and proposed that the appearance of the Milky Way in the sky represented our view of its starry skin. Kant was unaware of the first part of his argument, but seized upon the second, correctly conceiving of the sun as belonging to a flattened system of stars—a galaxy.

Kant realized that disk-shaped galaxies, viewed at random angles, would produce the appearance of seemingly round, oval, and linear “nebulae.”

The elliptical nebulae, Kant wrote, present us with just such apparitions. The nebulae are “systems of many stars” lying “at immense distances.”
³
Here for the first time was a portrait of the universe as consisting of galaxies adrift in the vastness of cosmological space.

Kant’s book, titled
Universal Natural History and Theory of the Heavens
, was published—if that is the word—in 1755, but its publisher immediately went bankrupt, the books were seized to satisfy his debts, and the world, consequently, heard little of it. Kant dedicated it to Frederick the Great, but many better-known artists and philosophers were dedicating their works to this singularly enlightened monarch—Johann Sebastian Bach, for one, had recently composed his
Musical Offering
in Frederick’s honor—and the king never saw Kant’s book.

Frederick did, however, come upon the idea of a universe of galaxies, by another and even less likely avenue. His acquaintanceship with it began one evening in March 1764 when he entered a darkened room, nearly all its candles extinguished, to interview,
for membership in the Berlin Academy of Sciences, a candidate whose appearance and manner were so off-putting that the friends who had arranged the meeting had feared that Frederick would never admit him if he could see him clearly.

The man in the dark was Johann Heinrich Lambert, and his friends had ample grounds for their concern. Lambert’s appearance was unsettling: His forehead was so high that most of his face stood above, not below, the eyebrows, and he dressed uniquely, in a scarlet tailcoat, turquoise vest, black trousers and white stockings, an outfit to which, on special occasions, he added a broad ribbon tied in two bows, one adorning his pigtail and the other his chest. Though his eyes were piercing he seldom looked directly at anyone, preferring, instead, to strike a profile. If an interrogator tried to step around to get a look at him, Lambert would turn slowly on his heel, maintaining the profile, a human moon.

“Would you do me the favor,” said Frederick to the darkling Lambert, “of telling me in what sciences you are specialized?”

“In all of them,” Lambert replied, addressing a point in space ninety degrees away from the king.

“Are you also a skillful mathematician?” asked Frederick.

“Yes.”

“Which professor taught you mathematics?”

“I myself.”

“Are you therefore another Pascal?” asked Frederick, referring to the great mathematician of the previous century.

“Yes, Your Majesty,” replied the voice in the dark.
⁴

Frederick turned away, barely able to contain his laughter, and left the room. That night at dinner he remarked that he had just met the biggest blockhead in the world. But Lambert, when consoled by his friends on the outcome of the interview, serenely assured them that he would get the appointment, since should Frederick “not name me, it would be a blot in his own history.”
⁵
And, indeed, following a review of his publications, Lambert was appointed to the Academy.

Among his works was a collection of essays titled
Cosmological Letters
, which this solitary man, so freakish-looking that children followed him through the streets as they might a fakir in a loincloth, had written as a series of letters to an imaginary friend. In it, Lambert proposed that the sun lies toward one edge of a disk-shaped system of stars, the Milky Way, and that there are “innumerable
other Milky Ways.”
⁶
He indicated that he had arrived at this theory while gazing for long hours at the night sky: