ILLUSTRATION BY TOMI UM

By the time that Felix Eberty, a German jurist and amateur astronomer, anonymously published “The Stars and World History,” in 1846, it was well known that light had a finite speed. Ole Rømer, a Danish scientist working in Paris, had proved as much more than a century and a half earlier. It took the sun’s rays a little over eight minutes to reach Earth, Jupiter’s up to fifty-two minutes, and Uranus’s more than two and a half hours. Eberty was particularly fascinated by what this delay meant for a faraway observer of our planet. Perched on a distant star, he wrote, such a person might “see the earth at this moment as it existed at the time of Abraham.” Furthermore, by hopscotching across the cosmos, “he will be able to represent to himself, as rapidly as he pleases, that moment in the world’s history which he wishes to observe at leisure.” Eberty had witnessed great gains in the speed of transportation and communication during his lifetime, and he believed that humanity might soon be travelling even faster than light.

Later authors continued the thought experiment. The French astronomer Camille Flammarion, writing in 1873, envisioned a remote planet with a light-sensitive surface. “We may imagine this world to be not spherical but cylindrical, and to stand in space like an imperishable column on which the events of terrestrial history engrave and enroll themselves,” he wrote. Lovers separated by time or circumstance could replay “the dear scenes they enjoyed together on earth,” perhaps including “views of very secret things.” Criminals would find themselves incapable of eluding justice, because each of their misdeeds would “transmit itself eternally into infinity,” carried by light. Death would lose its finality; if we wanted, Flammarion suggested, we could watch the Battle of Waterloo in reverse, “a Waterloo of the afterlife.” The popular-science writer Aaron Bernstein joined in. The great cosmic postal service, he wrote, knew neither past nor present: “Alexander the Great is still conquering the world.”

Among the impressionable young Germans who read Eberty and Bernstein was one named Albert Einstein. (He recalled devouring Bernstein’s work, in particular, “with breathless attention,” and it may have inspired one of the conjectures that led to his special theory of relativity.) Indeed, the older authors had a profound influence on how the physicist’s ideas about the universe came to be popularized. Einstein put the finishing touches on general relativity, the second part of his grand theory, at the end of 1915, declaring himself “contented but kaput.” The following year, he embarked on a mission of public education, using fanciful imaginings like those of Eberty and the rest to explain the theory and explore its strange implications. He published a book, “Relativity: The Special and General Theory,” with the desire that it might, he wrote, “bring some one a few happy hours of suggestive thought.” Several years earlier, the French physicist Paul Langevin had delivered a lecture on special relativity in which he asked for an audience volunteer to hop aboard “the projectile of Jules Verne” and experience time dilation. Einstein chose more familiar conveyances: his stories featured “our old friend the railway carriage.”

In 1919, with some cosmic help from a solar eclipse, the predictions of general relativity were proved valid. “New Theory of the Universe,” a headline in the London Times crowed. “Newtonian Ideas Overthrown.” The true meaning and significance of Einstein’s theories could now reach a wide audience. Bertrand Russell, a man otherwise known for brilliant but stuffy mathematical and philosophical work, authored “The ABC of Relativity,” in which dinner plates changed shape, from circular to oval, according to one’s perspective, and flies landing on stagnant pools served as models for stars bending space-time. Chief among the relativity evangelists, though, was Arthur Eddington, the straitlaced British astronomer who led the eclipse observations. His stories proved particularly enthralling to the press. A few weeks after the results were announced, he gave a talk at Trinity College, Cambridge, that the New York Times summarized with the headline “Professor Eddington, 6 Feet to the Eye, Explains How It May Be Really Only 3 Feet.” A year later, in “Space, Time and Gravitation,” he asked readers to imagine an aviator travelling at a hundred and sixty-one thousand miles per second, almost nine-tenths the speed of light. The pilot’s watch would seem, to a terrestrial observer, to tick twice as slowly; his cigar would seem to burn twice as long. Then, in another lecture to university students, Eddington invoked star-crossed lovers, just as Flammarion had:

Suppose that you are in love with a lady on Neptune and that she returns the sentiment. It will be some consolation for the melancholy separation if you can say to yourself at some—possibly prearranged—moment, “She is thinking of me now.” Unfortunately a difficulty has arisen because we have had to abolish Now … She will have to think of you continuously for eight hours on end in order to circumvent the ambiguity of “Now.”

Many readers swallowed relativity stories as quickly as they could be printed, but the French philosopher Henri Bergson, who had attended Langevin’s relativity lecture years earlier, was profoundly irritated by scientists’ growing prominence as public intellectuals. The philosopher had been, until then, more famous than Einstein, known for having launched his own “Copernican revolution” (as William James put it), which introduced a notion of time that could not be reduced to clocks. Einstein and Bergson quibbled with each other’s views for the rest of their lives. The physicist’s talent, the philosopher implied, was not so different from that of H. G. Wells, whose novel “The Time Machine” had considered time as a fourth dimension, just as general relativity did; perhaps both fascinated the public because of their fictional qualities more than their scientific ones. Relativity enthusiasts, he argued, should be careful to “distinguish the real from the symbolic,” to avoid elevating “a mathematical representation into transcendental reality.” They should go back to the original equations and seek to connect them to the “really real”—in other words, that which could actually be perceived. Nowhere could the philosopher find cigar-smoking aviators or transplanetary love stories.

Bergson’s objections were partly responsible for one of the most enduring curiosities of modern scientific history, which is that Einstein never won a Nobel Prize for his work on relativity. Rather, he received the award for his discovery of the photoelectric effect (itself no small feat). Svante Arrhenius, the chairman of the Nobel Committee for Physics, began his presentation speech, in late 1922, by putting relativity to one side: