Thomas Malthus in the late 18^th century stated that population growth proceeds at an exponential pace while growth in the food supply is arithmetic (linear) leading to inevitable periods of disease and starvation. Malthus argued, or more accurately, preached, that there were only two ways to prevent inevitable famine: actively curtail population growth or let nature take its course. He advocated tariffs to spur local agricultural production and moral restraint. Modern day adherents of Malthusian theories coupled with climate, environmental, and social catastrophes include Paul Ehrlich author of The Population Bomb, and Garrett Hardin author Tragedy of the Commons, both who were concerned that resources could not keep pace with population growth. John Maynard Keynes, not necessarily a Malthusian, initially feared overpopulation would result in poverty. Later, he grew concerned that insufficient population growth would lead to labor shortages and economic stagnation. All Malthusian predictions fail because they underestimated human ingenuity: agricultural innovations, industrial advances, and the energy revolution continually expanded resources. While Malthusian thinkers predicted collapse, human ingenuity reshaped the future, standing on the shoulders of giants, we brought the sky closer instead of watching it fall.

Early in his career, Robert A. Heinlein acknowledged Malthusian concerns about overpopulation, but rather than advocating population control, he envisioned technological solutions to expand humanity’s reach. This idea provided the foundation for his 1956 juvenile novel, Time for the Stars, which explores interstellar colonization as a means of alleviating Earth’s burden. Faced with mounting population pressures, Earth launches an interstellar program to search for habitable worlds. The explorations will take place aboard spaceships that can accelerate up to but not beyond the speed of light. As the ships venture deeper into space at relativistic speeds, conventional communication with Earth suffers increasing delays, making real-time coordination nearly impossible. If the ships are lost or destroyed their discoveries will be delayed or lost completely. To solve this problem, Heinlein introduces the literary fictional concept of telepathic twins and triplets, individuals capable of instantaneous communication, unaffected by distance or time dilation.

Twins are recruited to maintain real-time communication with the ships, with one twin remaining on Earth while the other travels aboard the spacecraft. The twin on Earth ages much faster than the spacefaring twin traveling at near-light speeds. As the time gap widens, their telepathic link weakens, forcing the ship-bound twin to communicate with younger generations of their family on Earth.

This adventure becomes the sci-fi narrative for the concept of the twin paradox first proposed by Paul Langevin. In 1911 Langevin showed that a traveler moving close to the speed of light for two years would return to an Earth that had aged 200 years since his departure. At first, the paradox seemed to suggest that each twin should perceive the other as older, an apparent contradiction. Einstein resolved this by showing that time dilation is a fundamental consequence of special relativity, not an actual paradox. In special relativity, time dilation arises due to velocity, whereas in general relativity, it extends to curved spacetime via the equivalence principle. The traveler ages slower than his Earth-bound twin.

In Time for the Stars, Heinlein does more than illustrate relativistic physics, he champions the optimism that human ingenuity will always outweigh natural pessimism. It serves not only as a rebuttal to Malthusian gloom but also as a direct rejection of William Golding’s dystopian vision in Lord of the Flies, which Heinlein previously wrote in his 1955 utopian novel ‘Tunnel in the Sky’. Lord of the Flies in semitic languages translates directly to Beelzebub. In Indo-European languages Beelzebub, according to some, translates to ‘lord of the jungle’ a phrase with much less negativity than the semitic translation. Heinlein further expands on the lord of the jungle by introducing the German 20^th century concept of Lebensraum in chapter 3 of Time for the Stars titled Project Lebensraum. Lebensraum in his novel parallels the German concept in that it means territorial expansion as a pragmatic solution to overpopulation. Given the post-WWII connotations of Lebensraum, Heinlein’s use of the term is provocative, perhaps deliberately so, prompting reflection on whether space colonization is an ethical necessity or simply another form of expansionist imperialism. Heinlein believed in the problems of overpopulation, but he wanted a positive solution to that rather than a disturbing reach into limiting fertility. Project Lebensraum to Heinlein was likely a repurpose of Lebensraum as a brilliant solution to overpopulation and continued survival of the species.

Ultimately, Heinlein’s Tunnel in the Sky counters the pessimistic view of human nature, demonstrating that young people can build a functional society rather than descend into chaos, contrasting Lord of the Flies and reinforcing the themes of Project Lebensraum in Time for the Stars. As an extension of that logic, humanity must expand beyond Earth to secure its future.

Time for the Stars is more than a literary exploration of Einstein’s time dilation, it is a direct refutation of fear-driven pessimism, a celebration of humanity, and a testament to our quest for an enduring future among the stars.

Source: Time for the Stars by Robert A. Heinlein, 1956. Graphic: Robert A. Heinlein.