What if we could live for a million years?

Recently, scientists discovered bacteria that had been buried beneath the ocean floor for more than a hundred million years and was still alive. What would change if we could live for even just a million years? Two thoughts immediately come to mind. First, tenure in academia would have to be capped. Universities would have to limit faculty appointments to a century at most in order to refresh their talent pool and mitigate old-fashioned education and research dogmas. Second, a birthday cake cannot hold a million candles. Instead, the number of birthday candles could reflect the logarithm of our age. For a thousand-year-old, that would mean three candles.

Past generations used to say that even though we cannot postpone natural death, we can control how we live. They also believed that there is “nothing new under the sun.” Both statements are inaccurate from our current perspective. With advances in bioscience and technology, one can imagine a post-Covid-19 future when most diseases are cured and our life span will increase substantially.

If that happens, how would our goals change, and how would this shape our lives? Given the luxury of pursuing longer-term plans, we could accomplish more ambitious tasks. We could decide to care more about our planetary environment and interpersonal cooperation since pollution or hostilities carry long-term dangers. An extended life experience could make us wiser and more risk-averse since there is much more at stake. It would make little sense to send young soldiers to wars, or initiate wars in the first place.

But even with shrewd strategies, survival is by no means guaranteed. For example, the known correlation between brain size and body weight did not make dinosaurs smart enough to deflect the asteroid that killed them. Accidents are inevitable, and treatment centers will continuously be busy repairing nonfatal damages due to routine mishaps.

Increasing our fertility period in proportion to our life span will bring the risk of overpopulating Earth. With the current birth rate per person, the number of million-year-old people could increase to the untenable level of a hundred trillion. Moderating that would require a public policy that limits the birth rate to the desired level. Alternatively, travel ports could launch people into space to balance the birth rate and maintain a terrestrial population suitable for the available supply of food and energy.

The good news is that over a lifetime as long as a million years, space travel can take us to the nearest stars using existing chemical rockets. It would take merely 100,000 years to arrive at the habitable planet around Proxima Centauri with a space vehicle that travels at the speed of NASA’s New Horizons spacecraft. For passengers who live a million years, such a trip would appear just like the decade-long journey of New Horizons to Pluto within our current life span. Of course, the spacecraft will have to provide an enduring ecosystem and comfortable living conditions over this long journey. And the passengers will have to maintain a stable mindset for their journey’s goal and not lose faith, like a fisherman who, after a long hiatus without finding any fish, asks whether “the real purpose of fishing is catching fish.”

But in a million years, the nearest star to us will not be Proxima Centauri, and so we might have other targets in mind. In fact, the night sky will change as new stars move in and out from the vicinity of the sun. During this period, the Milky Way will exhibit tens of thousands of bright supernovae and other transients that will light up in the dark like cosmic fireworks. The nearest of those events could pose a threat to Earth's biosphere.

Since our current technologies advance exponentially on a timescale of several years, our future habitat on Earth will look entirely different a million years from now. What does a mature technological civilization look like after such a long time? Can it survive the destructive forces that its technologies unleash? One way to find out is to search for technosignatures of alien civilizations, dead or alive. Inevitably, all forms of life eventually disappear. The universe cools as it expands, and all stars will die 10 trillion years from now. In the distant future, everything will freeze; there will be no energy left to support life.

The nearer-term future, though, need not be so bleak. The immediate benefit of prolonging life is to keep loved ones alive for more time. The endpoint is inevitable, but as the Greek philosopher Epicurus noted in his Letter to Menoeceus, death should not be feared because we never meet it, since “when we are, death is not come, and, when death is come, we are not.” Troublemakers will also live longer and be confined in prison for improper behavior. Those whose freedom was inhibited by society always saw this as a silver lining: death brings the ultimate freedom from all societal chains. Unfortunately, this freedom arrives too late to do anything with it, as it is characterized in perpetuity by the acronym and slogan of the old British car Iris: “It Runs in Silence.” Like academic tenure, life sentences in prison should therefore be capped to a much shorter period than a million years.

The million-year timescale is an arbitrary choice, comparable to the entire period that has elapsed since our ancestral Homo erectus species emerged in Africa. It is conveniently shorter than the ages of the universe, the sun or the Earth. In principle, one could imagine a life that lasts a billion years, during which stars turn on and off in the sky just like light bulbs. Against the backdrop of that long-term perspective, our current concerns about the world would seem as naive as the first thought in the head of a newborn baby.