Sometime this year Voyager 1, a probe sent from Earth 35 years ago, will cross a threshold no human-fashioned object has reached before. Passing through a sun-driven shock wave at the edge of the solar system, it will reach the icy dominions of interstellar space. Voyager is one of the fastest vessels we’ve ever blown out of Earth’s gravity well. Still, after three and a half decades of hyper-velocity spaceflight, it will take another 700 centuries for the craft to cross the distance to the nearest star.
Short of a scientific miracle of the kind that has never occurred, our future history for millenniums will be played out on Earth and in the “near space” environment of the other seven planets, their moons and the asteroids in between. For all our flights of imagination, we have yet to absorb this reality. Like it or not, we are probably trapped in our solar system for a long, long time. We had better start coming to terms with what that means for the human future.
Of course, we know this, on some level. But in a culture saturated with inbred notions of “progress” and an obsession with worlds seemingly just beyond our grasp, there is an expectation that sooner rather than later, we will be building an interstellar culture. In a kind of cosmic version of Manifest Destiny we assume that, unless something terrible happens, our science will be taking us to the stars sometime in the next few hundred years. Simply say “warp drive” to just about anyone and see if they know what you mean.
From “Star Trek” to “Star Wars,” from warp drive to hyperdrive — the idea of rapid interstellar space travel is such a deep meme for cultural visions of space and our future that Hollywood films don’t even have to waste time introducing them to the audience. You pull a lever and zap — you are in a new star system. How many people would be surprised to know that warp drive isn’t even a coherent concept, let alone a near-future technology?
The truth is we propel ourselves into space using much the same physics as the Chinese played with when they discovered what we came to call gunpowder more than 1,400 years ago. Blowing stuff up under us is just about the only way we know how to travel through the void.
But for the distances between the stars, that method simply won’t cut it. Even if we could find a way to increase the speed of our spacecraft a hundredfold — about the same ratio of speeds between a horse-drawn cart and a 747 jet plane — they would still take almost a thousand years to reach nearby stars, and as long to return. And while exciting theoretical research is under way into pilotless probes to the stars, the real possibility of large-scale human interstellar culture is considerably less thrilling.
Think about it. No salvation from population pressure on the shores of alien worlds. No release from the threats of biosphere degradation in the promise of new biospheres. No escape from our own destructive tendencies by spreading out among the stars like seedpods in the wind. For as many epochs in the future as there are epochs of human history in the past, we may simply have to make do, get by with what we have and, in the end, learn to get along.
I was just 15 when Voyager 1 left on its long journey. At that age I already knew I wanted nothing more than to be an astronomer. I was also sure that humanity’s future, even on the time scale of centuries, would be played out in the theater of the stars. Voyager’s departure on its interstellar mission convinced me we were well on our way toward that grand future where anything would be possible.
Today I am still in awe of that tiny box of electronics as it sails to the edge of the solar wind. I still believe it represents the best of human genius, ambition and hope. It is through these qualities that, I believe, we have taken the full measure of the stars.
But what we’ve learned in doing so brings me, as an adult and as an astrophysicist, to the hardest and most inconvenient truth of all. While our children’s children’s great-grandchildren will live with ever more powerful technology, they will also live ever more intimately with ever more billions of others in this, our corner of the cosmos. Looking back and forward, my bets are now on that same human genius, ambition and hope to rise to the occasion. We will have no other choice. There will be nowhere else to go for a very long time.
Adam Frank, a professor of physics and astronomy at the University of Rochester, is the author of About Time: Cosmology and Culture at the Twilight of the Big Bang and a co-founder of NPR’s 13.7 Cosmos and Culture blog.