There’s something in human DNA that makes us itch to explore. Having explored the farthest reaches of our home planet and our closest neighbors, we naturally set our sights on the cosmos. But to go farther, we might have to travel somewhere around light speed (186,282 miles per second). Is this even possible?
The biggest issue? Other stars are far. Really, really far. Alpha Centauri, one of our closest galactic neighbors, is still 4.35 light-years away. If Voyager 1, a spacecraft launched in 1977 and now thought to have been the first to ever leave the solar system, were headed to Alpha Centauri, the trip would take more than 70,000 years.
How Do We Get There?
It’s more likely that unmanned spacecraft can travel anywhere near light speed before humans do. Scientists have been looking into this for decades — research efforts like Project Orion, in the 1950s and 1960s, Project Daedalus from the 1970s, and Project Longshot from the 1980s relied on nuclear fission or fusion to propel the hypothetical spacecraft. They were all too expensive to get far past the planning stage, and lots of people had concerns about sending a nuclear warhead into space. Other researchers have suggested using energy from the sun or high-intensity lasers to power interstellar ships.
Some scientists have suggested toying with the laws of physics with strategies once relegated to the realm of science fiction. One such technique is a warp drive. Einstein’s Theory of Relativity suggests it might be possible to bend spacetime so that it compresses in front of a spacecraft and expands behind it. “Perhaps a Star Trek experience within our lifetime is not such a remote possibility,” Harold “Sonny” White, the Advanced Propulsion Theme Lead for the NASA Engineering Directorate, told Gizmodo in 2012. And though it’s physically impossible to travel faster than light speed, a technique like this one could make it seem possible — in fact, 10 times the speed of light by White’s estimation, allowing a spacecraft to reach Alpha Centauri in just two weeks. NASA has built a prototype for such a ship, but it’s not clear yet just how feasible it would be.
Other researchers have looked at the possibility of wormholes, holes in the fabric of spacetime that would provide links or shortcuts for interstellar travelers to reach disparate parts of the universe. Though wormholes have been theorized, none has ever been discovered. Scientists think this might be because they might blip in and out of existence thanks to a quirk of quantum physics, or they might be too small. One researcher quoted in a 2014 article is skeptical that traveling via wormhole will ever be possible.
Even if we could create a ship that could travel closer to the speed of light or tinker with the laws of physics, it would still take a really long time to reach a potentially habitable exoplanet, such as those in the TRAPPIST-1 system, which is 40 light years away. Researchers have proposed putting humans in a state of suspended animation, sending frozen embryos into space, or sending a type of self-sustaining interstellar ark in which the descendants of the original colonizers are the ones that eventually arrive in another solar system (called a “generation ship”). None of these are feasible yet with today’s technology, but suspended animation at least is an active area of research.
Scientists also aren’t sure that humans could survive traveling faster than the speed of light. While some claim that humans at warp speed wouldn’t feel the acceleration according to one 2013 article from Popular Science, others say traveling at warp speed would feel like being hit with a beam from the Large Hadron Collider, or that the sheer amount of radiation would kill any humans on board. Humans entering a wormhole might meet a similar fate — the gravity involved might rip us apart.
Last year, famed cosmologist Stephen Hawking and investor Yuri Milner launched a contest called Breakthrough Starshot. The goal is to create a prototype for a tiny spaceship of Hawking’s design that could reach Alpha Centauri in 20 years. The prize is $100 million.
Separately, NASA will soon test its Orion Spacecraft. Granted, the goal of this mission is to put humans on Mars — a much more attainable goal given that we’ve already sent robots there. But the tests will cause humans to travel faster than ever before.
It’s hard to know when humans may get to visit another solar system. If Hawking and Milner get their way, we could send sophisticated robots to Alpha Centauri within a generation. To get humans there will likely take a bit longer. But we’ve overcome technological hurdles to speed before. It was once thought impossible to travel faster than the speed of sound, but now it’s done regularly. We are good at pushing the limits; if we have our sights set on something, we won’t stop until we achieve it.