Within the Star Trek universe, traveling across the galaxy is a breeze thanks to the famed warp drive. This fictional technology allows humans and other civilizations to zoom between star systems in days rather than centuries.
Such rapid travel times are impossible in the real world, because our best theory for the way the universe works, Einstein’s special relativity, says that nothing moves faster than the speed of light.
While current rocket propulsion systems are bound by this law, plenty of hopeful engineers and physicists are working on concepts that might bring us a step closer to Star Trek’s vision of racing across the cosmos.
“Currently, even the most advanced ideas behind interstellar travel entail trip times of decades and centuries to even the closest stars, due to the restrictions of special relativity, and our abilities—or lack of—to travel at an appreciable fraction of the speed of light,” says Richard Obousy, director and founder of Icarus Interstellar, a nonprofit dedicated to making progress toward interstellar flight.
“Being able to build starships with the capability to travel faster than the speed of light would open the galaxy for exploration and possible colonization by humans.”
Distances in space are so vast that astronomers usually measure them in light-years, the distance light can travel in a year’s time. A single light-year equals about six trillion miles.
The closest star to our solar system, Proxima Centauri, is 4.23 light-years away, so even traveling at the speed of light, a one-way voyage there would take 4.23 years. That may seem pokey, but it would be a huge improvement over current technology.
Right now, the fastest spacecraft headed away from Earth is Voyager 1, which is puttering along at about 38,600 miles an hour. At that rate, it would take more than 70,000 years to reach Proxima Centauri.
Still, various teams have proposed ways to at least reach a fraction of light speed and hasten our exploration of interstellar space.
Back in 1958, researchers at San Diego-based defense contractor General Atomics came up with Project Orion, which involved a spacecraft driven essentially by nuclear bombs. A controlled series of nuclear explosions would propel the ship at high speeds, rapidly carrying a hundred tons of cargo and eight astronauts to places like Mars and even the outer solar system.
Blueprints were also created showing how to adapt the technology for interstellar travel. However, all experimentation with this so-called nuclear-pulse propulsion came to a halt with the Nuclear Test Ban Treaty of 1963.
Announced earlier this year, the ambitious Breakthrough StarShot initiative represents a less explosive effort to undertake an interstellar mission. Run by a conglomerate of billionaires and big thinkers, including famed physicist Stephen Hawking, the project’s goal is to send a flotilla of postage stamp-size spacecraft to Alpha Centauri, a triple star system that’s 4.3 light-years away. (See “Is the New $100 Million ‘Starshot’ for Real?”)
The tiny spacecraft would be attached to a thin light sail, a piece of technology that would allow mission managers to propel the probes with lasers shining from Earth’s orbit. The lasers would accelerate the craft to 20 percent the speed of light, and the probes would arrive at their destination in roughly 20 years.
While many of the tiny travelers may never make it to Alpha Centauri, a few of them should survive and may even fly past any planets orbiting the far-off stars, beaming back data about these alien worlds.
“I’m incredibly excited to see private money being used to explore breakthrough ideas that may advance the field of interstellar flight,” Obousy says.
“I hope to see more like this in the future. While there are engineering challenges associated with the Starshot Initiative, none appear insurmountable.”
Of course, the real breakthrough would be a true warp drive, which requires technology to catch up with our theoretical designs.
In 1994, Trek fans got a glimmer of hope from Mexican theoretical physicist Miguel Alcubierre, who came up with a radical theory of hyper-fast space propulsion that doesn't break Einstein’s special relativity.
Instead of accelerating the spacecraft itself to light speed, why not bend, or warp, the fabric of space and time around the ship itself? Alcubierre presented calculations that produce a bubble in space-time in which one end is expanding and the other is contracting. A spaceship could, in theory, be carried along with the warp bubble and accelerated to velocities up to 10 times the speed of light.
While that sounds simple on paper, to make it work, we may need to harness exotic forms of matter, like antimatter, that for now are poorly understood. In addition, numerous unsolved issues plague the creation and control of a warp bubble, Obousy says.
“One such problem, for example, is the idea of causal disconnection, which implies that any spacecraft sitting within the bubble would not be able to ‘communicate’ with the exterior of the bubble, suggesting that a ship would not be able to ‘turn off’ the bubble once inside of it,” he notes.
As is often the case in space travel, developing true interstellar travel like what we see in Star Trek will require significant changes in the cost and energy requirements.
“Currently, the amount of energy and money required to entertain the notion of manned interstellar travel is measured in large fractions of global output—specifically, tens of trillions of dollars, and energy measured on the scale of what many large countries use annually,” he says.
Still, he adds, “the finest minds of the 15th century could not have predicted the technological wonders of the 21st century. Similarly, who are we to say what technology the humans of the 27th century will have mastered.”