When I was little, I spent a lot of time daydreaming about outer space. I wasn’t alone in my obsession. These were the years after the Apollo program, the era of Viking and Voyager, when the far reaches of our solar system seemed to be just beyond our grasp. We’d landed men on the moon and brought them safely home. Astronauts had unpacked a lunar rover and taken it for a spin across the lava bed of the Taurus-Littrow valley. What was next? Mars? The asteroid belt? Jupiter?
The movie Star Wars came out in 1977, five years after the last Apollo mission, feeding my insatiable appetite for all things extraterrestrial. Who didn’t thrill to the idea of “hyperspace,” which made travel between star systems as easy as pressing a button?
Alas, space travel hasn’t proven to be quite so easy. In the decades since Apollo, there have been plenty of Star Wars sequels, but not such great progress in manned spaceflight. Yes, there were the Space Shuttles, which delivered spectacular — and occasionally tragic — results. And there’s currently the International Space Station, a sort of United Nations in low earth orbit — and just about as exciting.
Our space program seems to have succumbed to the doldrums of middle age. If it isn’t immediately practical, if it doesn’t offer us a military advantage, faster data streaming, some other earth-bound benefit — why invest?
The Space Shuttles have been mothballed; NASA is buying seats on antiquated Russian rockets; and while there are plans in the works for a manned mission to Mars, does anyone really believe it’s going to happen?
So where does that leave the dream of interstellar travel?
Movies like Star Wars and Star Trek have popularized the idea of zipping from galaxy to galaxy, and even made it seem commonplace, but people tend to forget the fundamentally unpleasant reality of our universe: stars are very, very far apart.
Take our closest neighbor, Alpha Centauri, the third brightest star in the night sky. Alpha Centauri is 4.37 light years from our sun. That may not sound so bad. “Four years?” you say. “That’s how long I spent at college. And those years flew by.”
Unfortunately, 4.37 light years isn’t really a measure of time; it’s a measure of distance. Specifically, the distance light will travel if you say, “Ready, set, go!”, click your stopwatch, then click it again, 4.37 years later.
In that time, a single photon will have traveled about 5.8 trillion miles. That’s trillion, with a “t.”
There’s no way the human mind can comprehend such a distance. But here’s a little comparison that may help. It takes light about 1.2 seconds to travel from the earth to the moon, a distance of 240,000 miles or so.
So traveling to Alpha Centauri would be the equivalent of rocketing to the moon and back more than 50 million times.
To put it another way, if one of the Space Shuttles were outfitted for a really, really long journey, and its engines were made 10,000 times more powerful, it would still take a shuttle about 165,000 years to fly to Alpha Centauri.
And Alpha Centauri is the closest star!
With numbers like that, you can see why writers and filmmakers would create fictional devices like “hyperspace” or “warp drive.” No one wants a million years to elapse before the next action sequence. The only way to make interstellar travel work is to imagine a way to travel faster than the speed of light.
But there’s a problem. If Albert Einstein was right about the nature of time and space — and all of the experimental evidence to date seems to confirm his theories — then the speed of light is a kind of universal limit. Nothing can exceed it, ever.
Period.
Over the years, there have been dissenters willing to risk their colleagues’ ridicule, scientists who insist that the seemingly impossible may be possible after all. In 1994, a physicist named Miguel Acubierre published a paper outlining a theoretical method for traveling faster than the speed of light. Perhaps it would be possible to travel from point A to point B not in a straight line, as we understand distances, but rather to crumple the fabric of space-time, expanding it on one side of a spacecraft and contracting it on the other. Inside of such a “warp bubble,” normal time and gravity would continue to exist. The speed of light would not be exceeded.
But, by burrowing through the fabric of space-time like a needle through the folds of a curtain, the craft would pop out on the other side, having traveled faster than light could have traveled that same distance.
Acubierre’s equations work, but only by taking certain liberties. For instance, they assume the existence of certain kinds of “exotic matter” that violate the laws of physics, as we understand them.
Which, to a cynic, means that his equations don’t work at all.
But you don’t get into the field of faster-than-light travel if you’re a cynic. There are scientists actively exploring the feasibility of such a “warp bubble.” On July 22nd, The New York Times published a fascinating article on one of them, Dr. Harold White, who happens to work for NASA. It’s worth looking up.
For those naysayers out there, let’s not forget that in 1913, mankind was only ten years into powered flight. By the end of the century, we’d flown to the moon.
In 2013, the idea of traveling faster than light is still the stuff of science fiction. It’s hard to imagine mankind making significant progress towards that goal by the end of the 21st century.
But given the choice between the doldrums of middle age and a child’s overheated daydreams, I’ll take the daydreams every time.
