A practical way to travel between the stars is a must-have for space opera, and a sine qua non for our frequently vaunted future as a galactic society. But are we ever really going to boldly go to worlds around other suns?
We'll have to, if we hope to occasionally bump up against ornery aliens or perhaps trespass into some advanced race's galactic empire. For that, I think we'll need an action radius of at least 50 light-years, a distance that's far beyond the reach of our current rocket technology. Even today's speediest spacecraft would take a million years to rack up 50 light-years on their odometers. I feel confident that few folks will choose to endure a middle seat and microwave eats for 10,000 centuries.
So when will we have the Enterprise? When will we be able to floor the accelerator and get to another star system in a time that's short enough that the crew doesn't lose interest or simply start killing one another?
Plenty of people have spent plenty of time noodling this. They've considered all the various ways to get a rocket up to a relativistic velocity -- a respectable fraction of the speed of light. And problem number one is basic physics. It's easy to reckon that the oomph to hurl even a Smart Car-size spacecraft to another star at, say, 20 percent the speed of light (and land it when it arrives) is the energy contained in 50 billion gallons of gasoline. The tank's not big enough.
So engineers have looked at the practicality of non-chemical propulsion: fission or fusion rockets (barely adequate for the nearest stars), or the motive power of the fictional Enterprise -- matter-antimatter fuel. The last looks good on both blackboards and television, but in practice it requires solving the devastatingly daunting problem of producing the antimatter and safely storing it on or near the rocket.
Other approaches include dispensing with on-board fuel altogether, and either scooping it up en route, or nudging the ship starward with a high-powered laser beam from Earth. Another popular suggestion is to have the sun shove the craft into space using light pressure on a giant, solar sail.
If all else fails, there's always Plan B: the literally laid-back approach. Simply put the crew to sleep, and accept the fact that it's going to be a long ride. Unfortunately, bedly going where no man has gone before is not of much help if your goal is to truly interact with the cosmos.
All these schemes are either devilishly difficult, or as slow as Homer Simpson. So the gold standard for interstellar travel remains some sort of "warp drive" -- a method of distorting the geometry of space so that our craft can plunge to other worlds through a shortcut (a worm hole in the vernacular of those wishing to appear knowledgeable).
But unlike the more prosaic schemes noted above, worm hole travel is not a guaranteed possibility. Yes, there are solutions to Einstein's theory of General Relativity that suggest that if you could fall into a massive black hole on just the right trajectory, you'd be transported at the equivalent of faster-than-light speed to somewhere else in the universe. But while this sounds like the ultimate in cosmic rapid transit, no one can say for sure whether it's something we might someday have, or merely a seductive pipe dream.
However, here's another thought. What if we could send humans anywhere at the speed of light, and at a rock-bottom price?
That's eminently feasible if we send the information and not the protoplasm. No crew, just code.
Consider: The human genome consists of about 3.3 billion base pairs. Since there are only four types of pair, that amounts to 0.8 gigabytes of information, or about what you can fit on a CD. With a microwave radio transmitter, you could beam that amount of information into space in a few minutes, and have it travel to anyone at light speed.
But why stop there? The difference between your DNA and that of any other Homo sapiens is about 1.4 million base pairs, or only one part in three thousand! In other words, if you opt to transmit a DVD's worth of info, you can send your DNA sequence and -- as a bonus if you act now -- include 3,000 of your best friends by the simple expedient of encoding only their differences with you. Yes, the life experience and college education are not included, but at least our species could travel to the stars.
Sending a DVD's worth of data is fast, relatively cheap, and desperately easy. And the ability to send thousands (or millions) of individuals for little more than the single ticket price sure beats rocketry.
But of course there's the obvious problem that if anyone picks up this broadcast, will they know what to do with it?
They might. It seems reasonable to assume that any organic life will have a "blueprint" molecule (or set of molecules) that specify its hereditary structure. Sure, it might not be helical in form or based on exactly the same chemistry as DNA, but an architecture molecule might well be a common fact of life, even on other worlds.
And if that's so, then perhaps the ether is replete with Johnny Appleseed-like efforts to beam species around. It could be that the one piece of apparatus that any tech-savvy civilization will have is a good 3D printer, able to build, not just plastic gimcracks, but complex biology. Such things are being developed in earthly labs as you read this.
And sure, this scheme won't cut it if you want to boldly go to worlds devoid of intelligent beings, but think about it: How many Star Trek episodes involved sending the Enterprise to planets where the only inhabitants were bacteria?
There's exploration, and there's species radiation. For the latter, don't think rockets: think data links and 3D printers. Beam me up.