If you’ve taken the time to check out this article, you probably have also heard some of the hype regarding NASA’s experimental spacecraft engines. The granddaddy of them all was a supposed “warp drive” based on a theoretical constructed called the Alcubierre drive. If you’re a Star Trek fan, then you probably got goose bumps at the thought.
Does NASA really have plans for a warp drive? No, although there’s no doubt a large number of NASA scientists and engineers are sci-fi fans. But taxpayer dollars cannot be earmarked for dreams; they can only be used to pursue results. Right now, interstellar travel of any time is just a dream.
Let’s talk about the Alcubierre drive, a theoretical basis for faster-than-light (FTL) space travel. I’ll give you a little background first. We know that matter cannot move beyond the speed of light, and even getting it close is an exercise in extreme engineering. Einstein’s Theory of Relativity tells us that as a body accelerates toward the speed of light, its mass approaches infinity and it takes an infinite amount of energy to accelerate it further. To help you comprehend it visually, imagine the length of a body along its direction of travel contracting in proportion to the body’s velocity in that direction. Length contraction does, in fact, occur; it has been observed in laboratory experiments. The faster the body moves, the shorter it gets, thereby reducing its volume. If you do the math, it shows that the density of the body approaches infinity, and therefore the mass approaches infinity. So FTL travel by conventional propulsion is out. It will never happen.
What does that leave us with? Actually, it does leave us with something. It was Edwin Hubble (yes, that Hubble), who had actually studied law in college, who discovered the universe was expanding in 1929. Since then, we’ve discovered that the rate of expansion of the universe is accelerating. We’ve also discovered that the further apart two bodies in space are, the more rapidly they speed apart. If you take two bodies that are far enough apart, you’ll find they are moving apart faster than the speed of light. Space itself moves, and it can move faster than the speed of light.
This brings us to the theoretical warp drive. In Star Trek and other sci-fi worlds, the warp drive moves the spacecraft by bending the space around it, allowing the craft to travel at speeds not possible through conventional means. The Alcubierre drive works in a similar manner. It generates fields that expand space behind the craft and contract the space in front of it. There we go. We have a working theoretical model based on solid laws of physics. Next comes the engineering part.
What engineering part? If we had the means to manipulate the fabric of space-time in such a way, we’d be a far more technologically-advanced species. It would take some kind of exotic matter to do such a thing. One option to explore is the use of dark matter, which we know exists; in fact, most matter in the universe is dark matter. But we know it’s there simply because we have been able to calculate the mass of all matter in the known universe based on gravitational lensing. (Check out this article for an explanation.) We have no way of detecting it directly, of understanding its nature, or how to retrieve a sample. Another idea is to employ Casimir particles (check out this article), but there is no way to manipulate such particles to our own designs.
Of course, we don’t know what the future holds, and it’s entirely possible that we’ll be able to tap into the power of dark matter and/or Casimir particles. If we’re able to do that, there are other possibilities connected, too. Those options could open the door to space travel in other ways, and maybe even time travel. Who knows?
It’s also true that things like aviation and breaking the sound barrier were once deemed to be impossible. There’s nothing wrong with being optimistic about the future of space travel. If we, as a species, didn’t dream, we wouldn’t have goals, and we’d never try to improve anything. While we won’t be flying back and forth to other star systems within our lifetimes, we can certainly dream. Dream on!