Faster Than Light Travel Will We Ever Travel to the Stars?
Hal Plotkin, Special to SF Gate
Wednesday, October 18, 2000
In the two years I’ve been at this column, I’ve been overwhelmed by the many intelligent and well-informed e-mails that have come pouring in.
The response has been so good I’ve decided to go out on a bit of a limb.
An idea has been kicking around in the back of my head for nearly 20 years now and I’ve long wondered what, if any, merit it might have.
I figure one or more of my readers might know.
It concerns what may be the most important technical question of all time:
Will we ever be able to travel faster than the speed of light?
The answer is critically important because if nature really does have a cosmic speed limit, it means all those “Star Trek fantasies” about interstellar travel will forever be just that, fantasies. Even the closest large clusters of stars visible in the night sky are thousands of light years distant.
Like it or not, our current understanding of physics tells us we humans are pretty much stuck in this solar system. That is, until our sun eventually uses up all its stored energy in about 5 billion years or so and collapses, taking along with it any nearby life that might still be around.
Faster-than-light travel may be the only technology that could save humanity from extinction.
But if Einstein was right, faster-than-light travel will never happen.
Einsteinian physics tells us that anyone traveling that fast will be crushed into a tiny sliver of their former selves because mass increases with velocity.
The faster any type of matter moves, the denser it’s thought to become.
That’s why most scientists agree that physical travel at or even near light speed is simply impossible.
But science has been wrong before. A little over 50 years ago, for example, conventional engineering wisdom held that controlled flight past the speed of sound was physically impossible. Back then more than a few respected thinkers agreed that sonic shock waves would cause airplanes to lose control or to break up into tiny pieces. Those fears gained credence when the first few pilots who attempted supersonic travel died trying.
But in 1947, the team behind famed aviator Chuck Yeager finally figured out how to take the necessary precautions that led to the first successful hypersonic flight. Not only was it possible, Yeager later wrote, but the ride was so smooth “Grandma could be up there sipping lemonade.”
It’s unlikely Grandma will be sipping lemonade while traveling at light-speed anytime soon. The physical obstacles to faster-than-light travel appear insurmountable, especially when compared with something as simple as overcoming the effects of vibrations caused by a sonic boom.
Even so, I’ve been thinking about what strikes me as a simple and intuitive way to further test whether it will ever be possible to get anyone or anything moving that fast.
It would involve an experiment conducted in outer space, where factors such as gravity and friction caused by the atmosphere wouldn’t complicate things.
Here’s the idea:
First, imagine a thin rod one mile long in outer space, situated somewhere between Earth and a neighboring planet. Then imagine a motor at the exact center of the rod, at the half-mile point, that spins the rod such that the center of the rod rotates once per second. (Think of a long, thin baton being twirled in space. Each end of the baton makes one full circle with each single rotation).
If you remember your high school geometry, the circumference of a circle is calculated by multiplying its diameter by Pi.
So, assuming the one-mile-long baton maintains its structural integrity, each of its ends will travel Pi, or roughly 3.141592654 miles in the one second it took for one rotation.
For the sake of simplicity, let’s say each end of the rod travels 3 miles per second, just to make the next calculation easier.
Now, the speed of light in a vacuum is about 186,000 miles per second. That means if we can stretch the rod to one-third that length, or 62,000 miles long, and get it spinning in space once per second, the ends of the rod would have to be moving faster than the speed of light.
Which, at least according to theory, would be totally impossible.
And, to be sure, building a 62,000-mile rod in space and getting it spinning once per second would be an unimaginably cumbersome task.
Fortunately, however, we already have motors here on Earth capable of spinning things hundreds, even thousands of times faster than that. The disk drive in my computer, for example.
The quicker we can spin the baton in space, the shorter it needs to be for the ends of the baton to approach super-fast velocities. Even better, the ends of the baton would reach those speeds while the baton itself stays in the same physical location in space where it can easily be observed.
So, it might be possible to use centrifugal motion of the sort described above to push matter we can observe in nearby space to approach or — in the unlikely event Einstein missed something — maybe even exceed the speed of light using a baton or rod that’s just a few miles long, perhaps far shorter.
And, imagine that it’s not a rod or a baton at all. Imagine it’s just a stiff iron thread; all of a sudden a totally impractical experiment becomes far more manageable.
Iron might be a good material to use since it’s the super-dense matter nature leaves behind when giant stars have consumed their energy. But a non-conducting material might be a better choice. Figuring out which materials work best, even if none work perfectly, would be an added benefit.
For the record, one of the main arguments against even attempting such a thing goes something like this: We already know how matter reacts when it approaches the speed of light because we’ve seen what happens when we get some individual particles moving at those speeds in particle accelerators such as those at Lawrence Berkeley Laboratory and the Centre Europeen de Recherche Nucleaire, or CERN, in Geneva.
The predicted result sees the bar bending in space well before it reaches the speed of light until no amount of force can get it to move any faster.
Since all matter is made up of particles, the theory goes, we already know how larger pieces of matter will behave because we know what happens to their parts.
But that argument has always troubled me.
At best, earthbound particle accelerators tell us how individual particles act when subjected to certain conditions. But they can’t and don’t tell us much about how groups of particles, or other even smaller as yet undetected particles, might interact with each other when closely bound under the most extreme conditions.
It’s kind of like trying to figure out what’s happening on the freeway by looking at just one car. Or, to stretch another analogy, it’s similar to the way modern medicine sometimes treats one symptom without realizing it’s really part of some larger problem.
I have no specific evidence that physics suffers from a similar too-narrow focus. But it seems to be at least a possibility.
There are, of course, compelling reasons to believe Einstein had it right all along. There have, after all, been numerous experimental observations that have supported his many conclusions.
But we’ve never actually seen what happens when large quantities of matter approach the speed of light. That may be because it is in fact impossible. Or it may be because we just haven’t figured out how to do it yet.
That’s because so far it’s been impossible to test on earth, in part because anything moving that fast in any one direction would quickly race away from us before we could see what happened to it.
What’s more, the twirling baton experiment also would not work here on Earth because friction caused by the atmosphere would incinerate anything moving that fast.
Pre-Space Age scientists responded to those obstacles by envisioning the large particle accelerators we now have that use magnets and vacuum conditions to send tiny particles of matter hurtling at velocities that come within a whisker of light speed. The particles are then smashed into one another, or into other substances, in hopes of breaking them apart to see what smaller particles might lie within.
We’ve been looking at the trees. But given the opportunities that space-based light speed experiments afford, we might learn even more by taking another look at the forest.
The hunt for a better understanding of these issues becomes even more exciting when you realize that modern physics requires almost, but not quite, as many leaps of faith as does modern religion.
A consensus is now apparently emerging, for example, that all matter might be made up of invisibly tiny vibrating loops of a stringlike substance. Put unforgivably simply, the theory is that the frequencies of each loop’s vibrations are what determine the more familiar properties of matter that can be observed.
But what is the most fundamental building block of matter?
The truth is no one knows for sure because we haven’t seen it yet.
Given that, one wonders if there might be a little arrogance reflected in the assumption that science already knows how all matter behaves under all possible conditions.
Although they’re still very much in the minority, several theorists have recently suggested there could be a related way to create distortions in space that might allow faster-than-light travel.
Most mainstream physicists scoff at such possibilities. But some of the best of them, such as U.C. Riverside’s Philip Gibbs leave open at least the possibility that new knowledge may yet emerge.
Even if faster-than-light travel isn’t possible, we could still learn a lot about materials sciences and other related topics by taking the problem back from the theorists who now own it. Trial and error approaches almost always yield far better science than is achieved by a reliance on conventional wisdom or untested assumptions.
Who knows, even if it didn’t pass warp speed we might still end up with something like an interstellar catapult that could conceivably prove useful in other ways.
Spinning a thread in space might not let us travel faster than light. But I wonder if it might help us test our limits.
This work is licensed under a Creative Commons Attribution 4.0 International License.