Warp drives are as much of a sci-fi cliché as popular science articles that start by pointing out how cliché warp drives are in sci-fi. But despite seeming like nothing more than nifty pseudoscientific plot devices, they may just be surprisingly plausible, and there are people at NASA working on an honest to goodness demonstrator of the basic physics we’ll use to design a small scale prototype. Look, it’s an order of magnitude more complicated than rocket science, so it’s going to take a while to make it happen.
Basically, what a warp drive does is bend the very fabric of time and space around an object, then flexing that field to push it forward as fast, or faster than the speed of light. In sci-fi, a frequent quote is that instead of moving through the universe, the universe moves around you, but that’s not quite right. You’re creating your own little, infinitely movable bubble within the universe and using it to give you a boost, like using an airport walkway to get to a far away terminal instead of just hoofing it with your stuff.
The universe will stay the same and so will all of its laws. And inside your moving bubble, the situation is much the same. But the bubble itself, made of space rather than matter, can be moved in any direction without limits imposed by inertial mass. To extend the previous simile, if you were to run on a moving walkway after enough training, you could reach superhuman speeds, but your legs would not be moving you faster than human joints and muscles allow. You’ve just made the ground under your feet move as well to give you a cumulative boost without breaking any of nature’s limits.
Warp drives could become a real technology within the lifetimes of today’s toddlers because buoyed by what we’ve confirmed about our knowledge of general and special relativity, and much more computing power, we’re now getting glimpses of what it may be like to manipulate the very fabric of time and space. But before we get into the details of that, we should first talk about why we would want to build a warp drive, and how exactly one could bend time and space to make it work.
Simply put, space involves mind-numbingly large distances even if we try to cross it at the cosmic speed limit, that is the speed of light in a vacuum. Or as Douglas Adams taught us in the Hitchhiker’s Guide to the Galaxy, “Space is big. Really big. You won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.”
Getting to the Moon at the speed of light would take 1.3 seconds. Reaching the nearest star would take 4.3 years, putting fewer than 100 stars of the trillions upon trillions in the observable universe within reach in a human lifetime, even if we can hit that cosmic speed limit. There’s a technical catch to that involving time dilation, but that out of scope for this discussion. We first need to address a much more important snag in these calculations, the problem with getting up to the speed of light.
That problem has to do with inertial mass from Newton’s First Law. While we colloquially think of mass as what something weighs, mass and weight are two very different concepts. Weight is a measure of how much gravity is pulling an object down towards the biggest body in a system, which in our case is our planet. Mass, on the other hand, is an object’s resistance to being moved or brought to a stop. Like the First Law says, a body at rest will stay at rest unless acted on by an outside force. What keeps it at rest is what we call mass, and overcoming it is what makes space travel difficult.
To overcome that mass and go faster, you need more and more energy. If you’re driving in a car or flying in a plane, your inertial mass increases by extremely small increments. Even the acceleration you need to maintain a steady orbit around the Earth wouldn’t make much difference. But as you start approaching relativistic speeds, or an appreciable percentage of the speed of light, your inertial mass begins to grow until the very properties of space and time conspire to give you more mass instead of velocity.
Since the faster you move, the slower time flows for you from an observer’s standpoint, the less you can accelerate because at some point, said external observer would see that time stopped for you. To go faster than that would be the equivalent of forcing time in reverse which is impossible, so all that extra energy ends up going nowhere, adding to your resistance to outside forces, i.e. your mass. This is a manifestation of what’s known as the Lorenz factor, which we had to really simplify here in the interest of not having to cover much of general and special relativity.
With all that in mind consider that even charged subatomic particles will become too “heavy” to reach the speed of light after a certain point, much less spacecraft, so the only things that can travel as fast as light can’t have any mass whatsoever. If we can’t get the tiniest possible specs of what could be considered matter moving as fast as light, just try to imagine accelerating your interstellar spacecraft as big and heavy as several aircraft carriers and with thousands of humans on board to match the velocity of free electrons shot out by feeding black holes and supernovae.
That said, we have thought of a variety of very plausible means to getting massive spacecraft going really, really quickly. We could use small nuclear explosions to push our spacecraft, solar sails boosted by lasers, and there are even ideas for using contained antimatter explosions to get these ships up to as fast as 50% of the speed of light or 0.5c. In theory. However, in practice, a technical catch we set aside comes into play and starts making zooming around the solar system, much less traveling to others, really problematic.
Space is full of particles we can see as gas and dust in large enough clumps and at significant distances. While their density is infinitesimally low, plenty of this cosmic debris is still out there. Colliding with it at the speeds our fastest craft right now can achieve is no big deal. But trying to shove them out of the way at 0.1c in the inner solar system, where they’re at their peak density and where every spacecraft we will launch from anywhere closer to Earth than Jupiter has to traverse, may be suicidal. Relativistic ships would more or less get sandblasted into oblivion.
Think of walking into a mosquito. You probably wouldn’t even notice it. But if you ran into that mosquito as fast as a spaceship moving in Earth orbit, it would probably pierce right through you. Now imagine barreling through a swarm of them at the same velocity for more than a few minutes. That will be more or less what your relativistic spaceship will experience, and despite not being an insurmountable problem, all of the possible solutions require trade-offs that could really add up over the long haul.
Dust shields could absorb the worst of the bombardment over the journey, but they add mass. Electromagnetic shielding could repel anything in the way but will require more energy production and hence, fuel. The need to swap out shields or refuel to keep the shielding working would affect the craft’s effective range and mission planning, and may mean multiple, very different architectures for missions, complicating the economies of scale and the standardization needed to effectively carry them out if we want to really fan out through the galaxy one day.
While this may not be a big deal in our solar system and when traveling to some neighboring stars, ultimately you’re going to want to get yourself warp drives if you want a standardized mission profile. Think of something much like SpaceX’s ITS but on a truly cosmic scale. In fact, should NASA’s research start bearing fruit, it would be pretty safe to wager that Musk and Bezos will be competing to create warp ships and selling tickets for a life of adventure sailing through the galaxy in a time-space bubble.
How would they do it? By focusing enough energy around the craft into the right shape, and that shape is critical. The first ever proposal outlining what if would take to create a warp bubble, the Alcubierre drive — named after its creator, Mexican physicist Miguel Alcubierre — ended up requiring far more than the energy of literally everything that exists in the universe to power. Not only did it need massive bursts of outward energy in all directions, it had to keep itself from collapsing back on the spacecraft generating it.
Another look at it by physicists Richard Obousy and Gerald Cleaver used the Casimir effect, or quantum fluctuations in electromagnetic fields, and found that they could create the negative energy the warp drive required far more efficiently than Alcubierre’s proposal. Thus, according to them, warp drives needed the energy of vaporizing every atom making up Saturn for every cubic meter of your spacecraft’s volume, which was much, much better than using a universe’s worth of power, but also quite unworkable.
Finally, a physicist named Harold White at NASA decided to do some small scale experiments with lasers in controlled environments to see what stable shapes he could create when bending time and space on the scale of a lab bench. His revelation? Making the shape a variable bubble using a ring of energy around the craft could slash the power requirement to a mere 67.8 exajoules. That’s about 69% of America’s annual energy generation which is still a whole lot of power, but firmly within the realm of plausibility.
Unfortunately, there’s a catch. White’s scale warp drive uses a ring-shaped capacitor that creates an electromagnetic field and theoretically, triggers a significant enough Casimir effect to bend space around this capacitor. This effect is caused by the field interacting with what are called virtual particles, spontaneously occurring particle/anti-particle pairs in the basic makeup of space itself. It sounds kind of amazing, like matter and energy being drawn out of nothing, but that’s actually not what’s happening.
As you might have guessed by living in a universe where things do not tend to spontaneously explode with 100% efficiently in a blinding flash of gamma rays, those quantum effects are negligible on a macro scale. They have to be because these quantum instabilities balance each other out resulting in no net gain in energy or mass to the universe. Except when their life cycle gets disturbed by a black hole, or a powerful enough electromagnetic field.
The thought is that by generating a powerful enough field around the craft, these quantum fluctuations would create a cavity in space containing said craft and its occupants. In manipulating the shape of the field by changing the oscillations of the ring-shaped capacitors, you change the shape of that cavity, moving it in the desired direction. And herein lies the catch. The concepts presented by White, and Obousy and Cleaver, are fundamentally one and the same. They just disagree about the strength of the effect, but this disagreement affects some pretty fundamental physics.
What White is saying is that the rig he created to spot the warping with a very precise laser shows that the effect is much greater than thought. But many scientists say that the information he released is both insufficient for them to replicate his experiments and raises some red flags about whether his lasers are the right tools for the job. As mentioned already, since we’re not living in a universe where random explosions happen all the time, the Casimir effect has to have fairly strict limits.
If we can really lower the amount of energy we need to harness it for warp travel by close to 39 orders of magnitude, there are some very pressing and fundamental questions about physics that will have to be raised. And when you mess with the balance of virtual particles, some very strange things will happen involving exotic terms like “information paradox” and “monogamy of entanglement,” resulting in a very special form of radiation created by the warp bubble and affecting its inhabitants, much like what we think has to happen around the event horizon of a black hole.
It may be possible to harness it with the electromagnetic fields that created the bubble to create a feedback loop by which the warp ship can pick up its power as it accelerates, but at some point, this radiation would overwhelm any attempt to contain it and incinerate anything inside the warp bubble. So even in the best-case scenario, actually using a warp drive involves a rather delicate balancing act of enormous energies and forces that White has yet to address. But again, keep in mind that he’s yet to get this far.
Physicists are open to testing the limits of the Casimir effect, but they need to see concrete results published in a high impact peer-reviewed journal and independently reproduced. Lucky for White, if he can show such results, top publications would be competing for the paper and dozens of international teams would be happy to start replicating his experiments. It’s tempting to dismiss his bold claims and upbeat prognosis as attention-seeking cargo cult science, but considering the implications of what he’s trying to do, it would be a disservice to ourselves not to give him a real shot.
But even if he does fall short, the important takeaway is that we’re starting to really understand how to warp space and time to generate energy and to ultimately traverse the universe. In just two decades we went from thinking it would be either impossible or require thousands of years of research to put together even a preliminary design, to zeroing in on the phenomenon we can use to power a warp drive and how to best generate it. While this by no means guarantees we’ll get a warp drive in the foreseeable future, or ever to be totally realistic, we should take this as encouraging progress.
And in a time where we seem to be dragged backward on far too many key fronts, it’s important to try and stop and point out the fact that science is still moving forward and pursuing bold ideas, even ones as out there as an actual, honest to goodness warp drive. We, humans, are an inventive bunch, doubly so when we’re really determined to accomplish something, and even when we fail, we learn enough to either succeed in the future or find a new way to get where we want. It would be a big mistake to rule out warp drives just because they involve some very tricky physics.
[ illustration from FuturLabs’ Velocity. this article originally appeared in Rantt Politech ]