Space is vast. Really, really vast. So vast, in fact, that it would take Voyager 1, the furthest man-made object from earth, more than 73 millenia to reach the nearest star to our Sun, Proxima Centauri, at its current speed of over 38,000 mph, if it were headed that way to begin with. In short, if we’re ever going to find a way to explore beyond our own solar system, we need to find a way to bend the laws of physics to make faster-than-light travel possible.
A team of scientists working with DARPA, including warp drive pioneer Dr. Harold G “Sonny” White, may have just taken us one step closer to that reality with the announcement that they’ve discovered a space-warping bubble, the fundamental thing needed for the faster-than-light travel of the Star Trek universe.
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Before we jump ahead to romantic visions of space travel, Dr. White said, we need to think about what we could do with a microscale warp bubble, like the one his team discovered, before even dreaming of what it could be in the future. Dr. White is passionate about space travel, but says we need to start simple. “there may be lots of other things along the way before we ever get there that could have some really interesting implications,” he said.
What is a warp bubble?
This is a pretty complicated notion that involves a ton of math, but at its most basic level, a warp bubble is a bit of space that’s contracted in the front and expanded in the back. The contraction/expansion theoretically pushes the bubble, and its contents, forward at speeds surpassing the speed of light without ever violating the laws of physics: You’re not technically traveling faster than light, you’re surfing a bubble of condensed space.
Warp bubbles are also important because they eliminate a major problem of faster-than-light travel: Time dilation. Say you did manage to travel faster than light: Everything else outside of your craft would speed up, meaning that three-hour tour you took to a nice, tropical planet could have equated to years of time passing on earth. Put simply, if you plan to move faster than light while following the known laws of physics you had better say goodbye to everything you’ve ever loved before heading out.
Again, warp bubbles get around this problem because the space inside the bubble remains unaffected, so an hour of travel at warp speed would mean that only an hour passed for everyone else not currently in a pocket of sci-fi space.
Warp bubbles were long the domain of science fiction, until theoretical physicist Miguel Alcubierre came along and theorized his Alcubierre warp drive in 1994, which maintained general relativity while allowing for faster-than-light travel. The key upon which it rested, was an energy-density field that was configurable into a vacuum bubble that would make anything inside it have negative mass.
Unfortunately, the amount of energy required to operate an Alcubierre drive made it impossible, until 2012 when Dr. White proposed changes to the math and shape of the craft designed to create the field, which lowered the necessary energy from “impossible” to a power source the size of the Voyager 1 spacecraft. Since then, development of an actual warp bubble or Alcubierre drive has continued to be a distant dream.
Discovering a warp bubble
Fast forward to 2021, and Dr. White, whose 2012 paper was written while he worked at NASA as Advanced Propulsion Theme Lead, is doing research funded by DARPA on objects called Casimir cavities. These cavities are formed of two parallel plates with a pillar running between them. These things are small — mere microns in size — and they do something really interesting: Create a negative vacuum between the plates when exposed to a regular vacuum.
“You would anticipate zero pressure outside and zero pressure in the cavity, but what we find when we measure is negative pressure in between the plates,” Dr. White said.
“What we’re trying to do is explore the quantum vacuum at a fundamental level,” Dr. White said. “We think there’s a bit more to these vacuums than we currently know. Some of the unknown characteristics could be used to create some really useful technologies.” Hence DARPA’s interest.
These uses could include amazing things, like batteries based around what Dr. White calls “quantum vacuum solar cells” that would never run out of energy. Telecommunications products that use longitudinal waves undisturbed by buildings or natural barriers could be a potential use, as could photosensors that don’t suffer from chromatic aberration because they sense all elements of the EM spectrum evenly.
Potential applications aside, testing those cavities led to an interesting discovery: A negative vacuum energy field that looked just like a two-dimensional slice of an Alcubierre warp bubble.
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“Our custom Casimir cavities are basically two big planes with a long pole in the middle. The Alcubierre metric, by comparison, needs a total ring of negative vacuum energy density, which means it needs to look more like a lifesaver,” Dr. White said.
Having already done all the math and collected all the data that was generated by the experiment with the 2D version of the bubble that the team observed, the next logical step was to take that data and change the shape of the object in the center, getting rid of the pole and putting in the eerily Vulcan starship-esque shape shown at the top of the article.
After running simulations with the modified shape, the math just added up, Dr. White said. “We did a purposeful analysis using [the warp ship shape], and wow — hey, that matched the Alcubierre metric requirements.”
The warp bubble team has published a paper on their findings, which Dr. White says are in no way illustrative of a warp bubble analog: Their data shows that, given the right shape placed in the same physical cavities they’re experimenting with now, an honest-to-God warp bubble would be created.
“We can identify to the physics community that there is a real world type of structure that we can make that the analysis predicts. It will manifest a negative vacuum energy density, such that it would manifest a real nanoscale warp bubble, not an analog … this would be a real, no kidding nanoscale warp bubble,” Dr. White said.
The 299,792,458 m/s question: When’s first contact?
In the world of Star Trek, the warp bubble works basically the same way: The Enterprise isn’t actually travelling faster than light, it’s just surfing a cosmic space wave generated by its matter/antimatter warp core.
Zefram Cochrane was responsible for building the first functional warp-capable ship in the Trek universe in 2063, at which point the Vulcans, who just happened to be passing by, decided it was time to make first contact and welcome humans into the galactic community. We might be right on course, then, with Dr. White’s team laying the practical groundwork for theoretical concepts that takes us away from Earth and toward the stars.
So, when can humans expect to vacation on Risa, do business on Ferenginar, and study at the Vulcan Science Academy (conditional on meeting the strict entry requirements)? Let’s not get ahead of ourselves, says Dr. White.
“A lot of people wanna get straight into application: when are we gonna go make something like this fly? I get the motivation for that, but science is a slow, arduous process.” Dr. White says his motto has been “crawl, walk, run,” when it comes to this sort of cutting-edge stuff. Dreaming is important, he says, but so is doing the basic research that goes into finding additional applications that are practical and valuable now, in the age where we’re still terrestrially-bound.
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“I don’t have a crystal ball more than anyone else does. I don’t know when this idea could be applied to space travel, or even if that could even become a reality,” Dr. White said. That’s understandable given we are currently talking about warp bubbles generated in cavities smaller than the width of a human hair.
“Science will continue to turn the crank and hammer the rock, chipping slowly away at some of the unknown to get to more of the known,” said Dr. White. Consider this discovery just one chip in the right direction.