A NASA scientist working on a DARPA-funded research project has published a scientific paper announcing that a three-dimensional nanoscopic “warp bubble”, the holy grail of faster-than-light propulsion research, had been observed during an experiment designed to investigate quantum effects. Although a full-fledged warp drive capable of transporting travelers across the vastness of space is still a long way off, this development, along with the recent finding that a gravity-based propulsion system wouldn’t need unobtainable exotic matter to function, brings us one step closer to making this futuristic dream into present-day reality.
“To be clear, our finding is not a warp bubble analog, it is a real, albeit humble and tiny, warp bubble,” explains Dr. Harold G. “Sonny” White, the head of NASA’s Advanced Propulsion Team. “Hence the significance.” Dr. White is no stranger to the concepts of alternative forms of spacecraft propulsion, having worked on refining the mathematics underlying the theoretical Alcubierre drive, and having led NASA’s successful real-world testing of the controversial EmDrive, a reaction-less engine that uses only microwaves to produce thrust.
Although the generation of this real-world space-time distortion is indeed significant, White isn’t kidding when he refers to it as “humble and tiny”: the warp bubble that formed was discovered within an apparatus designed to investigate properties of what is known as the “Casimir effect”, a physical force that acts on two objects that are placed tens of nanometers apart—about the width of 100 atoms; it was within one of these “Casimir cavities” that White discovered the minute warp bubble.
Although the actual cause of the Casimir effect isn’t known, the effect, first predicted by Dutch physicist Hendrik Casimir in 1948, was demonstrated to be a real phenomenon in 1997. A typical Casimir cavity apparatus consists of two metal plates placed in a vacuum chamber, oriented so that their faces are within close proximity to one another. The effect becomes measurable when the objects are brought within one millionth of a meter of one another, with the force on the objects increasing as the gap is closed; at 10 nanometers the effect is strong enough to impart the equivalent of about 1 atmosphere of pressure, a significant force for an effect with no clear cause.
The prevailing theory behind the Casimir effect is that there is an imbalance in the number of virtual particles that ever so briefly manifest between the plates as compared to the ones that appear outside the assembly. Although they are no less real than the regular subatomic particles we’re familiar with, virtual particles are points in the quantum field that have the same properties of the ones that appear in our reality, but lack the energy to manifest as “physical” elementary particles. Randomly, these particles pop into existence out of the vacuum, only to disappear just as fast, but during their (very) brief time in our reality they act like regular particles, including having the ability to exert force on objects, just like their more permanent counterparts.
This manifestation of virtual particles is governed by the uncertainty principle, meaning that there are an infinite number of possible wavelengths these particles could take on while in our reality; however, when they manifest in an enclosed space, the wavelength of the particles appearing between the plates is limited to the harmonics that can exist within the confines of the cavity. This means that while the number of possible virtual particles that could manifest outside the plates is infinite, that number in between the plates is finite, leading to an imbalance in the number of interactions on each side of the plates, resulting in there being more force on one side than the other.
It’s this asymmetrical force that intrigues propulsion scientists like Dr. White: if this force can be harnessed and scaled up into the macroscopic world, it could provide us with a reactionless propulsion system, in that it would not rely on a finite store of fuel that has to be lugged along for a spacecraft to burn.
Since the experiment White was contracted to conduct wasn’t related to warp propulsion he was unable to follow up on the finding, but he has proposed the design of a future experiment to explore the concept further: the experiment would involve the construction of a 4-micrometer-wide cylinder (about one-tenth the width of a human hair) that encloses a 1-micrometer sphere—a design similar to the toroidal shape given to artistic depictions of theoretical warp craft—around which a nanoscopic warp bubble should form.
“This is a potential structure we can propose to the community that one could build that will generate a negative vacuum energy density distribution that is very similar to what’s required for an Alcubierre space warp,” White explains. He says that the tiny device could be easily built using “a nanoscribe GT 3D printer that prints at the nanometer scale.” Needless to say, such a small device, referred to as “a toy model” in White’s paper, couldn’t power something like an aircraft carrier-sized spacecraft like Star Trek’s USS Enterprise on its own, but the concept has the future potential to be scaled up for just such a purpose. But for now, White says that it is important to be patient as we learn to “crawl, walk, run.”
“It is [too] early to ask questions about some type of actual flight experiment,” White concludes. “In my mind, step one is to just explore the underlying science at the nano/micro scale.”
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