Ever since astronomers found that Earth and the Solar System are not unique in the cosmos, humanity has dreamed of the day when we might explore nearby stars and settle extrasolar planets. Unfortunately, the laws of physics impose strict limitations on how fast things can travel in our Universe, otherwise known as Einstein’s General Theory of Relativity. Per this theory, the speed of light is constant and absolute, and objects approaching it will experience an increase in their inertial mass (thereby requiring more mass to accelerate further).
While no object can ever reach or exceed the speed of light, there may be a loophole that allows for Faster-Than-Light (FTL) travel. It’s known as the Alcubierre Warp Metric, which describes a warp field that contracts spacetime in front of a spacecraft and expands it behind. This would allow the spacecraft to effectively travel faster than the speed of light while not violating Relativity or causality. For more than a decade, Dr. Harold “Sonny” White has been investigating this theory in the hopes of bringing it closer to reality.
Previously, Dr. White pursued the development of an Alcubierre Warp Drive with his colleagues at the Advanced Propulsion Physics Research Laboratory (NASA Eagleworks) at NASA’s Johnson Space Center. In 2020, he began working with engineers and scientists at the Limitless Space Institute, a non-profit organization dedicated to education, outreach, research grants, and the development of advanced propulsion methods – which they hope will culminate in the creation of the first warp drive!
Warp Fields 101
While the idea of “warp drives” and FTL have been with us for decades, these concepts have overwhelmingly been the stuff of science fiction and pure speculation. It was not until 1994 that an actual proposal was made to explain how FTL could work within the realm of known physics. The credit for this goes to Mexican theoretical physicist Miguel Alcubierre, who proposed what would come to be known as the “Alcubierre Drive” as part of his Ph.D. study at Cardiff University, Wales.
In his research paper, “The warp drive: hyper-fast travel within general relativity,” he offered a possible solution to Einstein’s field equations that considered how a spacecraft could achieve apparent Faster-Than-Light (FTL) travel without violating Relativity. Alcubierre concluded that it was possible, provided a field could be created with a lower energy density than the vacuum of space (aka. negative mass or “exotic matter“).
According to Alcubierre, quantum field theory allows for the existence of regions of spacetime that have negative energy densities. This is known as the Casimir Effect, which describes the attractive force between two surfaces in a vacuum. If a “ring” of negative mass could be created around a spacecraft, spacetime could theoretically be contracted in front of the ship and expanded behind. This would allow the spacecraft to effectively travel faster than the speed of light.
“By a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it, motion faster than the speed of light as seen by observers outside the disturbed region is possible,” he wrote. “The resulting distortion is reminiscent of the “warp drive” of science fiction. However, just as it happens with wormholes, exotic matter will be needed in order to generate a distortion of spacetime.”
Dr. White explained the concept to Universe Today via Zoom using an everyday metaphor. Basically, he said, it’s like using (what he refers to as) a “travelator,” those horizontal conveyor belts at major airports:
“Normally, you walk along at about three miles an hour going from one gate to another. But in some locations, you have these horizontal ‘travelators,’ and you step on top of them. So you’re still walking at three miles an hour, but the belt is moving as well. Conceptually speaking, the belt is contracting space in front of you and expanding space behind you, so that it augments your apparent speed. But locally, you’re still going at the same speed.”
This way, an object would not be violating Relativity since it is merely riding a wave generated by the expansion and contraction of local spacetime. This would allow spacecraft to circumvent the problems of time dilation (where time slows down as objects approach the speed of light), the massive increase in inertial mass, and the extreme energy required to keep accelerating. Ah, but there was a snag, and it was a doozy!
According to Alcubierre’s original paper, the amount of negative mass required to achieve a warp field was beyond anything humanity could achieve. However, his work has been revisited in the nearly thirty years since he first proposed it, and some of the strict energy requirements that he outlined have been reconsidered. In essence, revised calculations have shown that the