By Corey S. Powell
Physicist John Baez has another, more colorful word to describe the spate of recent reports about a breakthrough space engine that produces thrust without any propellant. The word starts with “bull–.” I won’t finish it, this being a family-friendly web site and all. Baez himself has softened his tone and now calls it “baloney,” though his sentiment remains the same: The laws of physics remain intact, and the “impossible” space drive is, as far as anyone can tell, actually impossible.
The story begins several years back with a British inventor named Roger Shawyer and his EmDrive, a prototype rocket engine which he claimed generated thrust by bouncing microwaves around in an enclosed metal funnel. Since no mass or energy emerged from the engine, Shawyer’s claim was another way of saying that he’d found a way to violate the conservation of momentum. In Baez’s words, “this is about as plausible as powering a spaceship by having the crew push on it from the inside.” Shawyer argued that he was exploiting a loophole within general relativity. Baez calls his explanation “mumbo jumbo.”
Everything in science is open to questioning, of course, but nobody is going to throw out all the textbooks on the say-so of a single inventor trying to raise money for his company, SPR Ltd. Conservation of momentum is one of the most fundamental and thoroughly confirmed principles in physics. The EmDrive therefore got little notice outside of the “weird science” web sites. Last year, a Chinese group reported success with a similar device, prompting another blip of fringe coverage but little more.
Then Guido Fetta (a self-described “sales and marketing executive with more than 20 years of experience in the chemical, pharmaceutical and food ingredient industries”) built a third version of the EmDrive, renamed the Cannae Drive. Fetta convinced a sympathetic group of researchers at the Eagleworks Laboratories, part of NASA’s Johnson Space Center, to give it a test. The results were maybe, tentatively, a little bit encouraging. And that is when the nonexistent propellant really hit the fan.
A number of publications that should have known better threw caution to the wind. “Nasa validates ‘impossible’ space drive” was the headline in an online story by WiredUK. The author, David Hambling, declared that an engine like the EmDrive could “take astronauts to Mars in weeks rather than months,” and even managed to work in nationalistic hand-wringing about “another great British invention that someone else turned into a success.” Soon the madness crossed the pond; “Space Engine Breaks Laws of Physics,” declared Popular Mechanics. “EmDrive is an Engine That Breaks the Laws of Physics and Could Take Us to Mars,” summarized Mashable.
Put It to the Rocket-Science Test
Perhaps we should take a long cool drink at this point. Let’s start with the “NASA validates” part. NASA is a huge agency, with more than 18,000 employees. The testing was done by five NASA employees in a lab devoted to exploring unorthodox propulsion ideas. The team leader is a researcher named Harold “Sonny” White, himself a proponent of ideas about faster-than-light warp drives that most of his colleagues have classified as physically impossible. The lead author is one of White’s Eagleworks teammates, David A. Brady. Calling this group “NASA”—as almost every popular news story has done—is a gross oversimplification.
Still, science is science: What matters are data, not motivations or semantics. Did White et al actually validate Fetta’s version of the EmDrive? The abstract of their paper, which was presented at a propulsion conference in Cleveland, is freely available online. Reading it raises a number of red flags. The methodology description makes it unclear how much of the testing took place in a vacuum—essential for measuring a subtle thrust effect. The total amount of energy consumed seems to have been far more than the amount of measured thrust, meaning there was plenty of extra energy bouncing around that could have been a source of error.
Worst of all is this statement from the paper: “Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust.” In other words, the Cannae Drive worked when it was set up correctly—but it worked just as well when it was intentionally
disabled set up incorrectly. Somehow the NASA researchers report this as a validation, rather than invalidation, of the device.
Did I say that was worst of all? I may have take that back. In the paper by White et al, they also write that the Cannae Drive “is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma.” That last bit stopped me. What’s a quantum vacuum virtual plasma? I’d never heard the term, so I dropped a note to Sean Carroll, a Caltech physicist whose work dives deeply into speculative realms of cosmology and quantum theory.
Read the full article here.