Hit the Brakes

In truth, we all probably knew it sounded too good to be true.  A few weeks ago, Star Trek fans and those who dreamed of space travel were beside themselves as a rumor circulating suggesting NASA had accidentally made progress toward the development of a warp drive, which would allow blindingly fast travel across the universe. When lasers were fired through an EmDrive’s resonance chamber, the beams appeared to be traveling faster than the speed of light, at once defying Einstein and making Mr. Sulu’s futuristic warp drive sound plausible, according to comments posted on NASASpaceFlight.com.

Within days, naysayers and researchers alike were bringing us back to reality.

“If you’re going to make an extraordinary claim like this — which violates the laws of physics — you’d better have extraordinary evidence to back it up. In particular, the laws you’re violating are really basic: Newton’s third law, since you’re having an action (thrust) without a corresponding reaction, and the law of conservation of momentum,” writes Ethan Siegel at Forbes. “The claimants propose no viable mechanism, but merely contend that all of science is experimental, so if the experiment gives you this thrust, then it’s our understanding of physics that needs revision, not the experiment.”

If results obtained during experimentation appear to conflict with the best available theories, the theories need to be revised, Siegel says. Several teams have claimed to detect the same kind of thrust allegedly noted in the EmDrive experiments.

He poses a series of questions to “aspiring (or armchair) scientists: What would be the criteria you’d demand as the extraordinary evidence necessary to convince you that this is real?,” and offers the following as his own litmus test:

  • A detection of thrust that scaled with input power: the greater the power, the greater the thrust, in a predictable relationship.
  • A thrust that was at least many standard deviations above the measurement error.
  • An isolated environment, where atmospheric, gravitational and electromagnetic effects were all removed.
  • A reproducible setup and a transparent device design, so that other, independent teams can further test and validate the device/investigate the mechanism.
  • And finally, a detailed results report with the submission of an accompanying paper to peer review, and acceptance by the journal in question.

The EmDrive experiments don’t meet most of those requirements, he concludes.

Over at Wired, Katie M. Palmer puts it even more bluntly, calling the warp drive rumor “poppycock.”

The last time the idea of getting tantalizingly close to warp drive surfaced, the enthusiasm was quashed thanks to what she says were “some pretty (ahem) obvious flaws” in the experiments. “The physicists hadn’t run the tests in a vacuum—essential for measuring a subtle thrust signal. And while they had tested the drive under multiple conditions, one of them was intentionally set up wrong. That setup produced the same thrust signatures as the other conditions, suggesting that the signals the physicists were seeing were all artifacts.”

While the group conducting the experiments now say they’ve addressed those problems, they’re making the same claims that were thrown out previously.

“Let’s be clear, though: Just because this time the group conducted its experiments in a hard vacuum doesn’t mean that an interstellar warp drive is soon to come,” she says. “Marc Millis, who headed up the now-defunct Breakthrough Propulsion Physics lab at NASA’s Glenn Research Center—which, like Eagleworks, was dedicated to finding science-fiction-sounding ways to move a spaceship—says there are plenty of other interactions between the drive and the test chamber that could account for the results. ‘Even if it was done in a hard vacuum,” Millis says, “you have to take into account the distance between the drive and the chamber wall, whether those walls were conductive, and the geometry of the system.’”

 

At the end of a lengthy and well-reasoned take-down of the warp drive-promising experiment, Palmer promises that when a warp drive is developed that “violates conservation of momentum, you’ll read about it here, accompanied by a big old mea culpa. But until then, don’t believe the hyperspace.”

For our previous coverage of the warp drive experiments, read here.

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