The EM Drive: A Skeptic’s Guide
The EM Drive recently took the internet by storm – the promise of interstellar travel being decades away instead of centuries got all of the Star Trek / Wars fans to take to their respective blogs and cry out with eager abandon. However, very few people stopped to apply real scrutiny to the claims that were being made, and that’s unfortunate because a little credulity shows that there’s not much promise in the EM Drive after all. First off:
This is not the first time the EM Drive has made headlines
Various researchers and scientists have been claiming to have built (or that they were at least close to building) a working EM Drive for quite a while now – this is nothing new. It seems that every few years, a story about the wonders of electromagnetic propulsion and how close we are to achieving it pops up and breaks the internet for a little bit.
However, one thing you might have noticed is that despite this story popping up every few years, we’re no closer to a working EM Drive as of yet. There’s actually a very good reason for this…
A real EM Drive will probably never exist because…physics
Unfortunately, the principle of the EM Drive violates a well-established and understood property of our universe – the Law of Conservation of Momentum. If you think back to your high school physics class, you’ll know that Conservation of Momentum is a universal property by which we all must abide – namely that the total momentum of two objects which collide in a closed system must equal the momentum of the two objects after the collision. So, why does the EM Drive break this rule?
The EM Drive, said to be a “reactionless drive”, would produce thrust without acting or being acted upon. This is simply not how physics works, and despite the claims of the man who originally conceived of the EM Drive, most physicists agree that it cannot function in our universe.
The claim that it’s already been tested in a vacuum was never verified
One of the main reasons the EM Drive caught the eye of the media again was that this time around, it was claimed that the drive had already been tested in a vacuum and was shown to produce thrust. Unfortunately, however, this claim was never verified – it was not made in reference to any evidence that the test had been performed or what the actual, verifiable results of that test were. In fact, the claim was never even “officially” made – it came from a forum post on the NasaSpaceFlight website.
As people interested in science, we should always be skeptical of claims like this one until we see evidence to support them. Even if the drive was verified as having been tested in a vacuum, this would not mean that there were no external forces acting on the drive. For instance, the size of the vacuum chamber would be key – who is to say that the walls of the chamber weren’t acting as a factor?
A big issue with this entire situation is that many, many blogs used these outlandishly promising headlines to describe what amounted to nothing new on the EM Drive front. This whipped the internet into a frenzy, and ultimately led to people (like us, although we’re a little late to the show) needing to step in and apply scrutiny to the topic. Just look at the headlines of some of these articles:
We should be much more skeptical with claims like these, which are obviously designed specifically to get you to click. They seem oddly reminiscent of certain “one weird trick: trainers hate him” ads we see all over the internet. Incredible claims require incredible evidence – and it would be incredible in the truest sense of the word for the EM Drive to be a real thing. It would represent one of the biggest breakthroughs in the history of science. This would be absolutely amazing, but we need to be sure it’s real before we start saving for an EM Drive-powered car.