Rocket engines as we know them have always produced propulsion by venting exhaust, which emerges at a high pressure as a result of combustion and causes an opposite reaction. In other words, whilst exhaust exits in one direction, the engine is propelled in the other.
This is in line with the principle of conservation of momentum; but the results of the EM Drive experiments suggest there may just be an exception to the rule.
The EM Drive, in theory, converts energy into thrust without emitting any sort of exhaust — bypassing the need for mass to be expelled in one direction in order to propel the rocket in the other.
Ever since its emergence in 2001, under Roger J. Shawyer of the small UK company known as Satellite Propulsion Research, the science behind this technology has been met with skepticism. Yet, in 2010, parallel developments in this area of were undertaken in China, where Professor Juan Yang reported the potential for electromagnetic propulsion to produce thrust in space without requiring combustion.
In early 2014, Dr. Harold White of NASA picked up on similar research and presented the idea at the Joint Propulsion Conference, explaining how propulsion was produced by magnetic fields in what is called a magnetohydrodynamic drive.
Photograph by Satellite Propulsion Research
Until now, no country had tested this technological phenomenon in a vacuum yet, despite it being the very environment in which it was claimed to function. Finally, this April, NASA tested the EM Drive in a vacuum and was able to produce thrust, confirming some of the claims about its potential.
The recent test also nullified some hypotheses which had suggested that thrust came from some minute form of heat convection — wherein a transfer of fluid or gas accompanies a transmission of heat as seen in the emission of fuel exhaust from modern day rockets.
With no stowaway fluids or gases causing accidental propulsion during the experiment, the science behind the EM drive has once again become a topic of debate. The technology appears to function as described, but remains without a clear explanation.
NASA’s EM drive may just be a piece of technology that truly accomplishes the impossible, however small the scale.
Despite all the excitement surrounding electromagnetic propulsion, the scientific community continues to deny its feasibility.
If the EM drive were to work as described, it would go against two of the most fundamental universal laws of physics: the conservation of energy, which states that you cannot create energy out of nothing, and the conservation of momentum, which states that any movement requires an equal and opposite movement to exist.
“It’s like saying you could get your car moving by sitting inside and pushing on the steering wheel” says Sean Carroll, physicist and cosmologist at the California Institute of Technology.
He adds that “the strongest bias we have is to believe things that we want to think are true”, highlighting the reason behind the countless EM drive rumours found both on the internet and in media.
In May, NASA officials confirmed Carroll’s words of caution, stating that “while conceptual research into novel propulsion methods by a team at NASA’s Johnson Space Center in Houston has created headlines, this is a small effort that has not yet shown any tangible results”.
Photograph by Satellite Propulsion Research
An important part of the uncertainty surrounding the experiments is that its measurements do not seem to be easily repeatable. When the drive creates propulsion, there is a flurry of thermal activity as metals expand and temperature varies, making results unpredictable and insignificant when compared to potential margin of error.
Before this technology is really considered a breakthrough, space agencies not only need to show evidence of repeatable measurements, but also need to demonstrate that it can be done at a much larger scale.
The future of space travel
If it were to be developed successfully, the EM Drive would not be powerful enough to enable travel at the speed of light, nor would it create a wormhole or bend space-time — at least not in any way that is currently proven.
However, the relationship between the EM Drive’s propulsion and quantum mechanics does indeed suggest that this technology could be groundbreaking not only in its use, but also in encouraging a new realm of knowledge for scientific study.
The bottom line is that the EM Drive is a curiosity which inspires both hope and skepticism as the scientific community eyes it with a “too good to be true” attitude, but still plans to continue pursuing the possibility of a new revolution in space travel.
Although many may regard this as an opportunity to begin our inevitable path towards Star Trek, there is still a long way to go.