Each action corresponds to an equal and opposite reaction: third law of dynamics. It is the principle on which space rockets are based, which burn propellant in one direction to go in the opposite direction.
However, a NASA engineer believes he can take us to the stars without any propellant, thanks to a special helical motor. An engine that would be the basis of all the spaceships of the future.
Drawn by David Burns of the Marshall Space Flight Center in Alabama, the "helical engine" exploits the effects of the alteration of mass that occur at speeds close to the speed of light. Burns has published a paper describing the concept on NASA's technical reporting server.
Needless to say, his work has met with some peer skepticism, but Burns believes the concept is valid, and will set the stage for many future space engines. "If someone proves that it doesn't work, I won't have a problem changing my mind, but that option is worth exploring, too," he says.
How does the helical motor work?
To understand the principle of the helical motor made by Burns, try to imagine a box on a surface that has no friction. Inside the box there is a bar around which a ring runs. If an impulse inside the box pushes the ring, it will slide forward as the box moves in the opposite direction. Once you hit the edge of the box, the ring will go back, and the box will too, reversing its direction. Under normal conditions, the third law of dynamics produces a right-to-left oscillation of the ring.
But what would happen, Burns wonders, if the ring's mass was larger when it goes in one direction and then small when it returns in the opposite direction? In fact, the action would be greater than the reaction, the third law of dynamics would be bypassed and the box would move further and further forward.
How can that ring change its mass?
This is not "forbidden" by physics. Einstein's special theory of relativity says that an object gains mass as it approaches the speed of light (an effect that can be minimally demonstrated by current particle accelerators).
In fact, if we replace the ring in the box with a particle accelerator, we have obtained the result. The ions inside the ring would be carried to speeds close to those of light (increasing the mass) when it goes in one direction and decelerating them (decreasing the mass) when they go in the other.
It can be done even better
Burns thinks that the system would have even more efficiency if it were done without a stick and a ring, and replaced everything with a single particle accelerator in the shape of a helix, capable of making the particles perform both lateral and longitudinal movement: a helical movement, precisely.
What about the box?
A rather large one would be needed at a guess. It is no coincidence that the sizes of this engine are in the order of 200 meters in length and 12 in diameter. The energy required is also enormous, according to the calculations: it takes 165 megawatts of energy to generate the thrust equal to 1 newton (it is the force we use to press a key on the keyboard).
For this reason the engine can only work in a "big box without friction" (or almost): cosmic space.
“With the right amount of time and energy, this engine could reach 99 percent of the speed of light in space,” says Burns.
An electromagnetic motor with thrusters, but without propellant
At the end of the 70s, Robert Cook, an American inventor, patented the design of an engine capable, according to him, of converting centrifugal force into linear motion.
30 years later, in the early 2000s, the English inventor Roger Shawyer proposed the EM drive, capable of converting it into a boost from microwaves.
In January 2017, a magnetic motor developed in NASA's Eagleworks Laboratory seemed to have hit the target, but more detailed tests revealed a design error in these magnetic propulsion engines. Phenomenon also known as "how to cast an engine".
Neither concept has yet been successfully tested: both are judged impossible for their violation of a key physics law, the law of conservation of angular momentum.
Martin Tajmar The University of Technology Dresden in Germany has tested the EM Drive (unsuccessfully) and believes the helical motor is likely to have the same problems.
"The way I see it, no inertial propulsion system will ever work in space environments," he says.
The principle of this impossible engine respects special relativity, which makes it special, but "unfortunately there is always an action-reaction mechanism to consider".
Burns has worked on his own, and admits that the engine model is rather inefficient. However, it is without prejudice to the principle, and believes that there is potential for improvement.
"I know the risks associated with introducing technologies such as cold fusion or EM Drive," He says. "I know my reputation will be debated, but you have to take the risk if you want to invent something new".
The impression is that of being in front of very interesting ideas of an extremely embryonic project. All ideas are present, but the whole appears premature.