With advancements in our understanding of the world around us we have grown accustomed to news of something new being possible for the first time practically, though it was theoretically proved long ago, to mention some common examples like space flight, discovery of black holes, and gravitational waves. But, what if something that was theoretically impossible, prevented by the laws of physics themselves emerges to be practically possible, despite all the laws against it? Magic!
Something similar happened when last year a NASA team of scientists at the Johnson Space Centre successfully tested the ‘impossible’ Electromagnetic Propulsion Drive aka EMP Drive, with peer review verifying their research positively later previous year. Right now there are various advance technologies to fuel us to space, like ion thrusters, hall thrusters, liquid fuel engine and light sails(still in somewhat evolving stage). The difference between these propulsion systems and the EMP Drive is that the latter uses no fuel!
The EMP Drive basically uses an electric field in a magnetic chamber to form microwaves, which bounce off inside a conical chamber, and due to difference in pressures between the wider end and the smaller end, a greater thrust results in one direction of the structure, and this thrust pushes the rocket off. Pretty simple, right? NO. The problem with the above over-simplified working is that to cause a thrust upwards, there needs to be something ejected downwards, due to one of the MOST BASIC laws of physics, Conservation Of Momentum. Unlike in traditional fuel propulsion systems, in which the exhaust gases from the oxidation of fuel, or ionized gases from ion thrusters are ejected out and their outward force causes a lift on the rocket, in EMP Drive there is no fuel, hence no exhaust, so nothing to cause the lift.
According to Newton’s Third Law of motion from which he derived the Conservation of Momentum itself says that every force has an equal and opposite reaction. Consecutively, no force means no reaction. Conservation of momentum states that in a closed system the total momentum remains conserved. For example picture you are rowing a boat. When you apply a backwards force on the water through the oar, the water in return pushes you front, and hence your boat moves ahead as the water is pushed back. Since there are no exhaust force of any kind, the initial momentum and force are zero for the EMP Drive. Hence there should be no opposite reaction force. If the propulsion system then lifts up this means there is a momentum in the upward direction, but in the absence of any exhaust gases, the total momentum isn’t conserved, and that is a serious problem. Newton isn’t happy. And neither are the physicists who are having sleepless nights because of this Propulsion system. So there is a very big flaw in our engine, and hence it should not work, right? Again, NO.
Apparently, in the test conducted by the NASA scientists at the Eagleworks lab, they observed an anomalous thrust signal of magnitude 1.6 millinewtons per kilowatt, that too after accounting for all possible errors. This EMP Drive was invented by American scientist and chemical engineer Guido Fetta based on the original design by the British scientist and engineer Roger Sawyer in 1999. The so called Cannae Drive(after Fetta’s company Cannae Inc.) is very small compared to the size of the traditional counterparts, and when build in the similar dimensions it can take us to Mars in just 70 days! To compare its current power output, the Hall Thruster produces a thrust of 60 millinewton per killowatt, one order higher than the EMP Drive, but we should also take into consideration the heavy amount of fuel it uses. Light sails on the other hand produce around 6.67 micronewtons per killowatt of thrust. They measured the thrust using a low thrust pendulum for input power 40 watts, 60 watts and 80 watts.
So the experiment checks out, then where is the problem? That is the biggest issue. No one actually knows the answer to that. There must be something happening that produces a downward force, which hasn’t yet been discovered, and might account for the validity of the Physics. But if not. We are in serious trouble. A very widely respected and important law is broken. Physics will need to be rewritten. Currently the explanation offered by one of the scientists is based on the ‘Pilot Wave Theory’, a version of the Quantum theory, opposite to the currently accepted version, the Copenhagen view. While the latter says that unless observed there is complete uncertainty in the position of particles, i.e. they behave as waves (their probability waves), but the pilot wave theory says that particles have definite position in space-time, and the discrepancies so observed are because of the disturbances by observation and was proposed by Louis DeBroglie in 1927, and has two principles, realism and determinism, and is a kind of hidden variable theory. Other explanations for the practical possibility of the EMP Drive is based on the pressure due to ‘quantum vacuum virtual plasma’, which basically credits the fluctuations, random birth and death of particles from the vacuum, in the quantum field, for the thrust effects.
Currently there is no evidence for any of the above two theories to be a valid explanation. Neither is there any other explanation. Researchers are spending hours trying to find a solution, and hopefully someone will. But the silver lining is that the system works, and if improved and successfully implemented in certain future, space travel will surely revolutionize. We can be able to reach the nearest star, Alpha Centauri in 92 years without deceleration. The above study was published in the American Institute of Aeronautics and Astronautics (AIAA)’s Journal of Propulsion and Power, through a paper titled, Measurement Of Impuslive Thrust From A Closed Radio Frequency Cavity In Vacuum.
We can just hope a solution and valid explanation is found soon, and hopefully the Conservation of Momentum holds, otherwise a lot of my first year physics will be changed, and all my efforts will be in vain. For a Better Future, Happy Reading!
-The Cosmogasmic Person