Space engine’s ‘impossible’ drive
EVERY action has an equal and opposite reaction. Or it should. It's how rockets work: they accelerate forward by burning fuel and ejecting exhaust in the opposite direction. Now, 20 years after its was first demonstrated, the US military is interested in a drive that generates thrust from nowhere.
If it works.
Something else may be at play.
Many physicists believe it is a simple - but minuscule - error.
It's an error that has been consistently reduced since the Shawyer EmDrive was first run in 1998.
It's tiny. And every time someone applies new checks and balances to the process, it seems to get tinier.
But, it's still there.
Tests by the worlds most advanced propulsion engineers, including NASA, still end up producing measurable thrust.
And, in the frictionless environment of space, that thrust accumulates. Over time, even the pressure equivalent to that of a piece of paper on your hand can accelerate a vehicle to interplanetary speeds.
It's a prospect that has the US Defence Advanced Research Projects Agency (DARPA) sinking a speculative $1.4 million into the idea.
"Given the number and diversity of claims about EmDrive and other exotic physics, my opinion then and now is that DARPA should invest modest sums to experimentally assess such claims, albeit only where credible experimental evidence exists," former DARPA researcher Jess Sponable told Popular Mechanics.
PURSUING THE IMPOSSIBLE
It's just a cone of copper. One end is sealed. The other is opened.
It's then pumped full of microwaves - generated from an electrical source that could include simple solar arrays.
Microwaves do produce pressure. Just not much of it.
The idea goes that the microwaves striking the closed end of the copper cone produce pressure - in essence giving it a 'push'. Those that go out the back produce none.
This is where physicists have a problem.
They argue this is exactly the same as someone trying to push a car by leaning on the steering while sitting in the driver's seat.
To get thrust, basic physics means there must be a reaction to drive the process.
Problem is, the copper cone experiment is producing a measurable force.
Germany, however, has found evidence it may have been caused by interference.
Nobody, however, can explain where it is coming from.
But, given the new international arms race, that doesn't matter.
"The DARPA mission is to embrace and advance transformational change in the US military, but … we must strive to beat the other guy to the punch line and ensure there will never again be another Sputnik moment," Sponable told Popular Mechanics, referring to the success of the Soviet Union in getting the first satellite into space.
NASCENT LIGHT MATTER INTERACTIONS
The science is entirely speculative. And utterly unfounded.
But DARPA has kicked off an initiative it calls NLM (Nascent light matter interactions).
It's re-examining the properties of electromagnetic and light waves.
Specifically, it wants to test the highly theoretical proposal that it can interact with spontaneous quantum 'bubbles' that pop in and out of existence.
Known as Unruh radiation, it is speculated this could be the unaccounted for 'fuel' that provides the EmDrive's thrust.
Called Quantised Inertia, it's a radical concept. It would also go against existing theories of the nature of dark energy and dark matter. But these remain highly speculative, too.
Most physicists believe the 'thrust' being recorded by the EmDrive is an unaccounted for external influence - such as the impact of the Earth's magnetic field on the copper making up the cone.
So DARPA will attempt to recreate this thrust through a new kind of experiment.
Instead of microwaves and copper, they will fire lasers through a loop to see how they interact. And another test will bounce lasers off assymetric mirrors.
Theoretically, these should produce the same effect as the EmDrive.
If successful, the results would be revolutionary.
atellites would not need to carry heavy fuel into orbit. Instead, they could coast around at will. Rockets could launch much larger space probes, as these probes also won't need to carry their own energy source.
It would also make interplanetary travel much easier.
Mostly, it would gut modern physics. Einstein's theories of general relativity and special relativity would have to be revisited. As would Newton's third law.
But that hasn't happened, yet.