Roger Shawyer’s “impossible” stardrive continues inching its way towards reality. The EmDrive is a RF resonant cavity thruster using microwaves, rather than reaction mass like liquid oxygen, to move. Keep in mind this isn’t a warp engine since it doesn’t bend spacetime. Yet the EmDrive has the potential to go faster than current technology, getting astronauts to Pluto in 18 months compared to New Horizons’s nine year journey, opening up the cosmos to humanity.
What makes this gadget “impossible” is its apparent violation of Newton’s Third Law: For every action, there is an equal and opposite reaction. Best analogy for the EmDrive’s counterintuitive mechanism is a person in a car pushing the steering wheel and the vehicle moves forward. Conventionally, a driver can only move the vehicle by pushing the back bumper. Shawyer insists no physical laws are violated by the EmDrive. The thrust happens because the microwaves have a group velocity greater in one direction when Einstein’s relativity is taken into account. A pretty neat trick.
But with extraordinary claims, there’s extraordinary skepticism. At first, skeptics claimed the source of the thrust was thermal convection from air heated by the microwaves. Paul March at Eagleworks put the kibosh on that, testing the EmDrive in a hard vacuum and still saw thrust. More recently skeptics suggest investigators are measuring the Lorentz force, a force exerted by a magnetic field on a moving electric charge, rather than thrust from the microwaves. Lorentz interactions are the principle behind loudspeakers, railguns, and particle accelerators. On Halloween Paul posted they’ve tested the EmDrive again, taking those interactions into account, and the anomalous thrust signals remain. Except he can’t show us ’til the peer-reviewed paper’s published. He does drop a few hints about how Eagleworks compensated for this complication.
I will tell you that we first built and installed a 2nd generation, closed face magnetic damper that reduced the stray magnetic fields in the vacuum chamber by at least an order of magnitude and any Lorentz force interactions it could produce. I also changed up the torque pendulum’s grounding wire scheme and single point ground location to minimize ground loop current interactions with the remaining stray magnetic fields and unbalanced dc currents from the RF amplifier when its turned on. This reduced the Lorentz force interaction to less than 2 micro-Newton (uN) for the dummy load test. Finally we rebuilt the copper frustum test article so that it is now fully integrated with the RF VCO, PLL, 100W RF amp, dual directional coupler, 3-stub tuner and connecting coax cables, then mounted this integrated test article at the opposite end of the torque pendulum, as far away as possible from the 2nd generation magnetic damper where only the required counterbalance weights now reside. Current null testing with both the 50 ohm dummy load and with the integrated test article rotated 90 degrees with respect to the TP sensitive axis now show less than one uN of Lorentz forces on the TP due to dc magnetic interactions with the local environment even when drawing the maximum RF amp dc current of 12 amps.
In the meantime there are quite a few makers building their own EmDrives at home. All one needs is a truncated cone of copper, a 2.45 Ghz magnetron from a typical microwave oven, wires and a source of electricity. Over on YouTube, iulian207 has been showing the world his adventures testing a homebrew EmDrive. By no means are his experiments happening under the same, strict conditions one could expect of NASA, but the results are provocative.
Should someone have the moxie, the cash, and the EmDrive’s physics are sound, we might be on the brink of a grand diaspora. A democratization of the plutocratic exit strategy where no human’s left behind. Science fiction has explored these scenarios in the past. Take Orion’s Arm, a collaborative, science fiction worldbuilding project and its entry on backyarders. In the 22nd and 23rd centuries, the little people gained access to tech that used to be the domain of governments and megacorporations. They cobbled together starships, flinging themselves into the dark hoping to find fame, fortune, freedom, or just a little peace and quiet. Closer to our own timeline is Jerry Oltion’s The Getaway Special. It’s a fun little novel about a scientist sharing his blueprints for a hyperdrive on the internet, enabling anyone with a septic tank, oxygen, and some electrical knowhow to chill out on an alien planet for the weekend.
We are living in interesting times.
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