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German Test Reveals That Magnetic Fields Are Pushing the EM Drive (arstechnica.com)
"Researchers in Germany have performed an independent, controlled test of the infamous EM Drive with an unprecedented level of precision," writes PvtVoid. "The result? The thrust is coming from interactions with the Earth's magnetic field." From the report: Instead of getting ahold of someone else's EM drive, or Mach-effect device, the researchers created their own, along with the driving electronics. The researchers used precision machining and polishing to obtain a microwave cavity that was much better than those previously published. If anything was going to work, this would be the one. The researchers built up a very nice driving circuit that was capable of supplying 50W of power to the cavity. However, the amplifier mountings still needed to be worked on. So, to keep thermal management problems under control, they limited themselves to a couple of Watts in the current tests. The researchers also inserted an enormous attenuator. This meant that they could, without physically changing the setup, switch on all the electronics and have the amplifiers working at full noise, and all the power would either go to the EM drive or be absorbed in the attenuator. That gives them much more freedom to determine if the thrust was coming from the drive or not.
Even with a power of just a couple of Watts, the EM-drive generates thrust in the expected direction (e.g., the torsion bar twists in the right direction). If you reverse the direction of the thruster, the balance swings back the other way: the thrust is reversed. Unfortunately, the EM drive also generates the thrust when the thruster is directed so that it cannot produce a torque on the balance (e.g., the null test also produces thrust). And likewise, that "thrust" reverses when you reverse the direction of the thruster. The best part is that the results are the same when the attenuator is put into the circuit. In this case, there is basically no radiation in the microwave cavity, yet the WTF-thruster thrusts on. So, where does the force come from? The Earth's magnetic field, most likely. The cables that carry the current to the microwave amplifier run along the arm of the torsion bar. Although the cable is shielded, it is not perfect (because the researchers did not have enough mu metal). The current in the cable experiences a force due to the Earth's magnetic field that is precisely perpendicular to the torsion bar. And, depending on the orientation of the thruster, the direction of the current will reverse and the force will reverse. The researchers' conclude by saying: "At least, SpaceDrive [the name of the test setup] is an excellent educational project by developing highly demanding test setups, evaluating theoretical models and possible experimental errors. It's a great learning experience with the possibility to find something that can drive space exploration into its next generation."
Even with a power of just a couple of Watts, the EM-drive generates thrust in the expected direction (e.g., the torsion bar twists in the right direction). If you reverse the direction of the thruster, the balance swings back the other way: the thrust is reversed. Unfortunately, the EM drive also generates the thrust when the thruster is directed so that it cannot produce a torque on the balance (e.g., the null test also produces thrust). And likewise, that "thrust" reverses when you reverse the direction of the thruster. The best part is that the results are the same when the attenuator is put into the circuit. In this case, there is basically no radiation in the microwave cavity, yet the WTF-thruster thrusts on. So, where does the force come from? The Earth's magnetic field, most likely. The cables that carry the current to the microwave amplifier run along the arm of the torsion bar. Although the cable is shielded, it is not perfect (because the researchers did not have enough mu metal). The current in the cable experiences a force due to the Earth's magnetic field that is precisely perpendicular to the torsion bar. And, depending on the orientation of the thruster, the direction of the current will reverse and the force will reverse. The researchers' conclude by saying: "At least, SpaceDrive [the name of the test setup] is an excellent educational project by developing highly demanding test setups, evaluating theoretical models and possible experimental errors. It's a great learning experience with the possibility to find something that can drive space exploration into its next generation."
It was presented at the Space Propulsion 2018 conference.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
The EM drive does use fuel - just not a propellant. It also gives such a small amount of thrust, one can only measure it with a carefully controlled setup. This experiment basically proves the thrust is created from the charged craft interacting with Earth's magnetic field.... and the thrust doesn't go up much if any as the power on the craft goes from 5 watts to 50 watts. So, we're basically looking at motion powered by Earth's EM, not the craft's EM.
We have about as much of a chance of boosting a craft into low Earth orbit with this as we do using a compass.
Perhaps it'll be useful for something one day, but all I can come up with right now would be Back to the Future II style hoverboards, but for dust mites instead of people given what little thrust it gives -- also it is hard to steer given it tends to only move in alignment with Earth's magnetic field.
Yes, it can be, and that system is called an electrodynamic tether, and it doesn't make use of the microwave cavity which is at the heart of the EM drive (which, according to this latest experiment, wasn't doing anything in the first place.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
OK, I've found what your second point refers to. "The laws of mathematics are very commendable, but the only law that applies in Australia is the law of Australia."
The first point probably has so many examples I can't be bothered looking for them, but if I did, I'd start with climate change.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Magnetotorquer bars have been used in space for dozens of years to desaturate the reaction wheels.
These are perfectly adjusted to their function (no need for fancy EM things) and generate pure torques when interacting with the Earth magnetic field.
Just, no forces, as, well, expected.
Herve S.
Not embarrassing at all, this is how real science is supposed to work. People propose theories and then look for ways to test and verify results.
Dear Gods, not again. Can we please just kill this thing once and for all?
*"Vegetable" is not a botanical category.*
"Vegetable" is a culinary term.
All vegetables are some part of a plant.
Botany always has a specific name for that part, but that does not exclude them from vegetables,
Salad does not cease to be vegetable for being botanically leaves or buds.
Celery does not cease to be a vegetable for being botanically a leaf stalk.
Artichoke does not cease to be a vegetable for being botanically a flower.
Carrot does not cease to be a vegetable for being botanically a root.
Tomato does not cease to be a vegetable for being botanically a fruit. Nor do squash, peppers, eggplant, cucumber, okra, avocado, or any number of others.
"Vegetable" refers to basically any part of a plant used for food, except those commonly placed firmly in more specific categories. One of those more specific categories is "fruit" (in the culinary sense), which usually requires it to be sweet and/or tart and used substantially for those qualities.
Some of the others are grain (usually botanically fruit before threshing), nuts (always botanically fruit), spices (includes a number of fruits botanically speaking), and herbs.
Culinary terms are made for utility in cooking, not for classification of plants - for that we have botany.
Thus the distinctions are inherently vague:
How big or mild-flavored does a leaf have to be to move from herb to vegetable?
At what size, mildness, or degree of dessication does a chili move from vegetable to spice?
How sweet would a plantain have to be to leave the vegtable section and move in with the banana?
Is it not fair to look for sugar cane and rhubarb in the fruit section, even though botanically they are not?
Is the sweet potato with the vegetables bacause it is a root or because of its usage? Or maybe in your shop it is not?
sudo ergo sum