Uncertain Propulsion Breakthroughs? (opens in new tab)

Here's what happened to it. The Austrian Institute of Technology tried the rotating superconductor thing with a big rotating superconductor and a fiber optic gyro nearby. No "dragging of the metric" was observed.[1] Too bad.

[1] https://arxiv.org/pdf/gr-qc/0608017.pdf

There was another paper about 15 years ago where a electrically pulsed, superconducting thin film was able to displace a pith ball from tens of meters, through walls. I can't find the paper but it was on arxiv. Some sort of gravity pulse; weird shit.

From Wikipedia Paracetamol article (https://en.wikipedia.org/wiki/Paracetamol#Mechanism_of_actio...):

"To date, the mechanism of action of paracetamol is not completely understood."

and:

"It is the most commonly used medication for pain and fever in both the United States and Europe."

"Not completely understood" is not the same as "we have no idea why it works", but still I find it telling for such a popular product.

But they (hopefully) tested the drugs in a double blind experiment. So they may not understand the exact mechanism, but they have a strong proof that taking the drug is useful.

In this case, all the em-drive test only give a very weak force that is very difficult to measure and may be caused by other causes (probably thermal because the device gets hot or something equivalent to an electromagnet because it use a current).

True. Before a surgery, never ask your anesthesiologist how exactly the anesthetic s/he'll give you works.. You might get an honest "we don't know" as an answer..

Very true. I'd not considered the medical world.

True, it's but this has been replicated. It may yet be an error, but it's not a one-off by now.

Yeah there is a very good chance that's still the case here. But would be cool if it's not experimental error.

Satellite orbits degrade overtime due to drag, among other things [1]. Operators counter this decay with periodic boosts. (The International Space Station is boosted, on average, once a month [2].) Boosting, even electric propulsion boosting, consumes propellant.

If this works by impelling against the Earth's magnetic field, provided it is more efficient than a simple magnet, it could still have a market with satellite manufacturers.

[1] https://en.wikipedia.org/wiki/Orbital_decay

[2] http://space.stackexchange.com/questions/9087/how-often-does...

If it does, I think that would be detectable. As the device gets into higher orbits, the magnetic field will get weaker and the force will drop. I'm not sure how much the orbit would have to change to make that apparent though. It might take a very long time.

Another way it might work is by freeing atoms from the backplate of the resonant cavity, like an ion thruster. I hope they include a method of measuring the degradation of the backplate.

I suspect it just won't work, though.

According to the inventor, The Mach thruster (also discussed, and potential underlying physics for the EmDrive) supposedly "pushes against" the Earth's gravity.

So no proof will ever be enough for some? Are EM-Deniers going to be a 'thing' now?

Oh I had thought that the asymmetric shape with the tapered cone shape was an important feature from the original inventor. But yea, hard to guess without more systematic theory to leverage off of yea..

From what I've read, the theory amounts to "there are more photons bouncing off the fat end versus the thin end hence thrust." Which personally I think is highly questionable given the low-energy regime involved.

It even says explicitly:

> Do you want to know our conclusions without any regard to how we reached those conclusions? ... If you answered “yes” to any of those questions, then you, like me, have natural human cognitive dysfunctions.

Actually, reading the article as a whole, I would say an even stronger conclusion is warranted - almost certainly bad science but we should keep investigating just in case.

The highest the actual summary reaches is "But also, despite those inadequacies, the possibility of a new force-producing effect cannot be irrefutably ruled out."

This.

> ...take the time to notice both the pros and cons of the article, not just the parts you want to be true. Deciphering reality takes time instead of just listening to reflexive beliefs. It requires that one’s mind be open to the possibility you might be right and equally open to the possibility you might be wrong.

Yet it's happened before in engineering history. Edison discovered the "Edison effect" - he put an extra plate in an incandescent lamp, and discovered that some current, not much, would flow to it through vacuum. This, in 1875, was the beginning of the vacuum tube. But lacking the theory to understand it, it couldn't be improved. Early on, it was thought that there had to be some air, or something, in the tube for it to work. But then it was discovered that hard vacuum worked better. This confused electrical inventors of the era - how could electricity conduct through a vacuum? It wasn't until 1904 that tubes started to be figured out.

Tube filaments are quite different than lamp filaments - tubes need a material where electrons are easily emitted from the surface. Tungsten is good for lamps but terrible for tubes. A little thorium oxide or barium oxide helps a lot. But there was no theory to indicate in what direction to go, and it took 30 years before trial and error produced results.

There is a list of improvements in the article under "Latest Paper".

Its mainly the need to carefully characterize and document all the test equipment and EM Drive support equipment to make sure its not caused by the test setup. This would involve testing with a dummy load so things like interactions with chamber wall can be ruled out or if there are, the effect can be mitigated or accounted for.

Basically they proved their test setup produces thrust, but haven't proven the thrust was a direct result of the EM Drive. They need to more rigor to prove its only the EM Drive and not a setup error (eg: something like the FTL neutrinos turning out to be a poorly tightened connector).

There are a ton of simple experiments that can be done in the lab that aren't being done by the people claiming that this thing works. The article mentions a few. The people launching something are going to get another inconclusive result with a high price. At least it isn't tax dollars.

So "space" is some magical place where measurement error does not exist?

Low earth orbit isn't perfect either. You still have micro gravity. And the experiment requires a lot of power, and very sensitive instruments to measure the phenomenon. How do you get sensitive instruments which are expected to be operating near their error threshold into orbit without damaging them?

Orbital experiments will have to be smaller, and use less power, so the effects will even be smaller. But the instruments will have to be tough enough to withstand 5G. And the apparatus could still be introducing other errors, like coolant momentum, which also isn't magically eliminated by being in space.

No, science is about disproving things. You come up with experiments to test if method a or b are wrong. The more experiments that fail to disprove a theory, the stronger the evidence for that theory is - and any new theory has to Either match the old results under the same tests, or give a good reason why it doesnt match.

Extraordinary claims require extraordinary evidence, which is why every good scientist expects this effect to go away (regardless of hope as to whether it is a real effect or not).