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Comment by debunkit | Hacker News Reader

Yes, and the is the point.

NASA would have had the means to eliminate most of those sources of errors. I wouldn't call these measurement errors though -> the measurement is fine - your setup is the source of error.

But they decided not to follow such a line of research.

And yes, they are right "We believe that this is a good education project to track down measurement errors".

The measurement error being the "thrust" that is due to your experimental setup.

But let them waste some more money, time and reputation and build this in space so they can find out it does not actually work.

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Did you create this account only to comment on this story? (just curious)

> NASA would have had the means to eliminate most of those sources of errors.

Yes. NASA as a whole yes. One group researching something that may or may not bear fruit no.

So it's natural they try to eliminate easier errors first. But (as an example) it's one thing to have a good vacuum, another one to have an excellent vacuum for testing. So first you test on the good vacuum.

> Did you create this account only to comment on this story? (just curious)

Yes i did, usually i just let certain topics pass by me and never comment here.

RF-cavities though are the very core to my line of research, so my acceptance for bs is very low in this regard.

If one wants to convince me of a thrust effect: build a prototype where the power source (a battery for example) and the RF-source are strapped onto the cavity, put the whole setup in a vacuum of your choice (i heard NASA has very nice and !large! facilities) and show me a sustained increase in impulse (just let it rotate for a while)

Was the listed amount of force enough to overcome the friction of whatever your hypothetical device is sitting on? It isn't like vacuum chambers don't still have gravity to contend with.

You don't need it to actually "move" (overcoming friction), you can just measure a force it is exerting or things like "hang it from the ceiling and measure a small displacement"

That's kind of what this whole paper is about...

> If one wants to convince me of a thrust effect: build a prototype where the power source (a battery for example) and the RF-source are strapped onto the cavity, put the whole setup in a vacuum of your choice (i heard NASA has very nice and !large! facilities) and show me a sustained increase in impulse (just let it rotate for a while)

Okay, but they aren't trying to convince you yet.

They're trying to convince themselves that it's worth spending the resources you describe.

Excellent point. They do mention performing an experiment with large angular displacement and a larger vacuum.

> To definitively rule out any residual concerns about thermal error sources, future test campaigns could employ a test apparatus capable of measuring small torques over much larger angular displacements. For example, a Cavendish balance approach properly designed to allow very large rotation angles such as 90, 180, or even 360 deg will not be susceptible to this type of thermal false positive.

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