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comment by ixnar
ixnar  ·  1432 days ago  ·  link  ·    ·  parent  ·  post: The 'impossible' EmDrive Thruster has received its first peer-reviewed paper

My bet is on this being a measurement error, or an extra force they didn't think about.

I e-mailed the main guy behind the paper and pointed out that they too easily disregard the possibility of this being an electrostatic effect because they say that can't be the case because the setup is "grounded". The air quotes are because I'm working on an electrostatic instrument, and our experience is that it is very hard to remove all surface charges. At the kind of forces this paper talks about it doesn't take much charge buildup for some nearby electric field to contribute force via Coulomb attraction. Any kind of grease stain or oxide patch can do this





user-inactivated  ·  1432 days ago  ·  link  ·  
This comment has been deleted.
ixnar  ·  1431 days ago  ·  link  ·  

Yep, this is why experimentalists have a bit of disdain for theoreticians

Devac  ·  1432 days ago  ·  link  ·  

    At the kind of forces this paper talks about it doesn't take much charge buildup for some nearby electric field to contribute force via Coulomb attraction. Any kind of grease stain or oxide patch can do this.

This is fascinating. How would you go about determining it as a source in general? I'm thinking of some slight force being at an angle to generated the effect, but that's pretty much principle of force superposition in action. The paper itself is way over my head, and will likely stay that way for quite a few years, but I'm curious how experimental specialists deal with grounding and surface charge 'residue'.

Seriously, I want all the details you can give me here.

ixnar  ·  1431 days ago  ·  link  ·  

One way to test it is to apply a static field and do some sweeps, maybe +-1/10/100/1000 V/m. Just insert some metal sheets in the chamber and apply a voltage

I'm working on a blog post about this, might have to draw some sketches

Devac  ·  1430 days ago  ·  link  ·  

    I'm working on a blog post about this, might have to draw some sketches

Thanks, I'm already looking forward to it.

Vad är din bloggaddress? ;)

ixnar  ·  1430 days ago  ·  link  ·