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The 'impossible' EmDrive could reach Pluto in 18 months?

wired.co.uk

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Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#111
post #55

Earlier quoted context omitted.

No it is because the Chinese test dumped kilowatts of energy into the test item but the NASA test used only miniscule power. The guy you replied to presented the facts in a misleading way.

I'm slightly more skeptical about EmDrive than optimistic, however, you are right: if someone has to distort the truth in order to make a point it might be time that they question their standpoint on a matter. This looks like a lot of opinions about science. Which is a logical contradiction. An opinion has absolutely no sway in determining whether or not the device works. Opinions have nothing to do with science. The…

The new test was at slightly lower power but within an order of magnitude of the original test: 700 W versus 2.5 kW. The measured effect, on the other hand, has decreased by more than four orders of magnitude.

I haven't studied the theory behind the device, but it's hardly a distortion to characterize such a disproportionate drop as a declining effect size in the face of additional testing.

Like you, I don't claim to have any idea whether this ultimately pans out. As I said, the ultimate test is to put one in space and see what it does. Until that (or at least a more promising lab test) happens, all we have is speculation. But my point is that more skepticism is warranted than was implied by the Wired headline and by some of the comments in this thread.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#112
post #7

It's good to see that someone finally got around to testing this in a vacuum. Here's the paper mentioned in this story: http://arc.aiaa.org/doi/abs/10.2514/6.2015-4083 High levels of skepticism are still warranted, as much as I would love for this to pan out. Every time this gets tested—presumably more and more carefully—the measured force gets smaller. The original test at Chinese Northwestern Polytechnical Universi…

The Chinese test used kilowatts rather than watts of power: http://www.you-tech.it/index.php/content/download/12369/1124...

To be clear, the Chinese test used 2500 watts, and this latest test used 700 watts. That is a decrease, but it's within a factor of 4.

On the other hand, the decrease in effect size is closer to a factor of 40,000.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#113
post #54
post #7

It's good to see that someone finally got around to testing this in a vacuum. Here's the paper mentioned in this story: http://arc.aiaa.org/doi/abs/10.2514/6.2015-4083 High levels of skepticism are still warranted, as much as I would love for this to pan out. Every time this gets tested—presumably more and more carefully—the measured force gets smaller. The original test at Chinese Northwestern Polytechnical Universi…

The difference in measure thrust is due to different test articles and testing done in different labs. The 720 mN result was from China and they dumped a ton of energy into it. The smaller 20 μN result was from NASA's testing which used far less power, so the resulting thrust measure was also smaller.

You're incorrect, 20 μN was measured in the Dresden test at 700W.
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