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A Mythical Form of Space Propulsion to be Tested (Again)

(12 posts)

  1. Steve R.

    Wired Magazine article: A Mythical Form of Space Propulsion Finally Gets a Real Test

    "So a team of physicists at Germany’s Technische Universität Dresden set out to create a device that would fill this need. Led by physicist Martin Tajmar, the SpaceDrive project aims to create an instrument so sensitive and immune to interference that it would put an end to the debate once and for all. In October, Tajmar and his team presented their second set of experimental EmDrive measurements at the International Astronautical Congress, and their results will be published in Acta Astronautica this August. Based on the results of these experiments, Tajmar says a resolution to the EmDrive saga may only be a few months away."

    Of particular interest. The EmDrive is a derivative of the Dean Drive. John W. Campbell was an outspoken advocate of the Dean Drive.

    A short blurb from the book Pseudoscience and Science Fiction by Andrew May.

    Will John Campbell's confidence finally be validated?

    Posted 7 months ago #
  2. oblomov

    "In late 2016, Tajmar and 25 other physicists gathered in Estes Park, Colorado, for the first conference dedicated to the EmDrive and related exotic propulsion systems."

    I would like to visit this event just to see what kind of a scene it is.

    Posted 4 months ago #
  3. Steve R.

    The EmDrive (Dean Drive) just resurfaced again. Analog (Jan/Feb 2020) has a science fact article: "Making Waves: The Inventions of John W. Campbell" where the Dean Drive is briefly mentioned.

    Wired has an article: A Mythical Form of Space Propulsion Finally Gets a Real Test. In summary, the tests appear to be inconclusive. "Over the course of 55 experiments, Tajmar and his colleagues registered an average of 3.4 micro-newtons of force from the EmDrive, which was very similar to what the NASA team found. Alas, these forces did not appear to pass the thermal drift test. The forces seen in the data were more indicative of thermal expansion than thrust."Further experimentation still in the works.

    Posted 4 weeks ago #
  4. Marian

    Campbell would be pleased that finally the drive is being tested. I want to correct what you said, Steve. Campbell was not an advocate for the Dean Drive. Campbell was an advocate for testing it. He only saw it once for an hour or two. I remember an editorial he wrote after all these years because it made such a vivid impression on me. He said he didn't care if it worked or not. What he cared about was the absolute refusal to examine it since if it worked, it would be such a breakthrough. His basic thesis was that everything should be examined until proven false or a breakthrough,

    Posted 3 weeks ago #
  5. Steve R.

    Marian, thank-you for your clarification. As you point out, theories need to be tested.

    Posted 3 weeks ago #
  6. CWJ

    Hi, your resident pedantic 'wet blanket' scientist here.

    I take some practical issue with 'everything should be examined,' both with 'everything' and with 'be examined.'

    Does 'everything' mean EVERYTHING? I mean, if I claim that, with the right spoken phrase, one can fly on a broomstick, should that claim be examined? Or if I claim that at some undetermined intervals, the laws of thermodynamics are lifted for fifteen seconds, should that claim be examined?

    I give these reductio ad absurdum examples to point out that not EVERYTHING should be examined. But once we establish that principle, then we have to argue over where to draw the line.

    There's also the second part 'be examined'--the passive voice is often a signal of a problem. 'Be examined' by whom? I mean, anyone is free to examine any claim they like. If one means, 'be examined by professional scientists and engineers,' well, we're busy people. We don't have infinite free time to examine all claims, as I often have to explain to people who come to my office with ideas they want me to 'examine.' So I have some experience on the issue of 'everything should be examined.'

    Basically, scientists and engineers want to invest time in examining claims that have a reasonable chance of being true. Now that means some claims that look unreasonable but in fact are true may be missed. On the other hand, spending too much time on untrue claims will also mean true but unexamined claims will be missed.

    Luckily, different scientists and engineers will draw the lines between 'reasonable' and 'unreasonable' differently, so that helps to spread the work and means low-probability but true claims can be verified.

    If someone wants to spend their time and their personal money to test the Dean drive or the EmDrive or whatever, fine. Would I? No. In fact I'd be willing to bet a sizeable amount of money against it. But if they want to test it, by all means, go ahead. If it works, it would mean a whole of of new interesting physics! But then, that's true of literally hundred of crackpot theories, so you'd have to give me good reason why to choose one over another...

    Posted 3 weeks ago #
  7. Marian

    My bad. CWJ, I would agree with your points except remember that I misquoted Campbell's editorial in the sense that it made a vivid impression on me as an early teen. So I was writing in haste remembering what I read quite a few decades ago. I should not have used the word "everything" because of course Campbell didn't. No engineer would.

    Posted 3 weeks ago #
  8. CWJ

    Marian, I figured you might have not quoted Campbell exactly, but my point still stands. It's not your bad, but it's something I hear quite a lot. As a physics professor I get occasional visits to my office from, um, people with alternate theories wanting me to spend time and energy 'investigating.' When I point out obvious flaws in their arguments, they sometimes become angry and accuse me of being brainwashed by the system. Usually I don't point out the obvious flaws, because I've been to that rodeo, and know one usually gets into a circular argument. I find that pointing out the mere impracticality of investigating every theory postulated is the most successful strategy.

    Of course, I get back the responses, "But I really *feel* this is right," and "But this will have such good results for humanity," to which I say, "But that's what everyone else says about their theory, too," and after a few rounds of that, my visitor leaves.

    In fact, we scientists are quite open-minded. There are a small but not negligible number of people doing experiments testing, to high precision, various assumptions in theories, such as the constancy of physical 'constants' or underlying symmetries. In a way, that is what the EmDrive is doing, because if it worked, it would violate certain cherished principles. But don't think for a moment that we physicists rest on our assumptions. There are people doing experiments that test those principles. The difference is, they have carefully thought out what experiments are likely to be the most sensitive and then have pursued them with very high precision, almost certainly better precision than the EmDrive experiment.

    Posted 3 weeks ago #
  9. JohnWThiel

    Calling Campbell's scientific writing pseudoscience is beating the dog long after it's necessary.

    Posted 3 weeks ago #
  10. Marian

    CWJ, just to clarify, Campbell never claimed a gut feeling about it. All he said was that as an engineer, he had not been able to find any flaw or phoniness. He also said he only saw the device once and that was not long enough for any real proof. So he thought it should be investigated. His frustration came about because of the scientists who said that kind of drive could not possibly work and therefore should not be investigated. Anyway, to wrap up, Jerry Pournelle attempted to follow up and soon realized Dean was either a fool or a phony. He never got to see the device. Here's his report
    I bring all this up simply because it's amazing how many times I've seen references to Campbell believing the Dean Drive worked when he never, ever said that.

    Posted 3 weeks ago #
  11. CWJ

    Marian, my point is not to cast aspersions on either you (sorry for accidentally doing that) or Campbell (shrug). The discussion inspired me to point out, generically, that completely uniform open-mindedness would not be practical. This is sometimes forgotten...

    Posted 2 weeks ago #
  12. Marian

    CWJ, don't worry. I did not feel aspersions were cast upon me. And I agree completely that completely uniform open mindedness would not be practical. I'm sorry about my sloppy writing.

    Posted 2 weeks ago #

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