10 ms·

'know it doesn't work' - seems a bit strong here. 1) While a violation of a widely accepted law of nature is indeed unlikely - it's not like it hasn't happened

'know it doesn't work' - seems a bit strong here. 1) While a violation of a widely accepted law of nature is indeed unlikely - it's not like it hasn't happened before. 2) There may yet still be some way to model the experimental data that at once makes the em-drive viable, while still preserving conservation of momentum. Still unlikely, but arguably more likely than 1). 3) And while these both remain unlikely - it is yet rational to have an increased credence for them while the experimental data remains unaccounted for. In fact, it's arguable that this increase of credence is significant - for if it were not, performing the necessary experiments to find out either way would be a waste of time. There are of course some very smart domain experts performing these experiments. Your tone and use of the word 'know' implies their irrationality. I would advise greater humility.

dzdt 11y ago
Can I 'know' that if I drop my phone it will fall to the floor? We 'know' the EmDrive doesn't work in exactly the same sense and nearly the same certainty.
- grovulent 11y ago
  If you believe we do indeed have that degree of certainty - then you believe the experiments are indeed a waste of time, and that the experimenters are behaving irrationally - contra 3). I think they are rational - and certainly it's rational for me to defer to their judgement on the matter. That's fine if you don't agree. But if you're replying in order to help me update my beliefs, then you'll need to provide a rebuttal to 3) - which you haven't. :)
  - dzdt 11y ago
    The rationality of performing the tests is social and societal reasons. The lab doing this has funding to test out-of-the mainstream ideas that could lead to new propulsion systems. By testing this kind of thing, even if they also 'know' it won't work, they get publicity and attention for themselves. It helps to keep the funding rolling, and builds operational experience testing small effects, and gives the scientists a chance to play "what if" thinking about possible new physics.
    - grovulent 11y ago
      That's quite a reasonable, if cynical, reply. To be honest I don't know how to evaluate the which of these two explanations of the scientist's behaviour are more likely. I'd like to see some data on how much one can obtain funding by performing what is, given your beliefs, literally garbage science. If we can establish at least precedent that scientists can attract funding on the basis of their projects that were (at the time, not in hindsight) - un-controversially junk research. Then your explanation would have the upper hand. If we can establish a clear pattern of such rewards, then you win a slam dunk.
      - physPop 11y ago
        There is a large difference between well thought out research ideas that break the mould (which absolutely deserve a fair chance and funding opportunities) versus those that are diametrically opposed to our current understanding of well tested science. The EmDrive is not the former.
    - AnthonyMouse 11y ago
      > The rationality of performing the tests is social and societal reasons. The rationality of performing the tests is that it's the basis of science. If someone claims something is possible, the role of science is not to respond with contempt and condescension, it is to prove the matter one way or the other. If the claimant is a crackpot then the experiment will prove it, which is what will happen most of the time. But not all of the time. The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka" but "That's funny..." —Isaac Asimov
      - talmand 11y ago
        The history of science is littered with prestigious people who "knew" that an idea was not worth experimenting with, so they did not while justifying it with their definitive statements. It is also littered with not so prestigious people that didn't "know" that the idea was not worth experimenting with and they found something interesting, whether it relates to the initial subject of the experiment or not. Those people were crackpots until they were not, it's been the way of science for a long time.
- kefka 11y ago
  Incorrect. The original phenomenon was discovered by observing sattelites around the earth. If their antenna was facing the same direction as they were moving, their orbit would decay at a faster rate. Whereas sattelites with rear facing antennas would decay slow than models predict. That's where this research started. Is it reaction less? Possibly. Possibly not. It could be something like ablative losses from the metal. Or it could be other sources of experimental error. But right now, the understanding of the experiment is showing some unknown mass effect much greater than equalivalent ion thrust drive. ___________________________ EDIT: This story is false. Read further down for source video by creator. Reasoning: Missile guidance systems during Cold War.
  - kbart 11y ago
    Interesting, I've never head of this phenomenon , do you have any sources? Quick googling reveals nothing.
    - kefka 11y ago
      My source is a comment from a user on reddit who has cited their sources before, along with accurately correcting errors when found. I'll look for the user, and ask of their source. ________________________________________ EDIT: Ok. It looks like the Satellite pushing story was just that: a story. That narrative came from the NASAspaceflight forums where Shawyer was misquoted and the "telephone game" ensued. The correct way this phenomenon was founded was during missile guidance and testing during the cold war. Proof: https://www.youtube.com/watch?v=GGTjy6atKMs https://www.youtube.com/watch?v=GGTjy6atKMs
- moron4hire 11y ago
  One time I dropped my phone and searched the floor for several minutes looking for it, only to eventually figure out that it had fallen behind my leg into the cuff of my pants. Sometimes unlikely things happen.
Steuard 11y ago
Every time these EM Drive people release another unconvincing result, oodles of people enthusiastically jump onto their bandwagon. Those of us who are experts in the subject matter (tenured physics professor with PhD from UChicago, here) try to make it clear why there's nothing worth getting excited about (e.g. https://news.ycombinator.com/item?id=9473209 https://news.ycombinator.com/item?id=9473209), and the crowd evidently doesn't care. Let me be emphatically clear: if your mental model of the scientific community doesn't include "There exist a whole lot of crackpots out there", your mental model of science is wrong. The odds of bold new ideas being crackpottery are far greater than the odds that some unappreciated genius has upended the well-tested laws of physics. (Believe me. I get their emails.)
- Alex3917 11y ago
  > if your mental model of the scientific community doesn't include "There exist a whole lot of crackpots out there", your mental model of science is wrong. Do you think this is a failure of your industry? E.g. there don't seem to be a lot of crackpots that go into plumbing or whatever. What is it about physics where it's apparently failing to provide most of the people in the field with adequate training?
  - Tloewald 11y ago
    Have you talked to a lot of plumbers?
  - scott_s 11y ago
    Most crackpots aren't in the field. The problem is that woking in physics requires an enormous amount of training, but some people are convinced they can contribute without that training.
    - deleted 11y ago
      [deleted]
  - Cerium 11y ago
    What about magnetic water cleaners? Anything crackpot is an attempt to usurp the way things are with the way people want them to be. Free energy, electric thrusters, magnetic health bracelets, one weird trick for clean teeth... these all apply to other professions but since they obviously don't work it is up to the physicist to ignore? explain? Physics is the belief in sanity in our confusing mess of a work. It is often an appeal to something simpler. What's the difference between a crackpot and a physicist? Physicists do science and get repeatable results.

dzdt 11y ago

Can I 'know' that if I drop my phone it will fall to the floor? We 'know' the EmDrive doesn't work in exactly the same sense and nearly the same certainty.

grovulent 11y ago
If you believe we do indeed have that degree of certainty - then you believe the experiments are indeed a waste of time, and that the experimenters are behaving irrationally - contra 3). I think they are rational - and certainly it's rational for me to defer to their judgement on the matter. That's fine if you don't agree. But if you're replying in order to help me update my beliefs, then you'll need to provide a rebuttal to 3) - which you haven't. :)
- dzdt 11y ago
  The rationality of performing the tests is social and societal reasons. The lab doing this has funding to test out-of-the mainstream ideas that could lead to new propulsion systems. By testing this kind of thing, even if they also 'know' it won't work, they get publicity and attention for themselves. It helps to keep the funding rolling, and builds operational experience testing small effects, and gives the scientists a chance to play "what if" thinking about possible new physics.
  - grovulent 11y ago
    That's quite a reasonable, if cynical, reply. To be honest I don't know how to evaluate the which of these two explanations of the scientist's behaviour are more likely. I'd like to see some data on how much one can obtain funding by performing what is, given your beliefs, literally garbage science. If we can establish at least precedent that scientists can attract funding on the basis of their projects that were (at the time, not in hindsight) - un-controversially junk research. Then your explanation would have the upper hand. If we can establish a clear pattern of such rewards, then you win a slam dunk.
    - physPop 11y ago
      There is a large difference between well thought out research ideas that break the mould (which absolutely deserve a fair chance and funding opportunities) versus those that are diametrically opposed to our current understanding of well tested science. The EmDrive is not the former.
  - AnthonyMouse 11y ago
    > The rationality of performing the tests is social and societal reasons. The rationality of performing the tests is that it's the basis of science. If someone claims something is possible, the role of science is not to respond with contempt and condescension, it is to prove the matter one way or the other. If the claimant is a crackpot then the experiment will prove it, which is what will happen most of the time. But not all of the time. The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka" but "That's funny..." —Isaac Asimov
    - talmand 11y ago
      The history of science is littered with prestigious people who "knew" that an idea was not worth experimenting with, so they did not while justifying it with their definitive statements. It is also littered with not so prestigious people that didn't "know" that the idea was not worth experimenting with and they found something interesting, whether it relates to the initial subject of the experiment or not. Those people were crackpots until they were not, it's been the way of science for a long time.
kefka 11y ago
Incorrect. The original phenomenon was discovered by observing sattelites around the earth. If their antenna was facing the same direction as they were moving, their orbit would decay at a faster rate. Whereas sattelites with rear facing antennas would decay slow than models predict. That's where this research started. Is it reaction less? Possibly. Possibly not. It could be something like ablative losses from the metal. Or it could be other sources of experimental error. But right now, the understanding of the experiment is showing some unknown mass effect much greater than equalivalent ion thrust drive. ___________________________ EDIT: This story is false. Read further down for source video by creator. Reasoning: Missile guidance systems during Cold War.
- kbart 11y ago
  Interesting, I've never head of this phenomenon , do you have any sources? Quick googling reveals nothing.
  - kefka 11y ago
    My source is a comment from a user on reddit who has cited their sources before, along with accurately correcting errors when found. I'll look for the user, and ask of their source. ________________________________________ EDIT: Ok. It looks like the Satellite pushing story was just that: a story. That narrative came from the NASAspaceflight forums where Shawyer was misquoted and the "telephone game" ensued. The correct way this phenomenon was founded was during missile guidance and testing during the cold war. Proof: https://www.youtube.com/watch?v=GGTjy6atKMs https://www.youtube.com/watch?v=GGTjy6atKMs
moron4hire 11y ago
One time I dropped my phone and searched the floor for several minutes looking for it, only to eventually figure out that it had fallen behind my leg into the cuff of my pants. Sometimes unlikely things happen.

Steuard 11y ago

Every time these EM Drive people release another unconvincing result, oodles of people enthusiastically jump onto their bandwagon. Those of us who are experts in the subject matter (tenured physics professor with PhD from UChicago, here) try to make it clear why there's nothing worth getting excited about (e.g. https://news.ycombinator.com/item?id=9473209 https://news.ycombinator.com/item?id=9473209), and the crowd evidently doesn't care. Let me be emphatically clear: if your mental model of the scientific community doesn't include "There exist a whole lot of crackpots out there", your mental model of science is wrong. The odds of bold new ideas being crackpottery are far greater than the odds that some unappreciated genius has upended the well-tested laws of physics. (Believe me. I get their emails.)

Alex3917 11y ago
> if your mental model of the scientific community doesn't include "There exist a whole lot of crackpots out there", your mental model of science is wrong. Do you think this is a failure of your industry? E.g. there don't seem to be a lot of crackpots that go into plumbing or whatever. What is it about physics where it's apparently failing to provide most of the people in the field with adequate training?
- Tloewald 11y ago
  Have you talked to a lot of plumbers?
- scott_s 11y ago
  Most crackpots aren't in the field. The problem is that woking in physics requires an enormous amount of training, but some people are convinced they can contribute without that training.
  - deleted 11y ago
    [deleted]
- Cerium 11y ago
  What about magnetic water cleaners? Anything crackpot is an attempt to usurp the way things are with the way people want them to be. Free energy, electric thrusters, magnetic health bracelets, one weird trick for clean teeth... these all apply to other professions but since they obviously don't work it is up to the physicist to ignore? explain? Physics is the belief in sanity in our confusing mess of a work. It is often an appeal to something simpler. What's the difference between a crackpot and a physicist? Physicists do science and get repeatable results.