EM Drive propulsion : fake or serious?

General
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Do you have any idea how many seemingly interesting results turn out to be just a simple error? It has happened so often, “I don’t believe this, it looks like a measurement error” is a perfectly acceptable response in almost all circumstances. Especially in circumstances that violate foundational concepts, like conservation of momentum.

You’ve accused unnamed entities of denialism.

A) The experiments have not produced the same results. They’ve produced non-null results, but they’ve not been consistent on their thrust-to-power ratio, and precious few of the results of these experiments have been published for peer review. Even those performed years ago.

B) I’ve not made any positive claims. Saying “this seems to be consistent with experimental error” is not a positive claim, it’s a dismissal based on lack of strong evidence. It means I’m not convinced. I require absolutely no evidence whatsoever in order to prove my lack of being convinced to you, or to anyone else. No one is saying “this is obviously experimental error A, B, or C”. If they were, they should definitely provide evidence that it’s A, B or C as opposed to D, E, or F.

You’re asking skeptics to justify their skepticism beyond “I don’t think the evidence is strong enough”. That doesn’t fly. Because, quite frankly, the evidence simply isn’t strong enough. Not when something like conservation of momentum is on the line.

C) [quote=“kamui, post:181, topic:1425”]
nor the one disclaiming it, can do it without a proof !
[/quote]
This is exactly wrong. Scientific discourse works very similar to criminal trials. Someone being tried for a crime doesn’t have to prove their innocence, and the scientific status quo does not need to be defended. It stands or falls based on the evidence in favour of the alternative.

Again, it’s logically impossible to prove a negative. This is why Russell’s Teapot is a thing: If I told you that there was a pot of tea in orbit around the Sun somewhere beyond Mars, and you told me there wasn’t, I don’t get to ask you to prove that it doesn’t exist.

I was right about what? I’m not making any claims. I just don’t think any of these almost completely unpublished results represent real physical results. And if any of them are, there is a long, long list of possible causes to dismiss before we get to entertain reactionless propulsion drives.

Again, no. The burden of proof lies on the person making a positive claim. No burden of proof is associated with negative claims, because negative claims cannot be proven!

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Just read that for the moment : when you say : it brakes the law of conservation of momentum, it’s a negative claim ?

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You… want evidence that a device… that a reactionless thrust drive violates the law of conservation of momentum? Reactionless thrust is the definition of a violation of conservation of momentum.

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No, I just want you to not claim that it brakes the law. There’s another possibility : the thrust measured is not an error of measurement, the device doesn’t break the law => there’s an explanation (to find) where this apparently reactionless (I’m not sure that its creator calls him the “reactionless thrust drive”) thrust drive is in fact a classic thrust drive, but a new phenomenon, never observed/measured before, create the opposite reaction we need to not break the law (like the effect/cause of the ffect/cause of an effect/cause of an effect/cause that combined with another effect/cause creates bla bla bla…) <= this last part is the very scientific part of my arg :smiley: but I’m sure you understand my point

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From what I’ve read:

  • the new explanation is very different from the one White’s team gave.
  • It doesn’t break conservation of momentum or the laws of thermodynamics anymore, only stuff like dark matter and maybe relativity (the difference between “you’ve better have diamond-hard proof there” and “hahahaha… no”)
  • It gives clear new predictions that can be tested about what design would give what force - meaning that when if new experiments don’t give the result, it will be disproven and become one more solution that was not it (which is a good thing, as it narrows the field of still possible solution, so that’s actually a progress).
    So (contrary to the work of the original team) it is still just under fringe (but still legitimate) science, and not under outright pseudoscience.

Then again, I’m an engineer, Jim, not a scientist!

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If it works the way that Schawyer thinks, then it absolutely violates the conservation of momentum, though. And if that’s the case, all that means is that it’s possible to violate momentum conservation. That’s a great big very huge deal, and requires a great big very huge pile of evidence, but saying that something violates momentum conservation isn’t the same thing as saying that it’s impossible.

So, uh, no. I’m not going to not say that these drives, if they operate as currently advertised, violate momentum conservation. And I don’t need any evidence of my own to support that. Again, this would be the dictionary definition of a violation of momentum conservation.

That’s completely possible. It’s also possible that it’s real thrust being caused by well known but not yet explored phenomena, too. But that’s not what Schwayer is claiming. That’s not what’s being tested. These are devices whose inventors claim are reactionless, and they’re being tested as reactionless drives. They’re interesting exactly because of the possibility, no matter how remote, that they are, in fact, violating momentum conservation.

McCulloch’s hypotheses are interesting, but they face an equally steep climb in challenging relativity, which is one of the most tested and most successful theories of all time. The idea of a variable speed of light has been floated and tested for a century now, as people try to trump or deny relativity, and every. single. experiment. has validated the constant and universal speed of light. And that’s without getting into the colossal mess that massive photons would imply.

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yes, sorry.

The creator says himself on his website (in the FAQ) that he thinks it doesn’t break the law. He has a theory for that, even if its theory is wrong, there’s maybe one, that’s all. Again stop claiming that he thinks that its EM Drive is reactionless. Even if he’s wrong, he’s right on what he thinks, you can guess.

___________________FAQ
4.
Q. Does the theory of the EmDrive contravene the accepted laws of physics or electromagnetic theory?
A. The EmDrive does not violate any known law of physics. The basic laws that are applied in the theory of the EmDrive operation are as follows:

Newton’s laws are applied in the derivation of the basic static thrust equation (Equation 11 in the theory paper) and have also been demonstrated to apply to the EmDrive experimentally.

The law of conservation of momentum is the basis of Newtons laws and therefore applies to the EmDrive. It is satisfied both theoretically and experimentally.

The law of conservation of energy is the basis of the dynamic thrust equation which applies to the EmDrive under acceleration,(see Equation 16 in the theory paper).

The principles of electromagnetic theory are used to derive the basic design equations.

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And yet he also claims to have developed a drive that produces thrust without expelling something behind it, while claiming it’s not a photon drive. Those are mutually exclusive things. He’s wrong about at least one of them.

Stop claiming that I’m claiming that he thinks?

So Schawyer says, but he’s proposing a drive that is nothing more than a light sail, but which produces more thrust than is possible with a light sail because… reasons. He claims the shape of the drive cavity produces an increased radiation pressure, which, in turn, causes an increase in thrust. That sounds, intuitively, like it should be true, but an increased pressure isn’t the same thing as an increased force. The maximum thrust that should be possible, if momentum is truly conserved, would be produced by a microwave laser. So, new momentum is apparently being created in this cavity if it’s able to out-perform a straight-up photon drive.

If that’s true, awesome, but, again, that’s the very definition of a violation of momentum conservation.

Either that, or Schawyer really, really isn’t explaining his theory very well.

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The latest chapter in the saga. Possibly a photon drive after all. Still lots of questions unanswered.

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I like that proponents of the EM Drive have finally resorted to arguments that are within the realm of CoE/CoM, but does anybody know if that’s how photons work? I’m trying to find a good article about it, but having little to no luck.

Edited back out, I’m not sure the article was contending the proposal.

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Does anybody know this source (is it a good one ?) ? If you do, how can I access to the rest of the article ?

http://arc.aiaa.org/doi/abs/10.2514/6.2015-4083

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http://www.sciforums.com/threads/em-drive-doesnt-defy-newtons-3rd-law-after-all.156764/

I haven’t found anything else on the subject, so maybe it has died off to obscurity. However, the thread linked seems to deny that photons behave as described, which leads me back to believing the idea remains bunk.

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Well, the AIAA is a legit organization, but the article is just for a a presentation the authors were giving at a conference. It’s little more than advertisement for a journal article that may have been forthcoming (which has yet to appear). It’s not peer reviewed, and wouldn’t have included much in the way of in depth discussion of the physics involved.

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Thank you kichae :slight_smile:

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Another piece about that AIAA presentation in this article:

Travel to the moon in 4 hours?

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http://io9.gizmodo.com/no-german-scientists-have-not-confirmed-the-impossibl-1720573809https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0ahUKEwjryt6SsdPOAhWB6yYKHdc_D04QFghIMAU&url=https%3A%2F%2F

Doubtful. That article you linked was posted a year ago, and still no peer-reviewed tests released. Furthermore, the professor himself concluded that the experiment did not confirm nor deny the effects, and that a build with better equipment and controls in place would be required. I cannot see the full paper, but others who have looked at it say that the effects appear to be thermal in nature due to the gradual increase of force when power is applied, and gradual decrease when it is shut off.

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Ugh, you’re right. So much hype without any follow up. Unfortunately one of the key signs of fake science. :frowning:

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These are theoretical physicists and engineers in good standing, but they’re just working on preliminary science at the very edge of detection limits. Most science leads to dead ends, and I strongly suspect this will, too.

At least most of these guys are doing it right: presenting their findings, negligible as they may be, at professional conferences. Unlike the wads who decided they were going to do science by press release and get members of the general population in a tizzy.

I mean, there’s a reason I roll my eyes whenever I see someone link to a 3 year old general press article about Sonny White, and it’s not just because I’m a bitter curmudgeon.

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I’m intrigued by the idea that it might be getting peer review approval. However,

“People all around the world have been measuring thrust. You’ve got guys
building them in their garages and very large organisations building
cavities too. They’re all generating thrust, there’s no great mystery.
People think it’s black magic or something, but it’s not. Any physicist
worth his salt should understand how it works, or if they don’t, they
should change their profession.”

From someone who can’t properly explain it himself is a bit classic.