[jdjdps]

I get really tired of these ignorant psuedo sceptic responses. It's so obviously a straw man attack it makes me cringe. Why are you so set on assuming that it is violating conservation of momentum? No one of import is claiming this. My god, authority must always be right! All who move beyond appeals to authority when constructing arguments must be decried as beyond the fringe! Heathens! Infidels! Traitors! Expell them from within the walls of science, from the walls of Freedom. Yeah muh Science/freedom/nationalism/whatever makes me feel safe by allowing me to feel like I belong and satisfies a psychological need to construct a them and us world. Ffs. Grow up. Seriously hacker news. Grow up. Please, please humanity, grow up. Arrrrgggghhhh. I cant even. - Edited to remove swear words

[Steuard]

I honestly don't even know where to begin in responding to this. You've called me (or my words) "ignorant" and "pseudo-skeptic", you've suggested that I have relied on appeal to authority in making my arguments, and you've implied that I'm motivated by an ignorant "us vs. them" mentality. You've told me to "grow up". All of that seems like pure personal attack, rather than any sort of robust engagement with ideas.

The only actual point of science that I can find here is your claim that "No one of import is claiming" that these drives violate conservation of momentum. In my original comment, I explicitly addressed this: the EmDrive FAQ's own attempt to explain how their drive doesn't violate momentum conservation seems to imply a violation of momentum conservation. Maybe I'm mistaken about that somehow: if so, I'd very much appreciate knowing how! (At the very least, I find it perhaps telling that the site's authors don't understand that their attempted answer is no answer at all.)

As for the personal attacks, I'll just give one piece of context for the "ignorant" bit. I'm a tenured professor with a Ph.D. in theoretical high energy physics from the University of Chicago. That doesn't give me any special magical authority to declare truth about the universe, but it does mean that I've got a pretty solid base of knowledge for my statements and (I hope) decent judgement about how confident to be in my beliefs about questions in my area of expertise. I work on crazy theories that might or might not wind up describing our world at all, so I'm very aware of both the vastness of our ignorance and the importance of pushing at its boundaries in bold and unconventional ways. And with all that background, I think these drive ideas sound entirely unreasonable. If you've got equally solid reasons to believe otherwise, more power to you, and I'd love to hear them.

[jdjdps]

I was angry at a great deal of posts like yours over a range of topics. Perhaps in this instance the anger was missplaced. In a previous post I have worked out how to articulate my concerns: A lot of the time posts with an overtly negative tone that claim to come from a place of rationality, are in fact reactionary. They claim to be defending a core of rationality from encroaching confusion, when in fact they are a symptom of irrationality, a result of the innapropriate application of emotional reasoning to areas of life where it has no explicative power. I believe that the rigidity of the models to be found within the minds of certain kinds of folks has less to do with the defense of rationality and more to do with the defense of identity. I find it extremely irritating to deal with people who are irrationally certain in an uncertain world - especially when they justify themselves by claiming they are just being more reasoned than the next man. Having said that I can hardly claim my post was anything but an emotional outburst.

[GhotiFish]

I got the same response when I informed /r/science that "No, no one in the OPERA Experiment actually believes that neutrinos are actually going faster than light and breaking special relativity, they're asking for input on what went wrong with their observations"

I got a tirade of responses just like yours informing me that I'm a biggot, childish, close minded, backwards thinking, co-dependent on authority, cretin who will be the responsible for the downfall of humanity. ect. ect. ect.

I believe I got down to -45 karma on that post, my lowest score ever, and I wasn't being aggressive or hauty or anything. I was just saying "they're just looking for explanations on their observations, there's no way it's actually happening."

I never got an apology for that, strangely enough.

[pdonis]

> Why are you so set on assuming that it is violating conservation of momentum?

Because the EmDrive experimenters themselves are saying that thrust is being produced without any exhaust--i.e., momentum is being added to the cavity in one direction, without any compensating momentum being ejected in the other direction. That violates conservation of momentum.

> No one of import is claiming this.

Not directly, perhaps, but that is the clear implication of the results they are claiming. No exhaust, no momentum conservation. If they were saying "oh, we did see some radiation being ejected in the other direction", that would make a huge difference. But they're not.

> All who move beyond appeals to authority when constructing arguments must be decried as beyond the fringe!

It's you who are appealing to authority: you are saying there can't be violation of conservation of momentum, simply because the experimenters said there wasn't any. That's not how science works. You're supposed to question what they're saying; you're supposed to look at logical implications to see if what they're saying is all consistent. You're not supposed to just take them at their word.

[jdjdps]

'You're supposed to question what they're saying; you're supposed to look at logical implications to see if what they're saying is all consistent.' What you are doing here is saying - I will take my model of the world and check that their observations are consistent with what it predicts are physically possible. Then saying I found their observations to be inconsistent with how I expect the world to behave given my model. A natural follow on step from this is to conclude that they have missunderstood how their experiment is constructed - there is something about the way they are performing their experiment which is not accurately reflected in the model of their experiment. For instance there might in fact be conventional exhaust escaping from the device in a manner they had not anticipated. This is fine, this is also my interpretation. But where we differ is that I am very able to imagine a world where my model is innacurate and I appreciate that sometimes things that appear to require radically different models can in fact be produced by relatively minor ammendments. And that many people I meet seem to be very unwilling to question their own models and ammend them where necessary, upsets me. It upsets me because I believe in many instances it is born of the same kinds of irrationality that the whole enterprise of rational thought was designed to fix in the first place. At times, to me, it feels like it has become just another church for people to cling to. The rigid models I percieve within public discourse on these topics are a symptom of the very same creeping irrationality that they are purportedly defending against.

[pdonis]

> What you are doing here is saying - I will take my model of the world and check that their observations are consistent with what it predicts are physically possible.

Conservation of momentum has been confirmed by many, many experiments; it's not just a feature of my or anyone's "model" of the world.

> there might in fact be conventional exhaust escaping from the device in a manner they had not anticipated.

Yes, that's quite possible. But as far as I can tell, the experimenters are not even considering that possibility, or checking for it.

> I am very able to imagine a world where my model is innacurate

Sure, imagining a world in which momentum is not conserved is easy. But, as I said above, experiments have shown us that we do not live in such a world.

Of course it is logically possible that momentum is conserved almost all the time, instead of absolutely all the time, and these experiments just happened to be the first ones anyone ever ran that poked reality in a place where momentum was not quite conserved. But in Bayesian terms, my prior for that being the case is much, much lower than my prior for the experimenters having made a mistake somewhere. Experimenters make mistakes all the time; but nobody has yet discovered any violation of a conservation law.

[jdjdps]

'it's not just a feature of my or anyone's "model" of the world.'

This may just be semantics, but I dont see how you could argue that it isnt a feature of a model of the world. A neural representation of the world shared amongst a group of humans. Tested against reality in the best ways we can imagine. But it is still just a model, it is not actual reality. Are you really so sure about those priors? You are also have a very influential prior there which supposes that that if the device functions, it does so because it violates conservation of momentum. Surely you cant know this? Are there really no other explanations which fit more neatly with our current models?

[pdonis]

> it is still just a model, it is not actual reality.

We have a model that includes conservation of momentum. But experiments have shown that reality also includes conservation of momentum--that that feature of the model is an accurate representation of reality.

> Are you really so sure about those priors?

Yes.

> You are also have a very influential prior there which supposes that that if the device functions, it does so because it violates conservation of momentum.

That isn't a prior; it's a hypothesis--the one the EmDrive proponents are claiming.

> Are there really no other explanations which fit more neatly with our current models?

"The experimenters have made a mistake somewhere" is another explanation which fits in more neatly with our current models. Their mistake could be that the device isn't actually producing thrust, or it could be that it's producing thrust because it's ejecting radiation out the back end which they aren't detecting. Either one of those invalidates the EmDrive proponents' claims.

[jdjdps]

I give up. I think you're wrong, you think I'm wrong. I dont have time to iron out all the mistakes you are making and Im sure you feel the same way.