Electromagnetic Drive Produces Thrust in Vacuum: NASA:

Oh yeah - and many bare the scars from the slashing paws and ripping fangs of our very own bold lion who fearlessly puts down all counter-mainstream thinking. But now we have cause to wonder if that picture is entirely accurate:

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Right. Right! So strange then. That the OP linked challenge to an absolute bedrock central tenet of mainstream physics - energy-momentum conservation - is met with such mouse-like lets-cautiously-wait-and-see quiet from our usually bold lion. You were given links in #12 - one to rigorous treatment, by a well-respected mainstream figure, of the general case of energized cavities. The other to the scathing opinion and general arguments of a very mainstream respected physics authority. Would you be at all capable of spotting any possible, presumably very subtle, flaw in the reasoning of either of those two, that might somehow allow credence to the reported anomalous cavity thrusts? A silly question in a way but it really should be asked.

 

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I have now read both links that Q-reeus posted in post no. 12. The first seems to be mainly showing off a lot of unnecessary maths to demonstrate the bleedin' obvious - that this thing can't produce a net thrust if modern physics is correct. However the second one ("John Baez") gives some background to the Eagleworks project that could account for why they have tested this thing. It seems they have built a test facility to look for tiny, novel, effects and this microwave contraption may simply be a cheap guinea pig, to test their testing facility, as it were. If so, the value in it will be the learning process to eliminate sources of measurement and interpretation error.

But certainly, the more one looks at this microwave device, the more implausible it seems.

 

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The only question that needs to be asked is you certainly have an axe to grind.
Keep your pants on fella, you'll have a coronary!

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The concept in question is not totally out of the question as yet, and as you so vehemently like to present.
And either way, if I get wind of any final results, I'll post them either way, as long as that meets with your approval.

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Despite the obvious tickets you have on yourself, I'm sure you are not privileged to all that others know about this.
Be rest assured as other interesting articles come to my notice, they will also be posted, along of course with my continued refutation of any outlandish claims by "would be's if they could be's".
Have a good day my friend!

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You of course neglect to mention that "ALL" the many you speak of that have had to face my slashing paws, had a few other pairs of slashing paws to contend with, and that this same "ALL" were all non professionals, all "would be's if they could be's" and most in the alternative section.....None had any evidence, some claimed to rewrite 20th/21st century cosmology, others had TOEs [four from memory] and the occasional fool claiming the most tried and tested theory in physics, GR, was wrong.

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All come here [or other science forums] to preach there nonsense, as they are unable to gain a hearing anywhere else. Fools, charlatans, and despots is all they have ever been.

 

Strictly true in that one could simply point to the well-known momentum analogue of Poynting theorem: https://en.wikipedia.org/wiki/Momentum#Electromagnetism
But rather dry and not particularly physically intuitive. Given the extant claims by Shawyer (EM-drive), Fetta (Cannae Drive) - including numerical field simulations ostensibly pinpointing the source of anomalous thrust, detailed field analysis by Egan is imo quite fitting. And very useful in giving a feel as to how and where the E & B contributions provide overall cancellation - and that for both TE and TM modes.

For me the more important aspect he covered was the 'vacuum plasma' bogus BS put out by the NASA bods involved. Strictly speaking he was not correct in saying there cannot be a vacuum plasma - humungous field strengths afaik still not obtainable except in exceedingly brief particle accelerator collisions, can in principle at least, as Schwinger showed decades ago, 'polarize the vacuum'. Which however is totally irrelevant to the cavity experiments in question.

 

Stock paddoboy line - only the lie down and have a Panadol bit missing.

You too 'mate'.

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. And nice of you to again sidestep my questions while giving the impression of meaningfully responding. Such 'skills' sort of compensating for lack of such in actual physics understanding.

 

Shame on all of 'them'. Still it would have been nice of you to give an actual reasoned reason for choosing to sit on the fence re this thread topic. But best not provoke a lion.

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Yes I find the invocation of vacuum fluctuations - yet again - rather irritating. It seems a lot of people are bamboozled by the misleading concept of "virtual particles" and of course gosh-wow journalists love them. But then I suppose the experimenters in this case are mainly engineers rather than quantum physicists, so perhaps excusable - even if they are made to look a bit silly in due course.

By the way it seems there is a Wiki article about all this, which looks to me as if it is fairly dispassionate: http://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster

 

Oh don't be an utter goose.
I'm sitting on no fence. I'm yet to be convinced that this is yet an 100% no go or invalid concept. Sorry if that ruffles your feathers.

 

You had no question worthy of a reply.

 

An interesting read and points to numbers of other claimants and theories/designs I was unaware of. Chasing all those leads down might be fascinating - but also another time & effort sinkhole!

 

...despots?...posting on SciForums?...

...despots...??

 

If the King of the Jungle roars forth that at least one despot is/has been in our midst, who are we to challenge such an absolute authority? Hmm... what's the dictionary definition of despot again?

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Hi exochemist:
While doubt rightly questions this drive due to the reality of the fundamental principals of physics, it seems to me the question really concerns the quantum vacuum and what is actually taking place there.
On that score and the fact that if this is viable, the rewards will be incalculable, and on that score alone, I prefer to sit back and wait for total confirmation, one way or the other, rather then the agenda driven spite that is now being conducted by Idiots.

 

Here is the link from the other thread:

http://www.sciforums.com/threads/nasa-validates-seemingly-impossible-space-thruster.142215/

my comments begin mostly on page 8.

 

Thanks Walter......I had forgotten about it.

 

Which btw was posted already back in #12 - something already forgotten by another poster.

Right, so let me comment on your #147 there (and #154 is similar):

Well they simply tested for thrust - 'virtual particle vacuum plasma' is just their stab at underpinnings of a 'theory' that might somehow get round the problem of what ME's have to say. Very doubtful they envisaged real pair production. For starters such production would be internal to the cavity - how would such real pairs then make it through the cavity walls? For that matter, how would such real pairs not instantly recombine to form gamma radiation - all internal to the cavity and all doing squat in terms of any net thrust?
But then one should ask what it takes to generate real particle pairs from the vacuum. Gave a hint in #45, and now check out eqn (1) here: http://arxiv.org/abs/hep-ph/0304139
Like I wrote earlier - humungous. Care to work out the required energy and power densities - then integrated over a test cavity volume? He he he. Kaboom!

So, we presume they are not quite that silly and envisaged some truly subtle interaction with virtual pairs. And somehow it results in 'expulsion' of a stream of virtual pairs out one end of the cavity. Leave aside the slight issue of whether this makes any sense. Just grant it does for now. Could this somehow be just a legit action-reaction thing not violating energy-momentum conservation after all? One big problem. Lorentz invariance of the vacuum. Any 'expulsion' process must be strictly independent of relative speed of said cavity. Which immediately destroys any hope of such hypothetical process obeying energy conservation. As a matter of fact, if one folows the logic through, there is no sensible way to figure out an energy requirement for 'expulsion' even within the cavity rest frame.

Shawyer, who's idea is not based on 'virtual plasma' interactions, cooked up a BS 'theory' that supposedly allowed thrust yet conserved energy: http://emdrive.com/theory.html
In the hope some supporter may wish to step in to defend his theory, I will refrain from pointing out certain glaring issues. It would be more enjoyable to tear strips off any would-be supporter. I find it PUTRID that one or two who dare to sit in judgement of me, shame themselves with their abject ignorance of the physics applying to this topic. That is not aimed at you WW.

 

I think fence-sitting is underrated

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. Anyway, I sought Prof. Alcubierre's opinion on this subject. Here's what he said:

I also contacted Dr. Paul March, but he can't publicly comment, so I won't post his reply. But it sounds like he's working on some very cool and exciting stuff.

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Nice bit of response eliciting from an expert there tashja. Nothing surprising and just one more voice for the 'nay' based on standard argument. But interesting in one way in that Alcubierre himself is the originator of what many consider a way-out means of propulsion, but at least one that comes from a solution of the EFE's - so deemed possible in principle.

 

Thanks tashja.
Professor Alcubierre doesn't give it much hope I see. At least his view I can respect.
Anyway, we'll wait and see how it is finalised.
Thanks again tashja for the good work.