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#2680
by
Chrochne
on 07 Feb, 2016 16:02
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I've avoided twitter, but noticed #emdrive is somewhat active so I created @rfmwguy there since I've seen my moniker mentioned. That's all I need, another locale to keep me distracted 
Oh well, at least I dumped reddit several months ago and can afford to replace it. 
Sorry, but with Twitter limiting Tweet length to 140 characters, I fail to see how #emdrive is doing any good to the controversy surrounding the EM Drive. Looking at the superficial content in
https://twitter.com/hashtag/emdrive?lang=en
this seems to be corroborated. 
It is the fastest way to get news around. You are right Dr. Rodal that twitter is also a pool of speculations.
I believe the twitter is more active on EmDrive for two reasons. First is that there were a rumours that EW might release a paper this month. Dont know where those rumours started. Second is that EmDrive went under the skin of many folks and really kicked their imagination. This way it really is its own subculture on its own. On my personal note I think it is a good thing, because this topic will not let people sleep until it is solved.
By the way if the DIY want to get their message around I suggest to tweet from time to time on twitter as well. Mass media are curse of this age, but it can be also helpful to get your message around...One more thing. do not try to react on every message somebody tweets to you there. You will get crazy and your social life will go to hell...Just post what you want to say and leave it be.
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#2681
by
rfmwguy
on 07 Feb, 2016 19:41
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Twitter is new to me. Seems more like an announcement platform rather than a discussion forum. I can live with that.
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#2682
by
Rodal
on 07 Feb, 2016 19:58
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Twitter is new to me. Seems more like an announcement platform rather than a discussion forum. I can live with that.
It should be an announcement platform for real news. Instead #emdrive has posts like this (latest post)
Latest post on:
https://twitter.com/hashtag/emdrive?lang=en The #Dharma #spacecraft, equipped with a #revolutionary #emdrive, at the moment of the #launch for the first #interstellar #mankind #space #expedition. Interestignly, while the spacecraft was being #secretly built, it was #concealed under the cloak of an #orthodox #church in #Brest #Belarus.
https://www.instagram.com/p/BBfNGzyyDj9/Twitter needs NSF moderators
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#2683
by
Mulletron
on 07 Feb, 2016 20:11
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#2684
by
dustinthewind
on 07 Feb, 2016 20:47
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I wanted to take back any speculation that space time might be a form of matter other than light that has friction with matter while it flows into a planet. This idea is flawed. The problem is a rocket falling from infinity to some height can acquire escape velocity which for a gravitational well is some limited velocity.
We all know a rocket can exceed this velocity with a boost and still be accelerated along the way, exceeding escape velocity, which excludes the concept of friction between some massive flowing space time and the rocket.
I don't think this excludes electromagnetic interaction with the vacuum though.
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#2685
by
A_M_Swallow
on 07 Feb, 2016 21:10
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Twitter is new to me. Seems more like an announcement platform rather than a discussion forum. I can live with that.
Twitter is head lines and conversations. In depth discussions belong elsewhere.
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#2686
by
Rodal
on 07 Feb, 2016 21:14
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Perhaps my memory is failing me or I wasn't participating in the discussion at the time, but were the reference provided in the link below to the other forum discussed here? I searched and couldn't find. I know we've covered this sort of thing in detail.
https://www.reddit.com/r/EmDrive/comments/448i2k/is_the_emdrive_a_negative_energyevanescent_wave/czr1626
https://iafastro.directory/iac/archive/tree/IAC-13/C4/P/IAC-13,C4,P,1.p1,x16863.brief.pdf
http://arxiv.org/abs/1001.0839
Edit:
Surely one of the evanescent wave theory fans or diametric drive theory fans have already covered this right?
Frobnicat and I are further discussing the theoretical consequences of negative mass-energy. Posts are "under construction": work in progress. See this latest post:
http://forum.nasaspaceflight.com/index.php?topic=39214.msg1488987#msg1488987 . However I am hesitant to post much about this in this EM Drive thread until further analysis because the considerations at the moment are best discussed mathematically (concerning conservation of momentum) and I would rather not engage into discussions of whether it is possible to actually fabricate nowadays negative mass or whether the EM Drive force,
if real (rather than an experimental artifact) can be explained this way. Some people
in the "R forum" don't seem to understand that it is routine in physics to consider "what if" questions (like whether one can stabilize a wormhole with negative mass) without getting into practical engineering of whether the concept could ever be possible from an engineering feasibility viewpoint. Discussing whether one could stabilize a wormhole does not imply that one claims to have a way to make wormholes or create negative mass
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#2687
by
Mulletron
on 07 Feb, 2016 21:44
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#2688
by
rfmwguy
on 07 Feb, 2016 22:35
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I wanted to take back any speculation that space time might be a form of matter other than light that has friction with matter while it flows into a planet. This idea is flawed. The problem is a rocket falling from infinity to some height can acquire escape velocity which for a gravitational well is some limited velocity.
We all know a rocket can exceed this velocity with a boost and still be accelerated along the way, exceeding escape velocity, which excludes the concept of friction between some massive flowing space time and the rocket.
I don't think this excludes electromagnetic interaction with the vacuum though.
Dusty, don't think the crew here minds speculation at all. If it has holes in it, you'll get a civil response. Unlike unmoderated forums, you won't face arrogant, juvenile replies. Keep on firing your synapses...Docs kept me in line with good intents several times
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#2689
by
Rodal
on 07 Feb, 2016 22:36
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Not that I have any "negative mass" to play with to confirm, but from what I've read, if such a "negative effective mass" existed within the EmDrive, the thing would fly big end first....and the whole apparatus would fall to the Earth (no antigravity).
https://drive.google.com/folder/d/0B4PCfHCM1KYodE55Q0YxYXcyZnc/edit
Where is the mathematical formulation to back that statement for a small amount of negative mass-energy in the electromagnetic resonant asymmetric cavity? In Minotti's paper, the direction of the force is mode-shape dependent. Concerning the extraneous gravitational effects of Earth's magnetic field Minotti goes over that those extra effects could cancel out due to nonlinearity.
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#2690
by
Mulletron
on 07 Feb, 2016 22:38
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In the table in the screenshot linked to above.
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#2691
by
Rodal
on 07 Feb, 2016 22:43
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In the table in the screenshot linked to above.
Inapplicable to an electromagnetic resonant asymmetric cavity, since those considerations (
https://drive.google.com/folder/d/0B4PCfHCM1KYodE55Q0YxYXcyZnc/edit) are simply using Newton's law of gravitation (
https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation) between two lumped masses, one with positive mass and the other one with negative mass
instead of properly considering General Relativity coupling with electromagnetism (a unified field theory) in an electromagnetic resonant asymmetric cavity as considered in Minotti's paper.
The gravitational effect of the whole Earth (mass = 5.972 × 10^24 kg) is insignificant compared to the electromagnetic force from a tiny magnet (mass = a fraction of a kg):
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#2692
by
spupeng7
on 07 Feb, 2016 23:42
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...
1) While Maxwell's equations are linear, the Navier Stokes equations of fluid dynamics governing thermal natural convection (lift and drag effect due to air heating) are nonlinear.
...
Firstly, thanks to you and Rmfwguy for responding to my, as yet, poorly formed question about inertia.
Secondly, reading back into thread 6 my curiosity was gripped by the notion of Maxwell's equations being linear. In what sense is this the case?
Link is to Ruth Bamford's fabulous paper, I so hope she is right about this...
Maxwell's equations are linear differential equations as long as one uses linear constitutive equations, which has been the case in all the Meep studies in these threads (although one of the powerful features of Meep is that it can analyze nonlinear constitutive equations as well), FEKO Boundary Element Method, and COMSOL Finite Element Analysis, and as shown on my T-shirt:
Since the EM Drive experiments conducted up to now have used air or vacuum as the inner medium and copper as the metal for its inner surface, there has not been a need to use a nonlinear constitutive equation. Even if one were to use a material with a nonlinear constitutive equation (nonlinear constitutive relations between the fields E, D, H and B), the nature of the nonlinearity would be clearly solely due to the nonlinearity of the material itself.
...And there was light
Dr Rodal, a technician in Melbourne suggested a solid inner frustum a few years back, are you thinking the same thing?
Attached are two older papers about waveguide tapers. Not sure of their relevance...
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#2693
by
spupeng7
on 07 Feb, 2016 23:44
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Another Special Announcement - Please keep our EMDrive friend Phil Wilson, The Traveller in your thoughts. He is back in the hospital as of today. Get well soon, Phil - Your NSF friends.
Please be well good Phil, we need you...
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#2694
by
Rodal
on 07 Feb, 2016 23:49
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...
Dr Rodal, a technician in Melbourne suggested a solid inner frustum a few years back, are you thinking the same thing?
Attached are two older papers about waveguide tapers. Not sure of their relevance...
Q1: Dr Rodal, a technician in Melbourne suggested a solid inner frustum a few years back, are you thinking the same thing?No, I am not suggesting that. Actually I don't understand the suggestion: what is the solid inner frustum made of? (is it a dielectric?), what are its dimensions and location, and what is the reason for the suggestion?
Q2: Attached are two older papers about waveguide tapers. Not sure of their relevance...Thank you so much for those two references
which I had not previously seen.
The first one from the Bell Journal (1967) is excellent !
Large 177 ft. horn reflector antenna at AT&T satellite communications facility in Andover, Maine, USA, used in 1960s to communicate with the first direct relay communications satellite, Telstar.
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#2695
by
spupeng7
on 08 Feb, 2016 00:35
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...
Dr Rodal, a technician in Melbourne suggested a solid inner frustum a few years back, are you thinking the same thing?
Attached are two older papers about waveguide tapers. Not sure of their relevance...
Q1: Dr Rodal, a technician in Melbourne suggested a solid inner frustum a few years back, are you thinking the same thing?
No, I am not suggesting that. Actually I don't understand the suggestion: what is the solid inner frustum made of? (is it a dielectric?), what are its dimensions and location, and what is the reason for the suggestion?
Q2: Attached are two older papers about waveguide tapers. Not sure of their relevance...
Thank you so much for those two references which I had not previously seen.
The first one from the Bell Journal (1967) is excellent !
I think Dean's idea was to have a solid copper frustum and somehow make it resonate. An inside out, or rather an outside in, emdrive. Not sure if this would be feasible or useful or how it would work.
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#2696
by
Mulletron
on 08 Feb, 2016 01:08
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#2697
by
Rodal
on 08 Feb, 2016 01:12
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#2698
by
Mulletron
on 08 Feb, 2016 01:13
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Are you saying that's the reason for the sign change?
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#2699
by
Rodal
on 08 Feb, 2016 01:18
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Are you saying that's the reason for the sign change?
It is for an asymmetric electromagnetic resonant cavity (theoretically (Minotti) it can display a force in either direction depending on the electromagnetic mode shape). I don't know what experiment you are referring to when stating <<The diametric drive experiment we keep kicking around >> ? who is kicking it around? what experiment? A real physical experiment or a though-experiment?
