Propellantless propulsion from plain-old Special Relativity

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Diogenes
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Re: Propellantless propulsion from plain-old Special Relativ

Postby Diogenes » Mon Mar 30, 2015 3:04 pm

‘What all the wise men promised has not happened, and what all the damned fools said would happen has come to pass.’
— Lord Melbourne —

alexjrgreen
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Re: Propellantless propulsion from plain-old Special Relativ

Postby alexjrgreen » Mon Mar 30, 2015 3:30 pm

Ars artis est celare artem.

RERT
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Re: Propellantless propulsion from plain-old Special Relativ

Postby RERT » Mon Mar 30, 2015 3:42 pm

Back to the root topic I'm afraid... I just read the paper - the Arxiv version.

The says nothing I could spot about reaction forces, but simply does a careful calculation of the total force on two current loops in the case where the Lorentz force propagates at the speed of light. The answer (equation 50) manifestly need not be zero.

They have a fairly high opinion of themselves, with their short list of references being Newton, Maxwell, Heaviside, Einstein, Feynman, basic texts in mechanics and electrodynamics, and a 2012 paper on a similar subject!

Unfortunately the antiquity of that list would also imply that this should not really be news. I did find this quote in one of my undergrad texts, which might be pertinent:

"...the magnetic force of interaction, in contrast to the Coulomb electric force, thus violates Newtons Third law. So, therefore does the total force. [...] There are no particular grounds for supposing that Newton's third law must apply to electromagnetic forces. On the other hand it does turn out [...] that the law of conservation of momentum in a closed system can be retained by ascribing momentum to the electromagnetic field."

DeltaV
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Re: Propellantless propulsion from plain-old Special Relativ

Postby DeltaV » Mon Mar 30, 2015 4:23 pm


GIThruster
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Re: Propellantless propulsion from plain-old Special Relativ

Postby GIThruster » Mon Mar 30, 2015 4:31 pm

That sounds like it was written by an engineer for engineers. I know of no physicists who would so casually admit a failure of conservation.

I don't think most people rightly understand what a terrible thing it would be, for conservation to not hold. It is a dictate of pure reason, and as such a requirement for science to be worth doing. If there are ever circumstances under which conservation does not hold, these are really circumstances beyond some counter-intuitive dictate of QM or such, but rather a denial of the laws of logic that describe how our universe operates. If the basic principle of conservation does not obtain, there is no point in doing science, because it cannot lead us to a real working knowledge of the universe. Conservation is THAT kind of important.

When you read stuff that says conservation is not satisfied, it is either sensationalistic grandstanding intended to garner attention, like the bullshit at Eagleworks; or it is an example of astonishing ignorance permeating the engineering culture where it certainly does not belong. Both of these happen often. I had a discussion the other day with a retired MS ME who was telling me how any situation where one had a Coefficient of Performance above 1, was an example of a violation of conservation and I explained to him again, just as I had 8 years ago, that he does not understand what conservation is all about and needs to stop using that language. That is a completely wrong understanding of what conservation is all about, and this stuff is just everywhere.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

DeltaV
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Re: Propellantless propulsion from plain-old Special Relativ

Postby DeltaV » Mon Mar 30, 2015 4:55 pm

I r engenear.

As Wanser points out in

[DEAD LINK]http://www.mehtapress.com/mehtapress/Journals/Journal-of-Space-Exploration/Volume-2-Issue-2/vol_2_issue_2_file_5.pdf[DEAD LINK]

,

traditional concepts of momentum conservation revolve around the assumption of constant masses. Variable masses upset the dogmatic applecart.

Tuval and Yahalom are, however, relying on emitted EM for momentum balance in a constant-mass system, thusly in compliance with tradition.

[EDIT: Fixed dead link]
Last edited by DeltaV on Sat Oct 31, 2015 10:46 pm, edited 1 time in total.

RERT
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Re: Propellantless propulsion from plain-old Special Relativ

Postby RERT » Mon Mar 30, 2015 5:04 pm

GIThruster: the guy whose textbook I quoted (P.C.Clemmow of Cambridge University), as well as DeltaV, explicitly says that momentum conservation can be recovered. Tuval and Yehalom say the same thing at the start of their paper in the revised format. Nonetheless, the mechanical system will experience a propellantless force. I don't believe anyone is suggesting non-conservation of momentum, so I'm somewhat puzzled what you are railing against.

To quote further from the text, considering the interaction of two particles:

"the magnetic force on [particle 1] is (mu0/4Pi)*e1*e2*(V1 x(r x V2))/r^3,
and the magnetic force on [particle 2] is -(mu0/4Pi)*e1*e2*(V1 x(r x V1))/r^3

[the first] is the negative of [the second] only in the special case where V1 is parallel to V2. The magnetic force of interaction [...] thus violates Newton's Third Law..."

Which I think says the something very similar to the root paper, and a lot more concisely. What the paper adds is the scale of the effect for a vaguely practical setup.

R.

RERT
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Re: Propellantless propulsion from plain-old Special Relativ

Postby RERT » Mon Mar 30, 2015 5:08 pm

(V2 X (r X V1)), of course! R.

GIThruster
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Re: Propellantless propulsion from plain-old Special Relativ

Postby GIThruster » Mon Mar 30, 2015 5:27 pm

I'm not railing--just pointing out this is an improper use of the term, both in this paper, and especially in the recent conference paper Sonny caused all the fuss with by claiming he was violating conservation. This kind of language should have no place in the scientific community. It's just cheesy rhetoric and should not be pandered to as it invites us to think wrongly about conservation and about the basic project of science itself.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

D Tibbets
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Re: Propellantless propulsion from plain-old Special Relativ

Postby D Tibbets » Tue Mar 31, 2015 3:50 am

To error is human... and I'm very human.

palladin9479
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Re: Propellantless propulsion from plain-old Special Relativ

Postby palladin9479 » Tue Mar 31, 2015 8:21 am


paperburn1
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Re: Propellantless propulsion from plain-old Special Relativ

Postby paperburn1 » Tue Mar 31, 2015 11:45 am

By strict definition earth has not cleared its orbit.
Cruithne iss about 5 kilometers across, and has an elliptical orbit that takes it inside and outside Earth’s solar orbit. The orbital period of Cruithne is about the same as the Earth’s, and due to the strangeness of its orbit, this means it is always on the same side of the Sun we are. From our perspective, it makes a weird bean-shaped orbit, sometimes closer, sometimes farther from the Earth, but never really far away.
But it actually orbits the Sun, so it’s not a moon of ours. Our orbit is not technically clear.

So I have to go with Mr. Tibbets thinking again, are we a round planet( within 1 percent?) Are we a set radius or larger? Is our path stable?
I am not a nuclear physicist, but play one on the internet.

GIThruster
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Re: Propellantless propulsion from plain-old Special Relativ

Postby GIThruster » Tue Mar 31, 2015 4:37 pm

Just because I have no idea where to put it and it doesn't deserve its own thread.

http://astronomynow.com/2015/03/31/race ... tensifies/

And it has to do with SR sorta. . .kinda. . .it does really!
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

hanelyp
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Re: Propellantless propulsion from plain-old Special Relativ

Postby hanelyp » Tue Mar 31, 2015 6:24 pm

"Clearing" it's orbit is, as demonstrated by examples given, a poor criteria for being a planet. Dominating it's orbit is a better expression, all objects in stable orbits near that of the planet orbit the planet itself or are in some kind of stable relationship (resonance, Lagrange points ...).
The daylight is uncomfortably bright for eyes so long in the dark.

D Tibbets
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Re: Propellantless propulsion from plain-old Special Relativ

Postby D Tibbets » Wed Apr 01, 2015 12:26 am

To error is human... and I'm very human.


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