Talk:Reactionless drive

Thornson Inertial Engine

This page conveniently neglects to mention the Thornson Inertial Engine (TIE), although i think there used to be a seperate page for it.

The TIE has, so far, held up to all scrutiny.

- It still works when suspended

- It still works in a vacuum

- It still works when suspended in a vacuum --Arltomem 19:59, 15 August 2006 (UTC)[reply]

______________________________________________________________________________________________________________________________ Y'know, the conservation of energy and the conservation of momentum are really aspects of the same thing: in relativity, they combine to become the conservation law for the energy-momentum four-vector. Separating them amounts to pedantry. . . Anville 21:11, 7 June 2006 (UTC)[reply]

moved from inertial drive

Hmmm, there's currently only one link to this page. Aren't Alcubierre drives, Disjunction drives and Diametric drives intertial propulsion engines?

After reading the description of the Alcubierre drive, I would have to say it is not. It is not motion dependent on the function of inertia or internal movement. Indeed, assuming such a wave could be generated, the object to be carried along does not appear to need any moving parts at all. previously unsigned comment by Fresheneesz

Much of this article is a matter of opinion at best. At worst, it is false. If you are reading this believing that this is the last word, look elsewhere. Engines which do not use a propellant have been created, tested, and found functional. The Energy necessary to impart motion has been a problem. Ineffecient design has plagued the field. But, by creating internal momentum and then reabsorbing this momentum does not violate any law of physics. previously unsigned comment by User:71.215.54.11 2006-08-13T21:48:38

I think that a reactionless drive by definition violates the law of conservation of momentum. One cannot "reabsorb" momentum at a later time - thats a violation. Fresheneesz 08:06, 10 September 2006 (UTC)[reply]

The entire entry on reactionless propulsion should be deleted until Wikipedia stops its ridiculous policy of letting just anybody add 'information' and instead employs recognised experts (as Google plans to do). There is currently no scientifically accepted proof of the concept. All of the patents are based upon 'schoolboy howlers': the 'centrifugal' force, for instance, is a fictitious one (in the physical sense) and cannot be used to propel anything in space. Even the so-called Wisdom Drive would be reacting against the curvature of space. 'Lifters' exploit the electric wind effect, but there is a long history of the latter being mistaken for anti-gravity. Papers such as the Alcubierre one are purely speculative, and later theoretical papers have revealed flaws in his reasoning. NASA's Breakthrough Propulsion Project, and its enormously wasteful investigation of the non-existent 'Podkletnov effect', have made it the laughing stock of the worldwide physics community. Society trains experts in physics at great expense. It should try listening to them more, instead of to crackpot inventors. —Preceding unsigned comment added by 86.144.25.129 (talk) 05:43, 13 February 2008 (UTC)[reply]

Zero point theory

What about the Zero Point Theory? I don't see any direct reference to this, specifically, although this may or may not be identical to the "inertial drive" mentioned. GrammarGeek 08:36, 26 December 2006 (UTC)[reply]

What theory are you referring to? 93.97.167.53 (talk) —Preceding undated comment was added at 02:41, 23 December 2008 (UTC).[reply]

EMdrive

Here's one that some good publications & agencies seem to believe:

New Scientist
[www.freerepublic.com/focus/f-news/1455622/posts Reports of a government grant]

The claim here is basically that photons aren't bound by conservation of momentum, due to the difference between phase velocity and group velocity. Unfortunately, the engineer is quoted saying a production system would be designed to work "at absolute zero"[1], which tends to raise an eyebrow if you've looked at anything by Carnot. Perhaps that's a journalistic misquote, though, because the same source lists superconductors as having "near zero" resistivity.

I'll go ahead and make some redirects to the article from Roger Shawyer and his invention, the EMdrive. I only took two semesters of quantum, and that was years ago, but I remember phase and group velocity being surprising concepts that led to no surprising results. I trust my education more than the authority of The New Scientist, especially after their complete misunderstanding of amorphous alloys [2]; they didn't even mention dislocation theory, but instead printed something misleading and entirely inaccurate.

previously unsigned comment by User:Polyparadigm 2006-09-10T06:51:57

I wish I could read the rest of that new scientist article - however I doubt it would be any more helpful than the second. The second article says that light doesn't obey the conservation of momentum, however that is entirely untrue. Not only that, but the drive supposedly relys on the difference between phase velocity and group velocity. If you understand what group velociy is, then you know it is not the velocity of anything physical. No information, energy, matter, or anything else is transmitted at this "group velocity" - it is simply a pattern that we recognize visually. An equivalent example is two events that happen at close to the same time - like me clapping my hands here, and a star exploding 100 light-years in the distance. Of course I didn't cause the explosion, no information, or anything else was transmitted. But if you consider my hand clap, and the star's explosion to be part of the same entity, then you have a "group velocity" of much much greater than the speed of light. Group velocity cannot drive a spaceship anymore than clapping my hands can make a star explode. Fresheneesz 08:18, 10 September 2006 (UTC)[reply]

Thanks for refreshing my memory about group velocity. Yes, it fits the classic profile of using terms people aren't likely to understand the dictionary definition of to sell a bogus technology. It sounds like you're qualified to include this new device in the article; I don't believe I am.

By the way, sorry about the unsigned post. I assure you I didn't mean to be rude. It was late, and I've been off Wikipedia for a while, having gone cold turkey when it started impacting my carreer; I didn't even think of it.--Joel 06:00, 11 September 2006 (UTC)[reply]

This is my first posting of any kind to Wikipedia. I agree that invoking group velocity to explain anything sounds fishy, but in the absence of a detailed explanation of this EM drive I'm willing to give it the benefit of the doubt, for the following reason. Solar sails work by transfering some momentum from a photon to the sail, via red-shifting the photon. I could believe that a device could repeatedly transfer momentum from a photon to the drive on each bounce of the photon in a resonating cavity, each time decreasing the frequency of the photon. What is hard to believe is that bounces from one direction transfer more energy than bounces from the opposite direction. But maybe there is some way to selectively control the amount of momentum transferred based on the geometry or composition of the cavity. Ultimately, the photon will have to exit the drive opposite the direction of acceleration to have a net change in momentum of the drive. Of course, there is nothing "reactionless" about such a drive, so it's not violating anything. Until someone puts the technical paper describing the drive on-line, we won't be able to evaluate it carefully. -- User:Solar Fuel 14:23, 11 September 2006 PST

OK, after thinking about it, I realized that you can't transfer any more momentum from a photon to the drive by bouncing it around a resonator and then ejecting it than you would by just ejecting the photon without bouncing it. So the EM drive doesn't seem to make sense. -- User:Solar Fuel 14:46, 11 September 2006 PST

NPOV, inaccuracy and expansion

This entry seems to have a very snide tone, which is understandable considering that it is mostly about the debunked reactionless drives. However, it is definitely an NPOV issue. It also doesn't correctly define "reactionless drive", and simply states a priori that all such devices would violate Conservation of Momentum. They call that "including the conclusion in the premises", don't they?

It also needs to go into theoretical reactionless drives, such as the Alcubierre Warp. I have also heard of a reactionless drive that works within the boundaries of general relativity, known as "Inertia contol by metric patching", and it would behoove this entry to discuss it. There is, or was, also a page on the NASA site devoted to theoretical ideas for non-rocket based propulsion, including differential sails and similar ideas.

Rather than simply being snide about failures, this entry should discuss the theoretical possibilities of reactionless propulsion.

I'll do some of these changes myself, but I don't have all the resources necessary to make this page anything other than a power trip.

--71.223.34.127 17:28, 19 October 2006 (UTC)[reply]

Is the intro's definition incorrect? The first sentence seems pretty accurate to me. Fresheneesz 18:33, 14 December 2006 (UTC)[reply]

Redirects for disjunction drive and differential sail

Many people will probably get to this page searching for information on technologies like the disjunction drive and differential sail, so it should have links to them. 71.223.34.127 17:35, 19 October 2006 (UTC)[reply]

Never mind, I fixed my problem, that people would come here looking for theoretical drives, myself. This entry still has some serious NPOV issues, though.71.223.34.127 17:44, 19 October 2006 (UTC)[reply]

Centrifugal force drive

This page really needs some clean-up. There should be a clear delineation between discussions of the scientific soundness of the general concept, claims to invention, and treatment in science fiction. Right now it reads like a jumbled mess, and the very strict statement that reactionless drives necessarily require the violation of conservation of momentum is both uncited and inaccurate. A quick counter-example is Miguel Alcubierre's warp metric. Whether this solution or others in its class are physical or not is besides the question, none admit non-conversative flow of momentum. --Rev Prez 20:11, 30 March 2007 (UTC)[reply]

Well a more accurate definition is a form of propulsion not based around newton's 3rd law See here. Basically, this means that no "reaction" would happen - nothing would be hitting another, thus no momentum would be transfered. So a reactionless propulsion system isn't by *definition* a violation of the conservation of momentum, but according to modern physics, it must be. Without a reaction, momentum would be gained from nowhere. Any sort of Alcubierre metric would have to gain momentum from somewhere - a gravity wave isn't created from nothing. Fresheneesz 06:10, 11 May 2007 (UTC)[reply]

Introductory statement

This article deals with debunked claims to have produced a reactionless drive. For examples of theoretically possible drives that do not require a reaction mass, see Breakthrough Propulsion Physics Program.

Is this correct? After reading the Breakthrough Propulsion Physics Program, it seems that all the proposals there require some theories that do not exist yet. It is arguable then whether those approaches are "theoretically possible".

Lucian Busoniu 00:11, 10 May 2007 (UTC)[reply]

The remark that there must be mass reaction momentum exchange does not square with the fact that if I turn on a small electromagnet in the presense of an ferromagnetic marble, the marble will begin to move.

Something about electro-magnetic propulsion

--Mark J. Carter 23:24, 23 September 2007 (UTC)[reply]

Excuse me. What is that giant text above? I'm not going to read it, and I doubt anyone else will either. A 10 page essay on propulsion doesn't belong on talk pages here, and frankly i think its just taking up space - it should be archived or deleted.

"The remark that there must be mass reaction momentum exchange does not square with the fact that if I turn on a small electromagnet in the presense of an ferromagnetic marble, the marble will begin to move. "

If its a small electromagnet, you'll probably also notice that the electromagnet will also start to move. This is call magnetic attraction, and follows the law of convservation of momentum. In a frictionless vaccuum, the electromagnet will gain just as much momentum as the ferromagnetic marble loses. A net momentum change of 0. If one or both of those items is attached to something, that something will either contribute or gain momentum - as much momentum as the other contributes or gains. Fresheneesz 03:14, 29 September 2007 (UTC)[reply]

Reactionless drives do violate conservation of energy

The thing is that all inertial frames are equivalent (but each frame can have different energies).

What this means for reactionless drives though is that they can't work.

If you have an object moving and it is stopped by a reactionless drive, then for conservation of energy reasons that means that the reactionless drive *generates* energy/heat from the kinetic energy.

Trouble is, there's another inertial frame where the self-same object is initially stationary, and ends up moving backwards. This *takes* energy because the object gains kinetic energy. But we just said that it generated energy, not taking it. This is a contradiction.

It's therefore impossible, or it would have to involve some very weird properties (some weird unobtainium battery with different potential energy in different frames of reference or something really odd like that.) No such material is known.- (User) WolfKeeper (Talk) 14:38, 16 June 2008 (UTC)[reply]

The argument does not hold true if half the energy is conserved in one frame while the other half is conserved in a seperate frame. So that half is conserved as a change in momentum, while the other half is conserved as potential energy. Grav01 (talk) 20:27, 12 January 2009 (UTC)[reply]

I don't see how that could be, but anyway potential energy is the same in all the frames, whereas the other half, the kinetic energy would have to go both up and down.- (User) Wolfkeeper (Talk) 22:26, 12 January 2009 (UTC)[reply]

Interesting argument. You might have convinced me. Fresheneesz (talk) 09:52, 17 July 2008 (UTC)[reply]

Does this mean that conservation of momentum can be said to be an extension of the conservation of energy in relativistic terms? Fresheneesz (talk) 10:00, 17 July 2008 (UTC)[reply]

Of course the violation of conservation of momentum, alone, is enough to stop it from working since that is just as fundamental as conservation of energy. So this just reinforces it not being able to work: you'd for one need a preferred reference frame and that would require a kind of "aether", yet aether does not exist. mike4ty4 (talk) 07:58, 3 October 2008 (UTC)[reply]

Ridiculous argument that all "reactionless drives" defy energy conservation, someone seems to be mixing this up with perpetuum mobile, getting something for nothing, which is most likely totally impossible.

What at least the inertia engines do is using A LOT of energy to move the parts of the engine, and to change a SMALL PART of that energy into linear movement. Claiming that there is a requirement for friction to make it work is pretty much the same as claiming that a discus thrower couldnt possibly make the discus fly anywhere without himself flying the opposite direction... Because an inertia engine cant "throw" the weight used away(without becoming a "reaction" drive instead) but has to absorb the energy instead, it becomes dreadfully inefficient. In most versions this is done by having a tandem or dual tandem setup whose parts "throw" the energy you dont want in opposite directions, but perpendicular to the direction of wanted movement. All in all, you end up with a tiny surplus in one direction, but you spend perhaps more than 100 times as much energy to create the movement scheme. Which makes the claims about violating the conservation of energy pure nonsense. I wonder if the person who wrote this article understands what "reactionless" really means? It does NOT mean that there is not any action and reaction, it normally means there isnt any kind of chemical/physics reaction involved. It can also sometimes refer to expelling mass in one direction to gain momentum in the opposite direction. The author and several "discussers" seems to be having much trouble with this. 217.208.225.55 (talk) 22:08, 25 June 2009 (UTC)[reply]

You're talking about a photon drive. Photon drives are not reactionless engines; the light has momentum. In a true reactionless engine, nothing comes out at all.- (User) Wolfkeeper (Talk) 22:36, 25 June 2009 (UTC)[reply]

Huh??? How on earth do you translate the above to "photon drive"??? An inertia drive works by throwing weight around in such a pattern that you end up with a small "surplus" energy in one direction because the energy in all other directions is canceled out by the pattern movement.

Its like taking an out of balance gyro and constantly pouring energy into its rotation, eventually you get something that is moving around wildly(if in micro or zero gravity and vacuum at least, otherwise its more likely to flip-flop around haphazardly on the ground), except you couple up 2 or more equally unbalanced in such a way that the unbalance counteracts each other except in one direction. End result, as i said before, is that you convert a tiny portion of the circular motion energy into linear motion energy. Nothing comes out... Exactly what part of "Because an inertia engine cant "throw" the weight used away" above were you unable to understand or failed to read? If you cant handle a discussion in English i suggest i stick to pages in your own language. Conversion rate is horrible and its questionable how far such an engine can be scaled up in size, but thats not the same as "In spite of their physical impossibility" which is just a ridiculous statement that also isnt true, and seems to be the result of the article writer not understanding what s/he is writing about.

Beyond Jet Propulsion

First of all, I call for a re-writing of this entire article, because any shred of hope is anihilated by this writer or writers. If and when I get the time to do some research I will definetly do some editing. Second of all, If you believe in ufo's or the existence of ufo's, you have probably observed how they move in the air. Lightging fast and with turns of 90 degree angles or sharper at such speeds. These ufo's obviously do not use jest propulsion like we do, they must use some kind of other type of propulsion such a reactionless drive propulsion. Also in my opinion, in order for these saucers to make such radical movements with out disturbing the physical order within these crafts, they must have the ability to control or manipulate gravity within their crafts, or some kind of similar phenomena. I want to throw an idea out there, gravity is the result of mass in space...simply and basically, so if an object or machine or craft were to have the ability manipulate the density of mass or matter, the secondary result would be the manipulation of gravity. I hope someone can use this idea, if it's not already out there. drehectik@gmail.com —Preceding unsigned comment added by 71.190.40.181 (talk) 04:53, 16 July 2008 (UTC)[reply]

Those pesky aliens and their sharp turns. Can you ask them what happened to Alf next time you see them? (ATOE (talk) 05:22, 16 July 2008 (UTC))[reply]