Talk:Anti-gravity/Archive 1

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Archive This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Contents

Rewrite

I've attempted to restore the links removed by Pjacobi while re-framing the article into a form more likely to be acceptable. It's now much more readable, and should be NPOV enough to satisfy everybody.

If anyone has specific names, dates, and details about the claims in the "Anti-gravity in the context of non-mainstream physics" section, please add them, as the original version of the article was a bit vague about them.

--Christopher Thomas 22:20, 1 May 2005 (UTC)

Cavorite "seems reasonable?" No.

The article currently says:

it may seem reasonable to postulate a material that shields against gravity or otherwise interferes with the force. An example of such a material, cavorite, is a major deus ex machina of H. G. Wells' famous book, The First Men in the Moon.

If such a substance existed, you could simply put it under one side of a heavy flywheel and get perpetual motion.

Although Wells doesn't point it out explicitly, he seems to have been aware of the problem. In the novel, when Cavor actually creates Cavorite for the first time, it produces a ferocious air current:

"Well, so soon as it reached a temperature of 60 Fahr, and the process of its manufacture was complete, the air above it, the portions of roof and ceiling and floor above it ceased to have weight. I suppose you know - everybody knows nowadays - that, as a usual thing, the air has weight, that it presses on everything at the surface of the earth, presses in all directions, with a pressure of fourteen and a half pounds to the square inch? "
"I know that," said I. " Go on."
"I know that too," he remarked. " Only this shows you how useless knowledge is unless you apply it. You see, over our Cavorite this ceased to be the case, the air there ceased to exert any pressure, and the air round it and not over the Cavorite was exerting a pressure of fourteen pounds and a half to the square in upon this suddenly weightless air. Ah! you begin to see! The air all about the Cavorite crushed in upon the air above it with irresistible force. The air above the Cavorite was forced upward violently, the air that rushed in to replace it immediately lost weight, ceased to exert any pressure, followed suit, blew the ceiling through and the roof off.

The energy required to do this came from nowhere, just as the energy to propel Well's cavorite sphere comes from nowhere. Dpbsmith (talk) 01:15, 2 May 2005 (UTC)

  • The idea of postulating a screening or interfering material is what "seems reasonable". As you point out, Cavorite has problems. I'll modify the text to make this clearer. Any hypothetical material that affected gravity in a Newtonian universe would presumably have to do so in such a way that the resulting system still obeyed Newton's conservation laws. --Christopher Thomas 01:21, 2 May 2005 (UTC)
    • The complaints about cavorite don't actually work that way. The air doesn't cease to exert pressure. A small region in the shadow of the shielding would not be attracted gravitationally toward the earth, but the shadow isn't big enough to create such problems. The difference in air pressure would be so small they might be difficult to measure, and more importantly no conservation laws are violated. -- Waveguy 03:18, 24 July 2005 (UTC)

Image:Gravity-shield.png

The cavorite in A Deepness in the Sky was different, for the record. It levitated itself in the opposite direction of a gravitational field, and only when light was shining on it (presumably where it gets the energy necessary). — Omegatron 19:08, 10 November 2005 (UTC)

Disappearing link

The link to http://www.antigravity.org was removed, without indication of why. I've re-added it, as it does seem to contain the antigravity material described; if there's a good reason to remove it, please mention it in the "edit summary" field, or the talk page if a longer comment is needed.--Christopher Thomas 17:59, 11 May 2005 (UTC)

I removed it again. It's about a "private" theory, unpublished work. The only achievement of this theory is linkspamming, to get some Google links, but checking scholar.google.com, you see that it is not notable (both hist are unrelated). --Pjacobi 19:17, 2005 May 11 (UTC)
I've removed the link to http://www.antigravity.org on 08:58, May 11, 2005 (sorry, I did not fill the "edit summary" field by accident). It is a link to my website and I felt it was misrepresented here, as it is not about antigravity per se, but rather about my model of gravity (some would say "pet theory"). "Linkspamming" is unintentional and caused by the listing on dmoz.org and yahoo.com; and dmoz.org, being a free resource, is copied by many other websites. I admit name "antigravity.org" might be a bit misleading, but I always clearly stated what the website is about, it's just that majority of people do not read the content. Sergey

Göde

There is a million Euros to earn for a reproducable experiment:

These guys also report a list of failed experiments:

Shall we link them?

Pjacobi 13:58, July 11, 2005 (UTC)


Anon's diagram

This hypothetical zero-point anti-gravity device works by directional field induction. The differential (spinning inner bulb) throws a spiral vortex down to stabilize the device.
This hypothetical zero-point anti-gravity device works by directional field induction. The differential (spinning inner bulb) throws a spiral vortex down to stabilize the device.

I've moved 70.28.153.5 (talk · contribs)'s diagram to this page for discussion. My concerns with it are:

  • The text conveys that this device involves a spinning bulb, but beyond that is gibberish. It should presumably convey how the device is intended to induce fields, what medium the "vortex" is created in, and how this device relates to zero-point energy.
  • The diagram similarly fails to convey anything beyond some of the geometry of the device. The blue cloud and horn-shaped appendages presumably are intended to indicate something about its function, but fail to do so effectively.
  • The text does not clearly indicate that this is is a device that is intended to operate using principles not accepted by mainstream physics.

If these concerns can be remedied, then I think we could probably put a diagram similar to this back in. Until then, it should probably stay here. --Christopher Thomas 20:13, 11 July 2005 (UTC)

User:Waveguy uploaded it. It looks like original research to me, at first glance. - Omegatron 20:55, July 11, 2005 (UTC)
Since anti-gravity is hypothetical, the device itself is hypothetical. It doesn't actually have to work, but should agree with popular conceptions about such devices such as the warble sound coming from flying saucer engines, which hypothetically are powered by anti-gravity drive. The gibberish is readily explained as follows, but is a little long for the caption for the image.
  • Empty space has non-zero energy, a.k.a. zero-point energy. What happens if you pump in dark energy?
  • Incidentally, the device must be started in a Vacuum; once started, it repels particles.
  • Lyapunov is involved in the effects, because we want the device to approach and leave the vicinity of earth with zero change in potential energy; see Lyapunov tube.
  • The repulsive force is generated between the inner and outer gravity-shielded plates, and spills out the bottom. In an atmosphere this creates vortices, (which, by the way, vibrationally construct the kinds of patterns that result in crop circles).
  • drawing the field into a helical vortex stabilizes the effects, and creates the characteristic warble sound.
  • the horn-like appendages are a loop (shown in cross section) of a superconducting ring, part of the gravity shielding.
  • the blue is an electromagnetic fog effect created by rarified particles under the engine, which glow like a fluorescent light bulb.
  • none of this needs to be fully explained, true or testable, because this is a hypothetical device, but should be in agreement with UFO reports.
  • references:
  • Now if you think all this How it works part is original research, then let's just place artists's conception on the caption and remove the gibberish. -- 70.28.153.5 04:41, 12 July 2005 (UTC)
Note the psychological significance of each of these hypothetical anti-gravity devices: they are all very similar, so in fact any one of them would do, here.

A negative mass object would not be repelled by a positive mass object

Please clarify something for me!

A negative mass object would not be repelled by a positive mass. The Newtonian formula for the force of gravity is:

F = {-GMm \over r^2}

Where G is the gravitational constant, the two Ms are the masses of the two objects, F is the force and r is the distance between their centres of gravity. Does a negative value of F indicate a force towards the two objects common centre of gravity?

Assuming it does:

If one of the objects had negative mass, the force between them would be negative.

F = ma

If P represents the positive mass object and N represents the negative mass object and c represents the common centre of gravity. F is the force each object would experience and a is the acceleration each would experience.

       a--->   <---a
   <---F       <---F
       N           P           c

In this case, the two objects would be attracted. All definitions of F in Newtons gravitational formula state that a positive F means an attractive force. For two positive masses this would be exactly the same as a force in the direction of the common centre of gravity (the assumtption I worked on previously). However, if a positive F represents a force in the direction of the other object things are very different.


       a--->       a--->
   <---F           F--->
       N           P           c

As you can see, both bodies would accelerate in the same direction. If the magnitude of the mass of both bodies was equal, both would remain equidistant and constantly accelerating.

Note: This does not result in a violation of conservation of energy or momentum because the sum of the masses is zero. If the some of the masses was not zero, they would either converge or diverge in such a way that the sum of their momenta and kinetic energies would be zero.

Which of these cases is correct? All I know is that the article is incorrect in saying negative mass would be repelled by positive mass (although it may work the other way round). —The preceding unsigned comment was added by Ghazwozza (talk • contribs) .

The negative mass article should contain the same information. — Omegatron 19:02, 10 November 2005 (UTC)
Indeed it does, and Ghazwozza is completely right. I've fixed the article. Intangir 04:23, 6 December 2005 (UTC)
Oh weird, I didn't quite read Ghaz's comment closely enough. The sign of the force is relative to the location of the other object, not the center of mass of the system. In any case, an object with negative gravitational and inertial mass would not be repelled. Intangir 04:45, 6 December 2005 (UTC)

The Bell

A user recently added this to Bell:

I don't know whether it's worth a mention in this article (or its own article) or not, but I thought I would point it out to those who might be interested. — Catherine\talk 17:22, 18 December 2005 (UTC)

Large non-encyclopedic addition reverted

If someone wants to check, whether something can be salvaged: [3] --Pjacobi 20:15, 20 December 2005 (UTC)

Looks like straightforward copyright violation, to me, in addition to being POV and potentially OR. I didn't take a thorough look at it. --Christopher Thomas 23:01, 20 December 2005 (UTC)
Missed the grant of premission to duplicate at the top. Looking more like OR if the poster is the author, though. --Christopher Thomas 23:03, 20 December 2005 (UTC)

POV flag

My objections to the current version are as follows:

  1. Most physicists believe that at extremely high energies, gravity and the other fundamental forces unify, which would allow gravity to be manipulated in ways that are not readily apparent now. Actually, while physicists generally agree that it must be possible to formulate a quantum theory of gravitation, some prominent mainstream physicists suspect that gravitation may not be unified with the other fundamental forces. And it is certainly not true that there is a general expectation that any quantum theory of gravitation or TOE will lead to manipulation of the gravitational field (other than by moving mass around, of course).
  2. Claims that the U. S. government has secretly achieved electrogravitic propulsion, the claims of Thomas Townsend Brown, and the notion of electrogravity itself are all regarded as cranky by mainstream physics. Such claims are strongly linked to Area 51 type conspiracy theories. This entire section should be rewritten to more accurately characterize these claims as highly cranky, and to point out that despite the similar sounding names, gravitoelectromagnetism is part of mainstream physics and completely different from crank claims involving alleged "electrogravity".
  3. NASA, Boeing, and BAE Systems have all funded: in fact, Boeing appears to have officially denied this, and it seems that the NASA experiment was short lived and has been defunded, and that BAE may not have been directly involved in Project Greenglow. Authors need to be much more cautious and not accept on face value news reports in trade publications or even major news outlets. In particular, some BBC news stories were factually inaccurate (see alleged Boeing involvement).
  4. Robert Distinti's claims are regarded as cranky (his site is listed an crankdot).
  5. While the current characterization of the preprint by F. S. Felber is acceptably NPOV, I have just looked at it and am confident that the alleged effect is a coordinate effect which has been misinterpreted by an author who is apparently inexperienced in this field (in time I hope to explain that in greater detail elsewhere).

I can fix the problems myself but I thought I'd give the original authors the chance. ---CH 22:42, 16 February 2006

Regarding force unification, at unification energies you would indeed have processes that produced (or consumed) gravitons. However, just as electroweak unification effects aren't terribly useful for manipulating the weak nuclear force under laboratory conditions, I don't expect that ToE-style unification will have practical applications. I added the paragraph about it during my original rewrite as part of a list of potential mechanisms for antigravity-type effects (practical and impractical, and hopefully flagged as such). The article has mutated considerably in the meantime. Re. whether or not unification occurs, the most popular theories being actively researched (string theory and membrane theory variants) tend to assume that it does, so I'd consider unification worth mentioning.
Regarding Felber's paper, I was wondering when this was going to start showing up in articles. He did a massive press release recently (which doesn't look so good when papers aren't published in reputable print journals yet). My main concern with his proposed effects is that they should have very strong impact on particle accelerator interactions (with gamma values of a thousand or more, particles should be deflected out of collision paths, if I'm reading things correctly).
Regarding an overhaul of the article, it could probably stand with another rewrite, but I'm not in a position to do it any time soon. My last one is linked from my user page, if you want a starting point that might be a little more organized than the current article; your call.--Christopher Thomas 04:44, 17 February 2006 (UTC)
Purely speculation, but unification could have some effects on gravity. If you look at the early universe, then the faster expansion than what can be explained with gravitational theory stands out like a sore thumb. The hunt for the higgs particle could be good materials for this topic. Agreed on the clean-up of the crack-pot materials. -MegaHasher 05:31, 17 February 2006 (UTC)

More Felber material

The following was added by 24.44.77.99 (talk · contribs), and I've moved it here:

In February 2006, Space.com news reported a proposal for Antigravity craft.

At minimum, this material should have gone into the "non-mainstream" section, and certainly doesn't deserve an entire subsection. Felber has posted many press releases, but he has yet to produce peer-reviewed publications in respected journals about this model (arxiv doesn't count), so calling it a mainstream-endorsed model is quite a stretch. How much of a mention this should get depends on how notable it is. Does anyone in the field know of Felber's previous work?--Christopher Thomas 08:38, 18 February 2006 (UTC)

He has one earlier eprint on the arXiv, which I haven't taken the time to read (way too much to do as it is, arghgh!), but the abstracts of both seem almost perversely worded to mischaracterize Felber's alleged achievements.
First, as you probably know, the ZPEnergy website is a freelunch crank site (just look at the other "news items"!). The website SPACE.com seems to be an unfiltered grab bag, mostly legitimate news items but also featuring many cranky items related to freelunch claims regarding topics like "tabletop cold fusion", "energy from the vacuum", etc.
From my glance at the preprint on the alleged effect, it seems that Felber actually wrote down (an approximation of?) the geodesic equations in some alleged coordinate system for the Kerr vacuum, and either numerically integrated these or found an (approximate?) solution analytically. Hard to tell for sure without attempting to recreate his reasoning, which I am not inclined to do on the basis of what I've seen so far, because the paper is badly written and the author appears to be so inexperienced in this field, which tends to make error tracking an agonizing process. It is also easy to see at a glance that Felber appears not to be aware of the very well-known ultraboosts, which anyone who knows the literature would regard as obviously relevant, or to have considered the possibility that he is examining a coordinate effect. Felber seems to suggest that a rapidly moving Kerr object will be preceeded by a force beam of gravitational repulsion, which is certainly an extraordinary claim. (See also Podkletnov's claims regarding alleged gravitional reflection force beams.) Felber's second eprint is mentioned by Mashhoon without any comments yay or nay. To find out what leaders think, one would probably have to know physicists like Mashhoon, Jantzen, 't Hooft, Aichelburg who have published on ultraboosts and GEM. I don't know them, but 't Hooft has not been shy in calling a crank a crank in the past.
Since WP is an encyclopedia, I think the best course for the nonce is to continue to remove these wildly overblown claims (no doubt there will be more) and to ask our Felber fan(s) to take it to the talk page. Until such time as Felber publishes in respectable journals like PRD, CQG, GRG rather than Gallilean Electrodynamics or other cranky "journals" and until other physicists begin to publish follow-up work in those journals, Felber's claims should be regarded as fringe and illucid at best (to adopt the terminology of Crankdot).
I dislike the possibility that someone wanting attention need only make a sufficient amount of noise to garner a WP biography, which they can then fight endlessly over to present their (presumably non-NPOV) view of their own achievements, but must concede that this seems to accord with the populist philsophy of WP. Some might argue that a crank bio would be a convenient place to try to collect these arguments, but of course it never works that way, since the crank fans will argue in each talk page mentioning the crank.
I guess I don't really have any truly good advice to offer, alas. Musing on this kind of problem is depressing because the conclusion seems inescapable that over the next five or ten years WP is doomed to experience the same kind of degradation that happened in once enjoyable discussion forums like sci.physics (waaaay back this was not infested by cranks and loons, but populated by physicists and bright physics students). That would be too bad, but the WP model (like the newsgroup model) seems to have a fatal flaw: it is too slow to react to an evolving "threat environment". The crankdot compendium only lists a fraction of the actual number of crank websites, but a glance at that site shows that the membership of WikiProject GTR is outnumbered by hundreds to one, which suggests that eventually users like myself will be driven out of the WP community, just as happened in the newsgroups. I'd love to go wild writing new high quality articles, but I've been spending so much time trying to curb cranky edits that I haven't been able to write much new material for months. I wish more Wikipedians recognized how sad that situation is, from the point of view of providing a high quality free on-line encyclopedia, which was the original and highly laudable stated goal of the Wikipedia.---CH 23:25, 18 February 2006 (UTC)
You should spend more time articulating your views in more appropriate fora, such as Category:Wikipedia editorial validation and more directly Wikipedia:Stable versions which is where these issues are being discussed. linas 07:45, 19 February 2006 (UTC)

Gyroscopes

Dont gyroscopes exhibit anti gravity effects? Like Eric Laithwaites spinning disc weighing less then when not rotating!--Light current 06:45, 2 March 2006 (UTC)

The short answer is "no". This is a favourite topic for cranks (though it's usually a spinning, _superconducting_ disc in the versions that have been in vogue lately). This effect has never been duplicated in a reputable lab. There was another (brief) highly-publicized attempt to try to duplicate one of the more vocal claims recently.
The long answer is that an extremely massive spinning object _does_ affect the paths of objects around it in ways not consistent with _newtonian_ gravity, due to general relativity effects, but the effect is extremely small. This is not something that will ever be tested with gyroscopes - it's being tested using Earth (see Gravity Probe B). Even with something as massive as a planet rotating, incredibly sensitive instruments were needed to check for the predicted effects. It's only really, _really_ noticeable around objects like neutron stars and spinning black holes. It also doesn't really produce an antigravity-type effect; instead, it (more or less) causes space near the rotating object to be dragged along with it (frame-dragging), which can end up accelerating nearby objects laterally, and also applying torque. There isn't any material related to this that's suitable for the antigravity article, and crank claims about spinning discs are already covered.--Christopher Thomas 08:34, 2 March 2006 (UTC)

Have you actually viewed the Eric Laithwaite videos [4] demonstarting gyroscopic effects on weight?--Light current 17:13, 2 March 2006 (UTC)

Did you actually listen to what he said in the lecture, and do you actually remember the first-year mechanics courses you presumably took as an electrical engineer? The magic word is "appear lighter than it is". What's actually happening is a clever parlour trick. The important thing to realize is that the situation with the gyro extended and nonrotating is very different from the situation with the gyro extended and rotating, as in the latter, the gyro has to remain horizontal. The fact that the gyroscope is forced to remain horizontal means that, despite its center of mass being farther away from the pivot on the balance, the balance receives equal torque from both the counterweight and the gyroscope (as a change in arm angle results in equal vertical displacement of both masses). As Prof. Laithwaite described, it acts as if the mass of the gyro is centered on the pivot at the end of its arm (this is the same reason why you can spin up a gyro and balance it off the edge of a table). In practice, it doesn't behave _exactly_ like this, because torque applied by gravity turns into horizontal precession, but it's close enough for a nifty demonstration of the type shown in the video. As the arm, despite appearances, is in balance when the gyro is spun up, you can fine-tune the balance to make it go in any direction you please when let go (up or down). --Christopher Thomas 20:37, 2 March 2006 (UTC)

So the young boy on the turntable chair holding a 56 lb spinning wheel on a 2 ft shaft at arms length was not experiencing any effetive weight reduction in the wheel?--Light current 23:42, 2 March 2006 (UTC)

No. He is expreiencing all kinds of forces and torques; but if you put the boy, the chair, the gyro and everything else on a big scale, the combined weight of the system would not change. Contemplating the weight that registers on a scale is even more interesting if you think about a weighing a juggler while they are juggling a few heavy objects. linas 00:21, 3 March 2006 (UTC)

I agree that the total weight does not change but the apparent wieght at some points in the system does!. I was just suggesting including this stuff in the article as another example of a crankish idea about anti gravity.--Light current 00:26, 3 March 2006 (UTC)

The "apparent" weight doesn't change either, in this scenario. The torque it applies, however, does, because torque does strange things to gyroscopes (strange if you're not familiar with describing angular momentum with vectors, at least). The boy felt a solid 56 lbs, pressing downwards due to gravity, but felt it at his end of the stick (as the effect of gravity on the gyro-on-a-stick, to the first order, was to cause the stick to rotate sideways, not down). No reduction of weight, only of where it looks like it's coming from, and then only for a while (the approximation holds only while the torque applied to the system produces a change in angular momentum much less than the angular momentum of the flywheel). Get a $10 gyro from a toy store and try it yourself; it's great fun, you can do nifty parlour tricks like this demonstration, and you'll learn a lot about how gyros behave. --Christopher Thomas 06:17, 3 March 2006 (UTC)

So the boy still has the full weight of the spinning disc acting at his wrists but in a different direction from down?--Light current 02:11, 4 March 2006 (UTC)