Could Earnshaw be only thinking inside the box

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Discussion Overview

The discussion revolves around Earnshaw's Theorem and the possibility of achieving stable magnetic levitation using permanent magnets. Participants explore theoretical concepts, experimental approaches, and personal insights related to magnetic interactions and levitation techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant expresses skepticism about Earnshaw's Theorem, proposing a configuration of four magnets that could achieve stability by canceling each other's forces.
  • Another participant mentions that stable magnetic levitation is achievable with diamagnetic materials, suggesting an alternative approach to the problem.
  • Concerns are raised about the tendency of the proposed setup to slide off the magnetic field, which aligns with predictions made by Earnshaw's Theorem.
  • A participant suggests that angling the magnets outward might help centralize them, questioning if this could counteract the sliding issue.
  • There is a discussion about the potential role of an additional central magnet to anchor the configuration, though it is noted that the theorem implies some direction of slipping will always exist under its assumptions.
  • Links to commercial magnetic levitation devices are shared, indicating existing solutions in the market.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement. While some acknowledge the limitations imposed by Earnshaw's Theorem, others propose alternative configurations and challenge the theorem's applicability to their ideas. The discussion remains unresolved regarding the feasibility of achieving stable levitation with the proposed methods.

Contextual Notes

Participants note that the assumptions of Earnshaw's Theorem may not hold in all configurations, and the discussion includes various experimental setups that could potentially violate these assumptions. There is also mention of the need for specific conditions, such as the curvature of the magnetic field, which may affect the outcomes.

Mack7963
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Hello PF people
i just joined the forum after many many months of being driven insane concerning Earnshaw's Theorem, i myself am not a scientist or physicist so i am limited in the amount of knowledge that i have, but my curiosity won't let me accept what everyone else seems to be in agreement with.
As far as i can understand it is stated that a permanent magnet cannot achieve stable equilibrium, which is why they always attract, as i have discovered on many occasions, my own sense of logic tells me that this is due to each magnet having a single axis, so after thinking about this for a while, i had one of those archimedes moments, although i wasn't in the bath at the time, what if the the single axis became a shared axis, between two permanent magnet, let's say one magnet at point east and one at point west, joined via a rigid connection, my logic tells me that each magnet would cancel the other out, which as far as i can see would create a third state, stability, the problem i foresaw was that the magnets would try and flip the other way, using the north south axis, so using the same process and adding two more magnets to cancel out the potential north south flip, and connecting them with a rigid body would mean the magnets have no where to go, so all they can do is sit there above a surface made of permanent magnets, possibly using a halbach array for the surface, i honestly believe that with a four magnet rig connected to a cross shape, stable levitation of permanent magnets can be achieved. i have already built a platform form for the magnets to be mounted to, but sadly i built it to big, not taking into account that magnetic fields are curved, i did manage to hold the whole thing in one place but its tendency to slide off the field was the only issue, the usual flipping characteristic was not present, the next one i build will be a lot smaller so i can build a surface that it won't slide off. i would seriously love some feedback on this concept. i don't know if youtube links are allowed on here but i put a video on there of me doing this experiment, as i said at the beginning i am not a physicist so please don't be too harsh in your replies.
Thank you
Michael
 
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Trying to argue against math is usually a waste of time, so good luck with your experiment!

But stable magnetic levitation is possible using diamagnetic materials like water, or even frogs. All you need is a frog, and a VERY strong magnet ... http://www.ru.nl/hfml/research/levitation/diamagnetic/
 
Mack7963 said:
its tendency to slide off the field was the only issue
This is exactly the type of instability predicted by the theorem.
 
i get the arguing against math point, trouble is that won't satisfy my sense of logic until i actually see it not working, i believe the other term for this condition is stubbornness, thank you though for the good luck sentiment, i have seen the frog levitation experiment, all i need to do now is acquire a frog and a very very expensive 10 tesla magnetic coil, anyone have next weeks winning lottery numbers per chance?.
 
Dale
so if the sliding off the field is one of the issues, do you think that if the east west magnets where angled outwards then they would centralize themselves, again going back to each one canceling the other out, if one magnet is pushing against the other both with equal force, then the two magnets should stay in one place, as long as the curvature of the field is large enough, I'm also wondering if having a 5th magnet opposite to all the rest and central would not anchor the whole thing somehow.
 
Mack7963 said:
Dale
so if the sliding off the field is one of the issues, do you think that if the east west magnets where angled outwards then they would centralize themselves, again going back to each one canceling the other out, if one magnet is pushing against the other both with equal force, then the two magnets should stay in one place, as long as the curvature of the field is large enough, I'm also wondering if having a 5th magnet opposite to all the rest and central would not anchor the whole thing somehow.
The point of the theorem is that under the assumptions of the theorem there will always be some direction of slipping. All you can do is design things which violate the assumptions of the theorem.
 

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