Reason for strange magnetic ball movement I was playing with a set of those neodymium magnet spheres and noticed a couple of strange behaviors (which I believe are related so I'm only positing a single question) and I was hoping to get an explanation for.
When I roll a single magnet in a straight line on a wooden table, it doesn't travel in a straight line, but 'wiggles', and changes velocity, on both planes, fairly significantly. 
When I roll two magnets into each other (if I get the angle right), they join, and spin quite rapidly and for much longer than expected. Video ~15s in
I'd suspect the earths magnetic field is applying this force / supplying the energy, can someone confirm this, and include an explanation?
 A: The spinning is just the same effect as for the ice skater spinning faster when he pulls his arms in. Here the distance of the mass around the center of motion is reduced, which leads to an increased angular momentum. Same goes for your balls. If you roll them such that they would miss another, but are within the range in which they can attract each other, they will spin end up in this situation.
If you roll them straight into another, they will not rotate.
A: I've randomly found a possible explanation of what is occurring for one of the effects I noticed. 
For the case of rapidly spinning magnet pair, it appears this is 'powered' by gravity via precession of the magnets. I can't find anything else to confirm / refute this though. Anyone care to weigh in?
http://amasci.com/amateur/beads.html - 'Mysterious Energy Source' heading 
A: I think you are correct, it does have something to do with earth’s gravitational field. I am still working on how it exactly happens, but a strong evidence that supports my theory, and that can be replicated by you is as follows.
Join two magnetic balls that you have, or you can use any other magnet no matter the shape, so now you have one ball magnet and another magnet of any shape, what you want to do is mark the pole opposite to the side where the magnets contact. Now do that for the other pole too. ( the marking are supposed to be on the ball magnet). Now suspend the ball magnet freely on any surface and open a compass on your mobile phone, you will notice that the poles of your ball magnet align exactly with the compass. Therefore this provides us with proof that the magnet is indeed affected by earth’s magnetic field.
So the force acting on the magnet is identified, the next challenge is to understand how the force is able to move the ball magnet in a particular pattern each time, because if you notice every time you roll it, it will follow a particular pattern of wiggles, first it swerves to the left and the zig zags until the motion dies. No matter how many times you roll it, it will turn left first and the first  left turn is the strongest in magnitude in terms of displacement.
I dont think it is affected by any screws under your table as you can roll it on pretty much any surface and it will still follow the same pattern described above.
I hope you reply to this as soon as possible, i too noticed this phenomenon quite recently and want to discuss it with someone
