9 replies to this topic

[ChurchSkiz]

So I saw this today:

Cool magnet shiznit

You guys are the smartest people I know, I can't find an explanation on how this works, only scientific papers I don't understand. Can someone break it down for the laypeople?

It seems like the magnetic field is both simultaneously attracting and repelling the object with the same force.

[0x3a]

Here's the explanation by the same guys who showed it:

[Uziel2101]

A couple years ago I was looking into this magnetic levitation stuff, I stumbled upon this video(below) that shows how it works and explains a fair amount. What I don't understand about your video which I saw from a couple other people is how "locking" works, being able to move the object in a position and have it "lock" to that position, that certain was pretty cool.

[Cornstalks]

Superconductors allow electricity to flow freely. But electricity and magnetism are kinda one force, hence the electromagnetic force. Because electricity can flow unrestricted in the superconductor, this creates a side effect in the magnetic field. Specifically, superconductors do not allow a magnetic field inside them. They block it. It's like a solid wall to a magnetic field. So now you place a superconductor by a magnit, and it's forced to interact with the magnetic field of that magnet. But superconductors will completely block that magnetic field from penetrating them. So it creates a "cushion" around the superconductor. The magnetic field can't pass through the superconductor, but it can "flow" around it, which it does. If you remember any of your classic physics laws, hopefully you'll remember that an object in motion will stay in motion, and an object at rest will stay at rest, unless some kind of external force is applied. Things are lazy. They won't move unless you make them move. If the superconductor moved through the magnetic field, it would have to "push" the magnetic field. But it's lazy. So it won't. If you have a strong enough magnetic field, this cushion will be stronger than gravity, so the superconductor will just sit in its place.

Magnets can be arranged in certain ways, creating magnetic fields that "flow" in particular directions. Now you put a superconductor in that magnetic field you've arranged and created with some magnets, and depending on the way the magnetic field flows, the superconductor will interact with this magnetic field. Mostly, the superconductor will try to do what it's already doing, whether it's just sitting there or moving in a particular motion. The arrangement of the magnetic field can be conducive to particular movements of the superconductor, such as spinning, moving in a line, or moving in a circle, depending on the magnetic field and what you do with the superconductor (how you position it, if you spin it, if you push it, etc.).

This stuff has been around for a long time, but it's still cool to watch.

[way2lazy2care]

Is there a reason this would be better than just magnet vs magnet levitation for most purposes? While awesome, I fail to see the real world benefit of it over using magnets on magnets if you have to keep the superconductors supercooled.

[Cornstalks]

Is there a reason this would be better than just magnet vs magnet levitation for most purposes? While awesome, I fail to see the real world benefit of it over using magnets on magnets if you have to keep the superconductors supercooled.

Not yet, really. That's why the holy grail is a superconductor that works at room temperature. One hasn't been discovered yet. If it were discovered though, it would change everything. Computers would run ultra fast and low powered, and you could create magnetic levitation stuff (which would be better than magnet vs magnet because magnets actively repel each other, so it's incredibly hard to balance while floating in the air; get off center just slightly and you'll be pushed completely off center) that would be incredibly stable.

[way2lazy2care]

Not yet, really. That's why the holy grail is a superconductor that works at room temperature. One hasn't been discovered yet. If it were discovered though, it would change everything. Computers would run ultra fast and low powered, and you could create magnetic levitation stuff (which would be better than magnet vs magnet because magnets actively repel each other, so it's incredibly hard to balance while floating in the air; get off center just slightly and you'll be pushed completely off center) that would be incredibly stable.

Ahhh. That makes sense.

[MJP]

As soon as I saw that, it made me think of this: http://www.youtube.com/watch?v=GF1KKAs-RmY&feature=player_detailpage#t=254s

[Gaiiden]

Yeaaaa... I didn't look into this till today but some people on my twitter feed were like "Yay where's my hover board?" and everyone was talking "quantum" not "magnetism" so I was kinda amped up about it but then when I saw it I was like... "awww really?".

Same old shizz, but as noted by Cornstalks a much better way of doing magnetic levitation IF we ever get a room-temp superconductor. Ok who am I kidding - when we get one. It has to be out there, somewhere.

But that still won't give me my Back to the Future hover board

[driftingSpaceMan]

which would be better than magnet vs magnet because magnets actively repel each other, so it's incredibly hard to balance while floating in the air; get off center just slightly and you'll be pushed completely off center) that would be incredibly stable.

With attraction based magnetic levitation, it's actually impossible to stabilize without active control (modulating the magnets). This is because as you slip a bit too close to one magnet, the field grows stronger in that direction, and weaker in the opposed direction with distance.

http://en.wikipedia....haw%27s_theorem

It's pretty cool.

Sounds pretty complicated, but Maglev already uses active modulation of the magnets with modern technology to give large tolerances to allow economical track building. So, what once sounded commercially implausible is really not a big deal today with modern electronics (it's not entirely trivial, but it's largely a solved problem).

Other types use induction in coils outside the train to generate repulsive forces (Which are stable, but that only works while the train is moving)- sometimes they use superconductors to create the magnetic fields, but they aren't using the super-conductor/diamagnetic systems shown in these demonstrations.

Room temperature superconductors would be great for more efficient electromagnets, and computers that could be clocked up to relativistic limits without needing much cooling. Not sure if they'll do much for transportation levitation though...

Same old shizz, but as noted by Cornstalks a much better way of doing magnetic levitation IF we ever get a room-temp superconductor. Ok who am I kidding - when we get one. It has to be out there, somewhere.

But that still won't give me my Back to the Future hover board

It's plausible that there aren't any materials in the universe that would provide super-conduction at room temperatures. We don't know if there are or not- it may actually not exist. As temperatures increase, we find fewer and fewer viable super conductors.

Of course, it just as well may turn out that there are some materials that will do it.

That said, it's not actually all that difficult or expensive to cool things down; what we need is more efficient and compact insulators to keep them cool without multiple feet of insulation. Aerogel is a promising direction, but even it is only capable of moderate insulation.

If we pursue insulation in the way we have pursued capacitance, we may be able to engineer materials to give us thousand of molecule wide gaps of empty space in a computer case. In that instance, a relatively basic array of heat pumps might be able to maintain super conductivity.

Or maybe the liquid nitrogen man will come every day like the milk man to drop off your daily coolant ;)


As for the hover board, I'm afraid you're stuck with good old fashioned jet engines as your best option.